Optimization of food-grade medium for co-production of bioactive substances by Lactobacillus acidophilus LA-5 for explaining pharmabiotic mechanisms of probiotic.

This study aimed to optimize the co-production of conjugated linoleic acid (CLA), exopolysaccharides (EPSs) and bacteriocins (BACs) by Lactobacillus acidophilus LA-5 in dairy food-grade by-product. The factorial design revealed that the significant factors were temperature, time, and yeast extract. Then the response surface methodology was used for optimization. At the optimal conditions the viable cell number, CLA, EPSs, and inhibition activity were 2.62 ± 0.49 × 108 CFU/mL, 51.46 ± 1.50 µg/mL, 348.24 ± 5.61 mg/mL and 12.46 ± 0.80 mm, respectively. FTIR, GC, TLC, and SDS page analysis revealed the functional groups of pharmabiotics. The FTIR, GC, TLC, and SDS page analysis showed that both CLA isomers (c-9, t-11, and t-10, c-12) produced. The FTIR, GC, TLC, and SDS page analysis indicated that produced EPSs were composed of glucose, mannose, galactose, xylose, and fructose. FTIR, GC, TLC, and SDS page used to report BACs molecular weight, which showed two fractions by molecular mass 35 and 63 kDa. Previously the ability of different probiotic bacteria investigated and optimized the production of CLA, EPSs, and BACs, but, there was no report on the co-producing capacity of these bioactive metabolites by probiotics. The present work was investigated to optimize the co-production of pharmabiotic metabolites by L. acidophilus LA-5, in supplemented cheese whey as a cultivation medium.

Use of bacterial cellulose film modified by polypyrrole/TiO2-Ag nanocomposite for detecting and measuring the growth of pathogenic bacteria.

The aim of this study was to use of bacterial cellulose/polypyrrole/TiO2-Ag (BC/PPy/TiO2-Ag) nanocomposite film to detect and measure the growth of 5 pathogenic bacteria. For this purpose, at first, 13 BC/PPy/TiO2-Ag films were fabricated, then bacterial suspensions were prepared according to McFarland standard. The results showed that by increasing the bacterial concentration, the electrical resistance of sensors was decreased and there was a relation between bacterial concentration and bacterial type with electrical resistance change of sensors. The obtained data showed that the sensitivity of the sensors was increased with increasing the concentration of polypyrrole and TiO2-Ag. FT-IR and SEM tests were performed to investigate the interaction between nanoparticles and determine the size of nanoparticles. The BC/PPy/TiO2-Ag biosensors are portable and the response time of these sensors is very short for target analysis. Therefore, these sensors have the potential to improve biological safety as diagnostic tools.

Affecting parameters on fabrication of ß-D-galactosidase immobilized chitosan/poly (vinyl alcohol) electrospun nanofibers.

ß-galactosidase was successfully immobilized onto chitosan (CS)/polyvinyl alcohol (PVA) blend nanofibers through electrospinning. The effects of both polymer solution parameters and the electrospinning process conditions on the morphology of nanofibers and enzyme activity were studied. FESEM results showed that both morphology and diameter of the nanofibers were significantly influenced by the studied factors. The nanofiber mats obtained from CS/PVA at 50:50 mass ratio and conditions of 20 kV and 0.5 ml/h were selected as the optimized nanofibers, with the smallest diameter and most homogenous structure. On the other hand, catalytic activity of the ß-galactosidase -immobilized nanofibers (Enzyme-NF) was not significantly changed with these factors. The catalytic activity of Enzyme-NF was 57.03% of free enzyme activity at pH 6.8 and 4 °C. Furthermore, it showed more temperature stability compared to free ß-galactosidase at 50 °C. During 28 days of storage, Enzyme-NF samples retained 77% and 42% of its initial activity in 4 °C and 25 °C, respectively.