Effect of probiotics Lactobacillus paracasei subsp. paracasei Zhang on gut microbiota composition of young people living in Hainan

[Objective] Twenty-nine healthy young volunteers from Hainan were selected as the research objects to analyze the diversity of gut microbes and to explore the effects of Lactobacillus paracasei subsp. paracasei Zhang on the fecal microbiota. [Methods] Volunteers were supplemented with 1×1010 CFU LCZ powders per day for 14 days. Fecal samples were collected on 0, 14 and 28 days. Microbial composition and structure of fecal were analyzed by PacBio SMRT. [Results] Firmicutes and Bacteroidetes were the most abundant phylum. Meanwhile, Bacteroides were the predominant genus. At the species level, the dominant bacteria species were Faecalibacterium prausnitzii, Eubacterium rectale and Prevotella copri. After taking LCZ for 14 days, the dominant bacteria did not change significantly, while low-abundance bacteria such as Oscillospira and Parabacteroides were significantly increased（P<0.05）. In addition, volunteers were divided into two groups according to the changes of Lactobacillus. Butyricicoccus pullicaecorum, Lactococcus raffinolactis and Parabacteroides distasoni were significantly increased in samples of those with significantly increased content of Lactobacillus. Inversely, volunteers with no significant changes in the Lactobacillus content in their gut did not find similar changes. [Conclusion] Continuous consumption of probiotics LCZ for 2 weeks had no significant effect on the relative abundance of dominant bacteria in fecal microbiota of volunteers, while the low-abundance bacteria change significantly.