米糠阿魏酰低聚糖对肠道产阿魏酸酯酶菌菌群结构的调节机制研究

Feruloylated oligosaccharides (FOs) is an ester compound of oligosaccharides and ferulic acid in rice bran. Previous study indicated that FOs could be decomposed by specialized gut microbes with the feruloyl esterase-producing ability, and also promoted their proliferation. However, why FOs promoted the proliferation of feruloyl esterase-producing bacteria in the gut are still unclear. In this project, the common gene cluster of feruloyl esterase-producing bacteria in intestinal tract was excavated by microbiological comparative genomics, and the feruloyl esterase-producing bacteria bank was also constructed. Then, the relation among feruloyl esterase-producing bacteria, feruloyl esterase, and the metabolites of FOs were carefully analyzed to construct the metabolic network of FOs by which the FOs-dependent proliferation of feruloyl esterase-producing bacteria in the intestinal was explained. Then, the similarity and difference feruloyl esterase-producing bacteria community structure in the utilization of FOs were carefully evaluated by common gene cluster and 16s high-throughput sequencing. Besides, the specific intestinal microenvironments relating to FOs, as well as, the intestinal microbiota and barrier function and permeability are systemically evaluated. All of these intestinal environment may constitute a favorable ecology niche for these feruloyl esterase-producing bacteria. The results will provide scientific basis for the further understanding of the physiological basis of rice bran in the gut and high-value utilization of its by-products.

米糠阿魏酰低聚糖（FOs）是一种存在于稻谷麸皮中的低聚糖与阿魏酸的酯化物。前期研究表明米糠FOs到达肠道后可被产阿魏酸酯酶菌分解，并促进该菌的增殖，但其作用机制尚不明确。本项目拟通过微生物比较基因组学挖掘肠道中产阿魏酸酯酶菌的共性基因簇，构建产阿魏酸酯酶菌库；辅以产阿魏酸酯酶菌对米糠FOs的体外发酵，系统分析产阿魏酸酯酶菌-阿魏酸酯酶-FOs代谢物之间的规律，构建其利用米糠FOs的代谢网络，初步揭示米糠FOs促进产阿魏酸酯酶菌增殖的机制。同时，以共性基因簇为靶标，借助16s高通量测序，分析不同FOs对肠道产阿魏酸酯酶菌菌群结构调节的共性及差异性；进一步从肠道菌群、肠道微环境、肠道屏障及通透性等肠道内环境方面，最终阐释米糠FOs对肠道产阿魏酸酯酶菌菌群结构的调节机制。本项目的开展将为深入认识米糠在肠道内发挥作用的生理基础，实现对农产品加工副产物的高值化利用提供科学依据。

米糠阿魏酰低聚糖（FOs）是一种存在于稻谷麸皮中的低聚糖与阿魏酸的酯化物。前期研究表明米糠FOs到达肠道后可被产阿魏酸酯酶菌分解，并促进该菌的增殖，但其作用机制尚不明确。本项目通过不同手段确定米糠中FOs的最佳提取工艺；对小鼠粪便进行微生物培养，构建产阿魏酸酯酶菌库，并挑选活力最强的菌作为目标菌株；将目标菌株饲喂给以米糠作为碳源的肠炎小鼠，分析目标菌株对肠道菌群的影响机制。结果表明，FOs的最佳提取工艺是酶浓度：1800 U/mL，pH：4.0，反应时间：24 h，温度：45℃；粪便中收集60株乳酸菌，其中7株为优势菌株，优势菌株中1株为目标菌株，产阿魏酸酯酶实验显示该菌株的菌体和发酵上清均有透明圈，并且大小分别为25.59和17.30mm；动物实验表明目标菌株能明显改善肠炎小鼠体重下降和结肠缩短现象、降低疾病活动指数、改善肠道炎症状态、增强抗氧化能力、降低肝脾指数、增加结肠紧密连接蛋白ZO-1和Claudin-1水平、增加MUC1的表达、降低MUC2的表达、增加菌种多样性、乳酸杆菌和阿克曼菌的丰度；此外，NF-kB信号通路分析表明，添加产阿魏酸酯酶菌，显著增加了IKK-β和p65的表达，显著降低了IKB-α的表达。本项目的开展将为深入认识米糠在肠道内发挥作用的生理基础，实现对农产品加工副产物的高值化利用提供科学依据。