Detection and isolation of protein susceptible indigenous bacteria affected by dietary milk-casein, albumen and soy-protein in the caecum of ICR mice

In this study, we fed ICR mice with a high-sucrose diet containing 20% w/w of milk-casein (MC), egg-white (EW), or soy-protein (SP) for 14 days in order to detect the presence of protein-susceptible gut indigenous bacteria (P-SIB). The caecal microbiome was examined by 16S rDNA amplicon sequencing using a next-generation MiSeq system. Principal coordinate analysis of the operational taxonomic units (OTUs) revealed that the microbiomes differed among the three groups. Typical SIB found in the MC-fed group were Bacteroides acidifaciens-, Bacteroides sartorii-, Eisenbergiella sp., and Lachnospiraceae sp.-like; in the EW-fed group were Lactobacillus murinus and Enterococcus faecium/avium-like; and in the SP-fed group were Muribaculaceae sp.-like bacteria. We also found that a few Lachnospiraceae sp.- and Clostridium disporicum-like bacteria were suppressed in the EW-fed mice. Out of the P-SIB detected, B. acidifaciens, L. murinus, E. faecium, and E. avium could be isolated and identified using BL agar and 16S rDNA BLAST search, respectively.