Basin-scale variability of microbial methanol uptake in the Atlantic Ocean

Sargeant, Stephanie L; Murrell, J Colin; Nightingale, Philip N; Dixon, Joanna D

Abstract

© 2018 Author(s). Methanol is a climate-active gas and the most abundant oxygenated volatile organic compound (OVOC) in the atmosphere and seawater. Marine methylotrophs are aerobic bacteria that utilise methanol from seawater as a source of carbon (assimilation) and/or energy (dissimilation). A few spatially limited studies have previously reported methanol oxidation rates in seawater; however, the basin-wide ubiquity of marine microbial methanol utilisation remains unknown. This study uniquely combines seawater 14C labelled methanol tracer studies with 16S rRNA pyrosequencing to investigate variability in microbial methanol dissimilation and known methanol-utilising bacteria throughout a meridional transect of the Atlantic Ocean between 47° N to 39° S. Microbial methanol dissimilation varied between 0.05 and 1.68nmolL-1h-1 in the top 200m of the Atlantic Ocean and showed significant variability between biogeochemical provinces. The highest rates of methanol dissimilation were found in the northern subtropical gyre (average 0.99±0.41nmolL-1h-1), which were up to 8 times greater than other Atlantic regions. Microbial methanol dissimilation rates displayed a significant inverse correlation with heterotrophic bacterial production (determined using 3H-leucine). Despite significant depth stratification of bacterial communities, methanol dissimilation rates showed much greater variability between oceanic provinces compared to depth. There were no significant differences in rates between samples collected under light and dark environmental conditions. The variability in the numbers of SAR11 (16S rRNA gene sequences) were estimated to explain approximately 50% of the changes in microbial methanol dissimilation rates. We estimate that SAR11 cells in the Atlantic Ocean account for between 0.3% and 59% of the rates of methanol dissimilation in Atlantic waters, compared to

• Journal Article Type: Article
• Acceptance Date: Aug 10, 2018
• Online Publication Date: Aug 28, 2018
• Publication Date: Aug 28, 2018
• Deposit Date: Sep 3, 2018
• Publicly Available Date: Sep 3, 2018
• Journal: Biogeosciences
• Print ISSN: 1726-4170
• Electronic ISSN: 1726-4189
• Publisher: European Geosciences Union
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 16
• Pages: 5155-5167
• DOI: https://doi.org/10.5194/bg-15-5155-2018
• Keywords: basin-scale, variability, microbial, methanol uptake, Atlantic Ocean
• Public URL: https://uwe-repository.worktribe.com/output/858100
• Publisher URL: https://doi.org/10.5194/bg-15-5155-2018
• Contract Date: Sep 3, 2018