Modelling of growth kinetics of isolated Pseudomonas sp. and optimisation of parameters for enhancement of xanthine oxidoreductase production by statistical design of experiments

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.

Abstract: p-Chloro-meta-Xylenol (PCMX) is an environmentally hazardous phenolic compound having biocidal and antiseptic activity. Very few research publications addressed monitoring this contaminant. This paper presents a rapid sensing system to quantify it in waste water samples. The electrochemical activity of PCMX was exploited through a unique polymeric nanocomposite modified transducer for its quantification. Poly[(3,4-Ethylenedioxythiophene)-co-(o-phenylenediamine)] [P(EDOT-co-OPD)] was deposited through one-step electropolymerization technique on the glassy carbon electrode (GCE) modified by functionalized multi-wall carbon nanotubes (fMWCNTs). An optimized combination of these constituents was evaluated using response surface methodology (RSM) based Box-Behnken experimental design. This maximized the response for PCMX using differential pulse voltammetry (DPV). The sensing matrix was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The structural and morphological study of the modified film was conducted by Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), and field emission scanning electron microscope (FESEM). The anodic peak current could be read from a wide range of 0.5–225 μM calibration curve with a detection limit of 0.2545 μmol L−1. Interestingly this work did not use any biomaterial in the modification but achieved interference-free response with excellent selectivity, sensitivity (0.4668 μA μM−1 cm−2), reproducibility (RSD = 2.2%), and repeatability. The sensing platform showed good stability (85.7%) of 3 months even after 150 times repetitive use. Its applicability for real samples was established by good correlation with standard methods.

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.

Abstract: Since 1922 when Wu proposed the use of the Folin phenol reagent for the measurement of proteins, a number of modified analytical procedures utilizing this reagent have been reported for the determination of proteins in serum, in antigen-antibody precipitates, and in insulin. Although the reagent would seem to be recommended by its great sensitivity and the simplicity of procedure possible with its use, it has not found great favor for general biochemical purposes. In the belief that this reagent, nevertheless, has considerable merit for certain application, but that its peculiarities and limitations need to be understood for its fullest exploitation, it has been studied with regard to effects of variations in pH, time of reaction, and concentration of reactants, permissible levels of reagents commonly used in handling proteins, and interfering substances. Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.

Abstract: A new method called the neighbor-joining method is proposed for reconstructing phylogenetic trees from evolutionary distance data. The principle of this method is to find pairs of operational taxonomic units (OTUs [= neighbors]) that minimize the total branch length at each stage of clustering of OTUs starting with a starlike tree. The branch lengths as well as the topology of a parsimonious tree can quickly be obtained by using this method. Using computer simulation, we studied the efficiency of this method in obtaining the correct unrooted tree in comparison with that of five other tree-making methods: the unweighted pair group method of analysis, Farris's method, Sattath and Tversky's method, Li's method, and Tateno et al.'s modified Farris method. The new, neighbor-joining method and Sattath and Tversky's method are shown to be generally better than the other methods.

Abstract: The study of the growth of bacterial cultures does not constitute a specialized subject or branch of research: it is the basic method of Microbiology. It would be a foolish enterprise, and doomed to failure, to attempt reviewing briefly a \"subject\" which covers actually our whole discipline. Unless, of course, we considered the formal laws of growth for their own sake, an approach which has repeatedly proved sterile. In the present review we shall consider bacterial growth as a method for the study of bacterial physiology and biochemistry. More precisely, we shall concern ourselves with the quantitative aspects of the method, with the interpretation of quantitative data referring to bacterial growth. Furthermore, we shall considerz exclusively the positive phases of growth, since the study of bacterial \"death,\" i.e., of the negative phases of growth, involves distinct problems and methods. The discussion will be limited to populations considered genetically homogeneous. The problems of mutation and selection in growing cultures have been excellently dealt with in recent review articles by Delbriick (1) and Luria (2). No attempt is made at reviewing the literature on a subject which, as we have just seen, is not really a subject at all. The papers and results quoted have been selected as illustrations of the points discussed.

Abstract: A class of incomplete three level factorial designs useful for estimating the coefficients in a second degree graduating polynomial are described. The designs either meet, or approximately meet, the criterion of rotatability and for the most part can be orthogonally blocked. A fully worked example is included.