Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, Netherlands.
Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, Netherlands
Appl Environ Microbiol. 2020 Sep 1;86(18). doi: 10.1128/AEM.01188-20.
Industrial methanol production converts methane from natural gas into methanol through a multistep chemical process. Biological methane-to-methanol conversion under moderate conditions and using biogas would be more environmentally friendly. Methanotrophs, bacteria that use methane as an energy source, convert methane into methanol in a single step catalyzed by the enzyme methane monooxygenase, but inhibition of methanol dehydrogenase, which catalyzes the subsequent conversion of methanol into formaldehyde, is a major challenge. In this study, we used the thermoacidophilic methanotroph "" SolV for biological methanol production. This bacterium possesses a XoxF-type methanol dehydrogenase that is dependent on rare earth elements for activity. By using a cultivation medium nearly devoid of lanthanides, we reduced methanol dehydrogenase activity and obtained a continuous methanol-producing microbial culture. The methanol production rate and conversion efficiency were growth-rate dependent. A maximal conversion efficiency of 63% mol methanol produced per mol methane consumed was obtained at a relatively high growth rate, with a methanol production rate of 0.88 mmol/g (dry weight)/h. This study demonstrates that methanotrophs can be used for continuous methanol production. Full-scale application will require additional increases in the titer, production rate, and efficiency, which can be achieved by further decreasing the lanthanide concentration through the use of increased biomass concentrations and novel reactor designs to supply sufficient gases, including methane, oxygen, and hydrogen. The production of methanol, an important chemical, is completely dependent on natural gas. The current multistep chemical process uses high temperature and pressure to convert methane in natural gas to methanol. In this study, we used the methanotroph "" SolV to achieve continuous methanol production from methane as the substrate. The production rate was highly dependent on the growth rate of this microorganism, and high conversion efficiencies were obtained. Using microorganisms for the production of methanol might enable the use of more sustainable sources of methane, such as biogas, rather than natural gas.
工业甲醇生产通过多步化学过程将天然气中的甲烷转化为甲醇。在温和条件下，利用沼气进行生物甲烷转化为甲醇将更加环保。利用甲烷作为能源的甲烷营养菌在酶甲烷单加氧酶的催化下一步将甲烷转化为甲醇，但甲醇脱氢酶的抑制是一个主要挑战，该酶催化甲醇随后转化为甲醛。在这项研究中，我们使用嗜热嗜酸甲烷营养菌 "" SolV 进行生物甲醇生产。该细菌具有依赖于稀土元素活性的 XoxF 型甲醇脱氢酶。通过使用几乎不含镧系元素的培养介质，我们降低了甲醇脱氢酶的活性，并获得了连续生产甲醇的微生物培养物。甲醇的生产速率和转化率与生长速率有关。在相对较高的生长速率下，获得了最大的转化率 63% mol 甲醇/mol 甲烷消耗，甲醇的生产速率为 0.88 mmol/g（干重）/h。这项研究表明，甲烷营养菌可用于连续甲醇生产。大规模应用还需要进一步提高浓度、生产速率和效率，这可以通过进一步降低镧系元素浓度来实现，例如通过增加生物质浓度和新型反应器设计来供应足够的气体，包括甲烷、氧气和氢气。甲醇是一种重要的化学品，其生产完全依赖于天然气。目前的多步化学过程使用高温和高压将天然气中的甲烷转化为甲醇。在这项研究中，我们使用甲烷营养菌 "" SolV 从甲烷作为底物实现连续甲醇生产。生产速率高度依赖于该微生物的生长速率，并且获得了高转化率。利用微生物生产甲醇可能使生物沼气等更可持续的甲烷源得到利用，而不是天然气。
