title: Marine bacterioplankton diversity and community composition in an antarctic coastal environment.
abstract: The bacterial community inhabiting the water column at Terra Nova Bay (Ross Sea, Antarctica) was examined by the fluorescent in situ hybridization (FISH) technique and the genotypic and phenotypic characterization of 606 bacterial isolates. Overall, the FISH analysis revealed a bacterioplankton composition that was typical of Antarctic marine environments with the Cytophaga/Flavobacter (CF) group of Bacteroidetes that was equally dominant with the Actinobacteria and Gammaproteobacteria. As sampling was performed during the decay of sea-ice, it is plausible to assume the origin of Bacteroidetes from the sea-ice compartment where they probably thrive in high concentration of DOM which is efficiently remineralized to inorganic nutrients. This finding was supported by the isolation of Gelidibacter, Polaribacter, and Psychroflexus members (generally well represented in Antarctic sea-ice) which showed the ability to hydrolyze macromolecules, probably through the production of extracellular enzymes. A consistently pronounced abundance of the Gammaproteobacteria (67.8%) was also detected within the cultivable fraction. Altogether, the genera Psychromonas and Pseudoalteromonas accounted for 65.4% of total isolates and were ubiquitous, thus suggesting that they may play a key role within the analyzed bacterioplankton community. In particular, Pseudoalteromonas isolates possessed nitrate reductase and were able to hydrolyze substrates for protease, esterase, and β-galactosidase, thus indicating their involvement in the carbon and nitrogen cycling. Finally, the obtained results highlight the ability of the Actinobacteria to survive and proliferate in the Terra Nova Bay seawater as they generally showed a wide range of salt tolerance and appeared to be particularly competitive with strictly marine bacteria by better utilizing supplied carbon sources.
authors: Dipartimento di Biologia Animale ed Ecologia Marina (DBAEM), Università di Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166, Messina, Italy. alogiudice@unime.it
authors: Angelina
authors: A
authors: Lo Giudice
authors: Consolazione
authors: C
authors: Caruso
authors: Santina
authors: S
authors: Mangano
authors: Vivia
authors: V
authors: Bruni
authors: Maria
authors: M
authors: De Domenico
authors: Luigi
authors: L
authors: Michaud
mesh_terms: D000864:Antarctic Regions; D059001:Aquatic Organisms; D001419:Bacteria / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification*; D001483:Base Sequence; D044822:Biodiversity; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D017753:Ecosystem; D017404:In Situ Hybridization, Fluorescence; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D010933:Plankton / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S