Pathophysiology of high fat diet induced obesity: impact of probiotic banana juice on obesity associated complications and hepatosteatosis.

The high fat diet alters intestinal microbiota due to increased intestinal permeability and susceptibility to microbial antigens leads to metabolic endotoxemia. But probiotic juices reported for various health benefits. In this background we hypothesized that pectinase treated probiotic banana juice has diverse effects on HFD induced obesity and non-alcoholic steatohepatitis. 20 weeks fed HFD successfully induced obesity and its associated complications in experimental rats. The supplementation of probiotic banana juice for 5 months at a dose of 5 mL/kg bw/day resulted significant decrease (p < 0.05) in body weight (380 ± 0.34), total fat (72 ± 0.8), fat percentage (17 ± 0.07) and fat free mass (165 ± 0.02). Reduction (p < 0.05) in insulin resistance (5.20 ± 0.03), lipid profile (TC 120 ± 0.05; TG 160 ± 0.24; HDL 38 ± 0.03), liver lipid peroxidation (0.7 ± 0.01), hepatic enzyme markers (AST 82 ± 0.06; ALT 78 ± 0.34; ALP 42 ± 0.22), and hepatic steatosis by increasing liver antioxidant potential (CAT 1.4 ± 0.30; GSH 1.04 ± 0.04; SOD 0.82 ± 0.22) with normal hepatic triglycerides (15 ± 0.02) and glycogen (0.022 ± 0.15) contents and also showed normal liver size, less accumulation of lipid droplets with only a few congestion. It is concluded that the increased intestinal S. cerevisiae yeast can switch anti-obesity, antidiabetic, antioxidative stress, antioxidant and anti-hepatosteatosis effect. This study results will have significant implications for treatment of NAFLD.

Characterization and molecular modeling of polygalacturonase isoforms from Saccharomyces cerevisiae.

Earlier, low-temperature-active polygalacturonase isoforms from Saccharomyces cerevisiae PVK4 were isolated and purified. Substrate specificity of polygalacturonase isoforms indicated high affinity for pectins and very low enzyme activity towards non-pectic polysaccharides. To characterize the polygalacturonase isoforms, biochemical, spectral, and in silico approaches were used. The apparent Km and Vmax values for hydrolysis of pectin and galacturonic acid were 0.31 mg/ml and 3.15 mmol min/mg, respectively. Interestingly, the polygalacturonase isoforms were found to be more stable at optimal pH and temperature of 4.5 and 40 °C, respectively. These isoforms were reacted with different metal ions; Cd2+ and Ni2+ severely inhibited the enzyme activity, while Mg2+, Zn2+, Cd2+, Fe2+ Cu2+, and Ni2+ inhibited to a lesser extent, which clearly demonstrated that variations in enzyme activity were due to their differential binding affinity of metal ions. Furthermore, decrease in the viscosity of polygalacturonic acid and citrus pectin by these isoforms was approximately four and six times higher than the rate of release of reducing sugars. This indicates that polygalacturonase isoforms have an endo-mode of action. In addition to the above, thermostability of purified polygalacturonase isoforms was studied by circular dichroism and fluorescence spectroscopy. Circular dichroism showed 18% alpha helix and 57% beta sheets at pH 5, while at pH 7, 8, and 9 there was an increase of random coil. Fluorescence studies revealed small conformational changes, which were observed at 30-50 °C, while unfolding transition region was noticed between 60 and 70 °C. The purified enzyme fractions were analyzed by MALDI-TOF MS. Finally, 3D model structures for isoenzymes of polygalacturonase of S. cerevisiae were generated and validated as good quality models, which are also suitable for molecular interaction studies.

Enhanced production of xylanase by solid state fermentation using Trichoderma koeningi isolate: effect of pretreated agro-residues.

The main objective of this study was to isolate the fungal strain for enhanced production of xylanase using different agro-residues and fruit peels by solid state fermentation and its potentiality was tested on the pretreated corn cob. Fermentation was carried out with Trichoderma koeningi isolate using untreated and pretreated corn cob supplemented with pineapple peel powder showed higher production of xylanase 2,869.8 ± 0.4 (IU/g) and extracellular protein 7.6 ± 0.2 (mg/g) of corn cob, in the latter than the former yielding 1,347.2 ± 0.7 (IU/g) and 4.9 ± 0.1 (mg/g) of corn cob, respectively, at pH 6.5 and incubation period for 96 h. In the FT-IR spectrum, the bands at 1,155, 1,252 and 1,738 cm-1 had disappeared. This indicates the depolymerization of hemicellulose and the band at 1,053 cm-1 shows the presence of ß (1-4)-xylan in the pretreated corn cobs. The pretreated biomass hydrolysed with a xylanase concentration of 14 U and 6 h incubation showed mainly xylose and its oligosaccharides, which were quantified using HPLC. From the results we can conclude that pretreated energy-value and cheaply available agro-residues can be effectively used as substrates for the enhanced production of xylanase.