Fan Yi, Huang Xiaoning, Chen Jingyu, Han Beizhong
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
Key Laboratory of Viticulture and Enology, Ministry of Agriculture and Rural Affairs, Beijing, China.
Front Microbiol. 2020 Feb 6;11:138. doi: 10.3389/fmicb.2020.00138. eCollection 2020.
The existence and function of unculturable microorganisms are necessary to explain patterns of microbial diversity and investigate the assembly and succession of the complex microbial community. Chinese traditional alcoholic fermentation starter contains a complex microbial community harboring unculturable species that control the microbial diversity and have distinct functions. In this study, we revealed the presence, functions, and interactions of these unculturable species. Results of microbial diversity revealed by culture-dependent and metagenomic sequencing methods identified unculturable species and the potential functional species. Unculturable and sp. had a strong ability to form biofilms and co-existed as a mixed-species biofilm in the starter community. Using a hydrolase activity assay and fortified fermentation, we determined that the function of and sp. to produce ethanol and flavor compounds. Widespread microbial interactions were identified among the biofilm isolates. was the main component of the biofilm and dominated the metabolic activities in the mixed-species biofilm. The environmental adaptability and biomass of sp. were increased through its interaction with . The mixed biofilm of and sp. also provides a tool for correlating microbial diversity patterns with their function in the alcoholic fermentation starter, and may provide a new understanding of fermentation mechanisms. Formation of a mixed-species biofilm represents a strategy for unculturable species to survive in competition with other microbes in a complex community.
不可培养微生物的存在及其功能对于解释微生物多样性模式以及研究复杂微生物群落的组装和演替是必要的。中国传统酒曲含有一个复杂的微生物群落，其中包含不可培养的物种，这些物种控制着微生物多样性并具有独特的功能。在本研究中，我们揭示了这些不可培养物种的存在、功能及其相互作用。通过依赖培养和宏基因组测序方法揭示的微生物多样性结果确定了不可培养物种和潜在的功能物种。不可培养的[具体物种1]和[具体物种2]具有很强的形成生物膜的能力，并在酒曲群落中以混合物种生物膜的形式共存。通过水解酶活性测定和强化发酵，我们确定了[具体物种1]和[具体物种2]产生乙醇和风味化合物的功能。在生物膜分离物中发现了广泛的微生物相互作用。[具体物种1]是生物膜的主要成分，并主导了混合物种生物膜中的代谢活动。[具体物种2]通过与[具体物种1]的相互作用提高了其环境适应性和生物量。[具体物种1]和[具体物种2]的混合生物膜也为将微生物多样性模式与其在酒曲发酵中的功能相关联提供了一个工具，并可能为发酵机制提供新的理解。混合物种生物膜的形成代表了不可培养物种在复杂群落中与其他微生物竞争中生存的一种策略。
