Genus specific unusual carotenoids in purple bacteria, Phaeospirillum and Roseospira: structures and biosyntheses.
ABSTRACT Phototrophic bacteria necessarily contain carotenoids for photosynthesis, and a few phototrophic purple bacteria accumulate unusual carotenoids. The carotenoids in the genera Phaeospirillum and Roseospira were identified using spectroscopic methods. All species of the genus Phaeospirillum contained characteristic polar carotenoids in addition to lycopene and hydroxylycopene (rhodopin); hydroxylycopene glucoside, dihydroxylycopene, and its mono- and/or diglucosides. From the structures of these carotenoids, their accumulation was suggested to be due to absence of CrtD (acyclic carotenoid C-3,4 desaturase) and to possession of glucosyltransferase. Species of the genus Roseospira have been reported to have unusual absorption spectra in acetone extract, and they were found to accumulate 3,4-didehydrorhodopin as a major carotenoid. This may be due to low activity of CrtF (acyclic 1-hydroxycarotenoid methyltransferase). The study concludes in identifying genus specific unusual carotenoids, which is probably due to characteristic nature of some carotenogenesis enzymes.
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ABSTRACT: Phototrophic bacteria necessarily contain carotenoids for photosynthesis, and accumulate unusual carotenoids in some cases. The carotenoids in all established species of Rhodoplanes (Rpl.), a representative of phototrophic genera, were identified using spectroscopic methods. The major carotenoid was spirilloxanthin in Rpl. roseus and Rpl. serenus, and rhodopin in "Rpl. cryptolactis". Rpl. elegans contained rhodopin, anhydrorhodovibrin, and spirilloxanthin. Rpl. pokkaliisoli contained not only rhodopin but also 1,1'-dihydroxylycopene and 3,4,3',4'-tetrahydrospirilloxanthin. These variations in carotenoid composition suggested that Rpl. roseus and Rpl. serenus had normal substrate specificity of the carotenogenesis enzymes of CrtC (acyclic carotene 1,2-hydratase), CrtD (acyclic carotenoid 3,4-desaturase), and CrtF (acyclic 1-hydroxycarotenoid methyltransferase). On the other hand, CrtC of Rpl. elegans, CrtD of "Rpl. cryptolactis", and CrtC, CrtD, and CrtF of Rpl. pokkaliisoli might have different characteristics from the usual activity of these normal enzymes in the normal spirilloxanthin pathway. These results suggest that the variation of carotenoids among the species of Rhodoplanes results from modified substrate specificity of the carotenogenesis enzymes involved.Current Microbiology 05/2012; 65(2):150-155. · 1.52 Impact Factor
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ABSTRACT: Two strains (JA492(T) and JA590) of spiral-shaped, anaerobic, Gram-stain-negative, motile, purple non-sulfur bacteria were isolated from aquatic sediments from a bird sanctuary and a stream, respectively, and were characterized by a polyphasic taxonomic approach. Bacteriochlorophyll a and carotenoids (rhodopin, lycopene, hydroxylycopene glucoside and dihydroxylycopene diglucoside) were present as photosynthetic pigments. Intracellular photosynthetic membranes were of the stacked type. The major fatty acids were C(18 : 1)ω7c, C(16 : 0) and summed feature 3 (C(16 : 1)ω6c and/or C(16 : 1)ω7c) in both strains. Ubiquinones and menaquinones were present as major quinone components. The genomic DNA G+C contents of strains JA492(T) and JA590 were 63.8 and 61.5 mol%, respectively. Both strains were closely related (mean DNA-DNA hybridization >70 %). Phylogenetic analysis showed that the strains clustered with species of the genus Phaeospirillum of the family Rhodospirillaceae, class Alphaproteobacteria. Based on 16S rRNA gene sequence analysis, both strains showed highest sequence similarity with Phaeospirillum oryzae JA317(T) (97.2-97.4 %), Phaeospirillum molischianum DSM 120(T) (96.5-96.7 %), Phaeospirillum fulvum DSM 113(T) (96.7-96.9 %) and Phaeospirillum chandramohanii JA145(T) (96.5-96.7 %). DNA-DNA relatedness between strain JA492(T) and its closest relative in the genus Phaeospirillum was less than 42 %. It is evident from phenotypic, chemotaxonomic and molecular genetic data that strain JA492(T) represents a novel species of the genus Phaeospirillum, for which the name Phaeospirillum tilakii sp. nov. is proposed; the type strain is JA492(T) ( = NBRC 107650(T) = KCTC 15012(T)).INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 06/2011; 62(Pt 5):1069-74. · 2.11 Impact Factor