Methane hydroxylation by Methylosinus trichosporium OB3b: Monitoring the biocatalyst activity for methanol production optimization in an innovative membrane bioreactor

Abstract

A quasi-total loss of the bacterial hydroxylating activity was identified to be responsible for methanol production stop. Different strategies acting on the reaction mixture were implemented to apprehend the biocatalyst behavior in view to extend methanol production. Activity monitoring showed first that sodium formate addition did not maintain the biocatalyst activity and even disrupted bacterial equilibrium when added into the reaction mixture with still active biocatalysts. Reaction medium renewals had no influence on methanol production and highlighted a limited hydroxylating potential of the biocatalyst while addition of fresh biocatalysts in the reaction mixture resulted in methanol consumption. Finally, performing hydroxylation directly in the native bacterial culture appeared as a way to enhance methanol production by both release of intracellular methanol accumulated in the cells during cultivation and effective production by methane hydroxylation.