Detection of butyrate from a Clostridium cluster I (Clostridium sensu stricto) strain, Clostridium tertium, under anaerobic conditions

Lactic acid bacteria and Bacillus bifidus are well-known probiotics used as alternatives to conventional pharmacotherapy in infectious diseases. Butyric acid (butyrate) bacteria such as Clostridium butyricum are also useful probiotics but have been rarely studied. To identify new butyrate-producing bacterial species, we examined the production of organic acids, including butyrate, in Clostridium tertium and C. butyricum. Protein BLAST (BLASTP) searches for butyrate kinase (BUK) proteins in the genomes of C. tertium have identified two proteins. To confirm their presence in the genome of C. tertium, we detected two buk genes using polymerase chain reaction (PCR). As phosphotransbutyrylase (ptb), a buk gene adjacent gene, was also present in the announced C. tertium genome, which was confirmed using PCR. Next, we investigated butyrate production in C. tertium. Lactic acid (lactate), formic acid (formate), acetic acid (acetate), and butyrate were detected in both thioglycolate medium cultures. Thus, we concluded that C. tertium produces butyrate. Our findings describe a novel butyrate-producing bacterium as a potential probiotic.