AUTHOR=Dixon Joanna L. , Beale Rachael , Sargeant Stephanie L. , Tarran Glen A. , Nightingale Philip D. TITLE=Microbial acetone oxidation in coastal seawater JOURNAL=Frontiers in Microbiology VOLUME=5 YEAR=2014 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2014.00243 DOI=10.3389/fmicb.2014.00243 ISSN=1664-302X ABSTRACT=

Acetone is an important oxygenated volatile organic compound (OVOC) in the troposphere where it influences the oxidizing capacity of the atmosphere. However, the air-sea flux is not well quantified, in part due to a lack of knowledge regarding which processes control oceanic concentrations, and, specifically whether microbial oxidation to CO₂ represents a significant loss process. We demonstrate that ¹⁴C labeled acetone can be used to determine microbial oxidation to ¹⁴CO₂. Linear microbial rates of acetone oxidation to CO₂ were observed for between 0.75-3.5 h at a seasonally eutrophic coastal station located in the western English Channel (L4). A kinetic experiment in summer at station L4 gave a V_max of 4.1 pmol L^-1 h^-1, with a K_m constant of 54 pM. We then used this technique to obtain microbial acetone loss rates ranging between 1.2 and 42 pmol L^-1 h^-1.(monthly averages) over an annual cycle at L4, with maximum rates observed during winter months. The biological turnover time of acetone (in situ concentration divided by microbial oxidation rate) in surface waters varied from ~3 days in February 2011, when in situ concentrations were 3 ± 1 nM, to >240 days in June 2011, when concentrations were more than twofold higher at 7.5 ± 0.7 nM. These relatively low marine microbial acetone oxidation rates, when normalized to in situ concentrations, suggest that marine microbes preferentially utilize other OVOCs such as methanol and acetaldehyde.