Biosynthesis of Applicable Levan by a New Levan Producing Moderately Halophilic Strain Chromohalobacter salexigens and its Biological Activities (original) (raw)

A newly isolated moderately halophilic bacterial strain from Egyptian hyper saline source was identified as Chromohalobacter salexigens and was selected for its ability to produce extracellular levan. Different environmental and nutritional factors were optimized. These factors including initial pH, temperature, nitrogen source, sodium chloride concentration, phosphorous source in addition to the sequence incubation at optimum and cold temperature. The resulted polymer was identified by paper chromatography, NMR and FT-IR spectroscopy. Also chemical modifications (carboxymethylation and sulphation) were proceeded and the biological activity (fibrinolytic, prebiotic activity) of resulted levan and its derivatives were also determined. The highest quantity of levan (11.9 g l) was produced at pH 8, sodium chloride concentration 15%, ammonium sulphate as nitrogen source and sequence incubation at optimum followed by cold temperature. Chemically modified levan recorded high fibrinolytic ...