Antimutagenicity of Lactic Acid Bacteria from "Idly" Against Food-Related Mutagens.

Lactic acid bacteria from "Idly", a traditional cereal pulse product of southern India, were evaluated for antimutagenic properties. Effect of their presence in Salmonella mutagenicity assay with foodborne mutagens like spice extracts, amino acid pyrolysates, and aflatoxins was examined. Variation of antimutagenic potential at different growth stages of these lactic acid bacteria was examined in time-course studies. The enzyme profile was examined to determine any possible relationship between antimutagenicity and enzymes in these lactic acid bacteria. Most of the lactic acid bacteria tested were found to decrease mutagenicities exerted by these mutagens significantly. Time-course studies showed that antimutagenic ability decreased in stationary phase of growth of lactic acid bacteria. There was no correlation between antimutagenicity and enzyme profile quantifying proteolytic, lipolytic, and other enzymes of carbohydrate metabolism. Lactic acid bacteria from "Idly" were found to be effective in suppressing the mutagenicities of the kinds encountered in foods.

Antidiabetic effect of Lactobacillus GG in streptozotocin-induced diabetic rats.

Neonatally streptozotocin-induced diabetic (n-STZ) rats were given food containing Lactobacillus GG cells (GG) or a control diet (control), from 9 to 18 weeks of age. The GG cells significantly lowered the blood hemoglobin A(1C) (HbA(1C)) level and improved glucose tolerance in n-STZ rats (p<0.05). In the GG group, the serum insulin level at 30 min after glucose loading was significantly higher than in the control group (p<0.05).

Selection of acid tolerant bifidobacteria and evidence for a low-pH-inducible acid tolerance response in Bifidobacterium longum.

Acidity is an environmental condition commonly encountered by lactic acid bacteria and bifidobacteria in the gastrointestinal tract and fermented foods. In the present study, 22 strains of Bifidobacterium were screened for acid tolerance in artificial gastric juice (AGJ, pH 3.0) and fermented milk. AGJ tolerance was found to be strain-specific, with a pronounced variation among the strains. Several strains with a high survival rate in AGJ that belonged to Bifid. longum, Bifid. breve and Bifid. adolescentis were selected. Among them, only strain BL1 of Bifid longum was found to possess a high survival rate in fermented milk during refrigerated storage. Strain BL1 exhibited a survival rate of more than 25% in AGJ at pH 3.0 for 2 h and maintained a viable cfu level of more than 10(8) per gram of product in fermented milk (pH 4.6) under refrigerated conditions for 2 weeks. The acid tolerance of strain BL1 was found to depend on the final growth pH (<4.5). Rapid loss of acid tolerance was observed when the cells were shifted from acid to neutral conditions by addition of NaOH. Strain BL1 cells were able to maintain much higher intracellular pH under acid conditions, in comparison with those of AGJ sensitive mutant (BL1-S) or cells that lost acid tolerance following pH shifting from acid to neutral conditions. These results suggested that a cytoplasmic pH homeostasis system may function in the acid tolerance response in this strain.