Abstract:
Both methane (CH4) and carbon dioxide (CO2) are major greenhouse gases (GHGs); hence, effective pro cesses are required for their conversion into useful products. CH4 is used by a few groups of methan otrophs to produce methanol. However, to achieve economical and sustainable CH4 reduction
strategies, additional strains are needed that can exploit natural CH4 feed stocks. In this study, we eval uated methanol production by Methylosinus sporium from CH4 and synthetic gas. The optimum pH, tem perature, incubation period, substrate, reaction volume to headspace ratio, and phosphate buffer
concentration were determined to be 6.8, 30 C, 24 h, 50% CH4, 1:5, and 100 mM (with 20 mM MgCl2
[a methanol dehydrogenase inhibitor]), respectively. Optimization of the production conditions and pro cess parameters significantly improved methanol production from 0.86 mM to 5.80 mM. Covalent immo bilization of M. sporium on Chitosan significantly improved the stability and reusability for up to 6 cycles
of reuse under batch culture conditions. The immobilized cells utilized a synthetic gas mixture containing
CH4, CO2, and hydrogen (at a ratio of 6:3:1) more efficiently than free cells, with a maximum methanol
production of 6.12 mM. This is the first report of high methanol production by M. sporium covalently
immobilized on a solid support from a synthetic gas mixture. Utilization of cost-effective feedstocks
derived from natural resources will be an economical and environmentally friendly way to reduce the
harmful effects of GHGs.
