Modelling of growth kinetics of isolated Pseudomonas sp. and optimisation of parameters for enhancement of xanthine oxidoreductase production by statistical design of experiments
01 Mar 2019-Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering (Taylor & Francis)-Vol. 54, Iss: 1, pp 65-78
TL;DR: The effects of S0, pH and temperature were studied by Box-Behnken experimental design to evaluate the interactive effects of the significant variables influencing XOR production by CEBP1 and validated the second order polynomial model for the enzyme production.
Abstract: This report presents the substrate inhibitory effect of xanthine (XN) on microbial growth and optimisation of effective parameters to achieve high enzyme activity of xanthine oxidoreductase (XOR) t...
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15 May 2020
TL;DR: Overexpression of TSLP and JAK-STAT signaling pathway activation could reverse the effects of miR-142-5p on NASH, which might be a novel latent target for NASH therapy.
Abstract: This study aimed to figure out the underlying mechanism of miR-142-5p in the non-alcoholic steatohepatitis (NASH). Bioinformatics, luciferase assay and Western blot were performed. The NASH mouse model was established through feeding a high fat diet (HFD). Relative expressions of miR-142-5p, thymic stromal lymphopoietin (TSLP), inflammatory factors were detected by qRT-PCR. The injury level of liver was assessed via measurement of serum alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST). H&E staining and Masson's trichrome staining examine the liver fatty degeneration and fibrosis. MiR-142-5p and TSLP were differentially expressed and JAK-STAT signaling pathway was activated in the NASH group. Luciferase assay identified that TSLP was the downstream target of miR-142-5p. Through overexpression of miR-142-5p, ALT and AST in serum were inhibited, pro-inflammatory factors, liver fatty degeneration and fibrosis in liver tissues were decreased, while anti-inflammatory factors were increased. Overexpression of TSLP and JAK-STAT signaling pathway activation could reverse the effects of miR-142-5p on NASH. Taken together, overexpression of miR-142-5p could attenuate NASH progression via inhibiting TSLP and JAK-STAT pathway. MiR-142-5p might be a novel latent target for NASH therapy.
13 citations
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TL;DR: In this article, a novel polymeric nanocomposite modified transducer for quantification of p-Chloro-meta-Xylenol (PCMX) is presented.
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TL;DR: In this paper , a new design of biosensor based on polymeric nano(bio)composite has been proposed for the selective detection of xanthine to be used in the clinical analysis as well as food quality control.
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TL;DR: In this paper, the authors proposed a computational approach to calculate specific bacterial growth rate time-averaged over the entire sigmoidal log phase (including the decelerating phase) for incorporating the effect of metabolite-inhibition, in contrast to conventional studies where only the initial part (accelerating) of log phase was considered.
Abstract: A rigorous knowledge of the bacterial growth kinetics is essential for the scaling-up and optimization of biodegradation process conditions in a bioreactor. Although a great deal of literature is available on the modeling of bacterial growth kinetics considering the inhibition at high substrate-loading, the inhibition caused by toxic metabolic byproducts was not accounted in the bacterial growth kinetics. This work primarily aimed at developing a parametric bacterial growth model to account for metabolite inhibition, indicated by a decelerating log-phase growth, which was rarely discussed in the previous studies. An efficient azo-dye degrading bacterium (Bacillus subtilis MN372379) was isolated from the sludge-waste nearby a carpet-dyeing unit. The isolated bacterial strain was used to decolorize the simulated wastewater containing Congo red dye. This study proposed a computational approach to calculate specific bacterial growth rate time-averaged over the entire sigmoidal log phase (including the decelerating phase) for incorporating the effect of metabolite-inhibition, in contrast to the conventional studies where only the initial part (accelerating) of log phase was considered. The nature of metabolite inhibition was also determined and found to be non-competitive. Next, the computed time-averaged specific bacterial growth rate was incorporated into three substrate inhibition models to account for both, the metabolite and substrate inhibitions, and subsequently their kinetic parameters were also determined. Finally, the initial dye concentration and inoculum size were optimized to yield maximum dye utilization rate. This study paves the way for predicting bacterial growth kinetic with improved accuracy to enable a better optimization of bioreactors at the industrial scale.
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TL;DR: In this paper , a novel isolated phenol-resistant gram-negative bacterium, Pandoraea sp. strain BT102, is encapsulated in biopolymeric calcium alginate beads.
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References
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TL;DR: Although the bacterial enzyme exhibits a 6-7-fold greater turnover rate than bovine or avian enzymes, the catalytic efficiencies (as measured by V/K) are similar for all three enzymes.
Abstract: Xanthine dehydrogenase (XDH) is induced in Comamonas acidovorans cells incubated in a limited medium with hypoxanthine as the only carbon and nitrogen source. The enzyme has been purified to homogeneity using standard techniques and characterized. It contains two subunits with M(r) values of 90 and 60 kDa. Gel filtration studies show the enzyme to have an alpha 2 beta 2 native structure. No precursor form of the enzyme is observed on Western blot analysis of cell extracts obtained at various stages of enzyme induction. Metal analysis of the purified enzyme shows 1.1 Mo, 4.0 Fe, and 3.6 phosphorus atoms per alpha beta protomer. Cofactor analysis shows the enzyme to contain a single molybdopterin mononucleotide and one FAD per alpha beta protomer. Electron spin resonance and circular dichroism spectral studies of the oxidized and reduced forms of the enzyme suggest the Fe centers to be two nonidentical [2Fe-2S] clusters. Electron spin resonance signals due to Mo(V) and neutral FAD radical are also observed in the reduced form of the enzyme. Purified enzyme preparations ranged from 70% to 100% functionality. The enzyme is irreversibly inactivated by CN- and is inhibited on incubation with allopurinol. With xanthine and NAD+ as substrates the enzyme has a specific activity of 50 units/mg, a kcat value of 120 s-1, an activity/flavin ratio of 1930, and respective Km values of 66 and 160 mM. Using 8-D-xanthine as substrate, a DV value of 1.8 is found with no change in Km. Thus, the Km and KD values of the enzyme for xanthine are equal. These data show Comamonas XDH to exhibit structural properties similar to bovine milk xanthine oxidase/dehydrogenase and to chicken liver xanthine dehydrogenase. Although the bacterial enzyme exhibits a 6-7-fold greater turnover rate than bovine or avian enzymes, the catalytic efficiencies (as measured by V/K) are similar for all three enzymes.
29 citations
"Modelling of growth kinetics of iso..." refers background in this paper
...From the published literature it was noted that the structure of prokaryotic XDH differed considerably with respect to its molecular mass, subunit compositions and redox active site with variation of isolated species such as Pseudomonas putida,Rhodobacter capsulatus,([9,10]) Comamonas acidovorans.([11]) It was also reported that XDH isolated from Bacillus subtilis has three catalytic subunits with theoretical molecular masses of 30, 80 and 19 kDa([43]) and purified xanthine oxidase isolated from P....
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...Several bacterial species, such as Pseudomonas putida, Rhodobacter capsulatus, Comamonas acidovorans([11]) synthesise xanthine dehydrogenase (XDH) using purine alkaloids (i....
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TL;DR: The isolation of a xanthine dehydrogenase from Pseudomonas putida 40 which utilizes ferricyanide as an electron acceptor at high efficiency is presented and reveals a series of major and minor activity bands which display some selectivity toward both electron donors and acceptors.
Abstract: The isolation of a xanthine dehydrogenase from Pseudomonas putida 40 which utilizes ferricyanide as an electron acceptor at high efficiency is presented. The new activity is separate from the NAD+ and oxygen-utilizing activities of the same organism but displays a broad pattern for reducing substrates typical of those of previously studied xanthine-oxidizing enzymes. Unlike the previously studied enzymes, the new enzyme appears to lack flavin but possess heme and is resistant to cyanide treatment. However, sensitivity of the purified enzyme to methanol and the selective elimination of the activity when tungstate is added to certain growth media suggest a role for molybdenum. The enzyme is subject to a selective proteolytic action during processing which is not accompanied by denaturation or loss of activity and which is minimized by the continuous exposure of the activity to EDTA and phenylmethylsulfonyl fluoride. Electrophoresis of the denatured enzyme in the presence of sodium dodecyl sulfate suggests that the enzyme is constructed of subunits with a molecular weight of approximately 72,000. Electrophoresis under native conditions of a purified enzyme previously exposed to magnesium ion reveals a series of major and minor activity bands which display some selectivity toward both electron donors and acceptors. An analysis of the effect of gel concentration on this pattern suggests that the enzyme forms a series of charge and size isomers with a pair of trimeric forms predominating. Comparison of the rate of sedimentation of the enzyme in sucrose gradients with its elution profile from standardized Sepharose 6B columns suggests a molecular weight of 255,000 for the major form of the native enzyme.
20 citations
TL;DR: High Ki and Ki′ values and extremely high Ks and Ks′ values indicated that NJUST18 was able to grow on pyridine within a wide concentration range, especially at relatively high concentrations.
Abstract: Biodegradation of pyridine by a novel bacterial strain, Rhizobium sp. NJUST18, was studied in batch experiments over a wide concentration range (from 100 to 1,000 mg l−1). Pyridine inhibited both growth of Rhizobium sp. NJUST18 and biodegradation of pyridine. The Haldane model could be fitted to the growth kinetics data well with the kinetic constants μ* = 0.1473 h−1, Ks = 793.97 mg l−1, Ki = 268.60 mg l−1 and Sm = 461.80 mg l−1. The true μmax, calculated from μ*, was found to be 0.0332 h−1. Yield coefficient YX/S depended on Si and reached a maximum of 0.51 g g−1 at Si of 600 mg l−1. Vmax was calculated by fitting the pyridine consumption data with the Gompertz model. Vmax increased with initial pyridine concentration up to 14.809 mg l−1 h−1. The qS values, calculated from \(V_{ \hbox{max} }\), were fitted with the Haldane equation, yielding qSmax = 0.1212 g g−1 h−1 and q* = 0.3874 g g−1 h−1 at Sm′ = 507.83 mg l−1, Ks′ = 558.03 mg l−1, and Ki′ = 462.15 mg l−1. Inhibition constants for growth and degradation rate value were in the same range. Compared with other pyridine degraders, μmax and Sm obtained for Rhizobium sp. NJUST18 were relatively high. High Ki and Ki′ values and extremely high Ks and Ks′ values indicated that NJUST18 was able to grow on pyridine within a wide concentration range, especially at relatively high concentrations.
18 citations
01 Jan 2014-Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering
TL;DR: Five phenol-degrading bacterial species designated as CUPS-1 toCUPS-5 were isolated from the oil-effluent dumped sites of Haldia Industrial area of West Bengal, India and proved potential phenol degraders and hence used for biodegradation studies.
Abstract: Microbial degradation of phenol by pure bacterial species is a well-known approach towards alleviation of environmental pollution. In this study, five phenol-degrading bacterial species designated as CUPS-1 to CUPS-5 were isolated from the oil-effluent dumped sites of Haldia Industrial area of West Bengal, India. Detailed morphological, biochemical and molecular characterization identified CUPS-3 as a novel strain- Stenotrophomonas maltophilia (GU358076), while the others could be identified as Pseudomonas (CUPS-2, 5), Delftia (CUPS-1) and Micrococcus (CUPS-4) genera, respectively. Although all of these strains utilized phenol as their sole carbon source supporting growth, three among them, CUPS-2, CUPS-3 and CUPS-5 proved potential phenol degraders and hence used for further biodegradation studies. Degradation experiments were carried out for several initial phenol concentrations of 500 mg/L, 750 mg/L, 1000 mg/L, 1250 mg/L and 1500 mg/L. The novel strain, CUPS-3 could completely degrade 500 mg/L phenol w...
17 citations
"Modelling of growth kinetics of iso..." refers background in this paper
...Same pattern of result was reported for phenol degradation by Pseudomonas puida L.([24,25]) and cellulase production by Cellulomonas cellulans NRRL B4567([37])....
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TL;DR: This is the first report on production of high levels of caffeine demethylase in batch bioreactor with faster degradation rate and high tolerance to caffeine, hence clearly suggesting that Pseudomonas sp.
Abstract: The effect of various initial caffeine concentrations on growth and caffeine demethylase production by Pseudomonas sp. was studied in bioreactor. At initial concentration of 6.5 g l−1 caffeine, Pseudomonas sp. showed a maximum specific growth rate of 0.2 h−1, maximum degradation rate of 1.1 g h−1, and caffeine demethylase activity of 18,762 U g CDW−1 (CDW: cell dry weight). Caffeine degradation rate was 25 times higher in bioreactor than in shake flask. For the first time, we show highest degradation of 75 g caffeine (initial concentration 20 g l−1) in 120 h, suggesting that the tested strain has potential for successful bioprocess for caffeine degradation. Growth kinetics showed substrate inhibition phenomenon. Various substrate inhibition models were fitted to the kinetic data, amongst which the double-exponential (R
2 = 0.94), Luong (R
2 = 0.92), and Yano and Koga 2 (R
2 = 0.94) models were found to be the best. The Luedeking–Piret model showed that caffeine demethylase production kinetics was growth related. This is the first report on production of high levels of caffeine demethylase in batch bioreactor with faster degradation rate and high tolerance to caffeine, hence clearly suggesting that Pseudomonas sp. used in this study is a potential biocatalyst for industrial decaffeination.
16 citations