Ito Hidehiro, Yoshimori Kosei, Ishikawa Masahito, Hori Katsutoshi, Kamachi Toshiaki
Department of Life Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.
Department of Biomolecular Engineering, Nagoya University, Nagoya, Japan.
Front Microbiol. 2021 Mar 22;12:639266. doi: 10.3389/fmicb.2021.639266. eCollection 2021.
Methanotrophs have been used to convert methane to methanol at ambient temperature and pressure. In order to accumulate methanol using methanotrophs, methanol dehydrogenase (MDH) must be downregulated as it consumes methanol. Here, we describe a methanol production system wherein MDH expression is controlled by using methanotroph mutants. We used the MxaF knockout mutant of OB3b. It could only grow with MDH (XoxF) which has a cerium ion in its active site and is only expressed by bacteria in media containing cerium ions. In the presence of 0 μM copper ion and 25 μM cerium ion, the mutant grew normally. Under conditions conducive to methanol production (10 μM copper ion and 0 μM cerium ion), cell growth was inhibited and methanol accumulated (2.6 μmol·mg dry cell weight·h). The conversion efficiency of the accumulated methanol to the total amount of methane added to the reaction system was ~0.3%. The aforementioned conditions were repeatedly alternated by modulating the metal ion composition of the bacterial growth medium.
甲烷氧化菌已被用于在常温常压下将甲烷转化为甲醇。为了利用甲烷氧化菌积累甲醇，必须下调甲醇脱氢酶（MDH）的表达，因为它会消耗甲醇。在此，我们描述了一种甲醇生产系统，其中MDH的表达通过使用甲烷氧化菌突变体来控制。我们使用了OB3b的MxaF基因敲除突变体。它只能利用在其活性位点含有铈离子且仅在含有铈离子的培养基中由细菌表达的MDH（XoxF）生长。在0 μM铜离子和25 μM铈离子存在的情况下，该突变体正常生长。在有利于甲醇生产的条件下（10 μM铜离子和0 μM铈离子），细胞生长受到抑制，甲醇积累（2.6 μmol·mg干细胞重量·h）。积累的甲醇与添加到反应系统中的甲烷总量的转化效率约为0.3%。通过调节细菌生长培养基的金属离子组成，反复交替上述条件。
