title: Detection of Prochlorothrix in brackish waters by specific amplification of pcb genes.
abstract: Prochlorothrix hollandica is the only filamentous chlorophyll b (Chlb)-containing oxyphotobacterium that has been found in freshwater habitats to date. Chlb serves as a light-harvesting pigment which is bound to special binding proteins (Pcb). Even though Prochlorothrix was initially characterized as a highly salt-sensitive species, we detected it in a brackish water environment that is characterized by salinities of up to 12 practical salinity units. Using PCR and reverse transcription, we amplified pcb gene fragments of phytoplankton samples taken along a salinity gradient in the eutrophic Darss-Zingst estuary (southern Baltic Sea). After sequencing, high levels of homology to the pcbB and pcbC genes of P. hollandica were found. Furthermore, autofluorescence of Prochlorothrix-like filaments that indicated that Chlb was present was detected in enrichment cultures prepared from the estuarine phytoplankton. The detection of Chlb-containing filaments, as well as the pcb and 16S ribosomal DNA sequences, suggests that Prochlorothrix is an indigenous genus in the Darss-Zingst estuary and may also inhabit many other brackish water environments. The potential of using pcb gene detection to differentiate Prochlorothrix from morphologically indistinguishable species belonging to the genera Pseudanabaena and Planktothrix (Oscillatoria) in phytoplankton analyses is discussed.
authors.affiliation: Department of Aquatic Ecology, Institute of Biodiversity Research, Fachbereich Biowissenschaften, Universität Rostock, D-18051 Rostock, Germany. ulrike.geiss@biologie.uni-rostock.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Geiss
authors.forename: Ingo
authors.initials: I
authors.lastname: Bergmann
authors.forename: Miriam
authors.initials: M
authors.lastname: Blank
authors.forename: Rhena
authors.initials: R
authors.lastname: Schumann
authors.forename: Martin
authors.initials: M
authors.lastname: Hagemann
authors.forename: Arne
authors.initials: A
authors.lastname: Schoor
mesh_terms: D000818:Animals; D002734:Chlorophyll / Q000378:metabolism*; D004275:DNA, Ribosomal / Q000032:analysis; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010839:Phytoplankton / Q000382:microbiology; D019692:Prochlorothrix / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D045483:Rivers / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000378:metabolism*
chemical_list: D004275:DNA, Ribosomal; D045322:Photosynthetic Reaction Center Complex Proteins; D012336:RNA, Ribosomal, 16S; D002734:Chlorophyll; D012965:Sodium Chloride; C037184:chlorophyll b