Observational Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 7, 2015; 21(9): 2759-2769
Published online Mar 7, 2015. doi: 10.3748/wjg.v21.i9.2759
Fecal microbes, short chain fatty acids, and colorectal cancer across racial/ethnic groups
Christina M Hester, Venkatakrishna R Jala, Morgan GI Langille, Shahid Umar, K Allen Greiner, Bodduluri Haribabu
Christina M Hester, K Allen Greiner, Department of Family Medicine Research Division, University of Kansas Medical Center, Kansas City, KS 66160, United States
Christina M Hester, Shahid Umar, K Allen Greiner, University of Kansas Cancer Center, University of Kansas Medical Center, Kansas City, KS 66160, United States
Venkatakrishna R Jala, Bodduluri Haribabu, James Graham Brown Cancer Center and Department of Microbiology and Immunology, University of Louisville, Louisville, KY 40202, United States
Morgan GI Langille, Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada
Shahid Umar, Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS 66160, United States
Author contributions: Hester CM and Jala VR contributed equally as first authors on the manuscript, they contributed toward design, sample collection, analysis, and writing; Umar S, Greiner KA and Haribabu B contributed to design, analysis and writing; and Langille MGI contributed to analysis and writing.
Supported by The University of Kansas Cancer Center, U54CA154253 from the National Cancer Institute at the NIH, the University of Kansas Clinical Translational Science Program (Frontiers, CA123245 from the National Cancer Institute at NIH), 1R01CA138623 from the NCI at NIH, and the James Graham Brown Cancer Center, University of Louisville.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Christina M Hester, PhD, Assistant Professor, Department of Family Medicine Research Division, University of Kansas Medical Center, Kansas City, MS 3064, 3901 Rainbow Boulevard, KS 66160, United States. chester@kumc.edu
Telephone: +1-913-9456733 Fax: +1-913-5882095
Received: April 14, 2014
Peer-review started: April 15, 2014
First decision: June 10, 2014
Revised: July 12, 2014
Accepted: August 13, 2014
Article in press: August 28, 2014
Published online: March 7, 2015
Processing time: 328 Days and 16.6 Hours
Abstract

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 16S rRNA 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 16S 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.

Keywords: Colorectal cancer; Short chain fatty acids; Racial/ethnic disparities; Butyrate; Microbiota

Core tip: This brief report describes analysis of stool samples from 20 adult participants aged 50 years and above using 16S rRNA pyrosequencing. We found significantly lower short chain fatty acid levels and significantly different microbial profiles in African Americans vs Whites. We also found a significant correlation between the predicted butyrate kinase levels based on 16S rRNA gene abundance and stool levels of butyrate. These results should be useful in future analysis of colorectal cancer incidence and mortality differentials across racial/ethnic groups.