TY - JOUR
T1 - Characterization of the surface-active exopolysaccharide produced by Halomonas sp TGOS-10: understanding its role in the formation of marine oil snow
AU - Nikolova, Christina
AU - Morris, Gordon
AU - Ellis, David
AU - Bowler, Bernard
AU - Jones, Martin
AU - Mulloy, Barbara
AU - Gutierrez, Tony
PY - 2024/5/28
Y1 - 2024/5/28
N2 - In this study, we characterize the exopolymer produced by Halomonas sp. strain TGOS-10 –one of the organisms found enriched in sea surface oil slicks during the Deepwater Horizon oil spill. The polymer was produced during the early stationary phase of growth in Zobell’s 2216 marine medium amended with glucose. Chemical and proton NMR analysis showed it to be a relatively monodisperse, high-molecular-mass (6,440,000 g/mol) glycoprotein composed largely of protein (46.6% of total dry weight of polymer). The monosaccharide composition of the polymer is typical to that of other marine bacterial exopolymers which are generally rich in hexoses, with the notable exception that it contained mannose (commonly found in yeast) as a major monosaccharide. The polymer was found to act as an oil dispersant based on its ability to effectively emulsify pure and complex oils into stable oil emulsions—a function we suspect to be conferred by the high protein content and high ratio of total hydrophobic nonpolar to polar amino acids (52.7:11.2) of the polymer. The polymer’s chemical composition, which is akin to that of other marine exopolymers also having a high protein-to-carbohydrate (P/C) content, and which have been shown to effect the rapid and non-ionic aggregation of marine gels, appears indicative of effecting marine oil snow (MOS) formation. We previously reported the strain capable of utilising aromatic hydrocarbons when supplied as single carbon sources. However, here we did not detect biodegradation of these chemicals within a complex (surrogate Macondo) oil, suggesting that the observed enrichment of this organism during the Deepwater Horizon spill may be explained by factors related to substrate availability and competition within the complex and dynamic microbial communities that were continuously evolving during that spill.
AB - In this study, we characterize the exopolymer produced by Halomonas sp. strain TGOS-10 –one of the organisms found enriched in sea surface oil slicks during the Deepwater Horizon oil spill. The polymer was produced during the early stationary phase of growth in Zobell’s 2216 marine medium amended with glucose. Chemical and proton NMR analysis showed it to be a relatively monodisperse, high-molecular-mass (6,440,000 g/mol) glycoprotein composed largely of protein (46.6% of total dry weight of polymer). The monosaccharide composition of the polymer is typical to that of other marine bacterial exopolymers which are generally rich in hexoses, with the notable exception that it contained mannose (commonly found in yeast) as a major monosaccharide. The polymer was found to act as an oil dispersant based on its ability to effectively emulsify pure and complex oils into stable oil emulsions—a function we suspect to be conferred by the high protein content and high ratio of total hydrophobic nonpolar to polar amino acids (52.7:11.2) of the polymer. The polymer’s chemical composition, which is akin to that of other marine exopolymers also having a high protein-to-carbohydrate (P/C) content, and which have been shown to effect the rapid and non-ionic aggregation of marine gels, appears indicative of effecting marine oil snow (MOS) formation. We previously reported the strain capable of utilising aromatic hydrocarbons when supplied as single carbon sources. However, here we did not detect biodegradation of these chemicals within a complex (surrogate Macondo) oil, suggesting that the observed enrichment of this organism during the Deepwater Horizon spill may be explained by factors related to substrate availability and competition within the complex and dynamic microbial communities that were continuously evolving during that spill.
KW - Biodegradation, Environmental
KW - Halomonas
KW - Petroleum
KW - Petroleum Pollution
KW - Polysaccharides, Bacterial
KW - Seawater
KW - Surface-Active Agents
UR - http://www.scopus.com/inward/record.url?scp=85194763360&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0299235
DO - 10.1371/journal.pone.0299235
M3 - Article
C2 - 38805414
SN - 1932-6203
VL - 19
JO - PLoS ONE
JF - PLoS ONE
IS - 5
M1 - e0299235
ER -