Prediction of heavy metal biosorption mechanism through studying isotherm kinetic equations.

The kinetic constants for free and immobilized cells were determined by measuring reaction rates at different metal concentrations at the optimum reaction conditions. (Kmax and Vmax) were calculated from the slope and intercept of the straight lines. The pseudo-second-order rate constants are derived based on the sorption capacity of the solid phase, where K2 is the rate constant for the pseudo-second-order model. Determined experimentally by plotting t/q against t. The mean free vitality of adsorption (E) was figured as 2.62 kJ mol-1 and the extent of E communicated gives data on the adsorption mechanism. An E value ranging from 1 to 8 indicates physisorption and 8-16 kJ mol-1 predicts ion exchange. Thus, the evaluated value of 2.62 kJ mol-1 predicts the phenomenon of physisorption, which suggests that metal ions were favorably adsorbed by this biosorbent in a multi-layer fashion. The overall result suggested that 98.2% of U (VI) by biosorption of U in the mechanism of adsorption will include chemisorption mechanistic pathway: Langmuir, Freundlich, equations and the values of Kf 5.791 where KL 3.9 were determined from the linear plot of log qe vs. log Ce at 30 °C, indicating that metal ions were favorably adsorbed by this biosorbent in a multi-layer fashion and instrumentation of beads characterizing novel Binding sites using FTIR & SEM beside change in peaks position which assigned for its groups confirm biosorption of metal.

Cholesterol-lowering effects and safety assessment of Lactobacillus spp. in vivo and in vitro testing for human use as probiotic from the dairy product in Egypt.

BACKGROUND: The toxicity profile of lactobacilli may be strain dependent, so it should be considered for safe utilization of probiotics. Further, in vivo studies are necessary to evaluate their safety. RESULT: The ability of various probiotic strains to hydrolyze bile salts has been confirmed without noticeable hemolytic activity. Results revealed the presence of α-glucosidase, ß-glucosidase, α-galactosidase, and ß-galactosidase activity in all investigated isolates, while none of the isolates produced the carcinogenic enzyme ß-glucuronidase. The probiotic strains exhibited remarkable cholesterol-lowering impact. Also, we found no evidence of chronic toxicity under the experimental conditions based on gross pathological examination of the viscera and study of the spleen and liver weight ratios. These findings indicated that the investigated strains, either alone or combined with their metabolites, had no obvious adverse effect on the mice's general health status. CONCLUSION: There is prove that the investigated probiotic strains are safe to be utilized for enhancing of the growth performance and are free of adverse side effects.