AIM:To investigate differences in microbes and short chain fatty acid(SCFA) levels in stool samples from Hispanic and non-Hispanic African American,American Indian,and White participants.METHODS:Stool samples from twenty participants were subjected to analysis for relative levels of viable bacteria and for SCFA levels.Additionally,the samples were subjected to 16 S r RNA gene pyrosequencing for identification of bacteria present in the stool.We used a metagenome functional prediction technique to analyze genome copy numbers and estimate the abundance of butyrate kinase in all samples.RESULTS:We found that African Americans had significantly lower levels of acetate,butyrate,and total SCFAs than all other racial/ethnic groups.We also found that participant microbial profiles differed by racial/ethnic group.African Americans had significantly more Firmicutes than Whites,with enriched Ruminococcaceae.The Firmicutes /Bacteroidetes ratio was also significantly higher for African Americans than for Whites(P =0.049).We found Clostridium levels to be significantly and inversely related to total SCFA levels(P =0.019) and we found Bacteroides to be positively associated(P =0.027) and Clostridium to be negatively associated(P =0.012) with levels of butyrate.We also identified a correlation between copy number for a butyrate kinase predicted from 16 S r RNA gene abundance and levels of butyrate in stool.CONCLUSION:The identified differences in gut flora and SCFA levels may relate to colorectal cancer mortality differentials and may be useful as targets for future clinical and behavioral interventions. AIM: To investigate differences in microbes and short chain fatty acid (SCFA) levels in stool samples from Hispanic and non-Hispanic African American, American Indian, and White participants. METHODS: Stool samples from twenty participants were subjected to analysis for relative levels of viable bacteria and for SCFA levels. Additionally, the samples were subjected to 16 S r RNA gene pyrosequencing for identification of bacteria present in the stool. We used a metagenome functional prediction technique to analyze genome copy numbers and estimate the abundance of butyrate kinase in all samples.RESULTS: We found that African Americans had significantly lower levels of acetate, butyrate, and total SCFAs than all other racial / ethnic groups. We also found that participantmicmicellular profiles differed by racial / ethnic group .African Americans had significantly more Firmicutes than Whites, with enriched Ruminococcaceae. The Firmicutes / Bacteroidetes ratio was also significantly higher for African Americans th (P = 0.019). We found that Clostridium levels to be significantly and inversely related to total SCFA levels (P = 0.019) and we found Bacteroides to be positively associated (P = 0.027) and Clostridium to be negatively associated 0.012) with levels of butyrate. We also identify a correlation between copy number for a butyrate kinase predicted from 16 S rRNA gene abundance and levels of butyrate in stool. CONCLUSION: The identified differences in gut flora and SCFA levels may relate to colorectal cancer mortality differentials and may be useful as targets for future clinical and behavioral interventions.