Effect of increased pCO2 on bacterial assemblage shifts in response to glucose addition in Fram Strait seawater mesocosms
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Ray JL, Topper B, An S, Silyakova A, Spindelbock J, Thyrhaug R, DuBow MS, Thingstad TF, Sandaa RA
FEMS Microbiology Ecology
glucose, pyrosequencing, acidification, Fram Strait, Bacteria, V1-V2 16S rDNA amplicon library, mesocosm, 1 m3, Arctic ocean
Ocean acidification may stimulate primary production through increased availabilityof inorganic carbon in the photic zone, which may in turn change thebiogenic flux of dissolved organic carbon (DOC) and the growth potential ofheterotrophic bacteria. To investigate the effects of ocean acidification on marinebacterial assemblages, a two-by-three factorial mescosom experiment wasconducted using surface sea water from the East Greenland Current in FramStrait. Pyrosequencing of the V1-V2 region of bacterial 16S ribosomal RNAgenes was used to investigate differences in the endpoint (Day 9) compositionof bacterial assemblages in mineral nutrient-replete mesocosms amended withglucose (0 lM, 5.3 lM and 15.9 lM) under ambient (250 latm) or acidified(400 latm) partial pressures of CO2 (pCO2). All mesocosms showed lowrichness and diversity by Chao1 estimator and Shannon index, respectively,with general dominance by Gammaproteobacteria and Flavobacteria. Nonmetricmultidimensional scaling analysis and two-way analysis of variance of theJaccard dissimilarity matrix (97% similarity cut-off) demonstrated that the significantcommunity shift between 0 lM and 15.9 lM glucose addition at250 latm pCO2 was eliminated at 400 latm pCO2. These results suggest thatthe response potential of marine bacteria to DOC input may be altered underacidified conditions.
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