Faculty Publications

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    Isolation of Thiobacillus sp from aerobic sludge of distillery and dairy effluent treatment plants and its sulfide oxidation activity at different concentrations
    (Triveni Enterprises, 2007) Ravichandra, P.; Mugeraya, G.; Rao, A.G.; Ramakrishna, M.; Jetty, A.
    In the present study two strains of Thiobacillus sp were isolated from aerobic sludge of distillery and dairy effluent treatment plant using standard methods of isolation and enrichment. Experiments were conducted using isolated cultures in batch bioreactor with initial sulfide concentration of 75 and 150 mg/l. The effect of initial sulfide concentration on the activity of isolated Thiobacillus sp was studied. Sulfide oxidizing capacity was also determined at different initial sulfide concentrations. The results from the study indicate the possible isolation of Thiobacillus cultures from native source and application in the full-scale reactor. © Triveni Enterprises.
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    Biological sulfide oxidation using autotrophic Thiobacillus sp.: Evaluation of different immobilization methods and bioreactors
    (2009) Ravichandra, P.; Gopal, M.; Jetty, A.
    Aims: Evaluation of various immobilization methods and bioreactors for sulfide oxidation using Thiobacillus sp. was studied. Methods and Results: Ca-alginate, K-carrageenan and agar gel matrices (entrapment) and polyurethane foam and granular activated carbon (adsorption) efficacy was tested for the sulfide oxidation and biomass leakage using immobilized Thiobacillus sp. Maximum sulfide oxidation of 96% was achieved with alginate matrix followed by K-carrageenan (88%). Different parameters viz. alginate concentration (1%, 2%, 3%, 4% and 5%), CaCl2 concentration (1%, 2%, 3%, 4% and 5%), bead diameter (1, 2, 3, 4 and 5 mm), and curing time (1, 3, 6, 12 and 18 h) were studied for optimal immobilization conditions. Repeated batch experiments were carried out to test reusability of Ca-alginate immobilized beads for sulfide oxidation in stirred tank reactor and fluidized bed reactor (FBR) at different sulfide concentrations. Conclusions: The results proved to be promising for sulfide oxidation using Ca-alginate gel matrix immobilized Thiobacillus sp. for better sulfide oxidation with less biomass leakage. Significance and Impact of the Study: Biological sulfide oxidation is gaining more importance because of its simple operation. Present investigations will help in successful design and operation of pilot and industrial level FBR for sulfide oxidation. © 2009 The Society for Applied Microbiology.
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    Characterization and proinflammatory response of airborne biological particles from wastewater treatment plants
    (2011) Gangamma, S.; Patil, R.S.; Mukherji, S.
    Wastewater contains a variety of microorganisms, and unit operations in the plants could release these biological components into the air environment. These airborne biological particles could have adverse health effects on plant workers and the downwind population. This study provides a first report on the concentration and characterization of the airborne biological particles in six wastewater treatment plants in Mumbai, India. The study indicates that 49% and 27% of the samples exceed, respectively, the exposure limit for airborne endotoxin and bacteria in occupational settings. Endotoxin was identified as the single most important component of the particulate matter responsible for induction of proinflammatory indicator (tumor necrosis factor-?) in in vitro assay. Identification of several clinically important bacterial species in the samples suggests that the workers at the treatment plant are exposed to opportunistic and infectious bacteria. Principal component analysis was used to identify the groups among the bacterial species which serves as the signature for transport study. Analysis also shows that the component related to spore-forming bacteria is present in all samples. © 2011 American Chemical Society.
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    Experimental investigation and artificial neural network-based modeling of batch reduction of hexavalent chromium by immobilized cells of newly isolated strain of chromium-resistant bacteria
    (2012) Shetty K, K.V.; Namitha, L.; Rao, S.N.; Narayani, M.
    The batch bioreduction of Cr(VI) by the cells of newly isolated chromium-resistant Acinetobacter sp. bacteria, immobilized on glass beads and Ca-alginate beads, was investigated. The rate of reduction and percentage reduction of Cr(VI) decrease with the increase in initial Cr(VI) concentration, indicating the inhibitory effect of Cr(VI). Efficiency of bioreduction can be improved by increasing the bioparticle loading or the initial biomass loading. Glass bioparticles have shown better performance as compared to Ca-alginate bioparticles in terms of batch Cr(VI) reduction achieved and the rate of reduction. Glass beads may be considered as better cell carrier particles for immobilization as compared to Ca-alginate beads. Around 90% reduction of 80 ppm Cr(VI) could be achieved after 24 h with initial biomass loading of 14.6 mg on glass beads. Artificial neural networkbased models are developed for prediction of batch Cr(VI) bioreduction using the cells immobilized on glass and Ca-alginate beads. © Springer Science+Business Media B.V. 2011.
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    Production of Naringinase by a new soil isolate of Serratia Sp.: Effect of different carbon and nitrogen sources
    (2013) Pavithra, M.; Belur, P.D.; Saidutta, M.B.
    Four strains of Naringin degrading bacteria were isolated and tested for naringinase activity. All the four isolates showed extracellular naringinase activity. The one which showed consistently good activity in three different media was selected (2 U/L) and was identified by phenotypic characterization as Serratia Sp. In shake-flask trials, effect of various carbon and nitrogen sources was studied. Among all the carbon sources, glucose enhanced the naringinase production. Peptone supplemented with ammonium nitrate was found to be favourable. Maximum of 9.2 U/L naringinase activity was achieved in the medium comprising naringin, glucose, peptone, ammonium nitrate and salts.
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    Determination of specific oxygen uptake rate of Photorhabdus luminescens during submerged culture in lab scale bioreactor
    (2013) Belur, P.D.; Inman, F.L.; Holmes, L.D.
    Photorhabdus luminescens, a bacterial symbiont of entomoparasitic nematodes, was cultured in a 10 L bioreactor. Cellular density and bioluminescence were recorded and volumetric oxygen transfer coefficient (kLa) and specific oxygen transfer rates were determined during the batch process. Exponential phase of the bacterium lasted for 20 h, showing a maximum specific growth rate of 0.339 h-1 in a defined medium. Bioluminescence peaked within 21h, and was maintained until the end of the batch process (48 h). The specific oxygen uptake rate (SOUR) was high during both lag and early exponential phase, and eventually reached a stable value of 0.33 mmol g-1 h-1 during stationary phase. Maintenance of 200 rpm agitation and 1.4 volume of air per volume of medium per minute (vvm) aeration, gave rise to a kLa value of 39.5 h-1. This kLa value was sufficient to meet the oxygen demand of 14.4 g L-1 (DCW) biomass. This research is particularly relevant since there are no reports available on SOURs of symbiotic bacteria or their nematode partners. The insight gained through this study will be useful during the development of a submerged monoxenic culture of Heterorhabditis bacteriophora and its symbiotic bacterium P. luminescens in bioreactors. © 2013 © 2013 Taylor & Francis.
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    Enhanced production of napthoquinone metabolite (shikonin) from cell suspension culture of Arnebia sp. and its up-scaling through bioreactor
    (Springer Verlag, 2014) Gupta, K.; Garg, S.; Singh, J.; Kumar, M.
    Cell culture in shake flask and air-lift bioreactor was carried out to exploit the potential of Arnebia sp. for napthoquinone metabolite production. Cell suspension cultures of Arnebia were established from friable callus in liquid MS medium supplemented with 6-benzylaminopurine (BAP) (10 ?M) and indole-3-butyric acid (IBA) (5 ?M). Growth kinetic studies were done by using settled cell volume and fresh/dry cell weight method. Suspension cultures were maintained by sub-culturing at 10 days interval. A two-stage culture system is employed using growth medium (GM) and modified M9 medium (production medium) for cell biomass and naphthoquinone pigment production, respectively. Results showed that cultivation of cells under dark conditions at room temperature (25 ± 2 °C) enhanced the cell biomass from 100 to 625 g l-1. The pigment production was also found to be increased in dark conditions at room temperature. Alkaline pH found to have positive effect on pigment yield. In case of M9 medium constituents, absence of Na2SO4 does not affect the pigment yield. The current approaches have the cumulative effect to meet an increased level of (25.5 ?g/ml) metabolite production in air-lift bioreactor. © 2013 The Author(s).
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    Characteristics of airborne bacteria in Mumbai urban environment
    (Elsevier, 2014) Gangamma, S.
    Components of biological origin constitute small but a significant proportion of the ambient airborne particulate matter (PM). However, their diversity and role in proinflammatory responses of PM are not well understood. The present study characterizes airborne bacterial species diversity in Mumbai City and elucidates the role of bacterial endotoxin in PM induced proinflammatory response in ex vivo. Airborne bacteria and endotoxin samples were collected during April-May 2010 in Mumbai using six stage microbial impactor and biosampler. The culturable bacterial species concentration was measured and factors influencing the composition were identified by principal component analysis (PCA). The biosampler samples were used to stimulate immune cells in whole blood assay. A total of 28 species belonging to 17 genera were identified. Gram positive and spore forming groups of bacteria dominated the airborne culturable bacterial concentration. The study indicated the dominance of spore forming and human or animal flora derived pathogenic/opportunistic bacteria in the ambient air environment. Pathogenic and opportunistic species of bacteria were also present in the samples. TNF-? induction by PM was reduced (35%) by polymyxin B pretreatment and this result was corroborated with the results of blocking endotoxin receptor cluster differentiation (CD14). The study highlights the importance of airborne biological particles and suggests need of further studies on biological characterization of ambient PM. © 2014 Elsevier B.V.
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    New INH-pyrazole analogs: Design, synthesis and evaluation of antitubercular and antibacterial activity
    (Elsevier Ltd, 2015) Nayak, N.; Ramprasad, J.; Udayakumar, U.
    With the aim of developing promising antitubercular and antibacterial leads, we have designed and synthesized a new series of isonicotinohydrazide based pyrazole derivatives (5a-r). All new derivatives (4a-b and 5a-r) were screened for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MTB) strain. Four compounds 5j, 5k, 5l and 4b emerged as promising antitubercular agents with MIC of ?4.9 ?M which is much lower than the MIC of the first line antitubercular drug, ethambutol. The 3-chlorophenyl substituent at position-3 of the pyrazole ring enhanced the antiTB activity of the molecules. Three derivatives 5b, 5k and 4b exhibited promising antibacterial activity against the tested bacterial strains. The active molecules were nontoxic to normal Vero cells and showed high selectivity index (>160). The structure and antitubercular activity relationship was further supported by in silico molecular docking study of the active compounds against enoyl acyl carrier protein reductase (InhA) enzyme of M. tuberculosis. © 2015 Published by Elsevier Ltd.
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    Multistrain probiotic production by co-culture fermentation in a lab-scale bioreactor
    (Wiley-VCH Verlag info@wiley-vch.de, 2016) Jangra, M.; Belur, P.D.; Oriabinska, L.B.; Dugan, O.M.
    Most commercial probiotic products intended for pharmaceutical applications consist of combinations of probiotic strains and are available in various forms. The development of co-culture fermentation conditions to produce probiotics with the correct proportion of viable microorganisms would reduce multiple operations and the associated costs. The aim of this study was to develop a fermentation medium and process to achieve biomass comprising the desired proportion of two probiotic strains in co-culture. Initially, a quantification medium was developed, and the method was optimized to allow the quantification of each strain's biomass in a mixture. The specific growth rates of Lactobacillus delbrueckii spp. bulgaricus and Lactobacillus plantarum were determined in media with different carbon sources. The inoculum volume was optimized to achieve equal proportion of biomass in co-culture fermentation in test tubes. Next, fermentation was carried out in a 3-L bioreactor. A biomass concentration of 2.06 g/L, with L. delbrueckii spp. bulgaricus and L. plantarum in the ratio of 47%:53% (by weight), was achieved with concomitant production of 12.69 g/L of lactic acid in 14 h. The results show that with careful manipulation of process conditions, it is possible to achieve the desired proportion of individual strains in the final biomass produced by co-culture fermentation. This process may serve as a model to produce multistrain probiotic drugs at industrial scale. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.