{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T10:03:45Z","timestamp":1790762625432,"version":"4.1.0"},"reference-count":38,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T00:00:00Z","timestamp":1790467200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000780","name":"EC HORIZON 2020 Program SECRETed project","doi-asserted-by":"publisher","award":["101000794"],"award-info":[{"award-number":["101000794"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Int. J. Mol. Sci.","IJMS"],"abstract":"<jats:p>The thermophilic bacterium Rhodothermus marinus DSM 16675 represents a promising yet underexplored source of natural polymers with potential industrial applications. The aim of the current study was to screen for emulsifying activity in R. marinus cultures, identify conditions for production of the potential emulsifier, characterize the compound, and analyze the functional properties. Production trials in shake flasks combined with emulsification screening of the cell-free cultures showed that R. marinus produced an emulsifying compound, with fed-batch cultivation yielding up to 20 mg L\u22121 of crude emulsifying exopolymer. The purified exopolymer contained carbohydrates, proteins (19.22 \u00b1 0.3 wt%), and lipids (approximately 10 wt%), with rhamnose, arabinose, and mannose as predominant carbohydrate moieties in the produced polymer. Amino acid analysis and fatty acid analyses supported its amphiphilic nature. Dynamic light scattering revealed a bimodal particle-size distribution (Z-average 288.8 \u00b1 63.9 nm) and a moderately negative \u03b6-potential (\u221226.9 mV). The exopolymer exhibited highest emulsifying activity at 5 g L\u22121, with a critical micelle concentration (CMC) of 0.12 \u00b1 0.01 g L\u22121 and retained good performance over pH 3\u20139 and 4\u201325 \u00b0C, whereas elevated salinity and strongly alkaline conditions reduced its activity. These findings advance knowledge on microbial exopolymers and highlight their potential as natural bioemulsifiers.<\/jats:p>","DOI":"10.3390\/ijms27198651","type":"journal-article","created":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T16:50:54Z","timestamp":1790614254000},"page":"8651","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Characterization of an Amphiphilic Exopolymer from Rhodothermus marinus DSM 16675 Reveals Its Potential as a Natural Bioemulsifier"],"prefix":"10.3390","volume":"27","author":[{"given":"Roya R. R.","family":"Sardari","sequence":"first","affiliation":[{"name":"Division of Biotechnology and Applied Microbiology, Department of Process and Life Science Engineering, Lund University, Naturvetarv\u00e4gen 14, SE-221 00 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4919-8914","authenticated-orcid":false,"given":"Milad","family":"Mohammadi","sequence":"additional","affiliation":[{"name":"Division of Biotechnology and Applied Microbiology, Department of Process and Life Science Engineering, Lund University, Naturvetarv\u00e4gen 14, SE-221 00 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Lars","family":"Dahlgren","sequence":"additional","affiliation":[{"name":"Division of Biotechnology and Applied Microbiology, Department of Process and Life Science Engineering, Lund University, Naturvetarv\u00e4gen 14, SE-221 00 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8597-7050","authenticated-orcid":false,"given":"Eva","family":"Nordberg Karlsson","sequence":"additional","affiliation":[{"name":"Division of Biotechnology and Applied Microbiology, Department of Process and Life Science Engineering, Lund University, Naturvetarv\u00e4gen 14, SE-221 00 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1186\/1475-2859-6-9","article-title":"Potential and utilization of thermophiles and thermostable enzymes in biorefining","volume":"6","author":"Turner","year":"2007","journal-title":"Microb. Cell Fact."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Gallo, G., Imbimbo, P., and Aulitto, M. (2024). The undeniable potential of thermophiles in industrial processes. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms25147685"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Upadhyaya, C., Patel, H., Patel, I., and Upadhyaya, T. (2025). Extremophilic exopolysaccharides: Bioprocess and novel applications in the 21st century. Fermentation, 11.","DOI":"10.3390\/fermentation11010016"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1099\/00221287-134-2-299","article-title":"Rhodothermus marinus gen. nov., sp. nov., a thermophilic, halophilic bacterium from submarine hot springs in Iceland","volume":"134","author":"Alfredsson","year":"1988","journal-title":"Microbiology"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"fiae167","DOI":"10.1093\/femsec\/fiae167","article-title":"A genome-scale metabolic reconstruction provides insight into the metabolism of the thermophilic bacterium Rhodothermus marinus","volume":"101","author":"Kristjansdottir","year":"2025","journal-title":"FEMS Microbiol. Ecol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.carbpol.2016.08.062","article-title":"Evaluation of the production of exopolysaccharides by two strains of the thermophilic bacterium Rhodothermus marinus","volume":"156","author":"Sardari","year":"2017","journal-title":"Carbohydr. Polym."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e00140","DOI":"10.1016\/j.mec.2020.e00140","article-title":"Engineering the carotenoid biosynthetic pathway in Rhodothermus marinus for lycopene production","volume":"11","author":"Kristjansdottir","year":"2020","journal-title":"Metab. Eng. Commun."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3345","DOI":"10.1007\/s12010-022-04283-y","article-title":"Characterization of probiotic Pichia sp. DU2-derived exopolysaccharide with oil-in-water emulsifying and anti-biofilm activities","volume":"195","author":"Salimi","year":"2023","journal-title":"Appl. Biochem. Biotechnol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"191","DOI":"10.15171\/apb.2018.023","article-title":"Bioemulsifiers derived from microorganisms: Applications in the drug and food industry","volume":"8","author":"Hamishehkar","year":"2018","journal-title":"Adv. Pharm. Bull."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1007\/s11274-023-03611-6","article-title":"Sustainable production of bioemulsifiers: A critical overview from microorganisms to promising applications","volume":"39","author":"Franco","year":"2023","journal-title":"World J. Microbiol. Biotechnol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"735","DOI":"10.1007\/s00792-019-01129-0","article-title":"Cultivation technology development of Rhodothermus marinus DSM 16675","volume":"23","author":"Ron","year":"2019","journal-title":"Extremophiles"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1186\/s12934-022-01946-7","article-title":"Medium development and production of carotenoids and exopolysaccharides by the extremophile Rhodothermus marinus DSM16675 in glucose-based defined media","volume":"21","author":"Mukti","year":"2022","journal-title":"Microb. Cell Fact."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1038\/s41579-024-01098-y","article-title":"Microbial extracellular polymeric substances in the environment, technology and medicine","volume":"23","author":"Flemming","year":"2025","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"8896","DOI":"10.1021\/jf051468u","article-title":"A gas chromatography\/electron ionization-mass spectrometry-selected ion monitoring method for determining the fatty acid pattern in food after formation of fatty acid methyl esters","volume":"53","author":"Thurnhofer","year":"2005","journal-title":"J. Agric. Food Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1186\/1556-276X-8-381","article-title":"Characterization of magnetic nanoparticle by dynamic light scattering","volume":"8","author":"Lim","year":"2013","journal-title":"Nanoscale Res. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.jphotobiol.2012.06.004","article-title":"Role of curcumin on the determination of the critical micellar concentration by absorbance, fluorescence and fluorescence anisotropy techniques","volume":"115","author":"Mondal","year":"2012","journal-title":"J. Photochem. Photobiol. B"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"28245","DOI":"10.1039\/D2RA01679F","article-title":"Curcumin-PLGA based nanocapsule for the fluorescence spectroscopic detection of dopamine","volume":"12","author":"Zakaria","year":"2022","journal-title":"RSC Adv."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"8920","DOI":"10.1039\/D2SM01320G","article-title":"Determination of the critical micelle concentration of surfactants using fluorescence strategies","volume":"18","author":"Wu","year":"2022","journal-title":"Soft Matter"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e18613","DOI":"10.1016\/j.heliyon.2023.e18613","article-title":"Microbial exopolysaccharides in the biomedical and pharmaceutical industries","volume":"9","author":"Waoo","year":"2023","journal-title":"Heliyon"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1007\/s12010-013-0505-7","article-title":"Emulsifying, flocculating, and physicochemical properties of exopolysaccharide produced by cyanobacterium Nostoc flagelliforme","volume":"172","author":"Han","year":"2014","journal-title":"Appl. Biochem. Biotechnol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1002\/bit.22218","article-title":"Yield and physicochemical properties of EPS from Halomonas sp. strain TG39 identifies a role for protein and anionic residues (sulfate and phosphate) in emulsification of n-hexadecane","volume":"103","author":"Gutierrez","year":"2009","journal-title":"Biotechnol. Bioeng."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3190","DOI":"10.1074\/jbc.272.6.3190","article-title":"Glycine residues provide flexibility for enzyme active sites","volume":"272","author":"Yan","year":"1997","journal-title":"J. Biol. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Barchi, J.J., and Strain, C.N. (2023). The effect of a methyl group on structure and function: Serine vs. threonine glycosylation and phosphorylation. Front. Mol. Biosci., 10.","DOI":"10.3389\/fmolb.2023.1117850"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"21759","DOI":"10.1038\/srep21759","article-title":"Arginine side chain interactions and the role of arginine as a gating charge carrier in voltage-sensitive ion channels","volume":"6","author":"Armstrong","year":"2016","journal-title":"Sci. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"633","DOI":"10.3390\/ijms12010633","article-title":"Environmental applications of biosurfactants: Recent advances","volume":"12","author":"Cameotra","year":"2011","journal-title":"Int. J. Mol. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Nikolova, C., Morris, G., Ellis, D., Bowler, B., Jones, M., Mulloy, B., and Gutierrez, T. (2024). Characterization of the surface-active exopolysaccharide produced by Halomonas sp. TGOS-10: Understanding its role in the formation of marine oil snow. PLoS ONE, 19.","DOI":"10.1371\/journal.pone.0299235"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.cofs.2015.07.008","article-title":"Progress in natural emulsifiers for utilization in food emulsions","volume":"7","author":"Ozturk","year":"2016","journal-title":"Curr. Opin. Food Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/j.ijbiomac.2019.09.087","article-title":"Physicochemical characterization and emulsifying properties of a novel exopolysaccharide produced by haloarchaeon Haloferax mucosum","volume":"142","year":"2020","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Liu, F., He, W., Huang, X., Yin, J., and Nie, S. (2024). The emulsification and stabilization mechanism of an oil-in-water emulsion constructed from Tremella polysaccharide and citrus pectin. Foods, 13.","DOI":"10.3390\/foods13101545"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"167","DOI":"10.3923\/jas.2015.167.172","article-title":"A review on the effects of emulsions on flow behaviours and common factors affecting the stability of emulsions","volume":"15","author":"Lim","year":"2015","journal-title":"J. Appl. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"7342","DOI":"10.1039\/D0SM00321B","article-title":"Influence of salt concentration on the formation of Pickering emulsions","volume":"16","author":"French","year":"2020","journal-title":"Soft Matter"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1007\/s12551-016-0218-6","article-title":"Dynamic light scattering: A practical guide and applications in biomedical sciences","volume":"8","author":"Stetefeld","year":"2016","journal-title":"Biophys. Rev."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"388","DOI":"10.1016\/j.tibtech.2011.03.008","article-title":"Advances in bacterial exopolysaccharides: From production to biotechnological applications","volume":"29","author":"Freitas","year":"2011","journal-title":"Trends Biotechnol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1753","DOI":"10.1351\/pac200577101753","article-title":"Measurement and interpretation of electrokinetic phenomena (IUPAC Technical Report)","volume":"77","author":"Delgado","year":"2005","journal-title":"Pure Appl. Chem."},{"key":"ref_35","first-page":"153","article-title":"Principles of emulsion stabilization with special reference to polymeric surfactants","volume":"57","author":"Tadros","year":"2006","journal-title":"J. Cosmet. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1007\/BF00402307","article-title":"A comparative analysis of extreme thermophilic bacteria belonging to the genus Thermus","volume":"117","author":"Degryse","year":"1978","journal-title":"Arch. Microbiol."},{"key":"ref_37","first-page":"1","article-title":"Determination of structural carbohydrates and lignin in biomass","volume":"1617","author":"Sluiter","year":"2008","journal-title":"NREL Lab. Anal. Proced. Lab. Anal. Proced."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"103589","DOI":"10.1016\/j.jcs.2022.103589","article-title":"HPAEC-PAD analysis for determination of the amino acid profiles in protein fractions from oat flour combined with correction of amino acid loss during hydrolysis","volume":"109","author":"Sardari","year":"2023","journal-title":"J. Cereal Sci."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/27\/19\/8651\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T09:27:45Z","timestamp":1790760465000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/27\/19\/8651"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,27]]},"references-count":38,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["ijms27198651"],"URL":"https:\/\/doi.org\/10.3390\/ijms27198651","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,27]]}}}