Isolation and Identification of a Strain of Rhodopseudomonas palustris

Objective To screen and identify photosynthetic bacteria that could be used to treat bean wastewater. Methods Photosynthetic bacteria (PSB) were screened by enrichment culture from the sludge. The morphological and biochemical characteristics of the bacteria were determined using transmission electron microscope, live cells'scanning and testing of utilization of different carbon sources. In addition, the sequence of 16S rRNA of the PSB was analysed and the homology was compared with the standard strain according to the sequence in the GenBank. Results A strain NS-04 was screened from the sludge of the pond in Nanjing. The bacteria was Gram-negative in shape of ovoid or rod, with size of 0.6-0.9 μm wide and 1.2-2.0 μm long. The multiplication manner of the bacteria was binary fission. The photosynthetic membrane was lamellar type, which was under and parallel to intro-cytoplasmic membrane. The clone was brown with major pigments riched in carotenoids and bacteriochlorophylla. The bacteria could grow both under anaerobic condition in the light and aerobic condition in the dark. The bacteria could utilize many kinds of carbon sources and the growth of the cells could be prompted by yeast extract. The analysis of phylogenetic tree of 16S rRNA sequence indicated that the similarity of strain NS-04 and the standard strain of Rhodopseudomonas palustris in GenBank was 97%. Conclusion According to Bergey's Manual of Systematic Bacteriology, strain NS-04 was identified to be Rhodopseudomonas palustris.