No abstract

The rhodoquinone (RQ) composition was studied in representatives of 20 species of Rhodospirillaceae. Thin-layer chromatography, ultraviolet spectrophotometry, mass spectrometry, and high-performance liquid chromatography revealed that six of the 20 test species contained RQ as a major quinone in average amounts of 0.28 to 2.22 umol per g dry weight of cells. The predominant homologue of RQ in the six species was as follows: RQ-8-Rhodospirillum photometricum and an unknown species resembling Rhodocyclus gelatinosus; RQ-9+ RQ-10-Rhodopila globiformis; RQ-l0-Rhodospirillum rubrum, Rhodopseudomonas acidophila, and Rhodomicrobium vannielii. The taxonomic significance of RQ and other isoprenoid quinones is discussed in comparison with the new classification system for the phototrophic bacteria recently proposed by IMHOFF et al.

From polluted water of a lagoon pond a new type of denitrifying photosynthetic purple bacteria was isolated. With respect to morphology, fine structure, photopigments, requirement for growth factors, the range of utilization of organic substrates for phototrophic growth and DNA base ratio, the denitrifying strains show the closest resemblance to Rhodopseudomonas sphaeroides and were therefore described as a subspecies named R. sphaeroides forma sp. denitrificans. The new isolates grow well with nitrate anaerobically in the dark accompanying the evolution of nitrogen gas. They cannot assimilate nitrate as the nitrogen source for growth.

The 16S rRNA or rRNA gene sequences of the type strains of 5 species of Rhodobacter, Rhodopseudomonas blastica and Paracoccus denitrificans were determined. The sequence analysis revealed that Rhodobacter species, whose intracytoplasmic membrane systems were characteristically vesicular, composed a sole cluster. Rhodopseudomonas blastica, whose intracytoplasmic membrane system was lamellar, was included in the cluster of Rhodobacter. The phylogenetic co-clustering of these bacteria conformed to their possessing of the identical types of carotenoids. Paracoccus denitrificans, which is nonphototrophic, is a right member of the Rhodobacter cluster. Rhodobacter species, Rhodopseudomonas blastica and Paracoccus denitrificans are apart from the other phototrophic bacteria and have the common deletions of 21 bases at the positions 1258 to 1278 (Escherichia coli numbering system). It was demonstrated that the morphological character "intracytoplasmic membrane structure", that has been regarded as a generic criterion does not reflect the phylogeny in the phototrophic bacteria. The transfer of Rhodopseudomonas blastica to the genus Rhodobacter is proposed.

Fifty five strains of 13 species of Rhodospirillaceae and one strain of Chromatium vinosum were examined for isoprenoid quinone composition. These bacteria were divided into the following five categories on the basis of their predominant quinone patterns: Q-10-Rhodospirillum rubrum, Rhodopseudomonas palustris, Rhodopseudomonas capsulata, Rhodopseudomonas sphaeroides, and Rhodopseudomonas sulfidophila; Q-10--MK-10-Rhodopseudomonas acidophila; Q-9 ;-MK-9 -Rhodospirillum fulvum, Rhodospirillum molischianum, Rhodopseudomonas viridis, and Rhodopseudomonas globiformis; Q-8 -Rhodospirillum photometricum and atypical strains of Rhodopseudomonas gelatinosa; Q-8 -MK-8 -Rhodospirillum tenue, R. gelatinosa, and C. vinosur. The significance of the quinone system in Rhodospinillaceae taxonomy is discussed in comparison with available information on other taxonomic properties such as morphology and photosynthetic membrane systems and on some phylogenetic characteristics.Respiratory isoprenoid quinones are essential components of membranebound electron transport systems in bacteria. In addition to interest in their functions in electron transport mechanisms, a growing concern with the significance of the quinone system in bacterial systematics has led to intensive study. At present, the diagnostic value of isoprenoid quinones in bacterial taxonomy is well realized (1), and an analysis of isoprenoid quinone composition of bacterial strains is one of the most prevalent chemotaxonomic methods (2).There are some preliminary reports in the literature on predominant quinone patterns in phototrophic purple nonsulfur bacteria, Rhodospirillaceae (3-5). The available information on this subject has also been summarized in recent re-1 This study was presented in part at the Annual Meeting of the Society of Fermentation Technology,

No abstract

No abstract

No abstract