ALBERT

Description: From specimens of the bryozoan Membranipora membranacea collected in the Baltic Sea, bacteria were isolated on four different media, which significantly increased the diversity of the isolated groups. All isolates were classifiedaccording to 16S rRNA gene sequence analysis and tested for antimicrobial properties using a panel of five indicator strainsand six different media. Each medium featured a unique set of isolated phylotypes, and a phylogenetically diverse collection of isolates was obtained. A total of 96 isolates were assigned to 49 phylotypes and 29 genera. Only one-third of the members of these genera had been isolated previously from comparable sources. The isolates were affiliated with Alpha- and Gammaproteobacteria, Bacilli, and Actinobacteria. A comparable large portion of up to 22 isolates, i.e., 15 phylotypes, probably represent new species. Likewise, 47 isolates (approximately 50%) displayed antibiotic activities, mostly against grampositive indicator strains. Of the active strains, 63.8 % had antibiotic traits only on one or two of the growth media, whereas only 12.7 % inhibited growth on five or all six media. The application of six different media for antimicrobial testing resulted in twice the number of positive hits as obtained with only a single medium. The use of different media for the isolation of bacteria as well as the variation of media considered suitable for the production of antibiotic substances significantly enhanced both the number of isolates obtained and the proportion of antibiotic active cultures. Thus the approach described herein offers an improved strategy in the search for new antibiotic compounds

Description: The phylogenetic relationship of purple sulfur bacteria (PSB), of the order Chromatiales (class Gammaproteobacteria), was analyzed based on photosynthetic gene sequences of the pufL and pufM genes, and the results compared to phylogenetic trees and groupings of the 16S rRNA gene. Primers for pufL and pufM genes were constructed and successfully used to amplify the pufLM genes of members of 16 genera of Chromatiales. In total, pufLM and 16S rRNA gene sequences of 66 PSB strains were analyzed, including 29 type strains and 28 new isolates. The inferred phylogenetic trees of the pufLM and 16S rRNA genes reflected a largely similar phylogenetic development suggesting coevolution of these essential genes within the PSB. It is concluded that horizontal gene transfer of pufLM genes within the PSB is highly unlikely, in contrast to the Situation in other groups of anoxygenic phototrophic bacteria belonging to Alpha- and Betaproteobacteria. The phylogeny of pufLM is therefore in good agreement with the current taxonomic classification of PSB. A phylogenetic classification of PSB to the genus level is possible based on their pufL or pufM sequences, and in many cases even to the species level. In addition, our data support a correlation between Puf protein structure and the type of internal photosynthetic membranes (vesicular, lamellar, or tubular)

Description: Communities of green sulfur bacteria were studied in selected marine and saline habitats on the basis of gene sequences of 16S rRNA and the Fenna- Matthews-Olson (FMO) protein. The availability of group-specific primers for both 16S rDNA and the fmoA gene, which is unique to green sulfur bacteria, has, for the first time, made it possible to analyze environmental communities of these bacteria by culture-independent methods using two independent genetic markers. Sequence results obtained with fmoA genes and with 16S rDNA were largely congruent to each other. All of the 16S rDNA and fmoA sequences from habitats of the Baltic Sea, the Mediterranean Sea, Sippewissett Salt Marsh (Massachusetts, USA), and Bad Water (Death Valley, California, USA) were found within salt-dependent phylogenetic lines of green sulfur bacteria established by pure culture studies. This strongly supports the existence of phylogenetic lineages of green sulfur bacteria specifically adapted to marine and saline environments and the exclusive occurrence of these bacteria in marine and saline habitats. The great majority of clone sequences belonged to different clusters of the Prosthecochloris genus and probably represent different species. Evidence for the occurrence of two new species of Prosthecochloris was also obtained. Different habitats were dominated by representatives from the Prosthecochloris group and different clusters or species of this genus were found either exclusively or as the clearly dominant green sulfur bacterium at different habitats

Description: Easter Island is an isolated volcanic island in the Pacific Ocean. Despite the extended knowledge about its origin, flora, and fauna, little is known about the bacterial diversity inhabiting this territory. Due to its isolation, Easter Island can be considered as a suitable place to evaluate microbial diversity in a geographically isolated context, what could shed light on actinobacterial occurrence, distribution, and potential novelty. In the present study, we performed a comprehensive analysis of marine Actinobacteria diversity of Easter Island by studying a large number of coastal sampling sites, which were inoculated into a broad spectrum of different culture media, where most important variations in composition included carbon and nitrogen substrates, in addition to salinity. The isolates were characterized on the basis of 16S ribosomal RNA gene sequencing and phylogenetic analysis. High actinobacterial diversity was recovered with a total of 163 pure cultures of Actinobacteria representing 72 phylotypes and 20 genera, which were unevenly distributed in different locations of the island and sample sources. The phylogenetic evaluation indicated a high degree of novelty showing that 45% of the isolates might represent new taxa. The most abundant genera in the different samples were Micromonospora, Streptomyces, Salinispora, and Dietzia. Two aspects appear of primary importance in regard to the high degree of novelty and diversity of Actinobacteria found. First, the application of various culture media significantly increased the number of species and genera obtained. Second, the geographical isolation is considered to be of importance regarding the actinobacterial novelty found.