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Identification of arsenic resistant endophytic bacteria from Pteris vittata roots and characterization for arsenic remediation application
No full textMitigation of arsenic (As) pollution is a topical environmental issue of high R&D priority. The present investigation was carried out to isolate As resistant endophytes from the roots of Indian ecotype Pteris vittata and characterize their As transformation and tolerance ability, plant growth promoting charac- teristics and their role to facilitate As uptake by the plant. A total of 8 root endophytes were isolated from plants grown in As amended soil (25 mg As kg�1). These isolates were studied for minimum inhibitory concentration (MIC), arsenite As(III) e arsenate As(V) transformation ability, plant growth promoting (PGP) characteristics through siderophore, indole acetic acid (IAA) production, phosphatase, ACC deaminase activity, and presence of arsenite oxidase (aox) and arsenite transporter (arsB) genes. On the basis of 16S rDNA sequence analysis, these isolates belong to Proteobacteria, Firmicutes and Bacteroidetes families under the genera Bacillus, Enterobacter, Stenotrophomonas and Rhizobium. All isolates were found As tolerant, of which one isolates showed highest tolerance up to 1000 mg L�1 concentration in SLP medium. Five isolates were IAA positive with highest IAA production up to 60 mg/L and two isolates exhibited siderophore activity. Phosphatase activity was shown by only one isolate while ACC deaminase activity was absent in all the isolates. The As transformation study by silver nitrate test showed that only two strains had dual characteristics of As(III) oxidation and As (V) reduction, four strains exhibited either of the characteristics while other two didn’t confirmed any of the two characteristics. Presence of aox gene was detected in two strains and arsB gene in six isolates. The strain with highest As tolerance also showed highest IAA production and occurrence of arsB gene. Present investigation may open up further scope of utilizing these endophytes for up gradation of phytoextraction process
Significance of provisioning ecosystem services from moist temperate forest ecosystems: lessons from upper Kedarnath valley, Garhwal, India
No full textForests have been very important natural resource for rural subsistence lifestyle providing variety of and provisioning ecosystem services. Study was carried out in six villages of upper Kedarnath valley at an altitudinal gradient of 1400–2800. Paper examines the nature and extent of provisioning services from forests to hill locals living in nearby villages. Frequent field survey of 151 households from five villages in proximity to forest was conducted using semi-structured questionnaires followed by field surveys. Primary data were collected for basic household’s attributes, fuelwood, fodder, leaf litter and NTFP collection pattern. Simple descriptive methods were used for data analysis. The result shows that fuelwood contributes more than 95 % of total domestic fuel requirement in the study area with more collection during summers but more consumption during winter months due to extensive drop in day and night temperatures. Fodder collection is a major practice adding a lot to women drudgery, and winter fodder deficit is a major issue that leads to dry fodder collection from remote locations. Similarly the average seasonal collection figures were also high for leaf litter ranging from 120 to 89 kg/household/day. Collection of wild edibles is moderate, while for medicinal plants is low in the study area. Resource availability, collection and consumption depend on the family size, distance from forest area and economic condition of the household. More than 95 % of the household’s biomass demands and requirement in the study area are fulfilled completely from forests, while rest are procured from various sources such as agroforests and agriculture
Determination of arsenic extraction by Vetiveria zizanioides (L.)Nash plant for phytoremediation application
No full textThere is contradiction about Vetiveria zizanioides (L.) Nash as arsenic hyperaccumulator. The suitability of V. zizanioides plant for Arsenic (As) tolerance and accumulation in the plant biomass has been investigated for phytoremediation application. Plants were treated with 0, 25, 50, 75, 100 and 150 mg L−1 As levels in Hoagland
nutrient solution. Arsenic accumulation in shoot and root biomass was determined after 14 days. Metal extraction competency from matrix and accumulation in the above ground plant part revealed that V. zizanioides accumulate As at a low level. Inefficiency of As accumulation by this plant relates to the absence of arsenate reductase activity, transcript of the arsC gene which is crucial for As detoxification. Though, the V. zizanioides system sustains low level As stress, it is not suitable for As phytoextraction
Process Engineering Aspects of Vertical Column Photobioreactors for Mass Production of Microalgae
No full textMicroalgae cultivation can be made sustainable on a
large-scale by lowering the costs associated with
closed photobioreactors (PBRs). It can be achieved
through the appropriate design of closed PBRs to
achieve maximum productivity. The cultivation of
microalgae is very sensitive to temperature, pH,
shear stress, irradiance, and operating conditions of
the PBR. The understanding of design parameters is
a prerequisite for scale-up of gas-sparged vertical
column PBRs. The hydrodynamics of gas-sparged
vertical column PBRs play a very critical role in the
optimum production of microalgae and avoiding
the carbon loss (unabsorbed CO2 out of total supplied).
In this article, the effects of design parameters
on microalgae productivity in various
vertical column PBRs, i.e., flat panel, bubble column,
and airlift (draft tube) column, are critically
reviewed. The microalgae production in PBRs is\ud
essentially a three-phase operation. Hence, the
hydrodynamic aspects of two- and three-phase flow
in the vertical column PBR are emphasized with
respect to its scale-up prospect. The flow regimes
and CFD modeling aspects of gas-sparged PBRs are
also covered in this review
Response of Anaerobic Digester Sludge for Activator Aided Rapid Composting and its Effects on Compost Quality
No full textThe anaerobic treatment is in growing demand as an advanced methodology rendering sustainable treatment
option for organic wastes. The Anaerobic digester sludge (ADS) is the product of anaerobic digestion of organic
matter by microbial activity in an oxygen-deficit environment. It is a good supplement to soil as it enriches soil with
nutrients, increases the availability of minerals to plants and helps in soil conditioning. Though ADS is frequently
used in agriculture, there are opinions supporting the fact that ADS contains more recalcitrant than its nutritional
components. Hence, there is a need for the post-processing of ADS to make it compatible for soil application. In the
present study, an attempt has made to assess the response of ADS for CA aided composting and to study the
effectiveness composting on the quality of finished compost
BACTERIA ASSOCIATED WITH NON-ALCOHOLIC FERMENTED BAMBOO SHOOT FOOD PRODUCT
Get PDFPure bacterial cultures were isolated from fermented products collected from two locations of North East India (Assam and Arunachal Pradesh). Forty four variants were identified by 16S rRNA gene sequencing. The dominant microbial genera found were Bacillus, Paenibacillus followed by Oceanobacillus and Lactobacillus in Assam and Bacillus, Enterococcus, Lactobacillus in Arunachal-Pradesh food products. Bacillus isolates showed extracellular enzyme production (amylases, proteases and lipases) as analyzed through plate assay. GC-MS analysis showed beneficial chemical components like organic acids, esters, aminoacids, vitamins in fermented bamboo shoot products. Probiotic attributes of culturable bacterial isolates from bamboo fermentations gives promiscuity for human consumption. Beneficial microorganisms from bamboo shoot fermented food products of North-Eastern region of India were explored and compared using bioinformatics tools
Treatment of Common Effluent Treatment Plant Wastewater in a Sequential Anoxic–Oxic Batch Reactor by Developed Bacterial Consortium VN11
No full textA laboratory-scale anoxic–oxic sequential reactor system was seeded with acclimatized
mixed microbial consortium for the treatment of common effluent treatment plant
(CETP) wastewater having 7000–7400 mg L−1 of COD and 3000–3400 mg L−1 of BOD.
Initially, CETP wastewater was treated under anoxic reactor at 5000 mg L−1 of MLSS
concentrations, 5.26 ± 0.27 kg COD m−3 day−1 of organic loading rate (OLR) and 36 h of
hydraulic retention time (HRT). Further, the effluent of anoxic reactor was treated in oxic
reactor with an OLR of 6.6 ± 0.31 kg COD m−3 day−1 and 18 h HRT. Maximum color and
COD removal were found to be 72 and 85 % at total HRT of 2.25 days under anoxic–oxic
sequential reactor at 37 °C and pH 7.0. The UV–VIS, FTIR, NMR and GCMS studies showed
that majority of peaks observed in untreated wastewater were either shifted or disappeared
after sequential treatment. Phytotoxicity study with the seeds of Vigna radiata and Triticum
aestivum showed more sensitivity toward the CETP wastewater, while the products obtained
after sequential treatment does not have any inhibitory effects. The results demonstrated that
the anoxic–oxic reactor fed with bacterial consortium VN11 could bring about efficient
bioremediation of industrial wastewaters
Inhalation exposure or body burden? Better way of estimating risk - An application of PBPK model
No full textWe aim to establish a new way for estimating the risk from internal dose or body burden due to exposure of benzene in human subject utilizing physiologically based pharmacokinetic (PBPK) model. We also intend to verify its applicability on human subjects exposed to different levels of benzene. We estimated personal inhalation exposure of benzene for two occupational groups namely petrol pump workers andcar drivers with respect to a control group, only environmentally exposed.Benzene in personal air was pre-concentrated on charcoal followed by chemical desorption and analysis by gas chromatography equipped with flame ionization detector (GC-FID). We selected urinary trans,trans-muconic acid (t,t-MA) as biomarker of benzene exposure and measured its concentration using solid phase extraction followed by high performance liquid chromatography (HPLC). Our estimated inhalation exposure of benzene was 137.5, 97.9 and 38.7 ug/m3 for petrol pump workers,car drivers and environmentally exposed control groups respectively which resulted in urinary t,t-MA levels of 145.4 ± 55.3, 112.6 ± 63.5 and 60.0 ± 34.9 ug/g of creatinine, for the groups in the same order.We deduced a derivation for estimation of body burden from urinary metabolite concentration using PBPK model. Estimation of the internal dose or body burden of benzene in human subject has been made for the first time by the measurement of t,t-MA as a urinary metabolite using physiologically based pharmacokinetic (PBPK) model as a tool. The weight adjusted total body burden of benzene was estimated to be 17.6, 11.1 and 5.0 �g kg−1of body weight for petrol pump workers, drivers and the environmentally exposed control group, respectively using this method. We computed the carcinogenic risk using boththe estimated internal benzene body burden and external exposure values using conventional method.Our study result shows that internal dose or body burden is not proportional to level of exposure rather have a non-linear relationship. At a higher exposure level such as for occupational exposure of petrol pump workers and drivers, the conventionally estimated risk is higher than risk estimated from internal body burden. Likewise, for environmental exposure the conventional risk estimation predict lower level than estimated in our study. This emphasizes the importance of body burden and to consider it as a key parameter while estimating health risk at varying level of exposure
