The gut microbiota, a complex ecosystem of microorganisms of different kingdoms, impacts host physiology and disease. Within this ecosystem, inter-bacterial interactions and their impacts on microbiota community structure and the eukaryotic host remain insufficiently explored. Microbiota-related inter-bacterial interactions range from symbiotic interactions, involving exchange of nutrients, enzymes, and genetic material; competition for nutrients and space, mediated by biophysical alterations and secretion of toxins and anti-microbials; to predation of overpopulating bacteria. Collectively, these understudied interactions hold important clues as to forces shaping microbiota diversity, niche formation, and responses to signals perceived from the host, incoming pathogens and the environment. In this review, we highlight the roles and mechanisms of selected inter-bacterial interactions in the microbiota, and their potential impacts on the host and pathogenic infection. We discuss challenges in mechanistically decoding these complex interactions, and prospects of harnessing them as future targets for rational microbiota modification in a variety of diseases.

肠道微生物群是不同界微生物的复杂生态系统，影响宿主生理和疾病。在这个生态系统中，细菌间相互作用及其对微生物群落结构和真核宿主的影响仍未得到充分探索。微生物群相关的细菌间相互作用包括共生相互作用，包括营养、酶和遗传物质的交换；由生物物理改变和毒素和抗微生物剂分泌介导的营养和空间竞争；以捕食过多的细菌。总的来说，这些未充分研究的相互作用为塑造微生物群多样性、生态位形成以及对从宿主、传入病原体和环境感知到的信号的反应的力量提供了重要线索。在这次审查中，我们强调了微生物群中选定的细菌间相互作用的作用和机制，以及它们对宿主和病原体感染的潜在影响。我们讨论了机械解码这些复杂相互作用的挑战，以及利用它们作为各种疾病中合理微生物群修饰的未来目标的前景。