Proteomics Analysis of the Adhesion Activity of Lactobacillus acidophilus ATCC 4356 Upon Growth in an Intestine-Like pH Environment.

Many health effects of Lactobacillus acidophilus are desirable among these the adhesion ability is vital to enhance the possibility of colonization and stabilization associated with the gut mucosal barrier. In this study, the growth characteristics and the adhesion activity of L. acidophilus in the intestine-like pH environment (pH 7.5) are identified. The number of bacteria adhering to the HT-29 cells is found with a gradual increase trend (pH 5.5-7.5). This also leads to the morphological changes of L. acidophilus after exposure to different pH environments. Furthermore, with the help of the isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis, 207 proteins are detected differentially expressed at pH of 7.5. The use of GO analysis and KEGG analysis indicates three essential pathways related to the cell envelope peptide-glycan biosynthesis, carbohydrate metabolism, and amino acid metabolism are obviously changed. Adhesion related surface protein fmtB and PrtP are upregulated in pH 7.5 group. While the moonlight proteins like pyruvate kinase, which binds specifically to the mucin layer and inhibits the adhesive activity of L. acidophilus, is found downregulated. These results could be useful to understand the adhesion mechanism of L. acidophilus adapting for the gut mucosal barrier in the intestinal environment.

The Proliferation Mechanism of Lactobacillus plantarum RB1 Stimulated by Stachyose.

The proliferation mechanism of Lactobacillus plantarum RB1 promoted by stachyose was investigated in this work. The hydrolysis of stachyose, the glycometabolism, and the cytoactivity of L. plantarum RB1 were detected after proliferation. The specific activity of α-galactosidase of L. plantarum RB1 in the stachyose group was significantly higher than the control group (without stachyose), which indicated that the stachyose induced L. plantarum RB1 and produced more α-galactosidase to hydrolyze stachyose. The glycometabolism which includes glycolysis and tricarboxylic acid (TCA) cycle was significantly enhanced in the stachyose group compared with the control group. For the glycolysis, the reducing sugar content in the fermentation broth was significantly lower, while the lactic acid content and the specific activity of lactic dehydrogenase (LDH) as the key enzyme in glycolysis were higher than in the control group. For the TCA cycle, the specific activity of pyruvate dehydrogenase (PDH) as a gatekeeping enzyme leads glycolysis to TCA cycle energy-generating pathways was significantly enhanced compared with the control group. Moreover, the cell metabolic activity of L. plantarum RB1 in stachyose was significantly higher than the control group. These results indicated that the stachyose highly promotes proliferation of lactic acid bacteria (LAB) by inducing LAB to produce more α-galactosidase to hydrolyze stachyose, increasing glycometabolism and cytoactivity of LAB, which revealed the mechanisms how the stachyose promotes the proliferation of LAB.