Fig. 1

a Metabolic pathway for the production of d-LA from methane in Methylomonas sp. DH-1. d-LA is produced from pyruvate by heterologous expression of a gene encoding d form-specific lactate dehydrogenase (d-LDH). The glgA gene encoding glycogen synthase was deleted to prevent glycogen formation. Dashed arrows indicate multiple pathways. pMMO, particulate methane monooxygenase; MDH, methanol dehydrogenase; H6P, hexulose-6-P; F6P. fructose-6-P; b LA tolerance of Methylomonas sp. DH-1. Cells were grown in NMS medium supplied with 20% (v/v) methane and the indicated concentrations of LA. The medium pH was adjusted to 6.8. Error bars indicate standard deviations of three independent experiments