The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome.
The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome.
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DOI：
10.1371/journal.pone.0134116
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Dunn RR
中科院分区：
文献类型：
--
作者：
Beasley DE;Koltz AM;Lambert JE;Fierer N;Dunn RR
胃酸可能是影响脊椎动物肠道微生物群落多样性和组成的关键因素。我们进行了一项系统的综述，以检验脊椎动物胃的一个关键作用是通过在新的微生物分类群进入肠道之前过滤掉它们来维持肠道微生物群落的假说。我们建议，无论是以腐肉为食的物种，还是以亲缘关系密切的生物为食的物种，都应该要求最严格的过滤器(测量为高胃酸)，以保护其免受外来微生物的侵袭。相反，以较低营养水平或与它们有较远亲缘关系的食物为食的物种(例如草食动物)应要求限制最少的过滤器，因为接触病原体的风险较低。对哺乳动物和鸟类不同营养类群的胃酸进行比较表明，与食草动物或食肉动物相比，食腐动物和食肉动物的胃酸水平明显高于食草动物或食肉动物，它们以昆虫或鱼类等系统发育上相距较远的猎物为食。此外，我们发现，当胃酸在物种内自然变化(随年龄变化)或在减肥手术等治疗中变化时，对肠道细菌病原体和群落的影响符合我们的假设，即胃起到生态过滤器的作用。总而言之，这些结果强调了在研究物种内和跨物种的肠道微生物动态时，包括胃液酸碱度测量的重要性。
Gastric acidity is likely a key factor shaping the diversity and composition of microbial communities found in the vertebrate gut. We conducted a systematic review to test the hypothesis that a key role of the vertebrate stomach is to maintain the gut microbial community by filtering out novel microbial taxa before they pass into the intestines. We propose that species feeding either on carrion or on organisms that are close phylogenetic relatives should require the most restrictive filter (measured as high stomach acidity) as protection from foreign microbes. Conversely, species feeding on a lower trophic level or on food that is distantly related to them (e.g. herbivores) should require the least restrictive filter, as the risk of pathogen exposure is lower. Comparisons of stomach acidity across trophic groups in mammal and bird taxa show that scavengers and carnivores have significantly higher stomach acidities compared to herbivores or carnivores feeding on phylogenetically distant prey such as insects or fish. In addition, we find when stomach acidity varies within species either naturally (with age) or in treatments such as bariatric surgery, the effects on gut bacterial pathogens and communities are in line with our hypothesis that the stomach acts as an ecological filter. Together these results highlight the importance of including measurements of gastric pH when investigating gut microbial dynamics within and across species.