Department of Chemical Engineering and Environmental Technology, School of Insdustrial Engineering, University of Valladolid, Dr. Mergelina s/n, 47011, Valladolid, Spain.
Institute of Sustainable Processes, Dr. Mergelina s/n, 47011, Valladolid, Spain.
Microb Cell Fact. 2020 Jul 16;19(1):144. doi: 10.1186/s12934-020-01395-0.
Methylocella silvestris is a facultative aerobic methanotrophic bacterium which uses not only methane, but also other alkanes such as ethane and propane, as carbon and energy sources. Its high metabolic versatility, together with the availability of tools for its genetic engineering, make it a very promising platform for metabolic engineering and industrial biotechnology using natural gas as substrate.
The first Genome Scale Metabolic Model for M. silvestris is presented. The model has been used to predict the ability of M. silvestris to grow on 12 different substrates, the growth phenotype of two deletion mutants (ΔICL and ΔMS), and biomass yield on methane and ethanol. The model, together with phenotypic characterization of the deletion mutants, revealed that M. silvestris uses the glyoxylate shuttle for the assimilation of C1 and C2 substrates, which is unique in contrast to published reports of other methanotrophs. Two alternative pathways for propane metabolism have been identified and validated experimentally using enzyme activity tests and constructing a deletion mutant (Δ1641), which enabled the identification of acetol as one of the intermediates of propane assimilation via 2-propanol. The model was also used to integrate proteomic data and to identify key enzymes responsible for the adaptation of M. silvestris to different substrates.
The model has been used to elucidate key metabolic features of M. silvestris, such as its use of the glyoxylate shuttle for the assimilation of one and two carbon compounds and the existence of two parallel metabolic pathways for propane assimilation. This model, together with the fact that tools for its genetic engineering already exist, paves the way for the use of M. silvestris as a platform for metabolic engineering and industrial exploitation of methanotrophs.
嗜甲基菌（Methylocella silvestris）是一种兼性需氧的甲烷营养菌，它不仅可以利用甲烷，还可以利用乙烷和丙烷等其他烷烃作为碳源和能源。其高度的代谢多功能性，加上其遗传工程工具的可用性，使其成为利用天然气作为底物进行代谢工程和工业生物技术的极具前景的平台。
提出了嗜甲基菌的第一个基因组尺度代谢模型。该模型用于预测嗜甲基菌利用 12 种不同底物的生长能力、两个缺失突变体（ΔICL 和 ΔMS）的生长表型以及甲烷和乙醇的生物量产量。该模型结合缺失突变体的表型特征，表明嗜甲基菌使用乙醛酸穿梭途径同化 C1 和 C2 底物，这与其他已发表的甲烷营养菌的报道截然不同。已经鉴定并通过酶活性测试和构建缺失突变体（Δ1641）实验验证了两种丙烷代谢的替代途径，这使得鉴定出乙醛酸是通过 2-丙醇同化丙烷的中间产物之一。该模型还用于整合蛋白质组学数据，并确定适应不同底物的关键酶。
该模型用于阐明嗜甲基菌的关键代谢特征，例如其利用乙醛酸穿梭途径同化一碳和二碳化合物，以及丙烷同化的两条平行代谢途径的存在。该模型，加上已经存在的遗传工程工具，为利用嗜甲基菌作为代谢工程和工业开发甲烷营养菌的平台铺平了道路。
