Open AccessChemical structure and antioxidant activity of a new exopolysaccharide produced from Micrococcus luteus
Author(s) -
Mohsen S. Asker,
Osama H. El Sayed,
Manal G. Mahmoud,
Mohamed Fawzy Ramadan
Publication year - 2014
Publication title -
journal of genetic engineering and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.729
H-Index - 25
eISSN - 2090-5920
pISSN - 1687-157X
DOI - 10.1016/j.jgeb.2014.08.002
Subject(s) - micrococcus luteus , chemistry , ethanol precipitation , glycosidic bond , arabinose , mannose , dpph , glucuronic acid , polysaccharide , antioxidant , chromatography , galactose , biochemistry , xylose , fermentation , enzyme , escherichia coli , gene
An exopolysaccharide (EPS) reaching a maximum of 13 g/L was isolated from Micrococcus luteus by ethanol precipitation. The crude EPS was purified by chromatography on DEAE-cellulose and Sephacryl S-200, affording a polysaccharide active fraction (AEP) with a molecular weight of ∼137 kDa. AEP was investigated by a combination of chemical and chromatographic methods including FTIR, HPLC, periodate oxidation, methylation and GC–MS. Data obtained indicated that AEP was composed of mannose, arabinose, glucose and glucuronic acid in a molar ratio of 3.6:2.7:2.1:1.0, respectively. The main backbone consists of mannose units linked with (1→6)-glycosidic bonds and arabinose units linked with (1→5)-glycosidic bonds. There is a side chain consisting of mannose units linked with (1→6)-glycosidic bonds at C3, when all glucose and most of glucuronic acid are found in the side chain. The in vitro antioxidant assay showed that AEP possesses DPPH radical-scavenging activity, with an EC50 value of 180 μg/mL
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