Phototrophic Growth of Rhodopseudomonas gelatinosa on Citrate; Accumulation and Subsequent Utilization of Cleavage Products

Abstract

Rhodopseudomonas gelatinosa grows on citrate anaerobically in the light. Under aerobic conditions citrate cannot be utilized. Citrate is rapidly fermented by Rps. gelatinosa in the dark, and this fermentation is associated with limited growth (one generation). Anaerobically in the light citrate is decomposed much faster than its catabolic products can be used for the synthesis of cellular material. Therefore, acetate and malate are accumulated in the medium. The acetate concentration in the medium after complete consumption of citrate is higher than the original citrate concentration. Acetate is formed by the citrate lyase reaction and by partial degradation of oxaloacetate. After exhaustion of citrate, growth of Rps. gelatinosa continues at the expence of acetate.