Critical cross feeding mechanisms of microbial communities in the gut: menaquinone production and bacterial bioenergetics

微生物相互依赖于附近的群落成员，以获取营养和其他分子。我们团队最近的一项发现突显了细菌群落伴生物产生的某些代谢副产物的重要性，这表明醋酸盐被输送到结肠可以极大地促进Keystone细菌共生体的生长。醋酸酯是一种短链脂肪酸，通常被宿主迅速吸收，在结肠中不存在大量。它在结肠中的存在通常只是作为少量细菌发酵的副产品。粘性阿克曼氏菌特别受到醋酸盐的刺激，醋酸盐与其他细菌成员同时增加了孟喹酮(MK；维生素K2)的微生物生物合成。MK对哺乳动物和细菌都是一种重要的维生素，在产生能量的过程中也是如此。关于细菌产生能量的独特成分的信息很少。我们的新数据表明，在更广泛的社区背景下，细菌可能并不像传统上认为的那样自私。我们假设，参与能量产生的分子(如MK)的群落共享是调节肠道微生物群落动态进化的关键因素。在这里，我们的目标是更好地了解这种呼吸分子在肠道微生物区系中的主要机械相互作用。我们的第一个目标包括使用肠道模型，在那里我们将筛选促进粘液嗜酸杆菌的不同类型的醋酸盐，然后监测改变的MK生物合成如何影响系统。我们将收集一个细菌库进行进一步分析，并检查产生的MK变异体的类型。第二个目标将破译不同细菌MK类型在纯细菌和混合细菌培养中的影响和转移。这些研究将有助于弥合知识鸿沟，通过表征支持宿主适应物种共存的潜在能量产生网络来提高我们对人类肠道相关微生物群落的理解。此外，这些发现将适用于微生物生态、健康和食品工业的广泛方面。

Microbes interdepend on community members that are close in proximity for nutrients and other molecules. Highlighting the importance of certain metabolic by-products from bacterial community associates, a recent discovery from our group showed that acetate delivered to the colon could heavily promote keystone bacterial symbionts. Acetate is a short chain fatty acid which is usually rapidly taken in by the host and is not present in the colon in significant amounts. Its presence in the colon is typically only as a by-product of bacterial fermentation in small amounts. Akkermansia muciniphila is particularly stimulated by acetate which concurrently increased the microbial biosynthesis of menaquinone (MK; vitamin K2) with other bacterial members. MK is an important vitamin for both mammals and also bacteria in the process of energy generation. There is a paucity of information on the unique components that commensal bacteria for energy generation. Our new data suggests that bacteria in a broader community context may not be as selfish as they are traditionally perceived. We hypothesise that community sharing of molecules involved in energy generation, such as MK is a critical factor regulating the dynamic evolution of gut microbial communities. Here, we aim to better understand the major mechanistic interplay within the gut microbiota by this respiratory molecule. Our first objective encompasses using a gut model where we will screen for different acetate types which promote A. muciniphila and then monitor how altered MK biosynthesis impacts the system. We will collect a bacterial library for further analysis and examine the type of MK variant produced. The second objective will decipher the impact and transference of different bacterial MK types in pure and mixed bacterial cultures. These studies will help to bridge the knowledge gap to improve our understanding of human gut-associated microbial communities by characterizing the underlying energy-generating networks which support the co-existing of host-adapted species. Moreover, the findings will be applicable to broad aspects of microbial ecology, health and the food industry.