title: Abundance, depth distribution, and composition of aerobic bacteriochlorophyll a-producing bacteria in four basins of the central Baltic Sea.
abstract: The abundance, vertical distribution, and diversity of aerobic anoxygenic phototrophic bacteria (AAP) were studied at four basins of the Baltic Sea. AAP were enumerated by infrared epifluorescence microscopy, and their diversity was analyzed by using pufM gene clone libraries. In addition, numbers of CFU containing the pufM gene were determined, and representative strains were isolated. Both approaches indicated that AAP reached maximal abundance in the euphotic zone. Maximal AAP abundance was 2.5 x 10(5) cells ml(-1) (11% of total prokaryotes) or 1.0 x 10(3) CFU ml(-1) (9 to 10% of total CFU). Environmental pufM clone sequences were grouped into 11 operational taxonomic units phylogenetically related to cultivated members of the Alpha-, Beta-, and Gammaproteobacteria. In spite of varying pufM compositions, five clones were present in all libraries. Of these, Jannaschia-related clones were always found in relative abundances representing 25 to 30% of the total AAP clones. The abundances of the other clones varied. Clones potentially affiliated with typical freshwater Betaproteobacteria sequences were present at three Baltic Sea stations, whereas clones grouping with Loktanella represented 40% of the total cell numbers in the Gotland Basin. For three alphaproteobacterial clones, probable pufM phylogenetic relationships were supported by 16S rRNA gene analyses of Baltic AAP isolates, which showed nearly identical pufM sequences. Our data indicate that the studied AAP assemblages represented a mixture of marine and freshwater taxa, thus characterizing the Baltic Sea as a "melting pot" of abundant, polyphyletic aerobic photoheterotrophic bacteria.
authors.affiliation: IOW-Leibniz Institute for Baltic Sea Research, Seestrasse 15, 18119 Rostock, Germany.
authors.forename: Ivette
authors.initials: I
authors.lastname: Salka
authors.forename: Vladimíra
authors.initials: V
authors.lastname: Moulisová
authors.forename: Michal
authors.initials: M
authors.lastname: Koblízek
authors.forename: Günter
authors.initials: G
authors.lastname: Jost
authors.forename: Klaus
authors.initials: K
authors.lastname: Jürgens
authors.forename: Matthias
authors.initials: M
authors.lastname: Labrenz
mesh_terms: D020561:Alphaproteobacteria / Q000145:classification / Q000302:isolation & purification; D001420:Bacteria, Aerobic / Q000145:classification* / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics; D025541:Bacteriochlorophyll A / Q000096:biosynthesis*; D001483:Base Sequence; D020562:Betaproteobacteria / Q000145:classification / Q000302:isolation & purification; D015169:Colony Count, Microbial; D005618:Fresh Water / Q000382:microbiology; D020563:Gammaproteobacteria / Q000145:classification / Q000302:isolation & purification; D005798:Genes, Bacterial; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D018524:Phototropism; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012329:RNA, Bacterial / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000302:isolation & purification; D012623:Seawater / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D025541:Bacteriochlorophyll A; D045322:Photosynthetic Reaction Center Complex Proteins; C098543:PufM protein, Bacteria; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S