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Nikolova C, Morris G, Ellis D, Bowler B, Jones M, Mulloy B, Gutierrez T. Characterization of the surface-active exopolysaccharide produced by Halomonas sp TGOS-10: Understanding its role in the formation of marine oil snow. PLoS One 2024; 19:e0299235. [PMID: 38805414 PMCID: PMC11132480 DOI: 10.1371/journal.pone.0299235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 02/06/2024] [Indexed: 05/30/2024] Open
Abstract
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.
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Affiliation(s)
- Christina Nikolova
- Institute of Mechanical, Process, and Energy Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
| | - Gordon Morris
- Department of Chemical Sciences, School of Applied Sciences, University of Huddersfield, Huddersfield, United Kingdom
| | - David Ellis
- Department of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
| | - Bernard Bowler
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Martin Jones
- School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Barbara Mulloy
- Institute of Pharmaceutical Sciences, King’s College London, London, United Kingdom
| | - Tony Gutierrez
- Institute of Mechanical, Process, and Energy Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, United Kingdom
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Kaur N, Dey P. Bacterial Exopolysaccharides as Emerging Bioactive Macromolecules: From Fundamentals to Applications. Res Microbiol 2022; 174:104024. [PMID: 36587857 DOI: 10.1016/j.resmic.2022.104024] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/26/2022] [Indexed: 12/31/2022]
Abstract
Microbial exopolysaccharides (EPS) are extracellular carbohydrate polymers forming capsules or slimy coating around the cells. EPS can be secreted by various bacterial genera that can help bacterial cells in attachment, environmental adaptation, stress tolerance and are an integral part of microbial biofilms. Several gut commensals (e.g., Lactobacillus, Bifidobacterium) produce EPS that possess diverse bioactivities. Bacterial EPS also has extensive commercial applications in the pharmaceutical and food industries. Owing to the structural and functional diversity, genetic and metabolic engineering strategies are currently employed to increase EPS production. Therefore, the current review provides a comprehensive overview of the fundamentals of bacterial exopolysaccharides, including their classification, source, biosynthetic pathways, and functions in the microbial community. The review also provides an overview of the diverse bioactivities of microbial EPS, including immunomodulatory, anti-diabetic, anti-obesity, and anti-cancer properties. Since several gut microbes are EPS producers and gut microbiota helps maintain a functional gut barrier, emphasis has been given to the intestinal-level bioactivities of the gut microbial EPS. Collectively, the review provides a comprehensive overview of microbial bioactive exopolysaccharides.
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Affiliation(s)
- Navneet Kaur
- Department of Biotechnology, Thapar Institute of Engineering and Technology, Patiala, Punjab, India
| | - Priyankar Dey
- Department of Biotechnology, Thapar Institute of Engineering and Technology, Patiala, Punjab, India.
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Structure, physicochemical characterization, and antioxidant activity of the highly arabinose-branched exopolysaccharide EPS-M2 from Streptococcus thermophilus CS6. Int J Biol Macromol 2021; 192:716-727. [PMID: 34655584 DOI: 10.1016/j.ijbiomac.2021.10.047] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 12/28/2022]
Abstract
Streptococcus thermophilus CS6 could produce the high exopolysaccharide (EPS) level in optimized skimmed milk medium. However, physicochemical properties and structure of these polymers have not been fully characterized. In this study, two purified fractions (EPS-M1 and EPS-M2) exhibited good rheology, thermostability and antioxidant activity. Further monosaccharide composition, molecular weight and NMR analysis indicated EPS-M2 was composed of galactose, arabinose and glucose (5:2.5:1) with an average molecular weight of 2.22 × 104 Da and its suggested repeating unit was →6)-[α-L-Araf-(1 → 3)]-β-D-Galp-(1 → 4)-β-D-Galp-(1 → 6)-[α-L-Araf-(1 → 5)-{α-L-Araf-(1 → 3)}-α-L-Araf-(1 → 3)]-β-D-Galp-(1 → 4)-β-D-Galp-(1 → 6)-[β-D-Galp-(1 → 5)-α-L-Araf-(1 → 5)-α-L-Araf-(1 → 3)]-β-D-Galp-(1 → 6)-[β-D-Galp-(1 → 5)-α-L-Araf-(1 → 5)-{α-L-Araf-(1 → 3)}-α-L-Araf-(1 → 3)]-β-D-Galp-(1→. High EPS production relied on the expression of eps gene cluster and key enzymes of nucleotide sugar metabolism. Overall, EPS-M2 from a potential functional starter S. thermophilus CS6 provided opportunities for natural thickener, stabilizer, and antioxidant agent exploration in the food industry.
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Effect of Gamma Irradiation on Enhanced Biological Activities of Exopolysaccharide from Halomonas desertis G11: Biochemical and Genomic Insights. Polymers (Basel) 2021; 13:polym13213798. [PMID: 34771355 PMCID: PMC8588121 DOI: 10.3390/polym13213798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 02/07/2023] Open
Abstract
In this work, a native exopolysaccharide (nEPS) produced by Halomonas desertis G11 isolated from a Tunisian extreme environment was modified by gamma irradiation. Characterization as well as the antioxidant and antitumor activities of nEPS and its gamma-irradiated derivatives (iEPSs) were comparatively evaluated. In vitro and in vivo antioxidant potentials were determined by using different methods and through different antioxidant enzymes. The antitumor activity was checked against a human colon cancer cell line. Analyses of the complete genome sequence were carried out to identify genes implicated in the production of nEPS. Thus, the genomic biosynthesis pathway and the export mechanism of nEPS were proposed. Analyses of irradiation data showed that iEPSs acquired new functional groups, lower molecular weights, and gained significantly (p < 0.05) higher antioxidant and antitumor abilities compared with nEPS. These findings provide a basis for using iEPSs as novel pharmaceutical agents for human therapies.
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Banerjee A, Sarkar S, Govil T, González-Faune P, Cabrera-Barjas G, Bandopadhyay R, Salem DR, Sani RK. Extremophilic Exopolysaccharides: Biotechnologies and Wastewater Remediation. Front Microbiol 2021; 12:721365. [PMID: 34489911 PMCID: PMC8417407 DOI: 10.3389/fmicb.2021.721365] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/26/2021] [Indexed: 01/18/2023] Open
Abstract
Various microorganisms thrive under extreme environments, like hot springs, hydrothermal vents, deep marine ecosystems, hyperacid lakes, acid mine drainage, high UV exposure, and more. To survive against the deleterious effect of these extreme circumstances, they form a network of biofilm where exopolysaccharides (EPSs) comprise a substantial part. The EPSs are often polyanionic due to different functional groups in their structural backbone, including uronic acids, sulfated units, and phosphate groups. Altogether, these chemical groups provide EPSs with a negative charge allowing them to (a) act as ligands toward dissolved cations as well as trace, and toxic metals; (b) be tolerant to the presence of salts, surfactants, and alpha-hydroxyl acids; and (c) interface the solubilization of hydrocarbons. Owing to their unique structural and functional characteristics, EPSs are anticipated to be utilized industrially to remediation of metals, crude oil, and hydrocarbons from contaminated wastewaters, mines, and oil spills. The biotechnological advantages of extremophilic EPSs are more diverse than traditional biopolymers. The present review aims at discussing the mechanisms and strategies for using EPSs from extremophiles in industries and environment bioremediation. Additionally, the potential of EPSs as fascinating biomaterials to mediate biogenic nanoparticles synthesis and treat multicomponent water contaminants is discussed.
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Affiliation(s)
- Aparna Banerjee
- Centro de investigación en Estudios Avanzados del Maule (CIEAM), Vicerrectoría de Investigación Y Posgrado, Universidad Católica del Maule, Talca, Chile
- Centro de Biotecnología de los Recursos Naturales (CENBio), Facultad de Ciencias Agrarias Y Forestales, Universidad Católica del Maule, Talca, Chile
| | - Shrabana Sarkar
- Department of Botany, UGC-Center of Advanced Study, The University of Burdwan, Golapbag, Burdwan, India
| | - Tanvi Govil
- Department of Chemical and Biological Engineering, South Dakota Mines, Rapid City, SD, United States
- Composite and Nanocomposite Advanced Manufacturing – Biomaterials Center, Rapid City, SD, United States
| | - Patricio González-Faune
- Escuela Ingeniería en Biotecnología, Facultad de Ciencias Agrarias Y Forestales, Universidad Católica del Maule, Talca, Chile
| | | | - Rajib Bandopadhyay
- Department of Botany, UGC-Center of Advanced Study, The University of Burdwan, Golapbag, Burdwan, India
| | - David R. Salem
- Department of Botany, UGC-Center of Advanced Study, The University of Burdwan, Golapbag, Burdwan, India
- Department of Chemical and Biological Engineering, South Dakota Mines, Rapid City, SD, United States
- Department of Materials and Metallurgical Engineering, South Dakota Mines, Rapid City, SD, United States
| | - Rajesh K. Sani
- Department of Botany, UGC-Center of Advanced Study, The University of Burdwan, Golapbag, Burdwan, India
- Department of Chemical and Biological Engineering, South Dakota Mines, Rapid City, SD, United States
- BuGReMeDEE Consortium, South Dakota School of Mines and Technology, Rapid City, SD, United States
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