Faculty Publications
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Item Production of novel cell-associated tannase from newly isolated Serratia ficaria DTC(2010) Belur, P.D.; Gopal, M.; Nirmala, K.R.; Nainegali, N.Five strains of tannic acid degrading bacteria were isolated and identified by phenotypic characterization. All the five isolates showed cell-associated activity, whereas only three showed extracellular activity. Serratia ficaria DTC, showing the highest cell-associated activity (0.29 U/l), was selected for further shake-flask studies. Tannase synthesis was growth associated and reached the peak in the late stationary phase of growth. Organic nitrogen sources enhanced the tannase production. Peak tannase production of 0.56 U/l was recorded in the medium having the initial pH of 6. The pH and temperature optima of the enzyme were found to be 8.9 and 35°C, respectively. This is the first report of cell-associated activity in the case of bacterial tannase. Cell-associated tannase of Serratia ficaria DTC could be industrially important from the perspective of its activity at broad temperature and pH ranges, and its unusually high activity at pH 8.9. © The Korean Society for Microbiology and Biotechnology.Item Modelling and simulation of steady-state phenol degradation in a pulsed plate bioreactor with immobilised cells of Nocardia hydrocarbonoxydans(2011) Shetty K, V.S.; Verma, D.K.; Srinikethan, G.A novel bioreactor called pulsed plate bioreactor (PPBR) with cell immobilised glass particles in the interplate spaces was used for continuous aerobic biodegradation of phenol present in wastewater. A mathematical model consisting of mass balance equations and accounting for simultaneous external film mass transfer, internal diffusion and reaction is presented to describe the steady-state degradation of phenol by Nocardia hydrocarbonoxydans (Nch.) in this bioreactor. The growth of Nch. on phenol was found to follow Haldane substrate inhibition model. The biokinetic parameters at a temperature of 30 ± 1 °C and pH at 7.0 ± 0.1 are ? m = 0.5397 h -1, K S = 6.445 mg/L and K I = 855.7 mg/L. The mathematical model was able to predict the reactor performance, with a maximum error of 2% between the predicted and experimental percentage degradations of phenol. The biofilm internal diffusion rate was found to be the slowest step in biodegradation of phenol in a PPBR. © 2010 Springer-Verlag.Item Characteristics of a novel Acinetobacter sp. and its kinetics in hexavalent chromium bioreduction(2012) Narayani, M.; Shetty K, K.V.Cr-B2, a Gram-uegadve hexavalent chromium [Cr(VI)] reducing bacteria, was isolated from the aerator water of an activated sludge process in the wastewater treatment facility of a dye and pigment based chemical industry. Cr-B2 exhibited a resistance for 1,100mg/l Cr(VI) and, similarly, resistance against other heavy metal ions such as Ni2+ (800 mg/l), Cu2+ (600 mg/l), Pb2+ (1,100 mg/l), Cd2+ (350 mg/l), Zn2+ (700 mg/l), and Fe3+ (1,000 mg/l), and against selected antibiotics. Cr-B2 was observed to efficiently reduce 200mg/l Cr(VI) completely in both nutrient and LB media, and could convert Cr(VI) to Cr(III) aerobically. Cr(VI) reduction kinetics followed allosteric enzyme kinetics. The Km values were found to be 43.11 mg/l for nutrient media and 38.05 mg/l for LB media. Vmax values of 13.17 mg/l/h and 12.53 mg/l/h were obtained for nutrient media and LB media, respectively, and the cooperativity coefficients (n) were found to be 8.47 and 3.49, respectively, indicating positive cooperativity in both cases. SEM analysis showed the formation of wrinkles and depressions in the cells when exposed to 800 mg/l Cr(VI) concentration. The organism was seen to exhibit pleomorphic behavior. Cr-B2 was identified on the basis of morphological, biochemical, and partial 16S rRNA gene sequencing chracterizations and found to be Acinetobacter sp. © The Korean Society for Microbiology and Biotechnology.Item Production and characterization of biosurfactant produced by a novel Pseudomonas sp. 2B(2012) Aparna, A.; Srinikethan, G.; Smitha, H.Biosurfactant-producing bacteria were isolated from terrestrial samples collected in areas contaminated with petroleum compounds. Isolates were screened for biosurfactant production using Cetyl Tri Ammonium Bromide (CTAB)-Methylene blue agar selection medium and the qualitative drop-collapse test. An efficient bacterial strain was selected based on rapid drop collapse activity and highest biosurfactant production. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, 2B, identified the bacterium as Pseudomonas sp. Five different low cost carbon substrates were evaluated for their effect on biosurfactant production. The maximum biosurfactant synthesis (4.97g/L) occurred at 96h when the cells were grown on modified PPGAS medium containing 1% (v/v) molasses at 30°C and 150rpm. The cell free broth containing the biosurfactant could reduce the surface tension to 30.14mN/m. The surface active compound showed emulsifying activity against a variety of hydrocarbons and achieved a maximum emulsion index of 84% for sunflower oil. Compositional analysis of the biosurfactant reveals that the extracted biosurfactant was a glycolipid type, which was composed of high percentages of lipid (~65%, w/w) and carbohydrate (~32%, w/w). Fourier transform infrared (FT-IR) spectrum of extracted biosurfactant indicates the presence of carboxyl, hydroxyl and methoxyl functional groups. The mass spectra (MS) shows that dirhamnolipid (l-rhamnopyranosyl-l-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C 10-C 10) was detected in abundance with the predominant congener monorhamnolipid (l-rhamnopyranosyl-?-hydroxydecanoyl-?-hydroxydecanoate, Rha-C 10-C 10). The crude oil recovery studies using the biosurfactant produced by Pseudomonas sp. 2B suggested its potential application in microbial enhanced oil recovery and bioremediation. © 2012 Elsevier B.V..Item 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.Item Design, Synthesis, and Biological Evaluation of New 8-Trifluoromethylquinoline Containing Pyrazole-3-carboxamide Derivatives(HeteroCorporation, 2017) Nayak, N.; Ramprasad, J.; Udayakumar, U.The article describes the design, synthesis, and characterization of a new series of 8-trifluoromethylquinoline substituted pyrazole-3-carboxamides (9a, 9b, 9c, 9d, 9e, 9f, 9g, 9h, 9i, 9j, 9k, 9l, 9m, 9n, 9o, 9p, 9q, 9r, 9s, 9t) derived from different primary and secondary amines. The intermediate and target compounds were characterized using spectroscopic methods. The structures of intermediate 7 and target molecule 9d were evidenced by the single crystal X-ray study. All the synthesized target compounds (9a, 9b, 9c, 9d, 9e, 9f, 9g, 9h, 9i, 9j, 9k, 9l, 9m, 9n, 9o, 9p, 9q, 9r, 9s, 9t) and three intermediates (6, 7, 8) were screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv strain. Two compounds, 9k and 9t, showed significant inhibition activity with MIC of 3.13 µg/mL, which is comparable with the activity of standard drug, ethambutol. The carboxamides derived from benzylamine derivatives were more active than their aniline analogs. In general, the hybrid amides with a N-methylene linkage (-CONHCH2-) exhibited enhanced antitubercular activity. In the antibacterial screening, intermediate 3-hydrazinyl-2-methyl-8-(trifluoromethyl)quinoline (6) displayed remarkable activity against the tested bacterial strains. Further, the active anti-TB derivatives were non-toxic to benign NIH 3T3 cells, which demonstrate the lack of general cellular toxicity and hence signifies their suitability for further lead development. © 2015 HeteroCorporationItem Nisin gold nanoparticles assemble as potent antimicrobial agent against Enterococcus faecalis and Staphylococcus aureus clinical isolates(Editions de Sante editions.de.sante@wanadoo.fr, 2017) Pradeepa, n.; Bhat, K.U.; Vidya, S.M.Enterococci and staphylococci have the potency to acquire resistant to antibiotics and have emerged as serious nosocomial pathogens responsible for various diseases. The continuous seeking of new antimicrobials against these pathogens is the only way to avoid the rapid spreading of diseases. Controlled fabrication of existing antimicrobials with nanoparticles offers an alternative strategy to combat against these pathogens with an effective manner. In the present study, gold nanoparticles (AuNPs) were functionalized with nisin to kill a wide range of clinically isolated Enterococcus faecalis and Staphylococcus aureus strains. Nisin functionalized gold nanoparticles (NAuNPs) exhibited good inhibitory activity against all seven multidrug resistant (MDR) and eight non-MDR E. faecalis and S. aureus strains. Minimum inhibitory concentration of NAuNPs was >8–32 fold lower than nisin. Interestingly, antibiotic resistant was not observed by these pathogens up to 8 generation. TEM and AFM investigation revealed that, the antimicrobial action of NAuNPs appears to act in three sequential stages: membrane destabilization, pore formation, followed by intracellular fluid leakage. In addition, NAuNPs were non toxic and showed less hemolytic activity. These findings indicated that, the NAuNPs can be served as an alternative antimicrobial agent to treat a wide range of enterococcal and staphylococcal infections. © 2016 Elsevier B.V.Item Expression studies of Bacillus licheniformis chitin deacetylase in E. coli Rosetta cells(Elsevier B.V., 2017) Raval, R.; Simsa, R.; Raval, K.Chitin, the biopolymer of the N-acetylglucosamine, is the most abundant biopolymer on the planet after cellulose. However owing to its crystalline nature, its deacetylated derivative; chitosan is industrially more potent. This conversion on an enzymatic scale can be made using chitin deacetylase. The metagenomics library constructed from the soil exposed to chitin and chitosan yielded chitin modifying enzymes, one of them being chitin deacetylase (CDA) utilized for the present study. The gene was amplified and expressed using the pET 22b vector in E. coli Rosetta cells. The effect of two additives; chitin and glycerol on the CDA activity were studied. The inclusion of glycerol in the medium improved the biomass by 50% from the initial value of 1.25 g/l to 2.5 g/l. The activity of CDA increased from 90 ?mol/min/ml to 343 ?mol/min/ml. The CDA activity reported in the present paper is the highest observed for any strain. The addition of glycerol to the media not only helped improve the yield of the chitin deacetylase but also imparted value addition to the waste of the biofuel industry. © 2017 Elsevier B.V.Item Production of oxalate oxidase from endophytic Ochrobactrum intermedium CL6(Journal of Pure and Applied Microbiology micro_drkhan@yahoo.com 54, Near Post Office, Thana Street, Shahjahanabad Bhopal 462 001, 2018) Kumar, K.; Belur, P.D.Four oxalate degrading endophytic bacteria were isolated from oxalate rich Colocasia esculenta tubers. Based upon the oxalate oxidase (EC 1.2.3.4) activity produced in nutrient medium, one bacterium was selected and identified as Ochrobactrum intermedium by 16S rDNA sequencing. Studies on effect of nutritional and non-nutritional parameters showed that oxalate oxidase production is inducible, requires Manganese ions in the medium, and very low fill-up volume is beneficial. Shake flask fermentation carried out with medium comprising Sucrose, Ammonium chloride, Sodium oxalate along with basal salts gave 0.5 UmL-1 oxalate oxidase activity and 0.454 Umg-1specific activity after 65h of fermentation. © 2018 The Author(s).Item Isolation and identification of Pseudomonas from wastewater, its immobilization in cellulose biopolymer and performance in degrading Triclosan(Academic Press, 2019) Devatha, C.P.; Narasimhappa, N.Triclosan (TCS) is a well-known emerging contaminant got wide use in daily use products of domestic purpose, which provides the way to enter the ecological cycle, and is preferably detected in sewage treatment plants. In this study, TCS degrading bacteria (TDB) was isolated and identified from a wastewater treatment plant at the National Institute of Technology-Karnataka, Surathkal (NITK), India. The isolate was reported as Pseudomonas strain by performing 16S RNA Sequencing using BLAST analysis. Bacterial growth depends upon several environmental factors. Hence its growth optimization was carried out by response surface method (RSM) based central composite design (CCD) and validated by the artificial neural network (ANN). The Parameters or inputs used for optimization are pH, time (days), agitation (rpm) and sorbent dosage (?g/L). Experiments were conducted in batch mode to achieve optimum growth of bacteria based on RSM trial runs. The RSM model predictions were in better agreement with the experimental results and it was confirmed by ANN. The deviation lies within ±10% with experimental results compared to ANN for maximum trials. Hence optimized parameters were established and arrived at pH - 7, time - 13 days, agitation - 150 rpm, dosage - 1.5 ?g/L presented 69% removal of TCS. Minimum inhibitory assay of isolated strain was conducted to identify the degradation capacity of TCS and it was found out to be lesser than 0.025 mg of TCS. Later the strain was immobilized in two different matrices. One is biopolymer extracted from cellulose (Water Hyacinth) along with sodium alginate and second is free bacteria with sodium alginate and was made in the form of beads. The removal of TCS by TDB-cellulose-alginate (BCA) and TDB-Alginate (BA) beads were 58% and 30% respectively. Hence it was concluded that BCA beads showed effective removal compared to BA beads. Therefore, isolate can degrade TCS when the concentration ranges from 0.025 mg/L to 5.5 ng/L. © 2018 Elsevier Ltd