Studies On Probiotic Characteristics Of Lactobacillus Plantarum ZDY2013 And Its Regulation Under Acid Stress As Well As Modulatory Effect On Gut Microbiota Of Mice

Lactic acid bacteria are capable of regulating gastrointestinal microflora and promoting health of the host. In China there are abundant resources of lactic acid bacteria, however, there is still a gap for the research and development of probiotics with patent, high-quality and stress tolerance properties, when compared with other developed countries.In this paper, Lactobacillus plantarum ZDY2013 was obtained from Chinese traditional fermented foods(beans acid), and evalutated for its survival capacity under extreme environmental conditions(acid, bile salt, gastrointestinal fluids, and antibiotics). Our results showed that ZDY2013 kept a normal growth tendency in the MRS at p H 3.5, even maintaining a high survival ratio in MRS at p H 2.0 or with 0.3% bile salt. In simulated gastrointestinal fluid transfereing process, ZDY2013 achieved survival ratio as high as 65.84%. In addition, after fermentation in MRS for 24 h, expolysaccharide of ZDY2013 was up to 204 ± 7.68 mg/L in p H less than 3.5. Supernatant of ZDY2013 was capable of inhibiting the eight food-borne pathogens, including Listeria monocytogenes and Salmonella Typhimurium etc. Tolerantce of ZDY2013 to partial antibiotics suggested that ZDY2013 could be used as an joint therapy for regulating intestinal flora.Considering outstanding acid resistance of Lactobacillus plantarum ZDY2013, we further analyzed the acid response mechanism of ZDY2013. Gas chromatography-mass spectrometry(GC-MS) and reverse transcription-quantitative PCR(RT-q PCR) were used to analyze the changing of the cell membrane fatty acids and m RNA levels of ZDY2013 under acidic conditions. A comparison of composition of cell membrane fatty acids(CMFA) between acid challenged and unchallenged cells showed that acid adaption evoked a significantly higher percentage of saturated fatty acid and cyclopropane fatty acid in the former than the latter. In addition, analysis in acid-adapted cells at different p H values(ranging from 3.0 to 4.0) indicated that several genes were differently regulated, including those related to proton pumps, amino acid metabolism and sugar metabolism, and class I and class III stress response pathways. Remarkably, gene expression of arginine metabolic pathway was significantly up-regulated(p<0.05), wherein ornithine carbamyl transferase gene arg F, refined amino acid synthase gene arg G, arginine catabolic enzymes regulating gene arg R underwent a significant increase, 17.90, 5.26, 3.41 folds respectively. The results suggest that the enhancement of arginine metabolic flux and the coping mechanisms of Lactobacillus plantarum ZDY2013 under acid stress are particularly relevant.In order to verify the ability of ZDY2013 to regulate the intestinal microflora, PCR-DGGE and q PCR technology were used to analyze the regulation of intestinal flora in mice by ZDY2013. DGGE profile demonstrated that ZDY2013 administration altered the composition of the microbiota at various intestinal loci of the mice. Among them, the change in the cecum area the most significant, bacterial abundance significant increased(p<0.05). PCA analysis showed that, ZDY2013 fed and control groups of digitizing dotted go to a different area. Moreover, the q PCR test showed that the administration of ZDY2013 enhanced the populations of Bifidobacterium and Lactobacillus group in either colon or caecum, and reduced the potential enteropathogenic bacteria e.g. Enterococcus, Enterobacterium and Clostridium perfringens.In summary, Lactobacillus plantarum ZDY2013 is a potential probiotic strain with diverse pressure regulation mechanism, withstanding of extreme environment, and flora modulation in gut.