Evaluation of the Safety and Impact of Heat-Treated <i>Lactiplantibacillus plantarum</i> KM2 Fermentation on Gut Microbiome Architecture

Postbiotics, bioactive compounds from the fermentation process by probiotics, are gaining attention for their potential health benefits as safer alternatives to live probiotic microbes. <i>Lactiplantibacillus plantarum</i> is a well-studied probiotic species known for promoting gut health and immune modulation. However, the safety and effects of its postbiotic formulations on the gut microbiome structure remain less explored. This study presents a randomized, double-blind, placebo-controlled human study of KLP-KM2, a postbiotic consisting of heat-treated <i>L. plantarum</i> KM2 fermentation complex, in elderly participants. Over 12 weeks, KLP-KM2 consumption did not result in noticeable adverse reaction cases compared to the placebo. Nevertheless, the gut microbial diversity and taxonomic architecture of the KLP-KM2 recipients were differentiated from those of the placebo recipients after 12 weeks. A notable outcome was the increase in the number of subjects carrying <i>Veillonella</i> spp., which contributed to the distinct gut microbiome profiles observed between the two groups. Interestingly, KLP-KM2 facilitated the de novo colonization of <i>Veillonella</i> spp. in subjects who had not harbored these bacteria at the baseline. These results suggest the potential of KLP-KM2 as a safe and effective postbiotic intervention to enhance energy metabolism and mobility in older adults.