Regulatory effects of Lacticaseibacillus rhamnosus ZFM216 and its bacteriocin on intestinal microbiota in vitro

Lactic acid bacteria (LAB) represent a category of probiotics commonly found in the gastrointestinal tracts of both humans and animals. The bacteriocins synthesized by LAB strains are believed to play a crucial role in promoting intestinal health. Bacteriocin ZFM216-ab, comprised of two distinct components, was purified from the cell-free supernant of Lacticaseibacillus rhamnosus ZFM216 (CCTCC NO: M2020325). The molecular weights of these components were determined to be 991.58 Da and 1150.63 Da. Bacteriocin ZFM216-ab exhibits broad-spectrum antibacterial activity, exhibiting minimum inhibitory concentrations (MICs) of 7.50 μg/mL and 3.75 μg/mL against Listeria monocytogenes and Salmonella paratyphi B, respectively, in a concentration-dependent manner. In an in vitro human intestinal microbiota model, an increase in the population of Lacticaseibacillus was observed following intervention with L. rhamnosus ZFM216. In contrast, direct intervention with Bacteriocin ZFM216-ab led to a significant enhancement of Lactobacillus, Streptococcus and Faecalibacterium abundance. In both intervention groups, a reduction in Clostridium_sensu_stricto_1 and Paraclostridium was noted. Furthermore, the metabolic levels of short-chain fatty acids (SCFAs) in fecal samples were significantly elevated, particularly acetic acid and isobutyric acid. These findings highlight the potential of L. rhamnosus ZFM216 and its bacteriocin as promising candidates for the modulation of gut microbiota homeostasis.