Fecal microbes, short chain fatty acids, and colorectal cancer across racial/ethnic groups

Figure 1 Levels of individual and total short chain fatty acids by race/ethnicity. All values are in mg/mL of stool. A: The levels of short chain fatty acids (SCFAs) in stool across all four racial/ethnic groups; B: The levels of SCFAs for African Americans vs those of all other races/ethnicities. ¹Statistically significant difference by independent samples t test, two sided, equal variances not assumed. Acetate: P = 0.045; Butyrate: P = 0.043; Total SCFAs: P = 0.039.

Figure 2 Stool pH by race/ethnicity. A: Stool pH across all four racial/ethnic groups; B: Stool pH for African Americans vs those of all other races/ethnicities.

Figure 3 Human gut microbiota analysis from different racial/ethnic groups. The 16S rRNA gene (v1-v3 regions) was sequenced from fecal samples using 454 Jr. sequencing and analyzed using QIIME platform. A: The phylum distribution among different groups was generated by comparing with the GreenGene (gg_otus-4feb2011) data base; B: The ratio of Firmicutes and Bacteroidetes is represented among different racial/ethnic groups. Statistics were performed using unpaired two-tailed t test using Graphpad Prism 4.0 software (^aP < 0.05 vs control).

Figure 4 PICRUSt analysis of 16S rRNA and correlating with experimental butyrate levels. A: Spearman Correlation analysis suggest moderately strong correlation (r = 0.52) prediction of K00929 pathway (butanoate pathway) vs experimental butyrate levels with significant P value (P = 0.023); B: Box plot indicating relative abundance of KO K00929 across ethnic groups (* = mean; + = points beyond 25^th-75^th percentile).