Through an arsenal of microbial enzymes, the gut microbiota considerably contributes to human metabolic processes, affecting nutrients, drugs, and environmental poisons. Azoreductases are a predominant group of microbiota-derived enzymes involved in xenobiotic metabolism and drug activation, but little is known about how compositional changes in the gut microbiota correlate with its azo-reducing activity. To this end, we used high-throughput 16S rRNA amplicon sequencing, with Illumina MiSeq, to determine the microbial community composition of stool samples from 16 adults with different azo-reducing activity. High azo-reducing activity positively correlated with the relative abundance of phylum Firmicutes (especially genera Streptococcus and Coprococcus) but negatively with phylum Bacteroidetes (especially genus Bacteroides). Typical variations in the Firmicutes-to-Bacteroidetes and Prevotella-to-Bacteroides ratios were observed among samples. Multivariate analysis of the relative abundance of key microbial taxa and other diversity parameters confirmed the Firmicutes proportion as a major variable differentiating high and non-azo-reducers, while Bacteroidetes relative abundance was correlated with azo-reduction, sex, and BMI. This pilot study showed that stool samples with higher azo-reducing activity were enriched in Firmicutes but with relatively fewer Bacteroidetes. More samples and studies from different geographical areas are needed to bolster this conclusion. Better characterization of different azoreductase-producing gut microbes will increase our knowledge about the fate and differential human responses to azodye-containing drugs or orally consumed chemicals, thus contributing to efforts towards implementing microbiome testing in precision medicine and toxicology.

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与偶氮还原活性相关的人类粪便微生物组的组成变化：一项初步研究

通过微生物酶库，肠道微生物群对人体代谢过程有很大贡献，影响营养素、药物和环境毒物。偶氮还原酶是参与异生物质代谢和药物活化的主要微生物群衍生酶，但关于肠道微生物群的组成变化与其偶氮还原活性的相关性知之甚少。为此，我们使用高通量 16S rRNA 扩增子测序和 Illumina MiSeq，确定来自具有不同偶氮还原活性的 16 名成人粪便样本的微生物群落组成。高偶氮还原活性与厚壁菌门（尤其是链球菌属和粪球菌属）的相对丰度呈正相关，但与拟杆菌门（尤其是拟杆菌属）呈负相关。在样品中观察到厚壁菌与拟杆菌和普氏菌与拟杆菌比率的典型变化。对关键微生物类群的相对丰度和其他多样性参数的多变量分析证实厚壁菌门比例是区分高和非偶氮还原剂的主要变量，而拟杆菌属的相对丰度与偶氮还原、性别和 BMI 相关。该初步研究表明，具有较高偶氮还原活性的粪便样本富含厚壁菌门，但拟杆菌门相对较少。需要更多来自不同地理区域的样本和研究来支持这一结论。更好地表征不同的产生偶氮还原酶的肠道微生物将增加我们对含有偶氮染料的药物或口服化学品的命运和不同人类反应的了解，