Most Probable Number

The influence of wild fires on microbial community structure, soil organic matter, sulphur oxidising and nitrifying microbial populations in the floodplains of the Okavango Delta of Botswana was assessed. Microbial community structure was assessed by phospholipids ester-linked fatty acids (PLFA) quantification while microbial sulphur oxidisers were assessed by Most Probable Number (MPN). Community structure assessment showed that burning shifted the microbial community structure from single cellular bacteria being the dominant groups to filamentous fungi and actinomycetes being the most dominant groups. Generally burning increased the fungal component (18:2 ω6) matrix from 3.40 to 8.35 while the actinomycetes and sulphur reducing bacterial (10 Me 16:0) component also increased from 1.02 to 1.70 mostly in the floodplains. Generally, the organic matter content declined with burning. However, the influence of burning on soil pH was non conclusive. Soil microbial biomass carbon increased slightly after the fire. The number of heterotrophic and nitrite-oxidizing and sulphur reducing bacteria increased. Overall, these results indicate that burning significantly alters the microbial community structure as large above ground losses of nutrients during and after burning often results in low quantities of nutrients released into the soil. Figure 1. Map of the Okavango Delta showing mapped fire sites since 2000. Rectangular block indicates sampling site.

Soils of many potential soybean fields in Africa are characterized by low levels of biological nitrogen fixation (BNF) activities and often cannot support high soybean yields without addition of inorganic N fertilizers or external application of soybean rhizobia. The most probable number (MPN) technique was used to determine the bradyrhizobial populations that nodulate TGx soybean genotypes (a cross between nonpromiscuous North American soybean genotypes and promiscuous Asian soybean genotypes), cowpea or North American soybean cv. Clark IV, in soils from 65 sites in 9 African countries. The symbiotic effectiveness of isolates from these soils was compared to that of Bradyrhizobium japonicum strain USDA110. The bradyrhizobial population sizes ranged from 0 to 10 4 cells g À1 soil. Bradyrhizobium sp. (TGx) populations were detected in 72% and B. japonicum (Clark) in 37% of the soil samples. Bradyrhizobium sp. (TGx) populations were generally low, and significantly less than that of the cowpea bradyrhizobial populations in 57% of the samples. Population sizes of less than 10 cells g À1 soil were common as these were detected in at least 43% of the soil samples. B. japonicum (Clark) occurred in higher population densities in research sites compared to farmers' fields. Bradyrhizobium sp. (TGx) populations were highly correlated with biotic but not abiotic factors. The frequent incidence of low Bradyrhizobium sp. (TGx) populations is unlikely to support optimum BNF enough for high soybean yields while the presence of B. japonicum (Clark) in research fields has the potential to compromise the selection pressure anticipated from the indigenous Bradyrhizobium spp. (Vigna) populations. Bradyrhizobium isolates could be placed in four symbiotic phenotype groups based on their effectiveness on a TGx soybean genotype and the North American cultivar Clark IV. Symbiotic phenotype group II isolates were as effective as B. japonicum strain USDA110 on both soybean genotypes while isolates of group IV were effective on the TGx soybean genotype but not on the Clark IV. The group IV isolates represent a unique subgroup of indigenous bradyrhizobia that can sustain high soybean yields when available in sufficient population densities.

Abstract. Due to the fact that corrosion problems affecting the residual water treatment industry are varied and scarcely studied, this work presents an investigation of the corrosion behavior of important materials of engineering such as steel AISI-1018, AISI-304, and AISI-800 exposed to synthetic residual water under laboratory conditions. The electrochemical techniques used to asses the electrochemical behavior were linear polarization resistance (LPR), cyclic polarization curves (CPC) and electrochemical noise (ECN) techniques to determine corrosion rates, the susceptibility to localized corrosion and the most likely corrosion mechanism, respectively. In order to ascertain the amount of aerobic and anaerobic bacteria present on the steel surface, the Most Probable Number method (MPN) was employed. On the whole, the steels studied showed a better corrosion resistance in the following order: 800 > 304 > 1018. Also, the experimental results indicated that none of the steels demonstrated susceptibility to localized corrosion.

All the physical and biological parameters were determined. The temperature of water sample in studied area was between 26.4-28.5, lower than World Health Organisation (WHO) prescribed limit. The pH of the water samples in Northeast Bangalore is in range of 6.5-8.5, which was in accordance to WHO, Bureau for Indian Standard (BIS) and Central Pollution Control Board (CPCB). TDS values in water samples range from 200-820 mg/L. Nine samples showed higher TDS values and TSS values range from 20-400 mg/L. The samples S01, S04, S08, S14, S15, S19, and S20 contain high MPN Index above 50 and S02, S03, S05, S06, S07, S09, S10, S11, S12, S13, S16, S17, and S18 contain low MPN index below 50. BOD and COD values range from 1.2-5.2 mg/l and 8.8-42.1 mg/l respectively. All twenty samples showed higher DO values than the prescribed limit by WHO. But according to BIS and CPCB, S02, S05, were low than their required limit. S11, S15 and S17 were just at 6.0, rest were higher than their required limit. Seven bacterial strains were isolated from the twenty water samples i.e. Escherichia spp., Klebsiella spp., Shigella spp., Yersinia spp. Enterobacter spp., Vibrio spp., and Salmonella spp. The purification and disinfection is to control the bacterial contamination. Water samples from Northeast Bangalore investigated that moderately contaminated. The presence of bacteria in the water is the indication of poor quality of water. According to WHO, BIS and CPCB standards, the water can be used as drinking water with caution.

Increasing human population coupled with their daily activities has continued to impact on the quality of surface and underground water bodies. Hence, the need to assess the portability of some major sources of drinking water. In the study, the two major sources of drinking water (Hand dug wells and boreholes) within Amai Kingdom, one of the major growing communities in Ukwuani Local Government Area of Delta State, and currently hosting Novena University Campus, where analysed microbiologically to ascertain their portability. A total of 60 water samples were collected from the available boreholes and hand dug well sited within the five major quarters in Amai town, namely Umuekum, Umubu, Amai-Nge, Ishikaguma and Umuosele, and analysed for total heterotrophic microbial (bacterial and fungal) counts, coliforms and faecal coliforms using standard plate count and most probable number (MPN) techniques. The results where compared with WHO standard for drinking water sources. The mean total heterotrophic bacterial counts (THBC) were found to range from 8.0 x 10 1 – 6.4 x 10 3 cfu/ml for borehole water samples and 1.9 x 10 2 – 2.5 x 10 4 cfu/ml for well water samples. The total heterotrophic fungal counts (THFC) ranged from 0-2.0 x 10 2 cfu/ml and 0 – 6.0 x 10 2 cfu/ml respectively. Statistical analysis revealed that the THBCs were significantly higher (p<0.05) in well waters than in borehole water samples. Coliforms were present in all the water samples examined up to levels of 9-26 MPN/100ml, while a few borehole and entire well waters samples demonstrated positive results to faecal coliform test. The dominant bacterial genera encountered were sp. and Pseudomonas sp., while the fungal isolates were Penicillium sp. and Rhizopus sp. Comparing the findings with zero coliform count per 100 ml of water samples according to WHO standard for portable water, suggest that the microbial qualities of drinking waters from some borehole and majority of hand dug wells in Amai Kingdom are poor and possess threat to public health. Hence, simple water treatment method such as boiling, regular disinfection and cleaning of borehole storage vessels or tanks as well as general public education on proper disposal of sewage are recommended in the study area.

Abattoirs have to enumerate Escherichia coli on carcass surfaces as part of compulsory HACCP monitoring and they therefore need rapid and reliable methods. The objective of this study was to compare a conventional plating method with a faster, simpler method for detection and enumeration of E. coli in samples from naturally contaminated carcasses. The two methods were the conventional pour plate method of the Nordic Committee on Food Analysis; NMKL Method No. 125, and the enzymatic method of SimPlate Coliforms & E. coli. Materials were 588 cotton-cloth samples used for swabbing 100 cm 2 areas on four sites on cattle and lamb carcasses in three commercial abattoirs in Norway. E. coli was detected by at least one of the methods in 270 (46%) of the samples. Forty-five samples (8%) were positive only by SimPlate while 28 samples (5%) were positive only by NMKL125. Cohen's kappa value was 0.74 for detection/non-detection results, which showed a high level of agreement between the two methods. E. coli counts determined by the conventional NMKL125 method showed a high concordance correlation (ccc 0.80, slope 0.99) with most probable number (MPN) values obtained with SimPlate. SimPlate is a rapid and reliable method for detection and enumeration of E. coli and a suitable alternative method for use with swab samples from cattle and lamb carcasses.

Concern over the presence of fecal coliform in public drinking water supplies has been expressed in recent years in Pakistan since it has been regarded as pathogenic organism of prime importance in gastroenteritis. Two major drinking water distribution systems in the Cantt area of Rawalpindi district covering the Westridge and Tench areas was monitored over a 2-month period to determine the prevalence of fecal coliform and chlorine residual. The collected samples were examined for total chlorine, free chlorine residual, chloramines, total coliforms, fecal coliforms, and turbidity. The drinking water quality monitoring in the distribution network was performed by collecting samples from water source, overhead reservoir, and residential taps. In the Westridge area, total chlorine varied from the lowest value of 0.27 mg/L at Station # W-5 to the highest value of 0.42 mg/L at Station # W-2, total coliforms varied from 1.1 to 3.6 most probable number (MPN)/ 100 mL with presence of Escherichia coli in all samples, total dissolved solids (TDS) ranged from 199.5 to 205 mg/L, conductivity fluctuated between 399 and 411 μS/cm, and turbidity varied I. Hashmi (B) · S. Farooq · S. Qaiser

This study investigates the extra UV fluence needed to meet the International Maritime Organisation's ballast water discharge standards for the 10–50 μm size-class using the approved vital stain (VS) method compared to the Most Probable Number (MPN) method for organism viability assessment. Low-and medium pressure UV collimated beam treatments were applied to natural algae collected in temperate and tropical water environments and analysed using both methods. About 10 times higher UV fluence was required to meet discharge standards when using VS compared to MPN. Implementing a dark-hold period after UV treatments decreased algal viability. Length of dark-hold period to meet discharge standards decreased with increasing UV fluence. No significant differences between temperate and tropical samples were observed. The results showed that UV treated algae assessed using the VS method could meet discharge standards by increasing fluence and/or introducing a dark-hold period.

This study aimed to determine the occurrence of Vibrio parahaemolyticus in cockles (Anadara granosa) at a harvesting area and to detect the presence of virulent strains carrying the thermostable direct hemolysin (tdh) and TDH-related hemolysin genes (trh) using PCR. Of 100 samples, 62 were positive for the presence of V. parahaemolyticus with an MPN (most probable number) value greater than 3.0 (>1100 MPN per g). The PCR analysis revealed 2 samples to be positive for the tdh gene and 11 to be positive for the trh gene. Hence, these results demonstrate the presence of pathogenic V. parahaemolyticus in cockles harvested in the study area and reveal the potential risk of illness associated with their consumption.

Enumerations of nitrite-oxidizing bacteria in soil samples by a Most Probable Number technique, often showed relatively high cell numbers at a low nitrite concentration compared with the numbers of ammonium-oxidizing bacteria. It was hypothesized that the high numbers enumerated at low nitrite concentration would represent nongrowing or organotrophically growing cells of nitrite-oxidizing species. In this paper, the sensitivity of non-growing Nitrobacter species to high nitrite concentrations as well as to low pH was examined. Different Nitrobacter species were precultured at 0.5 mM nitrite. Non-growing cells differing in age were enumerated at different nitrite concentrations and pH values. The incubation

This paper describes a Bayesian technique for unsupervised classification of data and its computer implementation, AutoClass. Given real valued or discrete data, AutoClass determines the most probable number of classes present in the data, the most probable descriptions of those ...

The mycorrhizal status of several representative shrub species (Lavandula spp. and Thymus satureioides) in Moroccan semiarid ecosystems, was evaluated as well as their contribution to the mycorrhizal potential of the soil. Furthermore, the rhizosphere soils collected under these target species were tested for their influence on the growth of Cupressus atlantica, a tree species whose natural stands has declined in this area. Soil samples were collected from the rhizosphere of L. stoechas, L. dentata and of C. atlantica existing in the experimental area. Control samples were randomly collected from bare soil sites, away from plant influence.All the target species formed AM symbiosis and the extent of AM fungal colonization was not significantly different between plant species. No significant difference was detected between the total number of AM fungal spores of the bare soil and those recorded in the root zones of target species and C. atlantica. Three genera of AM fungi (Scutellospora, Glomus and Acaulospora) were present in the rhizospheres of the plant species and in the bare soil.The number of mycorrhizal propagules in soil originating from around the four target plant species was significantly higher than the one in the bare soil ( ). The most probable number (MPN) of mycorrhizal propagules per 100 g of dry soil ranged from 7.82 (bare soil) to 179.7 (L. dentata and C. atlantica) and 244.5 (L. stoechas and T. satureioides). As the total number of spores was not different for the soil of different origins, the increase of the mycorrhizal soil infectivity (MSI) mainly resulted from larger AM mycelial networks that constituted the main source of AM fungal inoculum. In addition, this MSI enhancement was linked with changes in the functioning of soil microbial communities. In a glasshouse experiment, the growth of C. atlantica seedlings was significantly higher in the C. atlantica and in the shrub species soils than in the bare soil. Although the AM inoculum potential is not sufficient to ensure the development of forest trees in Mediterranean ecosystems, the use of plant nurses such as T. satureioides or Lavandula spp. could be of great interest to restore a self-sustaining vegetation cover to act against desertification.

Temporal variations in the diatom benthic propagule (DBP) community and its role in the phytoplankton community in a monsoon-affected tropical estuary, Zuari estuary, Goa (India) is presented. The DBP from the sediments was enumerated using an extinction dilution method (Most Probable Number method), which allows estimation of resting stages through examination of germinated vegetative cells in culture. The DBP community was dominated by planktonic species belonging to the genera Skeletonema, Fragilariopsis, Thalassiosira and Chaetoceros. Benthic propagules (BP) of S. costatum and Fragilariopsis sp. were dominant throughout the year. Between these two species, only S. costatum showed a linear relationship between the BP and planktonic cells indicating that this species is particularly important in coupling of pelagic and benthic ecosystems. During the onset and restart of monsoon after an intermittent break, water column was stratified, with a low salinity layer arising from riverin...

Methanogenesis in thermophilic biogas reactors fed with different wastes is examined. The specific methanogenic activity with acetate or hydrogen as substrate reflected the organic loading of the specific reactor examined. Increasing the loading of thermophilic reactors stabilized the process as indicated by a lower concentration of volatile fatty acids in the effluent from the reactors. The specific methanogenic activity in a thermophilic pilot-plant biogas reactor fed with a mixture of cow and pig manure reflected the stability of the reactor. The numbers of methanogens counted by the most probable number (MPN) technique with acetate or hydrogen as substrate were further found to vary depending on the loading rate and the stability of the reactor. The numbers of methanogens counted with antibody probes in one of the reactor samples was 10 times lower for the hydrogen-utilizing methanogens compared to the counts using the MPN technique, indicating that other non-reacting methanogens were present. Methanogens that reacted with the probe against Methanobacterium thermoautotrophicum were the most numerous in this reactor. For the acetate-utilizing methanogens, the numbers counted with the antibody probes were more than a factor of 10 higher than the numbers found by MPN. The majority of acetate utilizing methanogens in the reactor were Methanosarcina spp. single cells, which is a difficult form of the organism to cultivate invitro. No reactions were observed with antibody probes raised against Methanothrix soehngenii or Methanothrix CALS-I in any of the thermophilic biogas reactors examined. Studies using 2-14C-labeled acetate showed that at high concentrations (more than approx. 1 mM) acetate was metabolized via the aceticlastic pathway, transforming the methyl-group of acetate into methane. When the concentration of acetate was less than approx. 1 raM, most of the acetate was oxidized via a two-step mechanism (syntrophic acetate oxidation) involving one organism oxidizing acetate into hydrogen and carbon dioxide and a hydrogen-utilizing methanogen forming the products of the first microorganism into methane. In thermophilic biogas reactors,, acetate oxidizing cultures occupied the niche of Methanothrix species, aceticlastic methanogens which dominate at low acetate concentrations in mesophilic systems. Normally, thermophilic biogas reactors are operated at temperatures from 52 to 560 C. Experiments using biogas reactors fed with cow manure showed that the same biogas yield found at 550 C could be obtained at 610 C after a long adaptation period. However, propionate degradation was inhibited by increasing the temperature.

A nested-PCR temporal temperature gradient gel electrophoresis (TTGE) approach was developed for the detection of bacteria belonging to phylogenetic cluster I of the genus Clostridium (the largest clostridial group, which represents 25% of the currently cultured clostridial species) in cheese suspected of late blowing. Primers were designed based on the 16S rRNA gene sequence, and the specificity was confirmed in PCRs performed with DNAs from cluster I and non-cluster I species as the templates. TTGE profiles of the PCR products, comprising the V5-V6 region of the 16S rRNA gene, allowed us to distinguish the majority of cluster I species. PCR-TTGE was applied to analyze commercial cheeses with defects. All cheeses gave a signal after nested PCR, and on the basis of band comigration with TTGE profiles of reference strains, all the bands could be assigned to a clostridial species. The direct identification of Clostridium spp. was confirmed by sequencing of excised bands. C. tyrobutyri...

Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers, cabbage, cucumbers, broccoli, strawberries, apples, and seven other types of produce. The numbers of fruits and vegetables was influenced by their availability at participating farms and varied from 11 strawberry samples to 108 tomato samples. Among the organic farms, eight were certified by accredited agencies and the rest reported the use of organic practices. All organic farms used aged or composted animal manure as fertilizer. The average coliform counts in both organic and conventional produce were 2.9 log most probable number per g. The percentages of E. coli-positive sam...

The impact of chromium on heterotrophic bacteria and photosynthetic microorganisms in three soils whose chromium contents ranged from 67 to 5490 mg Kg of dry soil-1 was investigated. Our results showed that a chronic high concentration of chromium in soil affected both oxygenic photosynthetic microorganisms and heterotrophic bacteria. Nitrogen-fixing cyanobacteria were not detected in the soil polluted with chromium using the Most Probable Number (MPN) test. Data obtained from enrichment cultures for nitrogen-fixing cyanobacteria showed that, in the soils with low chromium levels, Nostoc dominated and possessed numerous heterocysts. In the chromium polluted soil, cyanobacteria of the genus Nostoc were observed, but they were present in low number and rarely had heterocysts. Total colony-forming units (CFU) of heterotrophic bacteria ranged from 6.4×10 5 (contaminated soil 1) to 1.0×10 6 g soil-1 (uncontaminated soil B). A relationship was found between the number of Cr(VI)-tolerant bacteria and chromium levels in soil. Gram-positive bacteria were more metal tolerant than Gram-negative bacteria.

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) may influence soil microbial communities by altering the balance between resident populations. Our objective was to assess the effect of environmentally relevant levels (ERLs) of 2,4-D on microbial community function and on the population dynamics of 2,4-D degrading bacteria using a microcosm approach. The most probable number approach was used to enumerate 2,4-D-degrading soil bacteria. Carbon substrates utilization was tested with a microtiter-based oxygen sensor system to evaluate short-term functional shifts caused by herbicide treatment. Shifts in the community in response to potential toxicity of 2,4-D were assessed in the agricultural soil and a reference forest soil using the pollution-induced community-tolerance (PICT) approach. Results indicated that the agricultural soil had a stable 2,4-D degrading population able to use the herbicide as C and energy source, which increases immediately after an ERL dose of 2,4-D and remains high for about 1 month after exposure has ceased. An enhanced, dose-dependent response to 2,4-D as substrate was observed in the microtiter assay, while heterotrophic bacterial activity appeared mostly unchanged. The PICT assay showed higher tolerance to 2,4-D in the agricultural soil than in the unexposed forest soil. Our results suggest that agricultural use of 2,4-D at recommended level leads to selection for (1) a copiotrophic degrader population and (2) a persistently herbicide-tolerant, but functionally similar, microbial community.

A most probable number (MPN) method was adapted for enumeration of rumen fungi by adding the antibiotics penicillin and streptomycin to the medium to inhibit bacterial growth. The validity of the assay was verified using.a fungicide, cycloheximide, and by comparison to numbers determined in roll tubes. Concentrations of rumen fungi ranged from 1.5 x 10 3 to 1.5 × l0 6 per g of rumen contents. These concentrations were substantially higher than previously reported ranges. The utilization of both cellulose and soluble carbohydrates as substrates in a single medium allowed simultaneous estimation of total and cellulolytic fungal concentrations. A marked increase in fungal concentrations was observed in steers 1.5 h after feeding, with most of the increase (78%) occurring in the numbers of fungi associated with the solids fraction. Concentrations of tureen fungi in sheep decreased when concentrates were included in the animal's diet. Feeding frequency had little or no effect on the concentration of rumen fungi in steers.

Nitrate addition to oil field waters stops the biogenic formation of sulfide because the activities of nitrate -reducing bacteria ( NRB ) suppress the activities of sulfate -reducing bacteria ( SRB ). In general, there are two types of NRBthe heterotrophic NRB and the chemolithotrophic NRB. Within the latter group are the nitrate -reducing, sulfideoxidizing bacteria ( NR -SOB ). To date, no study has specifically addressed the roles of these different NRB in controlling sulfide concentrations in oil field produced waters. This study used different culture media to selectively enumerate heterotrophic NRB and NR -SOB by most probable number ( MPN ) methods. Produced waters from three sulfide -containing western Canadian oil fields were amended with nitrate as an electron acceptor, but no exogenous electron donor was added to the serum bottle microcosms. Changes in the chemical and microbiological characteristics of the produced waters were monitored during incubation at 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8C.

Phenanthrene-metabolizing soil microbial communities were characterized by examining mineralization of [14C]phenanthrene, by most-probable-number (MPN) counting, by 16S-23S spacer DNA analysis of the numerically dominant, culturable phenanthrene-degrading isolates, and by examining incorporation of [13C]phenanthrene-derived carbon into sterols and polar lipid fatty acids (PLFAs). An unpolluted agricultural soil, a roadside soil diffusely polluted with polycyclic aromatic hydrocarbons (PAHs), and two highly PAH-polluted soils from industrial sites were analyzed. Microbial phenanthrene degraders were not detected by MPN counting in the agricultural soil and the roadside soil. In the industrial soils, phenanthrene degraders constituted 0.04 and 3.6% of the total number of CFU. 16S-23S spacer DNA analysis followed by partial 16S DNA sequencing of representative isolates from one of the industrial soils showed that one-half of the isolates belonged to the genus Sphingomonas and the other...

The effect of the surfactants polyoxyethylene monostearate (Tween 60), polyoxyethylene monooleate (Tween 80), cetyl trimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS) on the estimation of bacterial density (sulfate-reducing bacteria [SRB] and general anaerobic bacteria [GAnB]) was examined in petroleum samples. Three different compositions of oil and water were selected to be representative of the real samples. The first one contained a high content of oil, the second one contained a medium content of oil, and the last one contained a low content of oil. The most probable number (MPN) was used to estimate the bacterial density. The results showed that the addition of surfactants did not improve the SRB quantification for the high or medium oil content in the petroleum samples. On other hand, Tween 60 and Tween 80 promoted a significant increase on the GAnB quantification at 0.01% or 0.03% m/v concentrations, respectively. CTAB increased SRB and GAnB estimation for the sample with a low oil content at 0.00005% and 0.0001% m/v, respectively.

Fecal coliform MPN CFU Bayesian analysis a b s t r a c t Most probable number (MPN) and colony-forming-unit (CFU) estimates of fecal coliform bacteria concentration are common measures of water quality in coastal shellfish harvesting and recreational waters. Estimating procedures for MPN and CFU have intrinsic variability and are subject to additional uncertainty arising from minor variations in experimental protocol.

A survey was designed to know the concentration of Naegleria fowleri in recreational areas in Hornos, Sonora, during a year. Samples were taken monthly at La Isleta and Las Palmas and the total amoeba counts were obtained by the most probable number method (MPN). The identification of N. fowleri was made by PCR. The maximum concentration of total thermophilic amoebae was 9175 MPN/L for La Isleta and 3477 MPN/L for Las Palmas. Thermophilic Naegleria were present mainly during summer and fall. October's concentrations were up to 201 MPN/L, at both places. The maximum concentrations of N. fowleri were 201 MPN/L and 18 MPN/L for La Isleta and Las Palmas respectively, and were isolated from August to October. The presence of N. fowleri in these particular natural bodies of water reinforces the need for adaptation of preventive measures to avoid cases of primary amoebic meningoencephalitis.

For much of the twentieth century, coliform bacteria and especially Escherichia coli have been used as indicators of possible post-processing contamination and the presence of E. coli as an indicator of fecal contamination in foods. In this study, 500 foods in 10 different groups, mainly dairy products, delicatessen products, salads, spices, cream cakes and fresh fruit and vegetable samples, were analyzed for the natural contamination of fecal coliforms and E. coli by the standard most probable number (MPN) method. The difference between weighted means of fecal coliforms and E. coli counts were only 0.246 log 10 MPN/g-ml (MPN/gram for solid samples, and MPN/milliliter for liquids). Enumeration results were also evaluated by Pearson's correlation coefficient (r), Cronbach's alpha (a) and determination coefficient (r 2 ) analysis. According to results, although 33 samples contained only non-E. coli fecal coliforms, the results of reliability analyses indicated that fecal coliform counts and E. coli counts may be used interchangeably (P<0.0001). It can be said that fecal coliform or, preferably E. coli analysis is sufficient for rapid routine determination of fecal contamination, at least for those food groups analyzed in this research.

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated sediment is an attractive remediation technique and its success depends on biodegradation kinetics, and the optimal condition for the PAH-degrading isolates; however, information on this aspect is still scarce. The effects of multi-factors on biodegradation of phenanthrene, a 3-ring model PAH, in contaminated sediment slurry by Sphingomonas sp. a bacterial strain isolated from surface mangrove sediment, were investigated using the orthogonal experimental design (form L16(45)). The most significant factors were salinity and inoculum size, while the effects of phenanthrene concentrations, nutrient addition and temperatures were insignificant. The optimal biodegradation condition in contaminated mangrove sediment slurry was 30 °C, 15 ppt salinity, a carbon/nitrogen ratio of 100:1 (the background ratio in sediment) and an inoculum size of 106 most probable number g−1 sediment. The phenanthrene biodegradation could be best described by the first order rate model, C = C0e−kt, where k (the rate constant) is equaled to 0.1185, under the optimal condition. The kinetic model was verified and its validity in predicting biodegradation by Sphingomonas sp. at various phenanthrene concentrations was proved by experimental data.

Spices can present high microbial counts and Clostridium perfringens, Bacillus cereus, Salmonella and Shigella, among others have been isolated from spices. C. perfringens is an important pathogen agent causing, among other diseases, enteritis in humans caused by C. perfringens ...

Five strains of sulfate-reducing bacteria were isolated from the highest positive dilutions of a most probable number (MPN) series supplemented with lactate and inoculated with sediments from the oligotrophic Lake Stechlin. The isolates were endospore-forming and were motile by means of laterally inserted flagella. They stained Gram-negative and contained b-type cytochromes. CO difference spectra indicated the presence of P582 as a sulfite reductase. Phylogenetic analyses of the 16S rDNA sequences revealed that the isolates were very closely affiliated with the genus Sporomusa. However, sulfate and amorphous Fe(OH) 3 , but not sulfite, elemental sulfur, MnO 2 , or nitrate were used as terminal electron acceptors. Homoacetogenic growth was found with H 2 /CO 2 gas mixture, formate, methanol, ethanol, and methoxylated aromatic compounds. The strains grew autotrophically with H 2 plus CO 2 in the presence or absence of sulfate. Formate, butyrate, several alcohols, organic acids, carbohydrates, some amino acids, choline, and betaine were also utilized as substrates. The growth yield with lactate and sulfate as substrate was 7.0 g dry mass/mol lactate and thus two times higher than in sulfate-free fermenting cultures. All isolates were able to grow in a temperature range of 4-37°C. Physiologically and by the presence of a Gram-negative cell wall, the new isolates resemble known Desulfosporosinus species. However, phylogenetically they are affiliated with the Gram-negative genus Sporomusa belonging to the Selenomonas subgroup of the Firmicutes. Therefore, the new isolates reveal a new phylogenetic lineage of sulfate-reducing bacteria. A new genus and species, Desulfosporomusa polytropa gen. nov., sp. nov. is proposed.

Three clinical isolates of Acanthamoeba (A. castellanii, A. polyphaga, and A. mauritaniensis) were used to evaluate the cysticidal activity of four different contact lens multi-purpose solutions (Complete Protec, ReNu MultiPlus, Solocare Aqua, and Opti-free Aldox). Enumeration of amoebic was carried out with the control and test samples at 0, 2, 4, 6, 8, 10, and 24 hours after being added to the solutions using the most probable number (MPN) technique. A contact lens solution which achieved a 3-log reduction of Acanthamoeba during the manufacturer&#39;s minimum recommended disinfection time (MMRDT) was considered an effective solution. The studied contact lens solutions demonstrated decreasing number of amoebic with increasing exposure times, but were not effective against Acanthamoeba cysts during the MMRDT. Solocare Aqua gave the greatest reduction in A. castellanii (0.70-log reduction) and A. mauritaniensis (0.33-log reduction) by 4 hours. Only Solocare Aqua caused a 3-log reduct...

A new mesophilic sulphate-reducing bacterium, designated strain DvO5 T (T ¼ type strain), was isolated from the outermost sulphate reduction-positive most-probable-number tube (10 À6 dilution) of an activated sludge sample, which had been oxygenated at 100% air saturation for 120 h. The motile, Gram-negative, curved 1 by 2-5 mm and non-spore-forming cells of strain DvO5 T existed singly or in chains. Strain DvO5 T grew optimally at 29 1C, pH 6.9 and 0.05% (w/v) NaCl in a medium containing lactate, sulphate and yeast extract. Sulphite, thiosulphate and elemental sulphur also served as electron acceptors whereas nitrate, nitrite or ferric iron were not reduced. Lactate, pyruvate, H 2 (with acetate as carbon source), ethanol and glycerol efficiently supported growth as electron donors. Pyruvate and malate were fermented. Strain DvO5 T reduced oxygen by oxidising endogenous polyglucose at rates ranging from 0.4 to 6.0 nmol O 2 /mg protein min depending on the oxygen concentration, the highest rates being observed at atmospheric oxygen saturation. The G+C content of the DNA was 57.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain DvO5 T was a member of the genus Desulfovibrio with D. magneticus (98.2% 16S rRNA gene sequence similarity) and D. burkinensis (97.5% 16S rRNA gene sequence similarity) being its closest relatives among validly described species. A similar phylogenetic affiliation was obtained by sequence analyses of the genes encoding the alpha and the beta subunit of dissimilatory sulphite reductase (dsrAB) as well as the alpha subunit of adenosine-5 0-phosphosulphate reductase (apsA) of strain DvO5 T. On the basis of genotypic and phenotypic characteristics, strain DvO5 T (DSM 16695 T , JCM 12613 T) is proposed as the type strain of a new species, Desulfovibrio aerotolerans sp. nov.

The present study was undertaken to examine the drinking water quality of Rawal Treatment Plant, Rawalpindi and its distribution network by collecting samples from eight different locations. The aim was to determine potential relationship between the presence of microorganisms and chlorine residual in the distribution network. Quantification of chlorine residual, turbidity, standard plate count (SPC), fecal and total coliforms by Most Probable Number (MPN) was performed. Three different forms of chlorine were measured at each sampling station such as free chlorine, residual chlorine, chloramines and total chlorine residual. A critical evaluation of data presented indicated that pH generally ranged from 7.02–7.30; turbidity varied from 0.34–2.79 NTU; conductivity fluctuated from 359–374 μS/cm; and TDS values were found to be ranging between 180–187 mg/l. Station # 7 was found to be most contaminated. The value of total chlorine was found to be 0.86 to1.7 mg/l at Station # 3 and 6, re...

Modern lifestyle markedly changed eating habits worldwide, with an increasing demand for ready-to-eat foods, such as minimally processed fruits and leafy greens. Packaging and storage conditions of those products may favor the growth of psychrotrophic bacteria, including the pathogen Listeria monocytogenes. In this work, minimally processed leafy vegetables samples (n ¼ 162) from retail market from Ribeirão Preto, São Paulo, Brazil, were tested for the presence or absence of Listeria spp. by the immunoassay Listeria Rapid Test, Oxoid. Two L. monocytogenes positive and six artificially contaminated samples of minimally processed leafy vegetables were evaluated by the Most Probable Number (MPN) with detection by classical culture method and also culture method combined with real-time PCR (RTi-PCR) for 16S rRNA genes of L. monocytogenes. Positive MPN enrichment tubes were analyzed by RTi-PCR with primers specific for L. monocytogenes using the commercial preparation ABSOLUTE Ô QPCR SYBR Ò Green Mix (ABgene, UK). Real-time PCR assay presented good exclusivity and inclusivity results and no statistical significant difference was found in comparison with the conventional culture method (p < 0.05). Moreover, RTi-PCR was fast and easy to perform, with MPN results obtained in ca. 48 h for RTi-PCR in comparison to 7 days for conventional method.

The population size of diazotrophic bacteria naturally associated with the maize rhizosphere can be affected by biotic and environmental factors. In this work we have evaluated the effect of two genotypes of maize, with and without nitrogen fertilization, on the population dynamics and distribution of diazotrophic bacteria associated with maize plants over different plant ontogenic stages. The study was carried out in a field experiment with and without nitrogen fertilization, using two maize cultivars (Santa Helena 8447 and Santa Rosa 3063) previously selected from 32 maize cultivars for the lowest and highest response to nitrogen fertilization, respectively. Microbiological and molecular approaches were used to characterize the diazotrophic bacterial population structure. Bacterial population was assessed by the most probable number using semi-solid N-free media, and by DNA isolation from soil and plant tissue followed by amplification of nifH gene fragments using nested PCR, and by RFLP analysis using the restriction endonucleases TaqI and HaeIII. The dynamics of the diazotrophic bacterial population were affected by the ontogenic stage of the maize plants, but not by the cultivar type. Roots were the preferred site of colonization, independent of cultivar type and growth stage. During the first stage of maize growth, addition of nitrogen fertilizer negatively affected the diazotrophic bacterial population.

New Zealand&#39;s freshwater ecosystems are subject to microbial contamination from a predominantly agricultural landscape. This study examines the spatial and temporal distribution of the human pathogen Campylobacter in the lower Taieri River, South Island (New Zealand). Enumeration of thermophilic Campylobacter from river samples was performed using a most probable number (MPN) method. Seasonal variation in Campylobacter levels was evident, with higher median levels detected in summer, when human exposure through recreational water use is maximal. Campylobacter levels varied significantly among the 10 sampling sites, increasing below a major tributary entering the river and then showing a downstream decrease. These changes probably resulted from inputs from adjacent farms and instream Campylobacter losses (settling, death). Two main peaks in the flux of Campylobacter were observed, one in winter and one in summer. A decrease in notified cases of campylobacteriosis in the human pop...

harvest are common practices to reduce their effect on disease and/or possible yield reduction. Sorption and desorption kinetics are essential components for mod-The presence of mulch residue on the soil surface eling the movement and retention of applied agricultural chemicals protects it from water and wind erosion and conserves in soils and the fraction of chemicals susceptible to runoff. In this study, soil water for crop production (Unger and Wiese, 1979). we investigated the retention characteristics of sugarcane (Saccharum spp. hybrid) mulch residue for atrazine (2-chloro-4-ethylamino-6-iso-Recycled crop residues can be a temporary storage mepropylamino-1,3,5-triazine) based on studies of sorption-desorption dium for herbicides, altering patterns of chemical diskinetics. A sorption kinetic batch method was used to quantify retenpersion in conservation tillage when compared with contion of the mulch residue for a wide range of atrazine concentrations ventional practices (Dao, 1991). The effect of surface and reaction times. Desorption was performed following 504 h of crop residues on interception, subsequent wash-off, and sorption using successive dilutions, followed by methanol extraction. movement of herbicides through soil are major concerns Atrazine retention by the mulch residue was well described using a associated with no-tillage practices. linear model where the partitioning coefficient (K d) increased with A number of studies quantified pesticide concentrareaction time from 10.40 to 23.4 cm 3 g Ϫ1 after 2 and 504 h, respectively. tions retained by crop residues. It is often assumed that Values for mulch residue K d were an order of magnitude higher than applied herbicides eventually would leach and be recovthose found for Commerce silt loam (fine-silty, mixed, superactive, ered by the soil. However, a previous year's crop resinonacid, thermic Fluvaquentic Endoaquepts) where the sugarcane crop was grown. A kinetic multireaction model was successful in describing dues may intercept chemical spray and thus reduce the sorption behavior with reaction time. The model was equally success-efficacy of soil-applied herbicide (Banks and Robinson, ful in describing observed hysteretic atrazine behavior during desorp-1982; Ghadiri et al., 1984; Crutchfield et al., 1985). In tion for all input concentrations. The model was concentration indelaboratory and field studies, Dao (1991) reported that pendent where one set of model parameters, which was derived from wheat straw exhibited a strong affinity for metribuzin all batch results, was valid for the entire atrazine concentration range. and its S-ethyl analog. The retention capacity was associ-Average atrazine recovery following six successive desorption steps ated with the lignin fraction of the wheat residues. Dao were 63.67 Ϯ 4.38% of the amount adsorbed. Moreover, a hysteresis (1995) reported that the addition of wheat straw to the coefficient based on the difference in the area between sorption and soil elevated organic C concentration in the near-surface desorption isotherms was capable of quantifying hysteresis of desorpzone of no-till soils, which resulted in two-to fivefold tion isotherms. increase in metribuzin retention. In a Michigan study, corn residues showed a sorption capacity for benzene, A recent shift of sugarcane harvesting technology ethylbenzene, and 1,2,3-trichlorobenzene that was 35 to from burning leaves to leaving leaves on the soil 60 times greater than that of the surface soil (Boyd et surface is raising several economic and environmental al., 1990). The sorption capabilities of corn residues concerns. The traditional whole-stalk harvest system is and soil organic matter for nonionic organic compounds where the whole stalks of sugarcane plants are piled, were nearly identical as indicated by the similarity of cut, burned, picked up, and transported to the mill. The their K oc values (K oc ϭ K d /OC). Here, K d represents the new system involves the use of a combine harvester that distribution coefficient for retention and OC the organic cuts the cane stalks into billets, which are directly loaded carbon fraction in the soil. They concluded that it maybe into wagons for transport to the mill. Extractor fans in unnecessary to distinguish the organic carbon in crop the combine harvester separate leaf material from bilresidue from humus carbon in soil when predicting nonlets. The plant residue falls to the soil surface. It has been ionic organic compounds sorption coefficients. In all reported that mulch produced from the leaf material and these investigations, the time-dependent nature of herplant residue can promote disease and lower yields in bicide retention by mulch residues on K d during sorption the subsequent ratoon crop (Richard, 1999). As a result, and desorption was not addressed. burning the leaves off the whole stalks before harvest or Atrazine is a triazine family herbicide used worldwide burning of the crop residue on the soil surface following since 1952 to control annual weeds in corn and sorghum, among other crops. Atrazine is a major herbicide that is used extensively in sugarcane production in Louisiana.

Composting of ®sh processing wastes and biosolids with wood by-products and yard trimmings was conducted during the summer of 1996 and winter of 1997 in NW Patagonia using: (i) static piles for ®sh oal and (ii) turning piles for biosolids. Fish oal was mixed with sawdust + wood shavings (FOC) at 3:1 ratio by weight and biosolids with wood shavings (BCw) and yard trimmings (BCt) at 1:1 ratio by volume. Samples were taken at six dates during the composting period and analyzed to determine the factors that predict compost maturity. Composting of biosolids was aected by the type of bulking agent during winter. Thermophilic temperatures P 55°C were sustained long enough to satisfy the USEPA requirements for processes to further reduce pathogens (PFRP) in FOC and BCt, and for processes to signi®cantly reduce pathogens (PSRP) in summer BCw, while in winter BCw temperatures were lower than those recommended for eective pathogen reduction. However, coliform fecal content in all BC treatments was less than 10 most probable number (MPN) g-1 dry sample at the end of the process. The ratio of water soluble carbon (WSC) to total nitrogen (TN) appeared to be a more adequate index to predict compost maturity than the ratio of total organic carbon to nitrogen.

A range of commercially available vegetables (n = 306) that are consumed in the minimally processed state in Malaysia was examined for the presence of Listeria spp. and Listeria monocytogenes to provide information on the occurrence of such organisms in these vegetables. Analysis was carried out using the most probable number-polymerase chain reaction (MPN-PCR) method. It was found that Listeria spp. and L. monocytogenes could be detected in 33.3% and 22.5% of the vegetables respectively. L. monocytogenes was more frequently detected in Vigna unguiculata (Japanese parsley) at 31.3% and Oenanther stolonifera (yardlong bean) at 27.2%.

Rhizobia were isolated from root nodules of three tree legumes inoculated with dilution series of two tropical soils. The diversity of the isolates obtained from different soil dilutions was assessed by PCR-RFLP analysis of the internally transcribed spacer (ITS) region between the 16S and 23S rRNA genes. In both soils there was a strong effect of dilution on the genetic diversity of the populations with apparent diversity decreasing with increasing dilution.

Enhancement of soil nitrogen (N) cycling by grazing has been observed in many grassland ecosystems. However, whether grazing affects the activity only of the key microbial functional groups driving soil N dynamics or also affects the size (cell number) and/or composition of these groups remains largely unknown. We studied the enzyme activity, size, and composition of five soil microbial communities (total microbial and total bacterial communities, and three functional groups driving N dynamics: nitrifiers, denitrifiers, and free N 2 fixers) in grassland sites experiencing contrasting sheep grazing regimes (one light grazing [LG] site and one intensive grazing [IG] site) at two topographical locations. Enzyme activity was determined by potential carbon mineralization, nitrification, denitrification, and N 2 fixation assays. The size of each community (except N 2 fixers) was measured by the most-probable-number technique. The composition of the total soil microbial community was characterized by phospholipid fatty acid analysis (PLFA), and the genetic structure of the total bacterial community was assessed by ribosomal intergenic spacer analysis. The genetic structures of the ammonia-oxidizing, nitrate-reducing, and N 2fixing communities were characterized by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) or by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) targeting group-specific genes. Greater enzyme activities, particularly for nitrification, were observed in IG than in LG sites at both topographical locations. The numbers of heterotrophs, nitrifiers, and denitrifiers were higher in IG than in LG sites at both topographical locations. The amplitude of changes in community size was higher than that of community enzyme activity. Phospholipid and nucleic acid analyses showed that the composition/structure of all the communities, except nitrate reducers, differed between IG and LG sites at both locations. For each community, changes in activity were correlated with changes in the occurrence of a few individual PLFAs or DNA fragments. Our results thus indicate that grazing enhances the activity of soil microbial communities but also concurrently induces changes in the size and composition/structure of these communities on the sites studied. Although the generality of our conclusions should be tested in other systems, these results are of major importance for predicting the effects of future disturbances or changed grazing regimes on the functioning of grazed ecosystems.

Ice cream produced by three large-scale and three small-scale manufacturers were studied to determine the microbial load or colony forming units per gram (cfu/g) using the standard aerobic plate count. Analyses for the most probable number/gram (MPN/g) of total coliforms and fecal coliforms, presence of coagulase positive Staphylococcus and Salmonella were also done in order to determine if the samples

A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor was assayed aiming to verify its performance in degrading benzene, toluene, ethylbenzene and xylene (BTEX). A 138 ml HAIB reactor filled with polyurethane foam matrices containing immobilized anaerobic biomass was initially fed with synthetic substrate containing protein, carbohydrates and lipids. Thereafter, BTEX degradation was evaluated in the presence of the co-solvents ethanol and lineal alkylbenzene sulphonate (LAS), in two sequential experiments. The inlet BTEX concentration ranged from 1.3 to 27.0 mg/L of each compound and outlet concentrations were lower than 0.1 mg BTEX/L for both the experiments with ethanol and LAS. An active enriched microbial consortium was observed in the reactor, containing BTEX-degraders, and also acetogenic, acetotrophic and hydrogenotrophic microorganisms. The results from the most probable number (MPN) tests indicated a decrease in the number of methanogenic archae, while ...

Population development of key groups of bacteria involved in municipal refuse conversion to methane was measured from the time of initial incubation through the onset of methane production. Hemicellulolytic bacteria, cellulolytic bacteria, hydrogen-producing acetogens, and acetate- and H(2)-plus-CO(2)-utilizing methanogens were enumerated by the most-probable-number technique with media containing oat spelt xylan, ball-milled cellulose, butyrate, acetate, and H(2) plus CO(2), respectively. Refuse decomposition was monitored in multiple replicate laboratory-scale sanitary landfills. A laboratory-scale landfill was dismantled weekly for microbial and chemical analysis. Leachate was neutralized and recycled to ensure methanogenesis. The methane concentration of the sampled containers increased to 64% by day 69, at which time the maximum methane production rate, 929 liters of CH(4) per dry kg-year, was measured. Population increases of 2, 4, 5, 5, and 6 orders of magnitude were measured...

Vibrio parahaemolyticus is found in aquatic environments and is the leading cause of gastroenteritis due to seafood consumption worldwide. We evaluated a quantitative real-time PCR (Q-PCR) assay with hydrolysis probes, to determine whether this method could be used for the efficient counting of total, tdh and trhpositive V. parahaemolyticus in shrimps. We assessed the specificity of this assay, using 62 strains from 12 non target bacterial species of the Vibrio, Photobacterium, Shewanella and Aeromonas genera. Only V. parahaemolyticus with the appropriate target gene generated a fluorescent signal. We assessed the robustness of this assay, by analyzing spiked shrimps by Q-PCR and traditional culture methods, using most probable number (MPN)-PCR. After a 6 h enrichment period, the assay successfully detected total and pathogenic V. parahaemolyticus in shrimps samples spiked with less than 5 V. parahaemolyticus cells/g of shrimp. The Q-PCR results obtained were compared with those obtained by most probable number (MPN)-PCR format. An excellent correlation between the two methods was observed in all cases (R 2 N 0.9742). The application of this Q-PCR assay to 85 natural shrimp samples also resulted in the successful quantification of V. parahaemolyticus in this matrix, and the counts obtained were correlated with those obtained by (MPN)-PCR (P = 0.2598). Thus, this rapid and sensitive Q-PCR can be used to quantify V. parahaemolyticus in natural shrimp samples. This assay could be proposed, in response to the demands of the European Commission, as a tool for testing for the presence of vibrios in crustaceans, making it possible to legislate in this domain.

Microorganisms are an integral part of the biogeochemical processes in wetlands, yet microbial communities in sediments within constructed wetlands receiving acid mine drainage (AMD) are only poorly understood. The purpose of this study was to characterize the microbial diversity and abundance in a wetland receiving AMD using fluorescence in situ hybridization (FISH) analysis. Seasonal samples of oxic surface sediments, comprised of Fe(III) precipitates, were collected from two treatment cells of the constructed wetland system. The pH of the bulk samples ranged between pH 2.1 and 3.9. Viable counts of acidophilic Fe and S oxidizers and heterotrophs were determined with a most probable number (MPN) method. The MPN counts were only a fraction of the corresponding FISH counts. The sediment samples contained microorganisms in the Bacteria (including the subgroups of acidophilic Fe-and S-oxidizing bacteria and Acidiphilium spp.) and Eukarya domains. Archaea were present in the sediment surface samples at ,0.01% of the total microbial community. The most numerous bacterial species in this wetland system was Acidithiobacillus ferrooxidans, comprising up to 37% of the bacterial population. Acidithiobacillus thiooxidans was also abundant. Heterotrophs in the Acidiphilium genus totaled 20% of the bacterial population. Leptospirillum ferrooxidans was below the level of detection in the bacterial community. The results from the FISH technique from this field study are consistent with results from other experiments involving enumeration by most probable number, dot-blot hybridization, and denaturing gradient gel electrophoresis analyses and with the geochemistry of the site.

Wastewater from tanneries contains high concentrations of organic matter, chromium, nitrogen, and sulfur compounds. In this study, an artificial wetland is is used as the tertiary treatment in a tannery in León Gto., México. It consists of three subplots with an area of about 450 ...

This study was designed to investigate the potability of sachet water sold in Nnewi metropolis. Ninety (90) sachet water samples obtained from 6 different manufacturers (J to O) were analyzed microbiologically by the multiple tube technique. The mean most probable number (MPN)/100 ml of faecal coliforms in the samples were as follows; J =7.1, K =1.1, L=1.3, M=1.5, N=4.3 and O=5.7. The mean coliform counts at 37°C/100 ml in the samples were: J=2, K=1.0, L=0.3, M=0.3, N=1.3 and O=3.0. Samples L and M were observed to belong to the excellent category while samples J, K, N and O were in the satisfactory category. The mean count at 44°C/100 ml inthe water samples were: J=3.3, K=0, L=0, M=0, N=1.3 and O=0.9 thus samples K, L and M belong to excellent category (A) while samples O, N and J belong to the satisfactory category (B). The prevalence of other bacteria isolated from the analyzed samples was Esch. coli (36%), Streptococcus faecalis (19.4%), Klebsiella pneumoniae (19.4%) and Staphyloccocus aureus (25%). In conclusion, some of the water samples were found to be in excellent condition and others in satisfactory conditions, efforts however should be made by the manufacturers to still improve.

An evaluation of the microbiological water quality from the Algarve region was conducted. The parameters were determined using two semi-automated most probable number methods, Colilert and Enterolert (IDEXX Laboratories, Inc.). These methods were developed for the enumeration of coliforms and enterococci, respectively. Since they are less time consuming in what refers to sample manipulation, incubation and results reading, they represent an extremely important advantage when we are concerned about water quality monitoring. Natural water samples were analysed for microbiological parameters, pH and salinity. The objective of this work was to set up that the Colilert and Enterolert methods are suitable to monitor the microbiological quality of natural recreational waters.