title: Spatial variations in microbial community composition in surface seawater from the ultra-oligotrophic center to rim of the South Pacific Gyre.
abstract: Surface seawater in the South Pacific Gyre (SPG) is one of the cleanest oceanic environments on earth, and the photosynthetic primary production is extremely low. Despite the ecological significance of the largest aquatic desert on our planet, microbial community composition in the ultra-oligotrophic seawater remain largely unknown. In this study, we collected surface seawater along a southern transect of the SPG during the Integrated Ocean Drilling Program (IODP) Expedition 329. Samples from four distinct sites (Sites U1368, U1369, U1370 and U1371) were examined, representing ~5400 kilometers of transect line from the gyre heart to the edge area. Real-time PCR analysis showed 16S rRNA gene abundance in the gyre seawater, ranging from 5.96×10(5) to 2.55×10(6) copies ml(-1) for Bacteria and 1.17×10(3) to 1.90×10(4) copies ml(-1) for Archaea. The results obtained by statistic analyses of 16S rRNA gene clone libraries revealed the community composition in the southern SPG area: diversity richness estimators in the gyre center (Sites U1368 & U1369) are generally lower than those at sites in the gyre edge (Sites U1370 & U1371) and their community structures are clearly distinguishable. Phylogenetic analysis showed the predominance of Proteobacteria (especially Alphaproteobacteria) and Cyanobacteria in bacterial 16S rRNA gene clone libraries, whereas phylotypes of Betaproteobacteria were only detected in the central gyre. Archaeal 16S rRNA genes in the clone libraries were predominated by the sequences of Marine Group II within the Euryarchaeota, and the Crenarchaeota sequences were rarely detected, which is consistent with the real-time PCR data (only 9.9 to 22.1 copies ml(-1)). We also performed cultivation of heterotrophic microbes onboard, resulting in 18.9% of phylogenetically distinct bacterial isolates at least at the species level. Our results suggest that the distribution and diversity of microbial communities in the SPG surface seawater are closely related to the ultra-oligotrophic oceanographic features in the Pacific Ocean.
authors: College of Marine Life Sciences, Ocean University of China, Qingdao, People's Republic of China.
authors: Qi
authors: Q
authors: Yin
authors: Bingbing
authors: B
authors: Fu
authors: Bingyu
authors: B
authors: Li
authors: Xiaochong
authors: X
authors: Shi
authors: Fumio
authors: F
authors: Inagaki
authors: Xiao-Hua
authors: XH
authors: Zhang
mesh_terms: D001105:Archaea / Q000235:genetics*; D001419:Bacteria / Q000235:genetics*; D058448:Biota; D017753:Ecosystem; D010140:Pacific Ocean; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012623:Seawater / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S
references: ISME J. 2011 Mar;5(3):507-18
references: 20668490
references: J Mol Evol. 1980 Dec;16(2):111-20
references: 7463489
references: Arch Microbiol. 1999 Aug;172(2):83-94
references: 10415169
references: Science. 2004 Dec 24;306(5705):2216-21
references: 15618510
references: Environ Microbiol. 2008 Sep;10(9):2200-10
references: 18637951
references: Environ Microbiol. 2010 Jul;12(7):1828-41
references: 20192970
references: Appl Environ Microbiol. 2000 Dec;66(12):5116-22
references: 11097877
references: Appl Environ Microbiol. 2003 Nov;69(11):6481-8
references: 14602603
references: Nature. 2005 Sep 22;437(7058):543-6
references: 16177789
references: Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12776-81
references: 21768380
references: Arch Microbiol. 2003 Sep;180(3):211-7
references: 12856110
references: Appl Environ Microbiol. 2007 Jul;73(13):4198-205
references: 17496136
references: Proc Natl Acad Sci U S A. 2009 Jul 14;106(28):11651-6
references: 19561304
references: Bioinformatics. 2007 Nov 1;23(21):2947-8
references: 17846036
references: Appl Environ Microbiol. 1997 Aug;63(8):3327-32
references: 9251225
references: Microbiol Mol Biol Rev. 2011 Jun;75(2):361-422
references: 21646433
references: Appl Environ Microbiol. 2005 Mar;71(3):1501-6
references: 15746353
references: ISME J. 2012 Jan;6(1):11-20
references: 21716307
references: Nature. 2004 Aug 26;430(7003):1027-32
references: 15329721
references: Proc Natl Acad Sci U S A. 1992 Jun 15;89(12):5685-9
references: 1608980
references: Microbiology (Reading). 1996 May;142 ( Pt 5):1097-1106
references: 8704951
references: Nucleic Acids Res. 2011 Jan;39(Database issue):D32-7
references: 21071399
references: Appl Environ Microbiol. 2010 Jun;76(12):3886-97
references: 20418441
references: Appl Environ Microbiol. 2007 Aug;73(16):5261-7
references: 17586664
references: Mol Biol Evol. 1987 Jul;4(4):406-25
references: 3447015
references: ISME J. 2009 Dec;3(12):1374-86
references: 19626056
references: Appl Environ Microbiol. 2004 Aug;70(8):4971-9
references: 15294837
references: Microbiol Res. 2005;160(2):127-33
references: 15881829
references: Syst Appl Microbiol. 1999 May;22(2):186-96
references: 10390869
references: Science. 2003 Nov 28;302(5650):1514-5
references: 14645833
references: Appl Environ Microbiol. 2000 Nov;66(11):4605-14
references: 11055900
references: Nature. 2001 Jan 25;409(6819):507-10
references: 11206545
references: Nucleic Acids Res. 2003 Jan 1;31(1):442-3
references: 12520046
references: PLoS One. 2011;6(9):e24570
references: 21931760
references: Appl Environ Microbiol. 2008 Jan;74(1):52-60
references: 17965206
references: FEMS Microbiol Ecol. 2004 Feb 1;47(2):161-77
references: 19712332
references: Appl Environ Microbiol. 2005 Dec;71(12):8228-35
references: 16332807
references: ISME J. 2012 Jun;6(6):1238-49
references: 22170429
references: Appl Environ Microbiol. 1993 Mar;59(3):695-700
references: 7683183
references: Appl Environ Microbiol. 2005 Jul;71(7):4117-20
references: 16000830
references: Nucleic Acids Res. 1997 Sep 1;25(17):3389-402
references: 9254694
references: Nucleic Acids Res. 2002 May 1;30(9):2083-8
references: 11972349
references: Int J Syst Evol Microbiol. 2005 Sep;55(Pt 5):2033-2037
references: 16166706
references: Appl Environ Microbiol. 2007 Mar;73(5):1576-85
references: 17220268
references: Environ Microbiol. 2003 Oct;5(10):828-41
references: 14510836