Detection and isolation of the typical gut indigenous bacteria from ddY mice fed a casein-beef tallow-based or egg yolk-based diet.

The effects of whole egg on the cecal microbiome of ddY mice has been reported. To investigate the existence of susceptible indigenous bacteria (SIB) to egg yolks (EY), mice were fed a diet containing either 20% (w/w) milk casein and 17% beef tallow (CT) or 12% milk casein and 27% EY for 14 days, and then, the cecal microbiome was analyzed by 16S rRNA (V4) amplicon sequencing. To isolate the typical species in each diet group, culture-dependent viable bacterial counts were determined on Blood Liver (BL) and Gifu Anaerobic Medium (GAM) agar plates. The amplicon sequencing analysis revealed typical CT-SIB, such as Lachnospiraceae-like bacteria, and EY-SIB, such as Allobaculum-, Lactobacillus murinus-, and Bacteroides vulgatus-like bacteria. Two of the detected SIB species, L. murinus- and B. vulgatus-like bacteria, were successfully isolated from the BL and GAM agar plates and defined using a 16S rDNA BLAST search. PRACTICAL APPLICATIONS: The SIB defined in the CT and EY groups might have some effects on the nutritional and functional chemical compounds in the milk casein, beef tallow, and/or EY. Analysis of its functional properties of the isolates might develop the new and unique probiotic strains.

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.

Typical indigenous bacteria in the cecum of ddY mice fed a casein-beef tallow diet or whole-egg diet.

With the aim to prove the existence of food ingredient-susceptible indigenous bacteria (SIBs) in the gut, the gut microbiota of ddY mice fed a diet containing 20% milk casein and 17% beef tallow (CT diet) or 40% whole-egg powder (Egg diet) for 14 days were analyzed by 16S ribosomal RNA gene (V4) amplicon sequencing. At the genus level, abundance levels of Desulfovibrionaceae sp., Oscillospira, and Bacteroides were high in mice fed the CT diet. At the operational taxonomic unit level, Bacteroides acidifaciens- and Bacteroides caecimuris-like bacteria were highly abundant in mice fed the CT diet. Faecalibaculum rodentium- and Allobaculum stercoricanis-like bacteria were highly abundant in the mice fed the Egg diet. These sets of taxa were assumed to be estimates of casein-tallow SIBs and egg SIBs, respectively, in the gut microbiome. Among the SIBs, B. caecimuris and F. rodentium could be isolated using blood and liver agar. PRACTICAL APPLICATIONS: B. caecimuris and F. rodentium are regarded as casein-tallow and/or egg SIBs in mice. It is possible to demonstrate functionality with orally administered food ingredients. Isolation and application of human or livestock SIB is considered promising for the development of new probiotics and functional foods.