Abstract: To evaluate the effect of Lactobacillus paracasei LC01 (LC01) on the mouse intestinal microbiota, Balb/c mice
were randomized and equally divided into four groups (n = 8). The live LC01, inactive LC01 and control groups were
administered with live LC01, inactive LC01 and resuspended buffer for a 2-week period, respectively. The colonization
group underwent a 2-week washout period after the administration of LC01. MiSeq high-throughput sequencing was used to
determine the intestinal bacterial composition of fecal samples collected at the end of every period. A significant increase in
Lactobacillus, Ruminococcaceae_UCG014 and Alistpes was observed in the live LC01 group compared with the control and
inactive LC01 groups. Furthermore, species-specific quantitative polymerase chain reaction and operational taxonomic unit
classification analysis revealed that LC01 could stimulate the proliferation of Lactobacillus gasseri and Lactobacillus reuteri.
After the washout period, operational taxonomic units could not be detected in the fecal samples. The results indicated a
modulation effect of LC01 on the intestinal microbiota in mice, suggesting that LC01 may have potential as a probiotic.

Key words: probiotic, Lactobacillus paracasei, fluorescent quantitative polymerase chain reaction, microbiota