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The phototrophic bacterium Rhodopseudomonas palustris has been reported to be versatile in photometabolism of aromatic compounds. However, the kinetics of degradation of aromatic compounds by R. palustris appears not to have been reported in the literature. In this laboratory a photosynthetic bacterium that was identified as Rhodopseudomonas palustris(bp) was isolated from a sample collected from a canal where refinery wastewater was discharged. The paper presents the results of the growth of the isolate on different aromatic compounds, their catabolic pathways, and the kinetics of their degradation. The doubling time of the isolate was found to be 23, 22, 17, 27, 20, 24, and 26 h for benzoate, p-hydroxybenzoate, cinnamate, p-coumarate, phenyl valerate, phenyl acetate, and cinnamyl alcohol respectively. It was also found that cinnamate, phenyl valerate, phenyl acetate, and cinnamyl alcohol were converted to benzoate, while p-coumarate was converted to p-hydroxybenzoate. The substrate inhibition constant (Ki) was found to be 1082, 1178, 1362, 1260, 3098, 1347, and 322 mg/L for benzoate, p-hydroxybenzoate, cinnamate, p-coumarate, phenyl valerate, phenyl acetate, and cinnamyl alcohol respectively. [ABSTRACT FROM AUTHOR]

A few photosynthetic bacteria have been isolated from a biological treatment system treating producer gas plant effluent. One of them was identified as Rhodopseudomonas gelatinosa on the basis of physiological and morphological characteristics. Biodegradation of aromatic compounds by R. gelatinosa appears not to have been reported in the literature. The culture was found to degrade benzoic acid, p-hydroxybenzoic acid, cinnamic acid, and p-coumaric acid. The doubling time for this culture was found to be 18, 19, 23, and 31 h for benzoic acid, p-hydroxybenzoic acid, cinnamic acid, and p-coumaric acid respectively. [ABSTRACT FROM AUTHOR]