Growth yields of methanotrophs 2. A theoretical analysis

Theoretical predications of methanotrophic growth yields have been derived using modifications of two available methods. Expected efficiencies of carbon incorporation and O₂/CH₄ or O₂/CH₃OH ratios have been calculated for cells with methane monooxygenase i) requiring NADH as sole source of reducing power and ii) utilizing reducing power supplied directly by methanol dehydrogenase, with carbon assimilation via the KDPG variant of the RuMP pathway. Comparison with results obtained in this and previous studies suggests that, at least under certain growth conditions, the oxidation of methanol to formaldehyde by Methylococcus capsulatus may be linked to production of 2ATP/O. Yields of M. capsulatus grown in high-copper medium are consistent with a direct coupling model ii) operating at reduced efficiency. An alternative model for coupling of methanol to methane oxidation has been presented.