Butyrate producing microbiota perform a number of activities important in supporting the normal function of the human gastrointestinal tract. The goal of this study was to determine the synergistic effects of lactate- and butyrate-producing bacteria on butyrate production in vitro co-culture. PCR was used to detect the genes butyrate kinase and butyryl-CoA transferase that contribute to butyrate production, in a panel of representative gut microbiota. Preliminary data suggested that two Clostridium sp. (ASF 500 and ASF 502) and one Eubacterium sp. (ASF492) possessed at least one of these genes for butyrate production. Co-culture experiments mixing a lactate-producer with a butyrate-producer showed an increase in butyrate production. Real-time quantitative PCR was used to estimate the number of bacteria in co-culture by targeting the 16S rDNA gene. Butyrate levels in the mixing experiment were analyzed using GC/MS. Preliminary results showed that butyrate genes are present in Clostridium sp. ASF 500 and ASF 502, however, assessment of butyrate production showed the butyrate levels do not correlate with the results from qPCR.