Summary auto-generated
This study describes two novel genera of aerobic bacteriochlorophyll a-containing bacteria isolated from Japanese soil samples. Three bacterial strains (NS89T, NS102, and NS130T) were characterized using 16S rRNA gene sequencing and DNA-DNA hybridization analysis. Phylogenetic analysis placed all three strains within the α-1 subclass of Proteobacteria, forming a distinct lineage most closely related to Roseococcus thiosulfatophilus. However, based on sequence similarity (94.2% between NS89T and NS130T, with NS130T showing <21% DNA homology to the other two strains) and phenotypic differences, the researchers divided the isolates into two separate genera. Strains NS89T and NS102, which shared identical 16S rRNA sequences and 86% DNA homology, were designated Paracraurococcus ruber gen. nov., sp. nov. Strain NS130T, with distinctive physiological properties and absorption spectra, was designated Craurococcus roseus gen. nov., sp. nov. Both genera are Gram-negative cocci that grow heterotrophically under aerobic conditions and contain bacteriochlorophyll a alongside spirilloxanthin and carotenoid pigments. These represent the first aerobic bacteriochlorophyll a-containing bacteria isolated from soil.
Key findings
- Two new bacterial genera (Craurococcus roseus and Paracraurococcus ruber) containing bacteriochlorophyll a were isolated from soil in Japan
- Phylogenetic analysis based on 16S rRNA sequences placed both genera in the α-1 subclass of Proteobacteria, distinct from other aerobic bacteriochlorophyll a-containing bacteria
- Paracraurococcus ruber strains exhibited 86% DNA homology and identical 16S rRNA sequences, while Craurococcus roseus showed <21% DNA homology to Paracraurococcus strains, justifying separate generic classification
- Both genera are non-motile, Gram-negative cocci that grow heterotrophically under aerobic conditions and require divalent cations for growth
- These represent the first reported isolation of aerobic bacteriochlorophyll a-containing bacteria from soil environments
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Abstract
Sequences of the 16S rRNA gene were determined for three strains of aerobic bacteriochlorophyll a-containing bacteria isolated from soil. The sequence of two strains (NS89(T) and NS102) were identical for approximately 1500 nucleotides. Phylogenetic analysis revealed that the three strains belonged to the alpha-1 subclass of the Proteobacteria, constituting one line of descent. The three strains are comparatively related to Roseoccus thiosulfatophilus, which is an aerobic bacteriochlorophyll a-containing bacterium. The 16S rRNA gene sequence similarity and the DNA-DNA relatedness allow the proposal of two new genera, Craurococcus gen. nov. and Paracraurococcus gen. nov. The type species are Craurococus roseus sp. nov. and Paracraurococcus ruber sp. nov., and their type strains are NS130(T) (=JCM 9933(T)) and NS89(T) (=JCM 9931(T)), respectively.