title: Physicochemical characterization of exopolysaccharides produced by Lactobacillus rhamnosus on various carbon sources.
abstract: The impact of five carbohydrate sources (glucose, maltose, galactose, sucrose, and lactose) on the chemical composition, structure, morphology, and physicochemical properties, as well as, viscosity of exopolysaccharides (EPSs) produced by Lactobacillus rhamnosus E/N was investigated. GLC-MS analysis and 2DNMR spectroscopy showed that the EPSs had the same primary structure independently of the carbon source used in the growth medium. The following EPS composition was elucidated: four rhamnose, two glucose, and one galactose residue with a pyruvate substituent. Molecular masses (M(w)) were determined by gel permeation chromatography, which revealed differences in M(w) distribution. EPS-Gal, EPS-Suc, and EPS-Lac showed heterogenic fractions of a high and low molecular weight, while EPS-Mal and EPS-Glc contained only a high-molecular-weight fraction. AFM microscopy revealed morphological differences in chain length, thickness, and branching. Differences in the Mw ratio and thickness of the polymer chain were correlated with high viscosity of EPS solutions. Our results indicate that a single bacterial strain, depending on the carbon source in the medium, can produce EPSs of different rheological properties.
authors.affiliation: Department of Biotechnology, Human Nutrition and Science of Food Commodities, University of Life Sciences in Lublin, Skromna 8, 20-704 Lublin, Poland. Electronic address: 3mj@wp.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Polak-Berecka
authors.affiliation: Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Choma
authors.affiliation: Department of Biotechnology, Human Nutrition and Science of Food Commodities, University of Life Sciences in Lublin, Skromna 8, 20-704 Lublin, Poland; Institute of Agrophysics of Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Waśko
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wrocław, Poland.
authors.forename: Sabina
authors.initials: S
authors.lastname: Górska
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wrocław, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Gamian
authors.affiliation: Institute of Agrophysics of Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Cybulska
mesh_terms: D005690:Galactose / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry*; D007785:Lactose / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008320:Maltose / Q000737:chemistry*; D008970:Molecular Weight; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry*; D014783:Viscosity
chemical_list: D011135:Polysaccharides, Bacterial; D013395:Sucrose; D008320:Maltose; D005947:Glucose; D007785:Lactose; D005690:Galactose
keywords: Exopolysaccharides (EPS); Lactobacillus rhamnosus; Physicochemical properties; Rheology; Structure