基于优化的多相连续结肠发酵模型,分析甲钴胺、氰钴铵影响肠道微生态的差异。通过设计正交实验优化培养基、对比实验发酵气体、通过电子鼻判断菌群结构是否稳定;最终建立了优化的体外模拟结肠发酵模型。向模型中加入甲钴胺或氰钴胺,对各组发酵液样品进行16S rRNA测序分析,测定酶活、短链脂肪酸,考察2种钴卟啉对肠道菌群的调控作用。结果表明,甲钴胺和氰钴胺都降低了肠道菌群的α-多样性,其中氰钴胺显著提高了与炎症和癌症相关细菌的相对丰度,而甲钴胺提高了产丁酸肠道菌的丰度。氰钴胺促进淀粉消化而甲钴胺抑制。2种钴卟啉都促进脂质代谢、萜类和聚酮类代谢、外源性物质降解,都抑制转录因子等次生代谢产物的合成、ABC转运蛋白、DNA修复和重组蛋白代谢、氮代谢以及磷酸转移酶系统代谢,且氰钴胺的抑制作用比甲钴胺组更强。不同钴卟啉对人体肠道菌群有不同的影响,但总体而言,甲钴胺更有利于人体肠道的健康。
This study aimed to analyze the effects of methylcobalamin and cyanocobalamin on gastrointestinal microecology in an optimized model of multistage continuous colonic fermentation. An in vitro simulated colonic fermentation model was established by optimizing the culture media via an orthogonal experimental design (OED) method. This model analyzed various gases supplemented to the fermentation system via comparative experiments and determined the stability of the microbial community structure with an electronic nose. After adding methylcobalamin and cyanocobalamin separately into the optimized model, the fermented broth samples were harvested for 16S rRNA sequencing, determining enzymatic activities, and measuring short-chain fatty acid (SCFA) levels to investigate the regulatory effects of these two cobalt porphyrins on the gastrointestinal microbiota. The results revealed that both methylcobalamin and cyanocobalamin reduced the alpha-diversity of the gastrointestinal microbiota. Cyanocobalamin significantly increased the relative abundance of bacteria associated with inflammation and cancer, whereas methylcobalamin increased the abundance of butyrate-producing enteric bacteria. Besides, our results also revealed that starch digestion was promoted and inhibited by cyanocobalamin and methylcobalamin, respectively. Both cobalt porphyrins promoted the metabolism of lipid, terpenoids, and polyketides as well as the degradation of exogenous substances and inhibited the synthesis of secondary metabolites such as the transcription factors, the ATP-binding cassette transporters (ABC transporters), DNA repair and recombination (DRR) proteins, nitrogen metabolism, and the phosphotransferase system. Additionally, cyanocobalamin exhibited greater inhibitory effects than those by methylcobalamin. This study suggests that different cobalt porphyrins may have different effects on the human gastrointestinal microbiota, and methylcobalamin is more beneficial for the human gastrointestinal health.
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