The in situ bacterial production of fluorescent organic matter; An investigation at a species level

Fox, B. G.; Thorn, R. M. S.; Anesio, A. M.; Reynolds, D. M.

Abstract

© 2017 The Authors Aquatic dissolved organic matter (DOM) plays an essential role in biogeochemical cycling and transport of organic matter throughout the hydrological continuum. To characterise microbially-derived organic matter (OM) from common environmental microorganisms (Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa), excitation-emission matrix (EEM) fluorescence spectroscopy was employed. This work shows that bacterial organisms can produce fluorescent organic matter (FOM) in situ and, furthermore, that the production of FOM differs at a bacterial species level. This production can be attributed to structural biological compounds, specific functional proteins (e.g. pyoverdine production by P. aeruginosa), and/or metabolic by-products. Bacterial growth curve data demonstrates that the production of FOM is fundamentally related to microbial metabolism. For example, the majority of Peak T fluorescence (> 75%) is shown to be intracellular in origin, as a result of the building of proteins for growth and metabolism. This underpins the use of Peak T as a measure of microbial activity, as opposed to bacterial enumeration as has been previously suggested. This study shows that different bacterial species produce a range of FOM that has historically been attributed to high molecular weight allochthonous material or the degradation of terrestrial FOM. We provide definitive evidence that, in fact, it can be produced by microbes within a model system (autochthonous), providing new insights into the possible origin of allochthonous and autochthonous organic material present in aquatic systems.

• Journal Article Type: Article
• Acceptance Date: Aug 17, 2017
• Online Publication Date: Aug 18, 2017
• Publication Date: Nov 15, 2017
• Deposit Date: Aug 29, 2017
• Publicly Available Date: Feb 18, 2018
• Journal: Water Research
• Print ISSN: 0043-1354
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 125
• Pages: 350-359
• DOI: https://doi.org/10.1016/j.watres.2017.08.040
• Keywords: dissolved organic matter, in situ microbial processing, excitation-emission matrix fluorescence spectroscopy, fluorescent organic matter, autochthonous allochthonous
• Public URL: https://uwe-repository.worktribe.com/output/878452
• Publisher URL: https://doi.org/10.1016/j.watres.2017.08.040
• Contract Date: Sep 7, 2017