ABSTRACT
In this study functional characteristics of 23 representative Lactobacillus strains isolated from the Maasai traditional fermented milk 'Kule naoto' were determined. The Lb. acidophilus group strains showed resistance to gastric juice and bile. In addition, some Lb. acidophilus strains expressed bile salt hydrolase activity, and had ability to assimilate cholesterol in vitro. In-vitro adhesion to HT29 MTX cells of up to 70% was recorded. Lb. fermentum strains showed almost 100% survival under simulated stomach acidic conditions and physiological salt concentrations of bile salts, hydrophobicity values were over 80%. Most strains of the Lb. casei and Lb. acidophilus groups showed aggregation abilities of above 50%. Many strains expressed a protective effect against N-methyl-N'-nitro-N-nitrosoguanidine induced DNA damage according to the 'comet assay' and none was virulent. The antibiotic minimum inhibitory concentration of selected strains was established. According to these results, the Lactobacillus spp associated with 'Kule naoto', contain potentially probiotic (functional) strains.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Adhesion/physiology , Cultured Milk Products/microbiology , Drug Resistance, Bacterial , Lactobacillus/physiology , Probiotics , Bile/microbiology , Cell Line , Colony Count, Microbial , Comet Assay , Dose-Response Relationship, Drug , Food Microbiology , Humans , Hydrogen-Ion Concentration , Kenya , Lactobacillus/drug effects , Lactobacillus/growth & development , Microbial Sensitivity Tests , Microbial ViabilityABSTRACT
From 22 samples of kule naoto, the traditional fermented milk products of the Maasai in Kenya, 300 lactic acid bacterial strains were isolated and phenotypically characterised by their ability to ferment different carbohydrates and by additional biochemical tests. Lactic acid bacteria (LAB), especially the genus Lactobacillus, followed by Enterococcus, Lactococcus and Leuconostoc, dominated the microflora of these samples. The major Lactobacillus species was Lactobacillus plantarum (60%), with a lower frequency of isolation for Lactobacillus fermentum, Lactobacillus paracasei and Lactobacillus acidophilus. Most strains produced enzymes such as beta-galactosidase and peptidases, which are of relevance to cultured dairy product processing, and exhibited similar patterns of enzymatic activity between species. Enterobacteriaceae could not be detected in 15 out of 22 samples (detection level 10(2)/ml). Conversely, yeasts (detection level 10(1)/ml) were detected in those samples in which Enterobacteriaceae were not found. The pH values of all these samples were < 4.5.
