Papers by P K Dhakephalkar
South Asian journal of experimental biology, Mar 11, 2016
Managing solid waste, especially fecal matter is a growing challenge worldwide. According to WHO,... more Managing solid waste, especially fecal matter is a growing challenge worldwide. According to WHO, 2.6 billion people lack access to adequate sanitation. Only 26-50 % of Indian population has access to proper sanitation facilities. The problem of untreated human excrement or night soil is not only restricted to urban development’s or defense camps; even religious gatherings are affected by the lack of sanitation. Religious event such as annual pilgrimage of Pandharpur is one such glaring example. Such defecated matter, if left untreated will cause environmental pollution and serious health hazards, which is evident from the offensive mal odor and associated pathogenic load. In the present investigation, we have described a bioprocess that uses a defined formulation comprising of microorganisms and harmless chemicals. The said bioprocess results in accelerated degradation of organic matter that reduces the environment polluting organic load associated with fecal excreta. The bioprocess also inhibits the health compromising microbial pathogens that are inhibited by various metabolites produced by Lactobacillus component of microbial formulation. The bioprocess also results in the generation of methane gas subsequent to organic matter deg-radation and can be used as a source of fuel. The process also generates or-ganic slurry that can be used as fertilizer/ organic manure. Thus, the present investigation has described a process for treatment of fecal excreta in closed or open environment to inhibit pathogens, mal odor, pollution associated with untreated fecal excreta.
Colloids and Surfaces B: Biointerfaces, 2019
Biosurfactant producing hypethermophilic microorganisms are essentially required for Microbial En... more Biosurfactant producing hypethermophilic microorganisms are essentially required for Microbial Enhanced Oil Recovery (MEOR) from high temperature oil reservoirs (above 90°C). In the present study, biosurfactant producing Clostridium sp. N-4, optimally growing at 96°C was isolated from a high temperature oil reservoir. Effect of pH, temperature and salinity on production and activity of N-4 biosurfactant was investigated. Biosurfactant produced by N-4 was partially purified by acid precipitation, characterized using FT-IR spectroscopy; and evaluated for its ability to enhance oil recovery in sand pack studies. The strain N-4 produced biosurfactant over a wide range of pH (5.0-9.0) and salinity (0-13%) at high temperature (80-100°C) and optimally at pH 7, 96°C and 4% salinity. N-4 biosurfactant was active at 37-101°C; pH, 5-10 and salinity of 0-12 % (w/v). N-4 biosurfactant, characterized as glycoprotein reduced the surface tension of water by 32 ± 0.4 mN/m at critical micelle concentration of 100 μg/ml. N-4 biosurfactant mobilized 17.15% of residual oil saturation in sand pack studies. Similarly, the strain N-4 also recovered 36.92% of the residual oil in sand pack studies under the conditions mimicking the environment of depleted high temperature oil reservoir. Thus, the biosurfactant producing Clostridium sp. N-4 was identified as a suitable agent for enhanced oil recovery from high temperature oil reservoirs.
3 Biotech, 2017
Extractive butanol fermentation with non-ionic surfactant, a recently explored area, has shown pr... more Extractive butanol fermentation with non-ionic surfactant, a recently explored area, has shown promising results with several advantages but is relatively less investigated. This work reports the extractive fermentation with selected non-ionic surfactants (L62 and L62D) to enhance butanol production using a high-butanol producing strain (Clostridium beijerinckii MCMB 581). Biocompatibility studies with both the surfactants showed growth. Higher concentrations of surfactant ([5%) affected the cell count. 15.3 g L-1 of butanol and 21 g L-1 of total solvents were obtained with 3% (v/v) L62 which was respectively, 43% (w/w) and 55% (w/w), higher than control. It was found that surfactant addition at 9th h doubled the productivity (from 0.13 to 0.31 g L-1 h-1 and 0.17 to 0.39 g L-1 h-1 , respectively for butanol and total solvent). Butanol productivity obtained was 2-3 times higher than similar studies on extractive fermentation with non-ionic surfactants. Interestingly, mixing did not improve butanol production.
Genome announcements, Jan 12, 2015
The first draft genome of Halostagnicola sp. A56, isolated from the Andaman Islands is reported h... more The first draft genome of Halostagnicola sp. A56, isolated from the Andaman Islands is reported here. The A56 genome comprises 3,178,490 bp in 26 contigs with a G+C content of 60.8%. The genome annotation revealed that A56 could have potential applications for the production of polyhydroxyalkanoate or bioplastics.
Journal of environmental biology / Academy of Environmental Biology, India, 2009
Microorganisms in Environmental Management, 2011
ABSTRACT Halophiles are salt-loving organisms inhabiting environments with the capacity to balanc... more ABSTRACT Halophiles are salt-loving organisms inhabiting environments with the capacity to balance the osmotic pressure of the environment and resist the denatur-ing effects of salts such as salt induced co-aggregation of proteins. They are diverse group of organisms that thrive extreme saline environments. Depending upon their requirement for salt concentration, they are classifi ed as halotolerant, moderately halophile and extreme halophile. Halophiles have been routinely isolated from marine salterns and hypersaline lakes with 3.5–4.5 M (20–30 g% NaCl). Extremely halophilic archaea were characterized from saline environment in different parts of Turkey, "Solar de Atacama", Chile, two salt lakes in Xin-Jiang, China. The family Halobacteriaceae contains 96 species classifi ed in 27 genera. Mechanism of salt tolerance and halophily has been studied to some extent. The organisms devise protection against high concentration of Na + . They are reported to produce certain biochemicals like glycine betaine which acts as compatible solute for high concentration of NaCl. The cell envelope and outer membrane shows modifi cation in composition based on ionic strength of outer environment. Extremophiles are being looked upon as a treasure of novel biomolecules, bio-materials and metabolites. Haloarchaeal enzymes are unusually stable and adapted to extreme environments thus are suitable candidates for applications in industrial processes that are performed under harsh conditions of high ionic strength. Bacteriorhodopsin, a photochemical produced by halophiles has a potential in conversion of light energy into chemical energy and electricity. Halophiles have wide range of biotechnological potential in industry e.g. biosurfactant production,biopolymers in oil recovery, proteases and amylases in detergent industry, poly-beta hydroxyalkanoate as biodegradable plastic, exopolysaccharide and bioremediation of contaminated hypersaline brines etc.
International Journal of Hydrogen Energy, 2010
A mesophilic high hydrogen producing strain DMHC-10 was isolated from a lab scale anaerobic react... more A mesophilic high hydrogen producing strain DMHC-10 was isolated from a lab scale anaerobic reactor being operated on distillery wastewater for hydrogen production. DMHC-10 was identified as Clostridium sp. on the basis of 16S rRNA gene sequencing. Various medium components (carbon and nitrogen sources) and environmental factors (initial pH, temperature of incubation) were optimized for hydrogen production by Clostridium sp. DMHC-10. The strain, in late exponential growth phase, showed maximum hydrogen production (3.35 mol-H 2 mol À1 glucose utilized) at 37 C, pH 5.0 in a medium supplemented with organic nitrogen source. Butyric acid to acetic acid ratio was ca. 2.3. Hydrogen production declined when organic nitrogen was replaced with inorganic nitrogen.
Chemosphere, 2009
The removal of AOX from bleach plant effluent of pulp and paper industry was studied using upflow... more The removal of AOX from bleach plant effluent of pulp and paper industry was studied using upflow anaerobic filter. In this paper biodegradation of AOX at different concentrations and effect of electron donors like acetate and glucose thereon in an upflow anaerobic filter at 20 d HRT is described. Results showed significant improvement in AOX degradation when electron donors such as acetate and glucose were supplemented to the influent. AOX degradation was 88% at 28 mg AOX L(-1) and 28% at 42 mg AOX L(-1). The percent degradation efficiency was enhanced to 90.7, 90.2, and 93.0 at 28 mg AOX L(-1) when the influent was supplemented with glucose, acetate and both glucose and acetate, respectively. Similarly, the efficiency was 57, 56.6 and 79.6 at 42 mg AOX L(-1) when the influent was supplemented with glucose, acetate and both glucose and acetate, respectively. The GC-MS analysis data indicated that supplementation of the influent with electron donor increased the biodegradability of number of chlorinated organic compounds.
A chromate-resistant strain of Pseudomonas mendocina MCM B-180 capable of reducing hexavalent chr... more A chromate-resistant strain of Pseudomonas mendocina MCM B-180 capable of reducing hexavalent chromium was found to harbour a single plasmid. Incubation o f the strain at 42°C for 24 h caused loss of chromate resistance as well as the plasmid, pARII80. Transformation of E. coli DH5ct with purified pARII80 plasmid DNA resulted in simultaneous acquisition of resistance to chromate and the appearance of plasmid in the transformants. Most importantly, the plasmid transfer was found to confer chromate reduction ability on to the E. coli transformants. Introduction: Many bacteria belonging to genera Pseudomonas, Aeromonas, Enterobacter, Escherichia, Bacillus, Streptomyces etc. can reduce Cr 6+ to Cr 3+ (Cervantes and Silver, 1992). The phenomenon has attracted considerable interest owing to its potential use in the bioremediation of chromate-containing industrial waste waters. Recently, a microbiological method for the removal of hexavalent chromium from chromate-bearing cooling tower eff...
Genome announcements, Jan 8, 2014
The thermophilic Geobacillus sp. strain FW23 was isolated from the Mehsana oil wells in Gujrat, I... more The thermophilic Geobacillus sp. strain FW23 was isolated from the Mehsana oil wells in Gujrat, India, during a screening for oil-degrading bacteria. Here, we report the draft genome sequence of Geobacillus sp. FW23, which may help reveal the genomic differences between this strain and the earlier reported species of the genus Geobacillus.
American Journal of Infection Control, 2011
We report for the first time 2 cases of multidrug-resistant Burkholderia cenocepacia J2315 isolat... more We report for the first time 2 cases of multidrug-resistant Burkholderia cenocepacia J2315 isolated from blood samples of patients without cystic fibrosis from a pediatric unit in a hospital in India. The first patient presented with community-acquired bacteremia, and the second patient was immunocompromised and developed hospital-acquired infection approximately 17 days after admission. The isolates from both patients were multidrug-resistant and strong biofilm producers. Surveillance cultures identified the secondary sources of the infections, but not the primary sources.
Letters in Applied Microbiology, 2001
To investigate the genetics of dimethoate degradation in Pseudomonas aeruginosa MCMB-427. Pseudom... more To investigate the genetics of dimethoate degradation in Pseudomonas aeruginosa MCMB-427. Pseudomonas aeruginosa MCMB-427 demonstrated the ability to degrade dimethoate, a synthetic organophosphate insecticide. Total DNA preparation of MCMB-427 revealed the presence of a 6.6 kbp plasmid (designated as pDMD427). Escherichia coli NovaBlue transformed with plasmid pDMD427 subsequently acquired the ability to degrade dimethoate. Curing of the plasmid by plumbagin or ethidium bromide resulted in the loss of ability of MCMB-427 to degrade dimethoate. Plasmid pDMD427 was stable in MCMB-427 over 20 passages without selection. Genes encoding resistance to norfloxacin and cobalt were also located on plasmid pDMD427. The ability of Ps. aeruginosa MCMB-427 to degrade dimethoate is plasmid-mediated and transferable to other strains. As far as is known, this is the first report of plasmid-mediated dimethoate biodegradation. This study contributes significantly towards an understanding of the genetics of bacterial dimethoate degradation.
International Biodeterioration & Biodegradation, 2007
Atrazine is one of the most environmentally prevalent s-triazine-ring herbicides. The widespread ... more Atrazine is one of the most environmentally prevalent s-triazine-ring herbicides. The widespread use of atrazine and its toxicity necessitates search for remediation technology. As atrazine is still used in India as a major herbicide, exploration of atrazine-degrading ...
International Biodeterioration & Biodegradation, 2008
Inception of microbiology in leather industry was with reference to tanning processes where major... more Inception of microbiology in leather industry was with reference to tanning processes where major concern was finished product bacteriology. Present investigation aims to study the bacteriology of unprocessed raw material, buffalo hide in particular using culture based and culture independent approach. Denaturing gradient gel electrophoresis (DGGE) analysis of the stored hide at different time intervals was done to study temporal
Biotechnology Letters, 2002
Pseudomonas mendocina isolated from soil degraded an insecticide, Monocrotophos (MCP), by 67% and... more Pseudomonas mendocina isolated from soil degraded an insecticide, Monocrotophos (MCP), by 67% and harbored a 7.4 kb plasmid, designated as pMCP424. On the basis of curing and transformation experiments, MCP degradation by Pseudomonas mendocinawas plasmid-borne and transferable to other bacteria.
Bioresource Technology, 2007
Bacillus cereus MCM B-326, isolated from buffalo hide, produced an extracellular protease. Maximu... more Bacillus cereus MCM B-326, isolated from buffalo hide, produced an extracellular protease. Maximum protease production occurred (126.87+/-1.32 U ml(-1)) in starch soybean meal medium of pH 9.0, at 30 degrees C, under shake culture condition, with 2.8 x 10(8) cells ml(-1) as initial inoculum density, at 36 h. Ammonium sulphate precipitate of the enzyme was stable over a temperature range of 25-65 degrees C and pH 6-12, with maximum activity at 55 degrees C and pH 9.0. The enzyme required Ca(2+) ions for its production but not for activity and/or stability. The partially purified enzyme exhibited multiple proteases of molecular weight 45 kDa and 36 kDa. The enzyme could be effectively used to remove hair from buffalo hide indicating its potential in leather processing industry.
Biotechnology Letters, 1996
A microbiological process using Pseudomonas mendocina was developed for the removal of Cr(VI) fro... more A microbiological process using Pseudomonas mendocina was developed for the removal of Cr(VI) from cooling tower effluent. The process, when carried out in a 20 liter continuous stirred tank reactor removed 25–100 mg chromate/l in 4.5–8 h with >99.9% efficiency in the presence of sugarcane molasses as nutrient. The process could sustain wide variations in pH (6.5–9.5), temperature (25°C–40°C) and was unaffected by commonly used biocides.
Advances in Water Resources, 1996
Biotechnology Letters, 1998
Pseudomonas mendocina when added in soil microcosms could immobilize 100 μg (2 mM) chromate/g soi... more Pseudomonas mendocina when added in soil microcosms could immobilize 100 μg (2 mM) chromate/g soil in 8 h by converting it into trivalent form. The chromate-contaminated soils, after microbiological treatment, supported growth of wheat seedlings without exerting any toxic effects. The method is potentially useful in the bioremediation of chromate-contaminated sites. © Rapid Science Ltd. 1998
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Papers by P K Dhakephalkar