Fig. 2

Ethanol and electricity co-production performances of knockout strains of lactate dehydrogenase. a Ethanol production yields of 5D, Δdld1, Δdld2, Δdld3, Δdld12, Δdld13, Δdld23, and Δdld123 knockout strains using glucose when run in the microbial fuel cell (MFC) for 24 h in an open circuit. b Ethanol production yields 5D and seven knockout strains using glucose when run in the MFC for 24 h in an external circuit. c Open-circuit potential (OCP) of original 5D strain and Δdld123 strain running in the MFC for 24 h. d External-circuit potential of original 5D strain and Δdld123 strain operating in the MFC for 24 h with a 1000 Ω resistor connected externally in the MFC. e Linear scan voltammetry curves of the original 5D strain and the Δdld123 strain in the MFC at a sweep speed of 2 mv/s. f Power density curves of the original 5D strain and the Δdld123 strain in the MFC at a sweep speed of 2 mv/s. The MFC was run at 35 °C and 500 rpm. Values are shown as the mean ± s.d. (n = 3)