Cell surface proteins play an important role in probiotic activities of Lactobacillus reuteri

BACKGROUND: Eight Lactobacillus reuteri strains, previously isolated from breast-fed human infant feces, were selected to assess the potential contribution of their surface proteins in probiotic activity. These strains were treated with 5 M LiCl to remove their surface proteins, and their tolerance to simulated stomach-duodenum passage, cell surface characteristics, auto aggregation, adhesion, and inhibition of pathogen adhesion to Caco-2 cells were compared with untreated strains. RESULTS: The survival rates, auto aggregation, and adhesion abilities of the LiCl-treated L. Reuteri strains decreased significantly (p< 0.05) compared to that of the untreated cells. The inhibition ability of selected L. reuteri strains, untreated or LiCl treated, against adherence of Escherichia coli 25922 and Salmonella typh iNCDC113 to Caco-2 was evaluated in vitro with L. reuteri ATCC55730 strain as a positive control. Among the selected eight strains of L.reuteri, LR6 showed maximum inhibition against the E. Coli ATCC25922 and S. typhiNCDC113. After treatment with 5 M LiCl to remove surface protein, the inhibition activities of the lactobacilli against pathogens decreased significantly (p< 0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated thatLR6 strains had several bands with molecular weight ranging from 10 to 100 KDa, and their characterization and functions need to be confirmed. CONCLUSIONS: The results revealed that the cell surface proteins of L. reuteri play an important role in their survivability, adhesion, and competitive exclusion of pathogen to epithelial cells.

Ground water quality in environmentally degraded localities of Panipat city, India.

Asystematic physico-chemical analysis of the groundwater at 41 different locations in Panipat city (Haryana), India has been taken up to evaluate its suitabilityfor domestic purposes. The data revealed considerable variations in the water samples with respect to chemical composition. For the analyzed water samples pH, EC, TDS, TA, TH, Na+, K+, Ca2+, HCO3-, Cl-, SO4(2-) and F(-) varied from 6.6-7.5, 0.09-3.28 mmhoS cm(-1), 700-2100 mg l(-1), 245-1054 mg l(-1) (as CaCO3), 153-520 mg l(-1) (as CaCO3), 57-560 mg l(-1), 5-22 mg l(-1), 36-95 mg l(-1), 298-1285 mg l(-1), 60-311 mgl(-1), 17-786 mg l(-1), 0.24-9.27 mg l(-1) respectively. All samples have high concentration of dissolved salts and all the samples were hard to very hard. Correlation coefficient "r" analysis has been worked out among different water quality parameters. The study shows a positive and significant, correlation of electrical conductivity with total dissolved salts (r = 0.979), total hardness (r = 0.507), sulphate (r = 0.453), total alkalinity (r = 0.725). Total hardness is positively and significantly correlated with magnesium (r = 0.833) and sulphate (r = 0.687). Where as total alkalinity was found to be positively and significantly correlated with bicarbonate (r = 0.992). Fluoride was higher than permissible limits in most of the samples.