title: Single bacterial strain capable of significant contribution to carbon cycling in the surface ocean.
abstract: Marine dissolved organic carbon (DOC) encompasses one of the largest reservoirs of carbon on Earth. Heterotrophic bacteria are the primary biotic force regulating the fate of this material, yet the capacity of individual strains to significantly contribute to carbon cycling is unknown. Here we quantified the ability of a single Alteromonas strain [Alteromonas sp. strain Scripps Institution of Oceanography (AltSIO)] to drawdown ambient DOC in a coastal ecosystem. In three experiments, AltSIO alone consumed the entire pool of labile DOC, defined here as the quantity consumed by the submicron size fraction of ambient microbial assemblages within 5 d. These findings demonstrate that complete removal of the labile DOC pool in coastal surface seawater can be achieved by a single taxon. During long-term incubations (>1 y) testing semilabile DOC consumption, AltSIO entered dormancy but remained viable, while the diverse assemblages continued to consume carbon. Given that AltSIO is a large bacterium and thus subject to increased grazing pressure, we sought to determine the ecological relevance of this phenotype. Growth dynamics in natural seawater revealed that AltSIO rapidly outgrew the native bacteria, and despite intense grazing pressure, was never eliminated from the population. A survey in the California Current Ecosystem revealed that large bacteria (≥40 fg C⋅cell(-1)) were persistent, accounting for up to 12% of total bacterial abundance and 24% of total bacterial biomass. We conclude that large, rapidly growing bacteria have the potential to disproportionately alter the fate of carbon in the mesotrophic ocean and play an important role in ecosystem function.
authors.affiliation: Marine Biology Research Division and bpedler@gmail.com.
authors.forename: Byron E
authors.initials: BE
authors.lastname: Pedler
authors.affiliation: Geosciences Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202.
authors.forename: Lihini I
authors.initials: LI
authors.lastname: Aluwihare
authors.affiliation: Marine Biology Research Division and.
authors.forename: Farooq
authors.initials: F
authors.lastname: Azam
mesh_terms: D020591:Alteromonas / Q000235:genetics / Q000502:physiology*; D018533:Biomass; D002140:California; D002244:Carbon / Q000737:chemistry; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000737:chemistry; D017753:Ecosystem; D020387:Food Chain; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000737:chemistry; D009792:Oceans and Seas; D012623:Seawater / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen
keywords: CCE; dissolved organic matter; marine biogeochemistry; microbial loop; ocean carbon cycle
references.citation: Sci Rep. 2012;2:696
references.pmid: 23019517
references.citation: ISME J. 2008 Dec;2(12):1194-212
references.pmid: 18670397
references.citation: Ann Rev Mar Sci. 2013;5:421-45
references.pmid: 22881353
references.citation: Proc Natl Acad Sci U S A. 2009 Sep 15;106(37):15527-33
references.pmid: 19805210
references.citation: Appl Environ Microbiol. 1999 Feb;65(2):514-22
references.pmid: 9925576
references.citation: Appl Environ Microbiol. 1987 Jun;53(6):1298-303
references.pmid: 16347362
references.citation: Proc Natl Acad Sci U S A. 2010 Sep 21;107(38):16420-7
references.pmid: 20807744
references.citation: Environ Microbiol. 2012 Sep;14(9):2361-78
references.pmid: 22697392
references.citation: Microb Ecol. 2000 Aug;40(2):148-158
references.pmid: 11029083
references.citation: Science. 2012 May 4;336(6081):608-11
references.pmid: 22556258
references.citation: Appl Environ Microbiol. 2011 Jun;77(12):4055-65
references.pmid: 21515719
references.citation: Adv Microb Physiol. 1971;6:147-217
references.pmid: 4950180
references.citation: Proc Natl Acad Sci U S A. 2008 Aug 12;105 Suppl 1:11512-9
references.pmid: 18695234
references.citation: Environ Microbiol. 2010 Mar;12(3):616-27
references.pmid: 19930445
references.citation: Environ Microbiol. 2012 Jun;14(6):1500-16
references.pmid: 22507662
references.citation: Nat Rev Microbiol. 2011 Feb;9(2):119-30
references.pmid: 21233850
references.citation: Appl Environ Microbiol. 1985 Jun;49(6):1488-93
references.pmid: 16346817
references.citation: Appl Environ Microbiol. 1979 May;37(5):805-12
references.pmid: 16345378
references.citation: Nature. 2008 Feb 7;451(7179):708-11
references.pmid: 18223640
references.citation: Arch Microbiol. 2000 Feb;173(2):138-45
references.pmid: 10795685
references.citation: Appl Environ Microbiol. 2013 Jan;79(1):177-84
references.pmid: 23087033
references.citation: Environ Microbiol. 2012 Sep;14(9):2348-60
references.pmid: 22639946
references.citation: Am Nat. 1999 Jan;153(1):73-82
references.pmid: 29578767
references.citation: Antonie Van Leeuwenhoek. 2002 Aug;81(1-4):293-308
references.pmid: 12448728
references.citation: Trends Microbiol. 2006 Jun;14(6):257-63
references.pmid: 16679014
references.citation: ISME J. 2010 Mar;4(3):427-39
references.pmid: 19940866
references.citation: Appl Environ Microbiol. 1999 Oct;65(10):4475-83
references.pmid: 10508078
references.citation: Appl Environ Microbiol. 2000 Jul;66(7):3044-51
references.pmid: 10877804
references.citation: FEMS Microbiol Ecol. 2000 Feb 1;31(2):153-161
references.pmid: 10640668
references.citation: Appl Environ Microbiol. 1998 Sep;64(9):3352-8
references.pmid: 9726882
references.citation: Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12776-81
references.pmid: 21768380
references.citation: Proc Natl Acad Sci U S A. 2013 Apr 9;110(15):6004-9
references.pmid: 23536290
references.citation: Appl Environ Microbiol. 2003 May;69(5):2624-30
references.pmid: 12732530
references.citation: PLoS One. 2011;6(9):e25266
references.pmid: 21980410
references.citation: Appl Environ Microbiol. 2000 Nov;66(11):4634-40
references.pmid: 11055904
references.citation: Environ Microbiol. 2012 Jan;14(1):191-206
references.pmid: 21981709
references.citation: ISME J. 2013 May;7(5):962-79
references.pmid: 23303369
references.citation: Nature. 2010 Nov 4;468(7320):60-6
references.pmid: 21048761