Trans-N-deoxyribosylase,i the enzyme that catalyzes deoxyribosyl transfer from deoxyribonucleosides to free purines and pyrimidines, was first demonstrated by MacNutt in Lactobacillus helveticus (1). It was subsequently found in other lactobacilli and related organisms that require deoxyribonucleosides for growth (2, 4). The nature of the reaction and the nonparticipation of phosphate were esta...

In recent years interest in the probiotic lactobacilli has been stimulated by the use of these bacteria in products that are claimed to confer health benefits on the consumer. The probiotic effects are usually strain-specific, meaning that a correct identification is important to link the strain to the specific health effect. Taxonomical characterization of probiotic strains only in phenotypic ...

Lactobacillus helveticus strain LP27 produced a bacteriocin, lactocin 27, in dialyzable and nondialyzable forms. No evidence was obtained to indicate that lactocin 27 was under the control of extrachromosomal plasmids. Lactocin 27 had a bacteriostatic effect on the indicator, Lactobacillus helveticus strain LS18. It inhibited primarily protein synthesis without affecting deoxyribonucleic acid a...

Lactobacillus helveticus is one of the species of lactic acid bacteria (LAB) most commonly used in the production of fermented milk beverages and some types of hard cheese. The versatile nature of this bacterium is based on its highly efficient proteolytic system consisting of cell-envelope proteinases (CEPs), transport system and intracellular peptidases. Besides use of L. helveticus in cheese...

Mucosal epithelia constitute the first barriers to be overcome by pathogens during infection. The induction of protective IgA in this location is important for the prevention of infection and can be achieved through different mucosal immunization strategies. Lactic acid bacteria have been tested in the last few years as live vectors for the delivery of antigens at mucosal sites, with promising ...

The conversion of amino acids into volatile and nonvolatile compounds by lactic acid bacteria in cheese is thought to represent the rate-limiting step in the development of mature flavor and aroma. Because amino acid breakdown by microbes often entails the reversible action of enzymes involved in biosynthetic pathways, our group investigated the genetics of amino acid biosynthesis in Lactobacil...

The photocatalytic inactivation of Gram negative Escherichia coli and Gram positive Lactobacillus helveticus by both TiO2 and ZnO with 365-nm ultraviolet (UV) light was studied in a batch reactor. Almost all the initial E. coli cell (10 CFU/ml) were inactivated in 40 min in the presence of 2 g/l ZnO. Photocatalytic inactivation of bacteria was found to follow first order kinetics with the highe...

Here, we used pyrosequencing to obtain a detailed analysis of the microbial diversities of traditional fermented dairy products of Mongolia. From 22 Airag (fermented mare's milk), 5 Khoormog (fermented camel's milk) and 26 Tarag (fermented milk of cows, goats and yaks) samples collected in the Mongolian provinces of Arhangai, Bulgan, Dundgobi, Tov, Uburhangai and Umnugobi, we obtained a total o...

Lactobacilli have been shown to promote health functions. In this study, we analyzed the mechanism by which four different strains of probiotics affected innate immunity, such as regulation of ROS, cytokines, phagocytosis, bactericidal activity, signaling by NF-κB pp65, and TLR2 activation. The production of ROS was dependent on the concentration and species of Lactobacillus. The results obtain...