Methanol Production from Biogas with a Thermotolerant Methanotrophic Consortium Isolated from an Anaerobic Digestion System

Thermotolerant methanotrophic consortia are desirable for their robustness under stressful environments during industrial applications. A thermotolerant methanotrophic consortium, MC-AD3, was enriched from digestate in an anaerobic digestion (AD) system and evaluated for cell growth and methanol production with biogas. MC-AD3 obtained cell yields of 0.22–0.40 g of cells/g of methane at temperatures from 30 to 55 °C and pH from 5.5 to 7.5 and achieved the highest cell yield of 0.4 g of cells/g of methane at 47 °C at a biogas/air ratio of 1:4 (v/v) and pH of 6.8. MC-AD3 produced 0.33 g/L of methanol at 47 °C, with a methanol conversion ratio of 0.47 mol of methanol/mol of methane. A biogas/air ratio of 1:1 (v/v) was found to be optimal for methanol production with MC-AD3. The cell growth and methanol production performance of MC-AD3 at 47 °C fell within the range of those obtained by other methanotrophic strains/consortia at lower temperatures.