Enhancing flora balance in the gastrointestinal tract of mice by lactic acid bacteria from Chinese sourdough and enzyme activities indicative of metabolism of protein, fat, and carbohydrate by the flora

In this study, we investigated the effect of administration of 5 strains of lactic acid bacteria (LAB) isolated from traditional Chinese sourdough on the flora balance of gastrointestinal tract of mice. We specifically measured Enterococcus, Enterobacter, Bacteroides, and Lactobacillus by plate count and real-time PCR methods, and α-glucosidase, lactate dehydrogenase, esterase, and aminopeptidase activities as indicative of metabolism of sugar, fat, and protein from LAB isolated from feces of mice in vitro. The results showed that administration of Lactobacillus acidophilus LAC0201 and Lactobacillus fermentum LFE0302 lowered the uricacid index of serum. Lactobacillus acidophilus LAC0201, L. fermentum LFE0302, as well as Lactobacillus curvatus LCU0401 administration resulted in a reduction in the opportunistic pathogens (i.e., Enterococcus and Enterobacter), meanwhile, administration of L. fermentum LFE0302 and Lactobacillus sp. ULA0104 resulted in an increase in the counts of Lactobacillus. Lactobacillus fermentum LFE0302 administration increased starch digestion of intestinal flora after 4 wk of feeding and also resulted in increased α-glucosidase activity in the intestinal flora after 3 wk of feeding. We found a similar trend in esterase activity after administration of L. acidophilus LAC0201 for 3 wk. Hence, our study suggested that LAB from Chinese sourdough might be used as potential probiotics to strengthen the flora balance in gastrointestinal tract and positively change the metabolism of nutrients through bacterial enzyme activities.