OKTAY YERLIKAYA, MERVE ACU, ASLI
AKPINAR*, OZER KINIK
*Corresponding author
Ege University, Faculty of Agriculture, Dept. of Dairy Technology, 35100, Bornova-Izmir, Turkey

Abstract

In this study, probiotic properties of 25 lactic acid bacteria (Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus rhamnosus, Lactobacillus plantarum, Enterococcus faecium, Enterococcus durans and Lactococcus lactis) such as bile salt deconjugation and bile salt resistance levels were compared. Wild type lactic acid bacteria strains were particularly used in this study.The most effective bile salt deconjugation among these bacteria was determined in E. faecium 58K, this was followed by E. durans 42E, Lb. bulgaricus K78, Lb. rhamnosus B-442 and Lb. bulgaricus RF24. Regarding the bile salt resistance, the highest viability was determined in Lc. lactis L21, and Lb. bulgaricus strains were found to be more resistant than S. thermophilus. Additionally, viability was detected in two strains of Lb. rhamnosus, these were followed by E. faecium 58K and E. durans 42E. Regarding bile salt deconjugation, it was concluded that Enterococcus species might be more effective, and regarding the viability in bile salt, Lactococcus lactis L21 was found to be more resistant. The highest hydrophobic activity was detected in S. thermophilus 70S strain, while the lowest was determined in S. thermophilus 82S strain. This result showed that hydrophobic properties of lactic acid bacteria may vary depending on the strain.

INTRODUCTION

Lactic acid bacteria (LAB) consist of a large number of bacterial genera including the species used in the production of dairy products as starter cultures. The most frequently used species of lactic acid bacteria are Lactobacillus, Lactococcus, Enterococcus, Streptococcus, Pediococcus, Leuconostoc, Weissella, Carnobacterium, and Tetragenococcus. Some interesting physiological characteristics of some lactic acid bacteria such as sustaining viability in the gastrointestinal tract allow them to be potentially used as probiotics. The ability of lactic acid bacteria to sustain viability in the gastrointestinal tract is associated with their ability to sustain viability in low pH and/or in the presence of bile salt and in a wide temperature range (1-5).

Bile salt deconjugation has an important role particularly in the regulation of intestinal microflora and reducing serum cholesterol levels. Before leaving the liver, bile acids are conjugated with one molecule of glycine or taurine amino acids. Conjugation is provided by amide base formed between the carboxyl group of the bile acids and the amino groups of the compound added. These novel ...