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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...com 9076 AGING MiRNA reveals a biological function by affecting the expression of a target gene by incompletely binding to a target gene [23]....
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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.
3 citations
TL;DR: In this paper , a novel isolated phenol-resistant gram-negative bacterium, Pandoraea sp. strain BT102, is encapsulated in biopolymeric calcium alginate beads.
1 citations
References
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TL;DR: Comparison of results obtained in continuous culture with results from exponential‐feed culture systems is shown to offer a novel experimental method for evaluating the effect of the cell age distribution on the properties and metabolic activity of a culture.
Abstract: High substrate concentrations inhibit growth and may distort the metabolism of microorganisms. Mechanisms causing substrate inhibition are discussed and used to derive several mathematical models representative of the entire concentration range, including stimulation of growth by low substrate concentrations. These kinetic models are tested with a variety of batch culture measurements of specific growth rate and respiration rate at widely-ranging substrate concentrations. Using one of the kinetic models, equations are developed for batch, continuous, and exponential-feed reactors. Comparison of results obtained in continuous culture with results from exponential-feed culture systems is shown to offer a novel experimental method for evaluating the effect of the cell age distribution on the properties and metabolic activity of a culture.
521 citations
TL;DR: The enzyme appears as an oxidase in the supernatant of rat heart, intestine, spleen, pancreas, lung and kidney and the enzyme of all organs but intestine can be converted into a dehydrogenase by dithioerythritol.
Abstract: 1. The ;xanthine oxidase' activity of rat liver supernatant, most of which behaves as an NAD(+)-dependent dehydrogenase (type D) can be rapidly converted into an oxidase (type O) by thiol reagents such as tetraethylthiuram disulphide, copper sulphate, 5,5'-dithiobis-(2-nitrobenzoic acid), N-ethylmaleimide and p-hydroxymercuribenzoate. Treatment with copper sulphate, if prolonged, leads to almost complete inactivation of the enzyme. The effect of these reagents is prevented by dithioerythritol, and in all cases but that of N-ethylmaleimide is reversed by the same thiol. 2. Dithioerythritol prevents and reverses the conversion of xanthine oxidase from type D into type O brought about by storage of rat liver supernatant at -20 degrees C, preincubation under anaerobic conditions, treatment with carbon or with diethyl ether, and reverses, but does not prevent, the conversion obtained by preincubation of the whole liver homogenate. 3. Conversion of the enzyme from type D into type O is effected by preincubation of rat liver supernatant with the sedimentable fraction from rat liver but not from chick or pigeon liver. The xanthine dehydrogenase activity of chick liver supernatant is not changed into an oxidase by preincubation with the sedimentable fraction from rat liver. 4. The enzyme activity of rat liver supernatant is converted from type D into type O during purification of the enzyme: the purified enzyme can be reconverted into type D by dithioerythritol. 5. The enzyme appears as an oxidase in the supernatant of rat heart, intestine, spleen, pancreas, lung and kidney. The enzyme of all organs but intestine can be converted into a dehydrogenase by dithioerythritol.
410 citations
Additional excerpts
...Corte and Stirpe([3]) reported XDH as a...
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...[2] Corte and Stirpe[3] reported XDH as a native form of XOD and both are responsible to control the rate limiting step of nucleic acid oxidation....
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TL;DR: There is a need to extend such studies to pilot scale as well as to full-scale field applications on microbial potentials to degrade chemical pollutants.
Abstract: Microbial growth on and utilization of environmental contaminants as substrates have been studied by many researchers. Most times, substrate utilization results in removal of chemical contaminant, increase in microbial biomass and subsequent biodegradation of the contaminant. These are all aimed at detoxification of the environmental pollutants. Several microbial growth and biodegradation kinetic models have been developed, proposed and used in bioremediation schemes. Some of these models include Monod’s, Andrews, Bungay’s weighted model, general substrate inhibition models (GSIM) and sum kinetic models. Most research on microbial potentials to degrade chemical pollutants has been performed on a laboratory scale. There is a need to extend such studies to pilot scale as well as to full-scale field applications.
Key words: Microbial growth, substrate utilization, biodegradation, kinetics, detoxification, organic contaminants, models, environmental pollutants.
243 citations
"Modelling of growth kinetics of iso..." refers background in this paper
...Study of growth kinetic models may explain the effect of substrate on the microbial growth and further production of enzyme.([16]) The first empirical Monod model for microbial growth kinetics was related to the increased rate of microbial growth with substrate concentration but did not explain substrate inhibition kinetics....
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TL;DR: One or more molybdenum hydroxylases have been found in organisms as different in complexity as man and bacteria, and in mammal's oxidation of hypoxanthine to xanthine and of x anthine to uric acid are steps in purine catabolism prior to excretion.
Abstract: Publisher Summary This chapter describes the enzymes, xanthine oxidase, xanthine dehydrogenase, aldehyde oxidase, and sulfite oxidase. In addition to the molybdenum hydroxylases, sulfite oxidase is discussed in this chapter, though it contains heme rather than flavin and no iron-sulfur. This is because it contains molybdenum, apparently in a chemical environment within the active center, which is quite like that of the metal in the other enzymes. The term xanthine oxidase is to be taken to refer to the enzyme from milk. The enzymes to be considered are widely distributed. Thus, one or more molybdenum hydroxylases have been found in organisms as different in complexity as man and bacteria. In mammal's oxidation of hypoxanthine to xanthine and of xanthine to uric acid are steps in purine catabolism prior to excretion, uric acid being the end product in primates. Individual humans, genetically deficient in xanthine oxidase, are apparently little the worse for the deficiency. The reduced oxygen derivatives are supposed to be available for coupled oxidation reactions—for example, in drug catabolism. The most obvious objection to this hypothesis is the conclusion, discussed in the chapter, that the dehydrogenase form of the xanthine-oxidizing enzymes is more native than is the oxidase form. It must be conceded that the true role of the enzymes in humans and many other species remains somewhat problematical.
186 citations
TL;DR: Evidence is presented that the Cys535 and Cys992 residues of rat liver enzyme are indeed involved in the rapid conversion from the dehydrogenase to the oxidase, and that these residues are responsible for the slow conversion.
138 citations
"Modelling of growth kinetics of iso..." refers background in this paper
...doprterin domains or by oxidation of sulfhydryl residues of protein molecule.([2]) Corte and Stirpe([3]) reported XDH as a...
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...XN or HX oxidation has been reported to take place in molybdopterin centre.([1,2,42]) Here, XDH and XOD are interconversible by proteolytic cleavage....
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...(6) In the presence of NADþ cofactor, enzyme activity was enhanced by about 50% confirming the preference of NADþ reduction at the FAD site.([2,9,10]) Specific activities were expressed as micromoles of substrate transformed per minute per milligram of protein at 25 C....
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...[2,10,41] Thus molecular weight of the subunits of xanthine oxidizing enzyme were nearly same even though source of enzyme varied....
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