Biological Characterization of Rhodomicrobium vannielii Isolated from a Hot Spring at Gadek, Malacca, Malaysia

Abstract

A purple nonsulfur anoxygenic phototrophic bacterium, identified as Rhodomicrobium vannielii, was isolated from water sample of a hot spring using glutamate-malate medium (GMM) and Pfennig’s M2 medium. The cells were motile, Gram negative, ovoid to spherical in shape and did not form intracellular sulfur globules. The isolate viewed under transmission electron microscope showed budding filament formation, which is a characteristic of Rm. vannielii. The isolate produced red pigment in both media. The dominant photosynthetic pigment is bacteriochlorophyll a and carotenoids of lycopene and rhodopin. The growth of Rm. vannielii was better in anaerobic-light condition compared to growth in aerobic-dark. Optimum carotenoid production was achieved in 24 hours culture in GMM (pH 7.0) without yeast-extract and incubated in anaerobic-light condition at light intensity of 2000 lux.