International Journal of Chemical and Environmental Sciences
Milkfish were sampled during premonsoon (2015) from the Hooghly River mouth Eco-region (HRME) and... more Milkfish were sampled during premonsoon (2015) from the Hooghly River mouth Eco-region (HRME) and Saptamukhi River/Creek mouth Eco-region (SRME) on the Northeast of Bay of Bengal. Metal accumulation and its impact on the antioxidant systems of different tissues of the fish were studied. Study showed Zn > Cu > Pb > Fe > Mn > Cd > Ni in the gills, muscles, and liver. Metal concentration in the liver and gills was found to be quite high compared to the muscle. Active responses were recorded in cases of lipid peroxidase, superoxide dismutase, catalase, glutathione peroxidase in gill, liver and muscle. Reduced glutathione and glutathione-S-transferase activities could be attributed to metal induced oxidative stress. Alteration in the antioxidant enzymes, glutathione system and induction of lipid peroxidation underlined the impact of metals contaminants in the fish indicated to the stress experienced by a heavily consumed piscine species such as milkfish.
The study was governed by the objective of investigating the antimicrobial effects of mangrove le... more The study was governed by the objective of investigating the antimicrobial effects of mangrove leaf extracts. The fresh and dried leaf extracts from Avicennia marina (Forssk.) Vierh., Avicennia officinalis L., Aegiceras corniculatum (L.) Blanco, Aegialitis rotundifolia Roxb., Acanthus ilicifolius L, Lumnitzera racemosa Willd., Excoecaria agallocha L. and Sonneratia apetala Buch-Ham. were found to have inhibitory effects on the milk spoilage microflora obtained from curd sample. Methanol and Acetone were used as extraction solvents and in comparison, extracts by acetone were observed to suppress the microbial growth to lesser extents. Leaf extracts of A. marina, A. officinalis L. racemosa and A. rotundifolia were able to exert relatively greater inhibitory effect on the milk spoilage microbial broth than others, although all the species expressed some degree of suppression. Interestingly A. rotundifolia, S. apetala, L. racemosa and E. agallocha demonstrated greater efficiency in form...
Advances in Intelligent Systems and Computing, 2018
Northeastern Region (NER) of India commonly experiences the occurrence of rigorous convective squ... more Northeastern Region (NER) of India commonly experiences the occurrence of rigorous convective squalls, commonly known as Thunderstorms (TS) or Nor’westers through the months of March to May. This study utilizes satellite images of Kalpana-1 satellite in Thermal Infrared (TIR) and Water Vapor (WV) channels to identify TS genesis, frequency, and track over the NER. The results obtained have been compared with Indian Meteorological Department (IMD) reports to check the accuracy of satellite image interpretations. 81 TS were detected over NER of India with 38 in the month of April and 43 in the month of May. The duration of TS follows an exponential distribution with maximum TS having lifetime of an hour or less and a few having lifetime of about 8–9 h. The TS occurred almost during any time domain of a day with maximum number of them occurring between 16 and 20 UTC. Most of the systems were formed and dissipated over the NER, while some systems were formed over the northwestern parts of Bihar, Jharkhand, and West Bengal and moved toward the NER under the influence of the Nor’westers collecting moisture, maturing, and dissipating over the NER. The dominant wind was from the northwest during the season. The precipitation from these TS accounts for 20–25% of annual rainfall and is very important for the agrarian economy of this region. The interpreted TS was found to be lesser (67%) than the number of events reported by IMD reports primarily because of the limitations in spatial resolution of the sensor.
This study aims to explore the variations in spatio-temporal characteristics of water quality fac... more This study aims to explore the variations in spatio-temporal characteristics of water quality factors of three estuaries in the western portion of the Indian Sundarbans. Reliable retrieval of near surface concentrations of parameters such as Chlorophyll-a, SST & TSM in various aquatic ecosystems with broad ranges of trophic needs has always remained a complex issue. In this study the application of C2RCC processor has been tested for its accuracy across different bio optical regimes in inland & coastal waters. Satellite images for the same period were also collected and analysed using the C2RCC processing sequence to retrieve values of factors like the depth of water, surface reflectance, water temperature, inherent optical properties (IOPs), chlorophyll-a, salinity and total suspended matter (TSM) using the SNAP software. During the 2017-2020 season, in situ sampling from specific locations and laboratory water quality analysis were carried out. The OLCI retrieved results were then...
The first author reports an error in the original version of this article. In the Figure 2 some o... more The first author reports an error in the original version of this article. In the Figure 2 some of the names of the mangroves have been incorrectly assigned to their respective pictures.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The book is aimed to serve as a repository of data generated during the tenure of my doctoral stu... more The book is aimed to serve as a repository of data generated during the tenure of my doctoral study and comprises the very significant experimental data procured from studies on one of the globally important well mixed estuaries in the vicinity of the Indian Sundarban and should be adequate enough in intriguing researchers aspiring to work on the same or relevant ecological aspects of planktonic diatoms. The thetical book ought to serve as a valuable reference to those who wish to study the ecological intricacies of the mangrove dominated, yet anthropogenically perturbed deltaic ecosystems of the northern coastal Bay of Bengal. The true success of the present venture lies in its eventual servitude to aspiring researchers and scholars in offering them a template to construct their hypotheses upon.
Abstract Nitrogen fixation and methane production in surface sediments of a long bioturbated beac... more Abstract Nitrogen fixation and methane production in surface sediments of a long bioturbated beach at the northeast coast of Bay of Bengal were quantified in vitro through gas chromatography. The beach was selected because it serves as a primary tourist destination and no prior data of it existed. The beach was segmented in littoral zones. Microbial assay was performed for all the sediment samples of the littoral subsection. The influence of the presence and absence of bioturbation on nitrogen fixation and methane production was investigated. One-way ANOVA revealed the statistical significance of the datasets through the rejection of null hypothesis.
Mangrove soil is considered as a rich source of organic carbon and provides a suitable habitat fo... more Mangrove soil is considered as a rich source of organic carbon and provides a suitable habitat for a large spectrum of microbes, particularly anaerobic microbes, owing to its anoxic nature. In particular, sulfate-reducing bacteria, along with methanogenic archaebacteria, play a pivotal role in the anaerobic remineralization of organic carbon (Dar, Kleerebezem, Stams, Kuenen, & Muyzer, 2008). Excessive organic carbon fluxes from litter fall and nutrients from river runoff have been reported to cause severe oxygen depletion in mangrove soil (Bosire, 2005). Hoehler and Alperin (2014) demonstrated that approximately 20%-39% of the annual global methane (CH 4) budget is contributed by wetlands, including mangrove ecosystems. The interaction and balance between populations of methanogenic archaebacteria and methanotrophic bacteria play a decisive role in the net fluxes of CH 4 from mangrove ecosystems (Conrad, 1996). Methanotrophs, which are CH 4-oxidizing bacteria, present at the aerobic interface of the anoxic soil substratum can substantially reduce benthic CH 4 emission (Oswald et al., 2015). The populations of both methanogenic and methanotrophic bacteria primarily depend on various
Abstract The behavior of dissolved Ca and Mg during mixing of sea and river waters had been studi... more Abstract The behavior of dissolved Ca and Mg during mixing of sea and river waters had been studied through a survey in the wastewater fed River Vidyadhari in the Sundarbans estuarine complex, India. The percentage variation for Ca was 79.9% during low tide and 95% during high tide with respect to chlorinity (10−3) and the same for Mg was 80% during low tide and 94.6% during high tide. The percentage addition and removal (PA & PR) was calculated with the help of the Theoretical Dilution Line (TDL) concept. A significant negative correlation between PA and PR of both Ca and Mg with chlorinity (10−3) was also observed. On the basis of the insignificant percentage variation (
Corrigendum to "The role of arsenic resistant Bacillus aryabhattai MCC3374 in promotion of rice s... more Corrigendum to "The role of arsenic resistant Bacillus aryabhattai MCC3374 in promotion of rice seedlings growth and alleviation of arsenic phytotoxicity" [Chemosphere 211 (2018) 407e419]
Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses incl... more Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses including heat and drought by dynamic climate changes. To alleviate these stresses, we investigated two bacterial stains, H26-2 and H30-3 in two cultivars ('Ryeokkwang' and 'Buram-3-ho') of Chinese cabbage in plastic pots in a greenhouse. We evaluated effects of bacterial strains on plant growth-promotion and mitigation of heat and drought stresses; the role of exopolysaccharides as one of bacterial determinants on alleviating stresses; biocontrol activity against soft rot caused by Pectobacterium carotovorum subsp. carotovorum PCC21. Strains H26-2 and H30-3 significantly increased fresh weights compared to a MgSO 4 solution; reduced leaf wilting and promoted recovery after re-watering under heat and drought stresses. Chinese cabbages treated with H26-2 and H30-3 increased leaf abscisic acid (ABA) content and reduced stomatal opening after stresses treatments, in addition, these strains stably colonized and maintained their populations in rhizosphere during heat and drought stresses. As well as tested bacterial cells, exopolysaccharides (EPS) of H30-3 could be one of bacterial determinants for alleviation of tested stresses in Chinese cabbages, however, the effects were different to cultivars of Chinese cabbages. In addition to bacterial activity to abiotic stresses, H30-3 could suppress incidence (%) of soft rot in 'Buram-3-ho'. The tested strains were identified as Bacillus aryabhattai H26-2 and B. siamensis H30-3 based on 16S rRNA gene sequence analysis. Taken together, H26-2 and H30-3 could be candidates for both plant growth promotion and mitigation of heat and drought stresses in Chinese cabbage.
Vertical occurrence of soil urease activity along with ammonia content from three distinct region... more Vertical occurrence of soil urease activity along with ammonia content from three distinct regions viz. Deep forest region (No tidal action and wave attack occurs as it is furthest from river shore and it contains maximum content of organic carbon and minimum soil salinity and silicate concentration. In this zone plenty of pneumatophores, below ground root and dense vegetation are found), Rooted region (It is situated in between Deep forest region and Un-rooted region. This region contains only pneumatophores but it is devoid of long roots and vegetations. It faces wave attack and tidal action less than that of Un-rooted region) and Un-rooted region (It is closest to river shore and faces maximum wave attack and tidal action; it contains minimum organic carbon but maximum soil salinity and silicate concentration. This zone is totally devoid of any roots, pneumatophores and vegetations) of Sundarban mangrove forest ecosystem, India revealed an interesting explanation. Soil urease activity showed a decreasing pattern with increase in depth from the deep forest region of the Sundarban forest ecosystem. Soil urease activity was found to be more sensitive to soil temperature and pH rather than soil salinity. This ensured that soil urease along with the microbes present in the Sundarban forest ecosystem are more tolerant to fluctuation in salinity than that of temperature. Soil ammonia concentration was found to be directly governed by the soil urease activity [The regression equation is Ammonia in soil = −1.64 + 0.0402 Urease Activity (R-Sq = 62.9%, P < 0.001, n = 41)].
A cellulase producing bacterium (E3 strain) was isolated from fecal matter of elephant and identi... more A cellulase producing bacterium (E3 strain) was isolated from fecal matter of elephant and identified as Bacillus sp. using 16S rDNA sequenced based molecular phylogenetic approach. While studying the effect of substrates like Carboxymethyl cellulose (CMC), avicel, starch, maltose, sucrose, glucose, fructose, galactose and lactose on cellulase production, it was found that CMC was best carbon source induced cellulase production followed by lactose in this bacterial strain. A positive synergistic effect of lactose with CMC was also observed with enhancement of 5-6 times in cellulase production. The optimum cellulase production was recorded with 1% CMC and 1% lactose when added individually in the Omeliansky's medium. The results showed that addition lactose with CMC greatly enhances the production and activity of various cellulase enzymes. The optimal fermentation conditions for the biosynthesis of cellulase by this strain were found to be temperature: 37˚C, pH 7.0. The nitrogen source NH 4 Cl at 0.15% was optimum for cellulase production by this bacterium.
Mangrove provides a unique ecological niche to different microbes which play various roles in nut... more Mangrove provides a unique ecological niche to different microbes which play various roles in nutrient recycling as well as various environmental activities. The highly productive and diverse microbial community living in mangrove ecosystems continuously transforms dead vegetation and recycle nitrogen, phosphorus, sulphur and other nutrients that can later be used by the plants. Mangrove ecosystems are rich in organic matter, and however, in general, they are nutrient-deficient ecosystems, especially of nitrogen and phosphorus. The present study investigated depth wise variation of nitrifying bacteria, nitrogen fixing bacteria, total bacterial population along with nitrate-nitrogen, nitrite-nitrogen and other physicochemical parameters of soil during pre-monsoon, monsoon and post-monsoon periods at three different sampling stations of mangrove sediments viz. deep forest region, rooted region and un-rooted region. The microbial population was also found maximum in the deep forest sediment relative to the other two sites. Populations of cultureable microbes were found maximum in surface soil and decreased with increase in depth in Sundarban mangrove environment. A decreasing trend of total microbial load, nitrifying and nitrogen fixing bacteria with increase in depth were recorded throughout the year. Present study revealed the relationship among depth integrated variations of physicochemical components (viz. soil temperature, pH, salinity, nitrite-nitrogen and nitrate-nitrogen concentration) and total microbial load, nitrifying and nitrogen fixing bacteria microbial populations.
Journal of Environmental Studies and Sciences, 2011
Abstract Human activities accelerate the input of plant nutrients sourced from agriculture, indus... more Abstract Human activities accelerate the input of plant nutrients sourced from agriculture, industrial waste, and sewage in the Hooghly River at the land ocean boundary of Indian Sunderban mangrove (21° 32′22° 40′ N and 88° 05′89° E). This study reports ...
Sundarban Mangrove forest is highly productive marine ecosystem where halophilic microbes activel... more Sundarban Mangrove forest is highly productive marine ecosystem where halophilic microbes actively participate in bio-mineralization and biotransformation of minerals. The population of aerobic halophilic microbes was studied to determine their distribution with the availability of different physicochemical parameters with increasing depth of this forest sediment. The present study revealed that microbes present in the top soil region were less tolerant to fluctuation in salinity than the middle and bottom segment. Microbes isolated from bottom segment showed higher growth rate in anaerobic condition. A decreasing trend of total microbial population and organic carbon content of soil were found with increase in depth. In contrary a reverse profile was found for salinity. A significant stratification was found to exist among microbial population and the salty nature of the soil of Sundarban Mangrove forest.
The mature root nodules of Phaseolus mungo (L.), a leguminous pulse, contain higher amount of ind... more The mature root nodules of Phaseolus mungo (L.), a leguminous pulse, contain higher amount of indole acetic acid (IAA) than non-nodulated roots. The tryptophan pool present in the mature nodule and young roots might serve as a precursor for the IAA production. Presence of IAA metabolising enzymes-IAA oxidase and peroxidaseindicate the metabolism of IAA in the nodules and roots. In culture, the symbiont, isolated from the nodules, produced a high amount of IAA, when tryptophan was supplied in the medium as a precursor. The symbiont preferred L-isomer over the DLor D-isomer of tryptophan for IAA production.The important physiological implication of the IAA production in the legume-Rhizobium symbiosis is discussed.
Ongoing climate change and anthropogenic activities are introducing stressors that affect the str... more Ongoing climate change and anthropogenic activities are introducing stressors that affect the structure and function of coastal ecosystems. This paper focuses on the fluvial fluxes and estuarine transport of nutrients from a tropical river (Mahanadi River) in Northeastern India and compares select nutrient and water quality parameters between 1983 and 2008. This estuary acts as a perennial source of CO 2 with a net annual flux to the atmosphere of about 135 tons. The non-conservative fluxes showed a net annual removal of 650 and 140 tons of phosphorus and nitrogen from the water column, respectively. Negative biogeochemical feedbacks that decreased the availability of N and P in 2008 relative to 1983 levels indicate major changes in biogeochemical responses towards fluvial fluxes of nutrient.
International Journal of Chemical and Environmental Sciences
Milkfish were sampled during premonsoon (2015) from the Hooghly River mouth Eco-region (HRME) and... more Milkfish were sampled during premonsoon (2015) from the Hooghly River mouth Eco-region (HRME) and Saptamukhi River/Creek mouth Eco-region (SRME) on the Northeast of Bay of Bengal. Metal accumulation and its impact on the antioxidant systems of different tissues of the fish were studied. Study showed Zn > Cu > Pb > Fe > Mn > Cd > Ni in the gills, muscles, and liver. Metal concentration in the liver and gills was found to be quite high compared to the muscle. Active responses were recorded in cases of lipid peroxidase, superoxide dismutase, catalase, glutathione peroxidase in gill, liver and muscle. Reduced glutathione and glutathione-S-transferase activities could be attributed to metal induced oxidative stress. Alteration in the antioxidant enzymes, glutathione system and induction of lipid peroxidation underlined the impact of metals contaminants in the fish indicated to the stress experienced by a heavily consumed piscine species such as milkfish.
The study was governed by the objective of investigating the antimicrobial effects of mangrove le... more The study was governed by the objective of investigating the antimicrobial effects of mangrove leaf extracts. The fresh and dried leaf extracts from Avicennia marina (Forssk.) Vierh., Avicennia officinalis L., Aegiceras corniculatum (L.) Blanco, Aegialitis rotundifolia Roxb., Acanthus ilicifolius L, Lumnitzera racemosa Willd., Excoecaria agallocha L. and Sonneratia apetala Buch-Ham. were found to have inhibitory effects on the milk spoilage microflora obtained from curd sample. Methanol and Acetone were used as extraction solvents and in comparison, extracts by acetone were observed to suppress the microbial growth to lesser extents. Leaf extracts of A. marina, A. officinalis L. racemosa and A. rotundifolia were able to exert relatively greater inhibitory effect on the milk spoilage microbial broth than others, although all the species expressed some degree of suppression. Interestingly A. rotundifolia, S. apetala, L. racemosa and E. agallocha demonstrated greater efficiency in form...
Advances in Intelligent Systems and Computing, 2018
Northeastern Region (NER) of India commonly experiences the occurrence of rigorous convective squ... more Northeastern Region (NER) of India commonly experiences the occurrence of rigorous convective squalls, commonly known as Thunderstorms (TS) or Nor’westers through the months of March to May. This study utilizes satellite images of Kalpana-1 satellite in Thermal Infrared (TIR) and Water Vapor (WV) channels to identify TS genesis, frequency, and track over the NER. The results obtained have been compared with Indian Meteorological Department (IMD) reports to check the accuracy of satellite image interpretations. 81 TS were detected over NER of India with 38 in the month of April and 43 in the month of May. The duration of TS follows an exponential distribution with maximum TS having lifetime of an hour or less and a few having lifetime of about 8–9 h. The TS occurred almost during any time domain of a day with maximum number of them occurring between 16 and 20 UTC. Most of the systems were formed and dissipated over the NER, while some systems were formed over the northwestern parts of Bihar, Jharkhand, and West Bengal and moved toward the NER under the influence of the Nor’westers collecting moisture, maturing, and dissipating over the NER. The dominant wind was from the northwest during the season. The precipitation from these TS accounts for 20–25% of annual rainfall and is very important for the agrarian economy of this region. The interpreted TS was found to be lesser (67%) than the number of events reported by IMD reports primarily because of the limitations in spatial resolution of the sensor.
This study aims to explore the variations in spatio-temporal characteristics of water quality fac... more This study aims to explore the variations in spatio-temporal characteristics of water quality factors of three estuaries in the western portion of the Indian Sundarbans. Reliable retrieval of near surface concentrations of parameters such as Chlorophyll-a, SST & TSM in various aquatic ecosystems with broad ranges of trophic needs has always remained a complex issue. In this study the application of C2RCC processor has been tested for its accuracy across different bio optical regimes in inland & coastal waters. Satellite images for the same period were also collected and analysed using the C2RCC processing sequence to retrieve values of factors like the depth of water, surface reflectance, water temperature, inherent optical properties (IOPs), chlorophyll-a, salinity and total suspended matter (TSM) using the SNAP software. During the 2017-2020 season, in situ sampling from specific locations and laboratory water quality analysis were carried out. The OLCI retrieved results were then...
The first author reports an error in the original version of this article. In the Figure 2 some o... more The first author reports an error in the original version of this article. In the Figure 2 some of the names of the mangroves have been incorrectly assigned to their respective pictures.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
The book is aimed to serve as a repository of data generated during the tenure of my doctoral stu... more The book is aimed to serve as a repository of data generated during the tenure of my doctoral study and comprises the very significant experimental data procured from studies on one of the globally important well mixed estuaries in the vicinity of the Indian Sundarban and should be adequate enough in intriguing researchers aspiring to work on the same or relevant ecological aspects of planktonic diatoms. The thetical book ought to serve as a valuable reference to those who wish to study the ecological intricacies of the mangrove dominated, yet anthropogenically perturbed deltaic ecosystems of the northern coastal Bay of Bengal. The true success of the present venture lies in its eventual servitude to aspiring researchers and scholars in offering them a template to construct their hypotheses upon.
Abstract Nitrogen fixation and methane production in surface sediments of a long bioturbated beac... more Abstract Nitrogen fixation and methane production in surface sediments of a long bioturbated beach at the northeast coast of Bay of Bengal were quantified in vitro through gas chromatography. The beach was selected because it serves as a primary tourist destination and no prior data of it existed. The beach was segmented in littoral zones. Microbial assay was performed for all the sediment samples of the littoral subsection. The influence of the presence and absence of bioturbation on nitrogen fixation and methane production was investigated. One-way ANOVA revealed the statistical significance of the datasets through the rejection of null hypothesis.
Mangrove soil is considered as a rich source of organic carbon and provides a suitable habitat fo... more Mangrove soil is considered as a rich source of organic carbon and provides a suitable habitat for a large spectrum of microbes, particularly anaerobic microbes, owing to its anoxic nature. In particular, sulfate-reducing bacteria, along with methanogenic archaebacteria, play a pivotal role in the anaerobic remineralization of organic carbon (Dar, Kleerebezem, Stams, Kuenen, & Muyzer, 2008). Excessive organic carbon fluxes from litter fall and nutrients from river runoff have been reported to cause severe oxygen depletion in mangrove soil (Bosire, 2005). Hoehler and Alperin (2014) demonstrated that approximately 20%-39% of the annual global methane (CH 4) budget is contributed by wetlands, including mangrove ecosystems. The interaction and balance between populations of methanogenic archaebacteria and methanotrophic bacteria play a decisive role in the net fluxes of CH 4 from mangrove ecosystems (Conrad, 1996). Methanotrophs, which are CH 4-oxidizing bacteria, present at the aerobic interface of the anoxic soil substratum can substantially reduce benthic CH 4 emission (Oswald et al., 2015). The populations of both methanogenic and methanotrophic bacteria primarily depend on various
Abstract The behavior of dissolved Ca and Mg during mixing of sea and river waters had been studi... more Abstract The behavior of dissolved Ca and Mg during mixing of sea and river waters had been studied through a survey in the wastewater fed River Vidyadhari in the Sundarbans estuarine complex, India. The percentage variation for Ca was 79.9% during low tide and 95% during high tide with respect to chlorinity (10−3) and the same for Mg was 80% during low tide and 94.6% during high tide. The percentage addition and removal (PA & PR) was calculated with the help of the Theoretical Dilution Line (TDL) concept. A significant negative correlation between PA and PR of both Ca and Mg with chlorinity (10−3) was also observed. On the basis of the insignificant percentage variation (
Corrigendum to "The role of arsenic resistant Bacillus aryabhattai MCC3374 in promotion of rice s... more Corrigendum to "The role of arsenic resistant Bacillus aryabhattai MCC3374 in promotion of rice seedlings growth and alleviation of arsenic phytotoxicity" [Chemosphere 211 (2018) 407e419]
Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses incl... more Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses including heat and drought by dynamic climate changes. To alleviate these stresses, we investigated two bacterial stains, H26-2 and H30-3 in two cultivars ('Ryeokkwang' and 'Buram-3-ho') of Chinese cabbage in plastic pots in a greenhouse. We evaluated effects of bacterial strains on plant growth-promotion and mitigation of heat and drought stresses; the role of exopolysaccharides as one of bacterial determinants on alleviating stresses; biocontrol activity against soft rot caused by Pectobacterium carotovorum subsp. carotovorum PCC21. Strains H26-2 and H30-3 significantly increased fresh weights compared to a MgSO 4 solution; reduced leaf wilting and promoted recovery after re-watering under heat and drought stresses. Chinese cabbages treated with H26-2 and H30-3 increased leaf abscisic acid (ABA) content and reduced stomatal opening after stresses treatments, in addition, these strains stably colonized and maintained their populations in rhizosphere during heat and drought stresses. As well as tested bacterial cells, exopolysaccharides (EPS) of H30-3 could be one of bacterial determinants for alleviation of tested stresses in Chinese cabbages, however, the effects were different to cultivars of Chinese cabbages. In addition to bacterial activity to abiotic stresses, H30-3 could suppress incidence (%) of soft rot in 'Buram-3-ho'. The tested strains were identified as Bacillus aryabhattai H26-2 and B. siamensis H30-3 based on 16S rRNA gene sequence analysis. Taken together, H26-2 and H30-3 could be candidates for both plant growth promotion and mitigation of heat and drought stresses in Chinese cabbage.
Vertical occurrence of soil urease activity along with ammonia content from three distinct region... more Vertical occurrence of soil urease activity along with ammonia content from three distinct regions viz. Deep forest region (No tidal action and wave attack occurs as it is furthest from river shore and it contains maximum content of organic carbon and minimum soil salinity and silicate concentration. In this zone plenty of pneumatophores, below ground root and dense vegetation are found), Rooted region (It is situated in between Deep forest region and Un-rooted region. This region contains only pneumatophores but it is devoid of long roots and vegetations. It faces wave attack and tidal action less than that of Un-rooted region) and Un-rooted region (It is closest to river shore and faces maximum wave attack and tidal action; it contains minimum organic carbon but maximum soil salinity and silicate concentration. This zone is totally devoid of any roots, pneumatophores and vegetations) of Sundarban mangrove forest ecosystem, India revealed an interesting explanation. Soil urease activity showed a decreasing pattern with increase in depth from the deep forest region of the Sundarban forest ecosystem. Soil urease activity was found to be more sensitive to soil temperature and pH rather than soil salinity. This ensured that soil urease along with the microbes present in the Sundarban forest ecosystem are more tolerant to fluctuation in salinity than that of temperature. Soil ammonia concentration was found to be directly governed by the soil urease activity [The regression equation is Ammonia in soil = −1.64 + 0.0402 Urease Activity (R-Sq = 62.9%, P < 0.001, n = 41)].
A cellulase producing bacterium (E3 strain) was isolated from fecal matter of elephant and identi... more A cellulase producing bacterium (E3 strain) was isolated from fecal matter of elephant and identified as Bacillus sp. using 16S rDNA sequenced based molecular phylogenetic approach. While studying the effect of substrates like Carboxymethyl cellulose (CMC), avicel, starch, maltose, sucrose, glucose, fructose, galactose and lactose on cellulase production, it was found that CMC was best carbon source induced cellulase production followed by lactose in this bacterial strain. A positive synergistic effect of lactose with CMC was also observed with enhancement of 5-6 times in cellulase production. The optimum cellulase production was recorded with 1% CMC and 1% lactose when added individually in the Omeliansky's medium. The results showed that addition lactose with CMC greatly enhances the production and activity of various cellulase enzymes. The optimal fermentation conditions for the biosynthesis of cellulase by this strain were found to be temperature: 37˚C, pH 7.0. The nitrogen source NH 4 Cl at 0.15% was optimum for cellulase production by this bacterium.
Mangrove provides a unique ecological niche to different microbes which play various roles in nut... more Mangrove provides a unique ecological niche to different microbes which play various roles in nutrient recycling as well as various environmental activities. The highly productive and diverse microbial community living in mangrove ecosystems continuously transforms dead vegetation and recycle nitrogen, phosphorus, sulphur and other nutrients that can later be used by the plants. Mangrove ecosystems are rich in organic matter, and however, in general, they are nutrient-deficient ecosystems, especially of nitrogen and phosphorus. The present study investigated depth wise variation of nitrifying bacteria, nitrogen fixing bacteria, total bacterial population along with nitrate-nitrogen, nitrite-nitrogen and other physicochemical parameters of soil during pre-monsoon, monsoon and post-monsoon periods at three different sampling stations of mangrove sediments viz. deep forest region, rooted region and un-rooted region. The microbial population was also found maximum in the deep forest sediment relative to the other two sites. Populations of cultureable microbes were found maximum in surface soil and decreased with increase in depth in Sundarban mangrove environment. A decreasing trend of total microbial load, nitrifying and nitrogen fixing bacteria with increase in depth were recorded throughout the year. Present study revealed the relationship among depth integrated variations of physicochemical components (viz. soil temperature, pH, salinity, nitrite-nitrogen and nitrate-nitrogen concentration) and total microbial load, nitrifying and nitrogen fixing bacteria microbial populations.
Journal of Environmental Studies and Sciences, 2011
Abstract Human activities accelerate the input of plant nutrients sourced from agriculture, indus... more Abstract Human activities accelerate the input of plant nutrients sourced from agriculture, industrial waste, and sewage in the Hooghly River at the land ocean boundary of Indian Sunderban mangrove (21° 32′22° 40′ N and 88° 05′89° E). This study reports ...
Sundarban Mangrove forest is highly productive marine ecosystem where halophilic microbes activel... more Sundarban Mangrove forest is highly productive marine ecosystem where halophilic microbes actively participate in bio-mineralization and biotransformation of minerals. The population of aerobic halophilic microbes was studied to determine their distribution with the availability of different physicochemical parameters with increasing depth of this forest sediment. The present study revealed that microbes present in the top soil region were less tolerant to fluctuation in salinity than the middle and bottom segment. Microbes isolated from bottom segment showed higher growth rate in anaerobic condition. A decreasing trend of total microbial population and organic carbon content of soil were found with increase in depth. In contrary a reverse profile was found for salinity. A significant stratification was found to exist among microbial population and the salty nature of the soil of Sundarban Mangrove forest.
The mature root nodules of Phaseolus mungo (L.), a leguminous pulse, contain higher amount of ind... more The mature root nodules of Phaseolus mungo (L.), a leguminous pulse, contain higher amount of indole acetic acid (IAA) than non-nodulated roots. The tryptophan pool present in the mature nodule and young roots might serve as a precursor for the IAA production. Presence of IAA metabolising enzymes-IAA oxidase and peroxidaseindicate the metabolism of IAA in the nodules and roots. In culture, the symbiont, isolated from the nodules, produced a high amount of IAA, when tryptophan was supplied in the medium as a precursor. The symbiont preferred L-isomer over the DLor D-isomer of tryptophan for IAA production.The important physiological implication of the IAA production in the legume-Rhizobium symbiosis is discussed.
Ongoing climate change and anthropogenic activities are introducing stressors that affect the str... more Ongoing climate change and anthropogenic activities are introducing stressors that affect the structure and function of coastal ecosystems. This paper focuses on the fluvial fluxes and estuarine transport of nutrients from a tropical river (Mahanadi River) in Northeastern India and compares select nutrient and water quality parameters between 1983 and 2008. This estuary acts as a perennial source of CO 2 with a net annual flux to the atmosphere of about 135 tons. The non-conservative fluxes showed a net annual removal of 650 and 140 tons of phosphorus and nitrogen from the water column, respectively. Negative biogeochemical feedbacks that decreased the availability of N and P in 2008 relative to 1983 levels indicate major changes in biogeochemical responses towards fluvial fluxes of nutrient.
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