Genomic Comparison of AP and DR131 with Emphasis on the Butyric Acid Biosynthetic Pathways.

Butyric acid is known to possess anticarcinogenic and antioxidative properties. The local lactic acid bacteria (LAB) strains AP isolated from the digestive tract of healthy Indonesian infants and DR131 from indigenous fermented buffalo milk () can produce butyric acid in vitro. However, the genes and metabolic pathways involved in this process remain unknown. We sequenced and assembled the 2.95-Mb AP and 4.44-Mb DR131 draft genome sequences. We observed that 98% of the 2870 protein-coding genes of AP and 97% of the 3069 protein-coding genes of DR131 were similar to those of an strain isolated from infant stools and an strain in sheep milk, respectively. Comparison of the genome sequences of AP and DR131 led to the identification of genes encoding butyrate kinase () and phosphotransbutyrylase (), enzymes involved in butyric acid synthesis in AP. In contrast, a medium-chain thio-esterase and type 2 fatty acid synthase facilitated butyric acid synthesis in DR131. Our results provide new insights into the physiological behavior of the two LAB strains to facilitate their use as probiotics.