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Exopolysaccharide production by Antarctic marine bacteria
thesisposted on 2023-05-27, 15:45 authored by Nichols, CAM
Antarctic marine bacteria isolated from sea ice and Southern Ocean particulate material were screened for exopolysaccharide (EPS) production. Ten strains were characterized using phenotypic (morphology), chemotaxonomic (whole cell fatty acid profiles) and phylogenetic (16S rDNA sequencing) techniques. These isolates were representatives of four genera including Pseudoalteromonas, Shewanella, Polaribacter and Flavobacterium, with one strain constituting a new bacterial genus in the family Flavobacteriaceae. After further phenotypic characterisation, this strain was given the name Olleya marilimosa, gen. nov., sp. nov. The ten strains were grown in batch culture and the EPS extracted, purified and partially characterized. Crude chemical, monosaccharide and molecular weight determinations showed that the EPS were diverse, even among closely related isolates. All EPS contained uronic acids to varying degrees and some also contained sulfate groups. Two EPS showed the presence of acetyl groups, with pyruvate present in at least one polysaccharide. The bacteria belong to phylogenetic groups that are dominant in sea ice and Southern Ocean particulate material according to previous studies that used culture dependent and independent techniques. These isolates were psychrotolerant, grew between 2 to 25¬¨‚àûC and had growth optima at approximately 20¬¨‚àûC. Growth and EPS production of one isolate belonging to the genus Pseudoalteromonas was examined at three temperatures: -2¬¨‚àûC, 10¬¨‚àûC and 20¬¨‚àûC. EPS yield at -2¬¨‚àûC and 10¬¨‚àûC was thirty-fold higher than at 20¬¨‚àûC. The EPS showed higher levels of uronic acids at lower temperature. The metal binding ability of a high molecular weight, highly viscous EPS produced by one sea ice bacterium was examined. High affinities for cadmium and copper were observed at the low concentration of EPS used. These results are a first step in assessing the ability of EPS produced by Antarctic marine bacteria to chelate dissolved trace metal such as iron, which are essential for growth and are limiting primary production in the Southern Ocean. The examination of EPS production by Antarctic marine bacteria provides new evidence that these biopolymers are abundant and diverse. Partial structural elucidation reveals important structure-function relationships. EPS such as those examined in this study may have a cryoprotective role or may impact on the availability of important trace metals. These findings point to the wider ecological role of EPS within the Antarctic marine environment. This study also provides incentive for further investigation into commercial usefulness of these biopolymers.
Rights statementCopyright 2005 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Chapter 2 appears to be the equivalent of a post-print version of an article published as: Nichols, C. M., Guezennec, J., Bowman, J. P., 2005. Bacterial exopolysaccharides from extreme marine environments with special consideration of the Southern Ocean, sea ice, and deep-sea hydrothermal vents: a review, Marine biotechnology, 7(4), 253-271. Post-prints are subject to Springer Nature re-use terms https://www.springer.com/gp/open-access/publication-policies/aam-terms-of-use Chapter 3 appears to be the equivalent of a post-peer-review, pre-copyedit version of an article published in Microbial ecology. The final authenticated version is available online at: https://doi.org/10.1007/s00248-004-0093-8 Chapter 4 appears to be the equivalent of the peer reviewed version of the following article: Mancuso Nichols, C., Garon, S., Bowman, J., Raguen‚àö¬Æs, G., Guezennec, J., 2004. Production of exopolysaccharides by Antarctic marine bacterial isolates, Journal of applied microbiology, 96(5), 1057-1066, doi:10.1111/j.1365-2672.2004.02216.x, which has been published in final form at https://doi.org/10.1111/j.1365-2672.2004.02216.x. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. Chapter 5 appears to be the equivalent of a post-print version of an article published as: Mancuso Nichols, C. A., Bowman, J. P., Guezennec, J., 2005. Effects of incubation temperature on growth and production of exopolysaccharides by an Antarctic sea ice bacterium grown in batch culture. Applied and environmental microbiology, 71(7), 3519-3523 Chapter 6 appears to be the equivalent of a pre-print version of an article published as: Nichols, C. M., Bowman, J. P., Guezennec, J., 2005. Olleya marilimosa gen. nov., sp. nov., an exopolysaccharide-producing marine bacterium from the family Flavobacteriaceae, isolated from the Southern Ocean, International journal of systematic and evolutionary microbiology, 55(4), 1557-1561. Copyright Nichols, Bowman and Guezennec, 2005. The definitive peer reviewed, edited version of this article is published in International journal of systematic and evolutionary microbiology, 55(4), 2005, https://doi.org/10.1099/ijs.0.63642-0