Anaerobic-Light Growth Kinetics of Rhodopseudomonas sphaeroides S

Abstract

The inhibitory effects of propionate and acetate, and enhancing ability of light on the growth rate of Rhodopseudomonas sphaeroides S were investigated in a modified turbidostat culture apparatus at different substrate concentrations and the light intensities. The experiments were carried out at 30^oC under anaerobic-light condition. Compared to acetic acid, propionic acid strongly inhibited the anaerobic-light growth of Rhodopsuedomonas sphaeroides S. The µ_m observed about 0.4 h^-1 from both acids, was considerably high at very low cell concentration of 12 mg/l and 3000 lux. In simulating the inhibition data, the modified equation of Haldane, µ =  and the generalized non-competitive inhibition model,

µ =   were the most suitable among the five models employed. From these equations, the inhibition constant, K_i and m increased with the increase in light intensity. This implied that the inhibitory effects of high concentration of propionic and acetic acids could be minimized when sufficient light energy was supplied.