Faculty Publications
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Item Biological treatment of toxic petroleum spent caustic in fluidized bed bioreactor using immobilized cells of thiobacillus RAI01(2008) Potumarthi, R.; Mugeraya, G.; Jetty, A.In the present studies, newly isolated Thiobacillus sp was used for the treatment of synthetic spent sulfide caustic in a laboratory-scale fluidized bed bioreactor. The sulfide oxidation was tested using Ca-alginate immobilized Thiobacillus sp. Initially, response surface methodology was applied for the optimization of four parameters to check the sulfide oxidation efficiency in batch mode. Further, reactor was operated in continuous mode for 51 days at different sulfide loading rates and retention times to test the sulfide oxidation and sulfate and thiosulfate formation. Sulfide conversions in the range of 90-98% were obtained at almost all sulfide loading rates and hydraulic retention times. However, increased loading rates resulted in lower sulfide oxidation capacity. All the experiments were conducted at constant pH of around 6 and temperature of 30?±?5 °C. © 2008 Humana Press.Item Controlled release of nutrients to mammalian cells cultured in shake flasks(2012) Hegde, S.; Pant, T.; Pradhan, K.; Badiger, M.; Gadgil, M.Though cell culture-based protein production processes are rarely carried out under batch mode of operation, cell line and initial process development operations are usually carried out in batch mode due to simplicity of operation in widely used scale down platforms like shake flasks. Nutrient feeding, if performed, is achieved by bolus addition of concentrated feed solution at different intervals, which leads to large transient increases in nutrient concentrations. One negative consequence is increased waste metabolite production. We have developed a hydrogel-based nutrient delivery system for continuous feeding of nutrients in scale down models like shake flasks without the need for manual feed additions or any additional infrastructure. Continuous delivery also enables maintaining nutrient concentrations at low levels, if desired. The authors demonstrate the use of these systems for continuous feeding of glucose and protein hydrolysate to a suspension Chinese Hamster Ovary (CHO) culture in a shake flask. Glucose feeding achieved using the glucose-loaded hydrogel resulted in a 23% higher integral viable cell density and an 89% lower lactate concentration at the end of the culture when compared with a bolus-feed of glucose. © 2011 American Institute of Chemical Engineers (AIChE).Item Production of naringinase from a new soil isolate, Bacillus methylotrophicus: Isolation, optimization and scale-up studies(2014) Mukund, P.; Belur, P.D.; Saidutta, M.B.Five strains of naringin-degrading bacteria were isolated and found to be positive for extracellular naringinase activity. The one that showed highest activity in the selective medium was identified by 16S rRNA analysis as Bacillus methylotrophicus. The best combination of carbon-nitrogen source was determined by employing two-level full factorial analyses, comprising 24 experiments in shake flasks. Sucrose-yeast extract showed significant increase in naringinase activity (7.46 U/L) compared to the basal medium. Naringinase production was found to be inducible and naringin was found to be the best inducer among naringin, naringenin, hesperidin, and L-rhamnose. Inoculum size of 2% (v/v) and age of 48 hr favored naringinase and biomass production. Highest naringinase activity of 8 U/L was observed at the initial medium pH of 6. Response surface modeling was applied based on central composite design to determine the effects of three independent variables (sucrose, yeast extract, and naringin) and their mutual interactions. In total, 20 experiments were conducted and a statistical model was developed, which predicted naringinase production of 10.61 U/L. Subsequently, verification experiments were conducted and validity of the model was verified. Bioreactor studies conducted with the optimized medium showed an enzyme production of 12.05 U/L within 34 hr of fermentation. Copyright © Taylor & Francis Group, LLC.Item Reduction of hexavalent chromium by a novel Ochrobactrum sp. - microbial characteristics and reduction kinetics(Wiley-VCH Verlag, 2014) Narayani, M.; Shetty K, K.A Gram negative hexavalent chromium (Cr(VI)) reducing bacteria, Ochrobactrum sp. Cr-B4 (genbank accession number: JF824998) was isolated from the aerator water of an activated sludge process of a wastewater treatment facility of a dye and pigment based specialty chemical industry. It showed a resistance for 1000mgL-1 Cr(VI). It exhibited resistance against other heavy metal ions like Ni2+ (900mgL-1), Cu2+ (500mgL-1), Pb2+ (800mgL-1), and Cd2+(250mgL-1), Zn2+ (700mgL-1), Fe3+ (800mgL-1), and against selected antibiotics. Cr-B4 could efficiently reduce 200mgL-1 Cr(VI) completely in nutrient and LB media and could convert Cr(VI) to Cr(III) efficiently. Cr(VI) reduction in nutrient media followed allosteric enzyme kinetics with Km values of 59.39mgL-1 and Vmax values of 47.03mgL-1h-1. The reduction in LB media followed Michaelis-Menten kinetics with Km values of 99.52mgL-1 and Vmax of 77.63mgL-1h-1. Scanning electron micrograms revealed the presence of extracellular polymeric secretions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Item Isolation, screening and production studies of uricase producing bacteria from poultry sources(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2014) Nanda, P.; JagadeeshBabu, P.E.Uricase (urate oxidase EC 1.7.3.3) is a therapeutic enzyme that is widely used to catalyze the enzymatic oxidation of uric acid in the treatment of hyperuricemia and gout diseases. In this study, three bacterial species capable of producing extracellular uricase were isolated from a poultry source and screened based on the size of the clear zone using a uric acid agar plate. The bacterial species capable of producing uricase with the highest uricolytic activity was identified as Bacillus cereus strain DL3 using a 16SrRNA gene sequencing approach. The time-course study of uricase production was performed and the medium was optimized. Carboxymethylcellulose and asparagine were found to be the best carbon and nitrogen sources. Maximum uricolytic activity was observed at pH 7.0 with an inducer concentration of 2.0 g/L. Inoculum size of 5% gave maximum uricolytic activity. The maximum uricolytic activity of 15.43 U/mL was achieved at optimized conditions, which is 1.61 times more than the initial activity. Further, enzymatic stability was determined at different pH and temperature. © 2014 Taylor and Francis Group, LLC.Item Inhibitory and stimulating effect of single and multi-metal ions on hexavalent chromium reduction by Acinetobacter sp. Cr-B2(Kluwer Academic Publishers, 2014) Hora, A.; Shetty K, V.Potential application of chromium reducing bacteria for industrial scale wastewater treatment demands that effect of presence of other metal ions on rate of Cr(VI) reduction be investigated, as industrial wastewaters contain many toxic metal ions. In the current study, the effect of different heavy metal ions (nickel, zinc, cadmium, copper, lead, iron) on chromium reduction by a novel strain of Acinetobacter sp. Cr-B2 that shows high tolerance up to 1,100 mg/L and high Cr(VI) reducing capacity was investigated. The alteration in Cr(VI) reduction capacity of Cr-B2 was studied both in presence of individual metal ions and in the presence of multi-metal ions at different concentrations. The study showed that the Cr(VI) reduction rates decreased in presence of Ni2+, Zn2+ and Cd2+ when present individually. Pb2+ at lower concentration did not show significant effect while Cu2+ and Fe3+ stimulated the rate of Cr(VI) reduction. In the studies on multi-metal ions, it was observed that in presence of Cu2+ and Fe3+, the inhibiting effect of Ni2+, Zn2+, Cd2+ and Pb2+ on Cr(VI) reduction was reduced. Each of these metals affect the overall rate of Cr(VI) reduction by Cr-B2. This work highlights the need to consider the presence of other heavy metal ions in wastewater when assessing the bioreduction of Cr(VI) and while designing the bioreactors for the purpose, as rate of reduction is altered by their presence. © 2014, Springer Science+Business Media Dordrecht.Item Optimization and kinetic modeling of cell-associated camptothecin production from an endophytic fusarium oxysporum NFX06(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Musavi, S.F.; Dhavale, A.; Mohan Balakrishnan, R.M.The production of cell-associated camptothecin (CPT) from an endophytic fungus Fusarium oxysporum NFX06 isolated from Nothapodytes foetida and its kinetics studies were proposed. Response surface methodology (RSM) based on central composite design (CCD) was used to construct a model to describe the effects of substrate concentration. Three independent variables (dextrose, peptone, and MgSO4) were successfully employed to study the yield of CPT under submerged fermentation. The maximum yield of CPT obtained from CCD was about 598.0 ng/g biomass. The model-validated optimum predicted CPT yield and experimental CPT yield from the biomass were found to be 628.08 ng/g and 610.09 ng/g at the concentrations of dextrose 42.64 (g/L), peptone 9.23 (g/L), and MgSO4 0.26 (g/L) respectively. The predicted yield of CPT was 4.90% higher than the value obtained from CCD and 2.85% higher than the value obtained from experiment conducted at optimum conditions. The kinetic parameters, maximum specific growth rate ?max = 1.212 day-1, growth-associated CPT production coefficient (? = 29.35 ng/g biomass), and non-growth-associated CPT production coefficient (? = 0.03 ng CPT/g biomass-day) were obtained. The logistic model was found suitable to predict mycelial growth with a high determination coefficient (R2). Luedeking-Piret and modified Luedeking-Piret models were employed to represent the product kinetics and substrate consumption kinetics. A good concurrence was found between the experimental and predicted values, representing that the unstructured models were able to illustrate the fermentation profile effectively. © 2015 Copyright Taylor & Francis Group, LLC.Item New indole-isoxazolone derivatives: Synthesis, characterisation and in vitro SIRT1 inhibition studies(Elsevier Ltd, 2015) Panathur, N.; Gokhale, N.; Udayakumar, U.; Koushik, P.V.; Yogeeswari, P.; Sriram, D.A new series of indole-isoxazolone hybrids bearing substituted amide, substituted [(1,2,3-triazol-4-yl)methoxy]methyl group or substituted benzylic ether at position-2 of the indole nucleus was synthesised using a facile synthetic route and the molecules were characterised using spectroscopic techniques. The molecules were screened against three human cancer cell lines to evaluate their in vitro cytotoxic property. Most of the trifluoromethyl substituted derivatives exhibited better growth inhibition activity than their methyl substituted analogues. The SIRT1 inhibition activity of two potent molecules (I17 and I18) was investigated and the SIRT1 IC50 values are 35.25 and 37.36 ?M, respectively for I17 and I18. The molecular docking studies with SIRT1 enzyme revealed favourable interactions of the molecule I17 with the amino acids constituting the receptor enzyme. © 2015 Elsevier Ltd. All rights reserved.Item Pathway identification, enzyme activity and kinetic study for the biodegradation of phenol by Nocardia hydrocarbonoxydans NCIM 2386(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Shetty, G.R.; Shetty K, K.V.Nocardia hydrocarbonoxydans NCIM 2386 (Nhy) can grow using phenol as a sole carbon source and has a strong ability to degrade phenol. The paper presents the main metabolism pathways and mechanism of phenol degradation by Nhy. Phenol was found to be degraded via meta cleavage of catechol by the action of enzyme catechol 2,3-dioxygenase. The enzyme was found to be both extracellular and cell bound. The cell bound and extracellular enzymes actively degraded phenol even in the absence of the organism. The rate of phenol degradation by extracellular enzymes as sole enzymatic process (in the absence of cells) was found to be almost similar to that with the whole cells, indicating the prominence of extracellular enzymes. Michaelis–Menten model was found to fit the degradation rate kinetics of total phenol for total phenol concentrations of less than 100 mg L?1and also the degradation rate kinetics of catechol at catechol concentrations of less than 80 mg L?1during the exponential growth phase of the organism. Michaelis– Menten model was found to fit the kinetics of catechol formation rate which is also equal to the actual rate of phenol degradation to catechol. Both phenol and catechol were found to be substrate inhibitory. © 2015 Balaban Desalination Publications. All rights reserved.Item Shear stress effects on production of exopolymeric substances and biofilm characteristics during phenol biodegradation by immobilized Pseudomonas desmolyticum (NCIM2112) cells in a pulsed plate bioreactor(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Veena, B.R.; Shetty K, K.V.; Saidutta, M.B.This article reports studies on a continuous pulsed plate bioreactor (PPBR) with the cells of Pseudomonas desmolyticum (NCIM2112) immobilized on granular activated carbon (GAC) used as a biofilm reactor for biodegradation of phenol. Almost complete removal of 200 ppm phenol could be achieved in this bioreactor. Biofilm structure and characteristics are influenced by hydrodynamic and shear conditions in bioreactors. In this article, the effect of shear stress induced by frequency of pulsation on biofilm characteristics during the startup period in the PPBR is reported. The startup time decreased with the increase in frequency of pulsation. The formation of biofilm in PPBR was found to have three phases: accumulation, compaction, and plateau. The effect of frequency on production of exoploymeric substances (EPS) such as, protein, carbohydrate, and humic substance is reported. An increase in shear stress induced by the frequency of pulsation increased the production of exopolymeric substances in the biofilm during startup of the bioreactor. Increase in shear stress caused a decrease in biofilm thickness and an increase in dry density of the biofilm. Increase in shear stress resulted in a smoother and thinner biofilm surface with more compact and dense structure. © 2016, Copyright © Taylor & Francis Group, LLC.