This study aimed to comparatively analyze the common and unique glycoside hydrolase (GH) family genes in Bifidobacterium. On this basis, a rapid method for isolating target Bifidobacterium strains from infant fecal samples was developed. The GH family genes of four bifidobacterial taxa, including B. breve, B. longum subsp. longum, B. bifidum and B. longum subsp. infantis, were compared, revealing that there were common and unique patterns in the GH family genes among these species, which could serve as molecular markers for the isolation and identification of Bifidobacterium strains. Based on colony polymerase chain reaction (PCR) and nucleic acid electrophoresis, a rapid method for the isolation and identification of the aforementioned bifidobacterial strains were successfully developed and applied to the isolation of B. bifidum. This method is characterized by not only high efficiency of isolation but also low costs. The results of this study contribute to a better understanding of the diversity of Bifidobacterium, thereby laying a foundation for future probiotic research and development.

Human milk is the most important source of nutrition in early infancy, which can meet all the nutritional needs in the first 6 months after birth. It contains many bioactive substances that can regulate the intestinal flora, promote the development of the immune system, and enhance the intestinal barrier. Human milk oligosaccharides (HMOs) are one of the active substances in human milk. They cannot be directly digested and absorbed by infants, but can be used as a prebiotic to stimulate the establishment and evolution of the gut microbiota. Bifidobacterium longum subsp. infantis is a dominant microorganism in the gut of breastfed infants, which has almost all gene clusters required for metabolizing the major HMOs, and its interaction with HMOs plays a key role in the early intestinal health of infants. This review summarizes the composition and structure of HMOs, describes the utilization of HMOs by B. longum subsp. infantis and summarizes the beneficial effects B. longum subsp. infantis exerts in infants by metabolizing HMOs, which will lay the foundation for exploring the interaction mechanism between HMOs and the gut microbiota, as well as its role in infant intestinal development and maturation.

In recent years, antibiotic-resistant pathogens have placed tremendous pressure on pathogen control within the livestock industry. Consequently, we have turned our attention to phages, a unique type of virus that has co-evolved with bacteria for an extended period. PE-1 is a bacteriophage strain capable of effectively controlling target pathogens and was isolated from samples collected from dead piglets suffering from intestinal disease and their living environment. Enterotoxigenic Escherichia coli (ETEC) K88 was employed as an inhibitory target to characterize the growth characteristics and in vitro antibacterial effects of bacteriophage PE-1. Morphological analysis tentatively classified phage PE-1 as belonging to the Podoviridae family. The one-step growth curve revealed that phage PE-1 had a short latent period of 10 min, a rise period of 20 min, and a burst size of 13 PFU/cell. The optimal multiplicity of infection (MOI) for phage PE-1 is 10, and the phage maintained normal activity at pH levels between 4−11 and temperatures no higher than 55 °C. Through two in vitro simulated test experiments, we evaluated the antibacterial efficacy of the bacteriophage. Our findings indicated that bacteriophage PE-1 delayed the growth activity of ETEC K88 by more than 2 h and reduced the proliferation rate of the host bacteria under infection conditions. Moreover, the bacteriophage decreased the concentration of host bacteria that reached the stationary phase. After inoculating the host bacteria with the optimal MOI, the host bacteria concentration dropped by nearly three orders of magnitude after 4 h. In conclusion, bacteriophage PE-1 demonstrates potential as an antibacterial agent for ETEC K88.