Rhodobacter veldkampii, a new species of phototrophic purple nonsulfur bacteria

We describe a new species of purple nonsulfur bacteria, which has the ability to grow under photoautotrophic growth conditions with sulfide as an electron donor and shows the characteristic properties of Rhodobacter species (i.e., ovoid to rod-shaped cells, vesicular internal photosynthetic membranes, bacteriochlorophyll a and carotenoids of the spheroidene series as photosynthetic pigments). In its physiological properties this new species is particularly similar to the recently described species Rhodobacter adriaticus, but it shows enough differences compared with R. adriaticus and the other Rhodobacter species to be recognized as a separate species. In honor of Hans Veldkamp, a Dutch microbiologist, the name Rhodobacter veldkampii sp. nov. is proposed

Phylogenetic taxonomy of the family Chlorobiaceae on the basis of 16S rRNA and fmo (Fenna-Matthews-Olson protein) gene sequences.

A new taxonomy of the green sulfur bacteria is proposed, based on phylogenetic relationships determined using the sequences of the independent 16S rRNA and fmo (Fenna-Matthews-Olson protein) genes, and supported by the DNA G + C content and sequence signatures. Comparison of the traditional classification system for these bacteria with their phylogenetic relationship yielded a confusing picture, because properties used for classification (such as cell morphology, photosynthetic pigments and substrate utilization) do not concur with their phylogeny. Using the genetic information available, strains and species assigned to the genera Chlorobium, Pelodictyon and Prosthecochloris are considered, and the following changes are proposed. Pelodictyon luteolum is transferred to the genus Chlorobium as Chlorobium luteolum comb. nov. Pelodictyon clathratiforme and Pelodictyon phaeoclathratiforme are transferred to the genus Chlorobium and combined into one species, Chlorobium clathratiforme comb. nov. The name Pelodictyon will become a synonym of Chlorobium. Strains known as Chlorobium limicola subsp. thiosulfatophilum that have a low DNA G + C content (52-52.5 mol%) are treated as strains of Chlorobium limicola; those with a high DNA G + C content (58.1 mol%) are transferred to Chlorobaculum gen. nov., as Chlorobaculum thiosulfatiphilum sp. nov. Chlorobium tepidum is transferred to Chlorobaculum tepidum comb. nov., and defined as the type species of the genus Chlorobaculum. Strains assigned to Chlorobium phaeobacteroides, but phylogenetically distant from the type strain of this species, are assigned to Chlorobium limicola and to Chlorobaculum limnaeum sp. nov. Strains known as Chlorobium vibrioforme subsp. thiosulfatophilum are transferred to Chlorobaculum parvum sp. nov. Chlorobium chlorovibrioides is transferred to 'Chlorobaculum chlorovibrioides' comb. nov. The type strain of Chlorobium vibrioforme is phylogenetically related to Prosthecochloris, and is therefore transferred to this genus as Prosthecochloris vibrioformis comb. nov. Consequently, the name Chlorobium vibrioforme will become a synonym of Prosthecochloris vibrioformis, and other strains that were assigned to this species are now considered to belong to Chlorobium luteolum, Chlorobium phaeovibrioides and 'Chlorobaculum chlorovibrioides', according to their phylogenetic relatedness

Transfer of Pfennigia purpurea Tindall 1999 (Amoebobacter purpureus Echler and Pfennig 1988) to the genus Lamprocystis as Lamprocystis purpurea

On the basis of its close phylogenetic relationship to Lamprocystis roseopersicina, the phototrophic purple sulfur bacterium originally described as Amoebobacter purpureus and recently transferred to Pfennigia purpurea is reclassified as Lamprocystis purpurea comb. nov. In addition, an emended description of the genus Lamprocystis is given

Taxonomic note: transfer of Rhodopseudomonas acidophila to the new genus Rhodoblastus as Rhodoblastus acidophilus comb. nov.

Rhodopseudomonas acidophila has unique properties among the phototrophic a-Proteobacteria and is quite distinct from the type species of Rhodopseudomonas, Rhodopseudomonas palustris. Therefore, the transfer of Rhodopseudomonas acidophila to Rhodoblastus acidophilus gen. nov., comb. nov., is proposed. This proposal is in accordance with other taxonomic reclassifications proposed previously and fully reflects the phylogenetic distance from Rhodopseudomonas palustris

Natural Products from Marine Fungi—Still an Underrepresented Resource

Marine fungi represent a huge potential for new natural products and an increased number of new metabolites have become known over the past years, while much of the hidden potential still needs to be uncovered. Representative examples of biodiversity studies of marine fungi and of natural products from a diverse selection of marine fungi from the author's lab are highlighting important aspects of this research. If one considers the huge phylogenetic diversity of marine fungi and their almost ubiquitous distribution, and realizes that most of the published work on secondary metabolites of marine fungi has focused on just a few genera, strictly speaking Penicillium, Aspergillus and maybe also Fusarium and Cladosporium, the diversity of marine fungi is not adequately represented in investigations on their secondary metabolites and the less studied species deserve special attention. In addition to results on recently discovered new secondary metabolites of Penicillium species, the diversity of fungi in selected marine habitats is highlighted and examples of groups of secondary metabolites produced by representatives of a variety of different genera and their bioactivities are presented. Special focus is given to the production of groups of derivatives of metabolites by the fungi and to significant differences in biological activities due to small structural changes

Functional gene studies of pure cultures are the basis of systematic studies of environmental communities of phototrophic bacteria and their species specific analyses

From the establishment of proper cultivation conditions of phototrophic sulfur bacteria 50 years ago up to today significant improvements have been made to systematically treat the phototrophic green and purple sulfur bacteria and identify them in environmental communities. Important steps for these improvements were first of all the description of a large number of pure cultures representing a proper fraction of environmental diversity, their correct taxonomic treatment and the clear definition of the taxa. Further important steps were the establishment of a phylogenetics-based taxonomy supported by 16S rRNA gene sequences and the demonstration of congruence between phylogenies based on 16S rRNA genes and functional genes. The formation of a large database of fmoA genes of green sulfur bacteria and of pufLM genes of purple sulfur bacteria and their obvious phylogenetic congruence with the 16S rRNA gene enabled detailed studies of environmental communities of these bacteria and the recognition of species and genera in natural habitats. The comprehensive studies of selected habitats yielded promising results and demonstrated the potential of this approach for the systematic characterization of environmental communities

Thioflavicoccus mobilis gen. nov., sp. nov., a novel purple sulfur bacterium with bacteriochlorophyll b.

A novel phototrophic purple sulfur bacterium was isolated from a flat, laminated microbial mat in a salt marsh near Woods Hole, Massachusetts, USA. The cells were monotrichously flagellated motile cocci with internal photosynthetic membranes of the tubular type. The main photosynthetic pigments were bacteriochlorophyll b and the carotenoid 3,4,3',4'-tetrahydrospirilloxanthin. The marine bacterium showed optimal growth in the presence of 2% salts. It was obligately phototrophic and strictly anaerobic. It grew photoautotrophically and photoassimilated acetate, pyruvate and ascorbate as the only organic substrates. In the presence of sulfide, elemental sulfur globules were formed inside the cells. Elemental sulfur was further oxidized to sulfate. The DNA base composition of the new bacterium was 66.5 mol% G+C. The 16S rDNA nucleotide sequence was most similar to strains of Thiococcus pfennigii, there being approximately 92-93% sequence similarity. The new bacterium is described as a new species and a new genus, and the name Thioflavicoccus mobilis is proposed; the type strain is 8321T (= ATCC 700959T)