Insights into C1 and C3 assimilation pathways in type I methanotrophic bacterium from co-production of 1,2-propanediol and lactate

Methanotrophic bacteria are attractive hosts for mining metabolic pathways of C1 assimilation to produce valueadded products. Herein, the type I methanotroph Methylotuvimicrobium alcaliphilum 20Z was employed to explore the carbon flux from methane and methanol via the EMP pathway to produce 1,2-propanediol (1,2-PDO). The production of 1,2-PDO on methane was found to be mainly restricted by the lower carbon flux toward the EMP pathway. The co-utilization of C1 substrates and glycerol (C3) could contribute to enhance 1,2-PDO. Lactate was co-produced in much higher amounts than 1,2-PDO. This unexpected product was probably derived from lactaldehyde by inherent aldehyde dehydrogenases. The 1,2-PDO production without increased accumulation of lactate was observed via establishing the acetol-based pathway by propane utilization with the overexpression of pmoD. This is the first study to provide experimental insights into the operation of metabolic routes for 1,2-PDO and lactate co-production from C1 and C3 compounds in methanotrophs.

Automated summary

The study explores the metabolic pathways of methane and methanol to produce 1,2-propanediol (1,2-PDO) using the type I methanotroph Methylotuvimicrobium alcaliphilum 20Z. It finds that the carbon flux from methane to the EMP pathway restricts the production of 1,2-PDO. Co-utilization of C1 substrates and glycerol enhances the production of 1,2-PDO, although lactate is co-produced in higher amounts. The study provides insights into metabolic routes for 1,2-PDO and lactate co-production from C1 and C3 compounds in methanotrophs.