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Elevated p CO 2 alters marine heterotrophic bacterial community composition and metabolic potential in response to a pulse of phytoplankton organic matter
Author(s) -
James Anna K.,
Kelly Linda W.,
Nelson Craig E.,
Wilbanks Elizabeth G.,
Carlson Craig A.
Publication year - 2019
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.14484
Subject(s) - phytoplankton , biology , heterotroph , environmental chemistry , seawater , organic matter , dissolved organic carbon , microbial loop , microbial population biology , carbon cycle , botany , bacteria , ecology , chemistry , nutrient , ecosystem , genetics
Summary Factors that affect the respiration of organic carbon by marine bacteria can alter the extent to which the oceans act as a sink of atmospheric carbon dioxide. We designed seawater dilution experiments to assess the effect of p CO 2 enrichment on heterotrophic bacterial community composition and metabolic potential in response to a pulse of phytoplankton‐derived organic carbon. Experiments included treatments of elevated (1000 p.p.m.) and low (250 p.p.m.) p CO 2 amended with 10 μmol L −1 dissolved organic carbon from Emiliana huxleyi lysates, and were conducted using surface‐seawater collected from the South Pacific Subtropical Gyre. To assess differences in community composition and metabolic potential, shotgun metagenomic libraries were sequenced from low and elevated p CO 2 treatments collected at the start of the experiment and following exponential growth. Our results indicate bacterial communities changed markedly in response to the organic matter pulse over time and were significantly affected by p CO 2 enrichment. Elevated p CO 2 also had disproportionate effects on the abundance of sequences related to proton pumps, carbohydrate metabolism, modifications of the phospholipid bilayer, resistance to toxic compounds and conjugative transfer. These results contribute to a growing understanding of the effects of elevated p CO 2 on bacteria‐mediated carbon cycling during phytoplankton bloom conditions in the marine environment.