Comparative Genome Analysis of the Photosynthetic Betaproteobacteria of the Genus Rhodocyclus: Heterogeneity within Strains Assigned to Rhodocyclus tenuis and Description of Rhodocyclus gracilis sp. nov. as a New Species.

The genome sequences for Rhodocyclus purpureus DSM 168T and four strains assigned to Rhodocyclus tenuis (DSM 110, DSM 111, DSM 112, and IM 230) have been determined. One of the strains studied (IM 230) has an average nucleotide identity (ANI) of 97% to the recently reported genome of the type strain DSM 109 of Rcy. tenuis and is regarded as virtually identical at the species level. The ANI of 80% for three other strains (DSM 110, DSM 111, DSM 112) to the type strain of Rcy. tenuis points to a differentiation of these at the species level. Rcy. purpureus is equidistant from Rcy. tenuis and the new species, based on both ANI (78-80%) and complete proteome comparisons (70% AAI). Strains DSM 110, DSM 111, and DSM 112 are very closely related to each other based on ANI, whole genome, and proteome comparisons but clearly distinct from the Rcy. tenuis type strain DSM 109. In addition to the whole genome differentiation, these three strains also contain unique genetic differences in cytochrome genes and contain genes for an anaerobic cobalamin synthesis pathway that is lacking from both Rcy. tenuis and Rcy. purpureus. Based on genomic and genetic differences, these three strains should be considered to represent a new species, which is distinctly different from both Rcy. purpureus and Rcy. tenuis, for which the new name Rhodocyclus gracilis sp. nov. is proposed.

Cellulosimicrobium fucosivorans sp. nov., isolated from San Elijo Lagoon, contains a fucose metabolic pathway linked to carotenoid production.

Cellulosimicrobium strain SE3T was isolated from the San Elijo coastal lagoon near San Diego. A whole genome-based phylogenetic comparison shows great heterogeneity within the Cellulosimicrobium genus. Based on average nucleotide identity, whole genome-based comparison, and the presence of a unique L-fucose metabolic pathway, strain SE3T was shown to belong to a novel species within the genus, together with five other strains. The name Cellulosimicrobium fucosivorans sp. nov. is proposed, with strain SE3T as the type strain. The strain encodes a unique alpha-L-fucosidase and the L-fucose metabolic pathway is homologous to the one recently described in Campylobacter jejuni. C. fucosivorans is able to grow on L-fucose, and interestingly, the biosynthesis of the yellow carotenoid is dependent on the presence of L-fucose in the media. The ability to metabolize fucose and the linked production of carotenoids are expected to provide C. fucosivorans with a competitive advantage in the sunny coastal lagoon area.

Sequencing of Coastal Lagoon Samples from the Piñones Lagoon, Puerto Rico, Reveals Important Role of Bacterial Sulfur Metabolism in the Lagoon Ecosystem.

This initial microbial analysis of the Piñones Lagoon shows a high representation of sulfur-oxidizing Sulfurimonas and sulfur-reducing Sulfurospirillum bacteria. These species are likely responsible for maintaining sulfur homeostasis and prevent the buildup of toxic sulfur components, but may contribute to nitrogen buildup, in the mangrove ecosystem.

Draft Genome Sequences of Thiorhodococcus mannitoliphagus and Thiorhodococcus minor, Purple Sulfur Photosynthetic Bacteria in the Gammaproteobacterial Family Chromatiaceae.

We have determined the draft genome sequences of Thiorhodococcus mannitoliphagus and Thiorhodococcus minor for comparison with those of T. drewsii and Imhoffiella purpurea According to average nucleotide identity (ANI) and whole-genome phylogenetic comparisons, these two species are clearly distinct from the Imhoffiella species and T. drewsii.