Proposal to Reclassify Companilactobacillus futsaii subsp. chongqingensis as a Later Heterotypic Synonym of Companilactobacillus futsaii subsp. futsaii

Previous studies have shown that Lactobacillus futsaii (now Companilactobacillus futsaii) can be subdivided at the subspecies level. The main purpose of this study is to explore whether this is correct by using a polyphasic taxonomic approach. Lactobacillus futsaii subsp. chongqingii was proposed and effectively published in 2019. The names L. futsaii subsp. chongqingensis corrig. and Lactobacillus futsaii subsp. futsaii were not validated until March 2023. However, in the reclassification of the genus Lactobacillus by Zheng et al. in April 2020, L. futsaii was transferred to Companilactobacillus as Companilactobacillus futsaii. So Lactobacillus futsaii subsp. chongqingensis and Lactobacillus futsaii subsp. futsaii should be transferred to Companilactobacillus futsaii now. In the present study, the relationship between L. futsaii subsp. chongqingensis and L. futsaii subsp. futsaii was re-evaluated. The type strains of L. futsaii subsp. chongqingensis and L. futsaii subsp. futsaii shared identical pheS and rpoA sequences, high dDDH value, similar phenotypic characteristics and fatty acid compositions, indicating that they belonged to the same subspecies. Here, we propose to reclassify Lactobacillus futsaii subsp. chongqingensis and Lactobacillus futsaii subsp. futsaii as Companilactobacillus futsaii subsp. chongqingensis comb. nov. and Companilactobacillus futsaii subsp. futsaii comb. nov., respectively, and Companilactobacillus futsaii subsp. chongqingensis as a later heterotypic synonym of Companilactobacillus futsaii subsp. futsaii.