p-Cresol is a neurotoxic and nephrotoxic carcinogenic aromatic substance produced as a result of microbial fermentation in the intestine. The derivatives of p-cresol (p-cresyl sulphate or p-cresyl glucuronide) have a deleterious effect on renal failure patients undergoing hemodialysis. Human gut seems to be inhabited with a diverse microbial population capable of detoxifying many aromatic compounds. However, the knowledge on the role of gut microbes in metabolizing p-cresol is limited. Hence, the present study aims to investigate p-cresol detoxification by intestinal bacteria isolated from human feces. Three potential p-cresol tolerant isolates were selected and identified as Enterococcus faecalis strains (UTD-1, UTD-2 and UTD-3) by 16SrRNA gene sequencing. All three E. faecalis isolates decreased the p-cresol concentration (30 µg/ml) at a higher rate with extracellular extracts (2.58–9.53 µg/ml) as compared to intracellular (0.55–5.28 µg/ml) extract. These three potential isolates also exhibited tolerance to gastrointestinal conditions for up to 60 min. Added to its potential, the expression of virulent genes (esp, gelE, and cyl) was found to be suppressed when subjected to bile stress under in vitro conditions. HPLC analysis displayed transformed products from extracellular extract treated samples were comparable to the metabolite standard of the p-cresol degradation pathway. Infrared spectral analysis too showed the spectrum similarity with metabolite standard. Thus, conclusively, intestinal isolates E. faecalis (UTD-1, UTD-2 and UTD-3) might be a promising candidate for mitigating p-cresol detoxification in uremic patients.

中文翻译：

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从人类粪便中分离出的肠道细菌对对甲酚的体外解毒研究

对甲酚是一种由肠道微生物发酵产生的具有神经毒性和肾毒性的致癌芳香物质。对甲酚衍生物（对甲酚硫酸盐或对甲酚葡萄糖醛酸）对接受血液透析的肾功能衰竭患者有有害影响。人类肠道似乎居住着能够解毒许多芳香化合物的多样化微生物群。然而，关于肠道微生物在对甲酚代谢中的作用的知识是有限的。因此，本研究旨在研究从人类粪便中分离的肠道细菌对对甲酚的解毒作用。通过 16SrRNA 基因测序，选择了三种潜在的对甲酚耐受分离株并鉴定为粪肠球菌菌株（UTD-1、UTD-2 和 UTD-3）。所有三个E。与细胞内提取物 (0.55–5.28 µg/ml) 相比，粪菌分离物在细胞外提取物 (2.58–9.53 µg/ml) 中以更高的速率降低对甲酚浓度 (30 µg/ml)。这三个潜在的分离株也表现出对胃肠道疾病的耐受性长达 60 分钟。除了其潜力之外，还发现在体外条件下受到胆汁压力时，毒性基因（esp、gelE 和 cyl）的表达受到抑制。HPLC 分析显示来自细胞外提取物处理样品的转化产物与对甲酚降解途径的代谢物标准相当。红外光谱分析也显示出与代谢物标准品的光谱相似性。因此，最终，肠道分离出粪肠球菌（UTD-1，