129 BIO 3B is classified as 129 BIO 3B.

129 BIO 3B is a lactic acid bacterium that has been safely used as a probiotic product for over 100 years. Recently, concerns about its safety have arisen because some species of belong to the vancomycin-resistant enterococci. The groups of with less pathogenic potential have been split into a separate species (). In this study, I investigated the phylogenetic classification and safety of 129 BIO 3B as well as 129 BIO 3B-R, which is naturally resistant to ampicillin. Mass spectrometry and basic local alignment search tool analysis using specific gene regions failed to differentiate 3B and 3B-R into or . However, multilocus sequence typing successfully identified 3B and 3B-R as the same sequence types as . Overall genome relatedness indices showed that 3B and 3B-R have high degrees of homology with . Gene amplification was confirmed for 3B and 3B-R with species-specific primers. The minimum inhibitory concentration of ampicillin was confirmed to be 2 µg/mL for 3B, which is within the safety standard for set by the European Food Safety Authority. Based on the above results, 129 BIO 3B and 129 BIO 3B-R were classified as . The absence of pathogenic genes except for in this study demonstrates that these bacteria are safe for use as probiotics.