The human gut microbiota, the vast community of microbes inhabiting the gastrointestinal tract, plays a pivotal role in maintaining health. Bacteria are the most abundant organism, and the composition of bacterial communities is strongly influenced by diet. Gut bacteria can degrade complex dietary carbohydrates to produce bioactive compounds such as short-chain fatty acids. Such products influence health, by acting on systemic metabolism, or by virtue of anti-inflammatory or anti-carcinogenic properties. The composition of gut bacteria can be altered through overgrowth of enteropathogens (e.g., Campylobacter, Salmonella spp.), leading to dysbiosis of the gut ecosystem, with some species thriving under the altered conditions whereas others decline. Various “biotics” strategies, including prebiotics, probiotics, synbiotics, and postbiotics, contribute to re-establishing balance within the gut microbial ecosystem conferring health benefits. Prebiotics enhance growth of beneficial members of the resident microbial community and can thus prevent pathogen growth by competitive exclusion. Specific probiotics can actively inhibit the growth of pathogens, either through the production of bacteriocins or simply by reducing the gastrointestinal pH making conditions less favorable for pathogen growth. This review discusses the importance of a balanced gut ecosystem, and strategies to maintain it that contribute to human health.

中文翻译：

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生物和细菌功能：对肠道和宿主健康的影响


人类肠道微生物群是栖息在胃肠道中的庞大微生物群落，在维持健康方面起着关键作用。细菌是最丰富的生物体，细菌群落的组成受饮食的强烈影响。肠道细菌可以降解复杂的膳食碳水化合物以产生生物活性化合物，例如短链脂肪酸。此类产品通过作用于全身新陈代谢或具有抗炎或抗癌特性来影响健康。肠道细菌的组成可以通过肠道病原体（例如弯曲杆菌、沙门氏菌属）的过度生长而改变，导致肠道生态系统失调，一些物种在改变的条件下茁壮成长，而另一些物种则下降。各种“生物”策略，包括益生元、益生菌、合生元和后生元，有助于在肠道微生物生态系统中重建平衡，从而带来健康益处。益生元促进常驻微生物群落有益成员的生长，因此可以通过竞争性排斥来防止病原体生长。特定的益生菌可以通过产生细菌素或简单地通过降低胃肠道 pH 值使条件不利于病原体的生长来主动抑制病原体的生长。本综述讨论了平衡肠道生态系统的重要性，以及维护有助于人类健康的策略。