PRODUCTION OF SUCCINOGLYCAN BIOGUM FROM DATE SYRUP BY Agrobacterium radiobacter AND INVESTIGATION OF ITS RHEOLOGICAL PROPERTIES

摘要

Microbial exopolysaccharides are widely exploited in many industrial fields for their capability of forming gels, stabilizing emulsions, creating viscous solutions and, generally, of altering the rheological properties of various products. Bacteria are an important source of these biopolymers and exopolysaccharides (EPS). Gums such as xanthan , gellan and curdlan have been isolated and applied to food product development. There has been a recent upsurge in interest in microbial biopolymers; several strains of lactic acid bacteria and Pseudomonas spp. have been screened for EPS production with novel properties. Succinoglycans are heteropolysaccharides synthesized by a variety of bacteria belonging to the family Rhizobiaceae (Rhizobium, Agrobacterium), as well as by other microorganisms such as Alcaligenes faec'alis var. myxogenes and Pseudomonas spp. They are acidic polysaccharides composed of octasaccharide repeating units in which galactose and glucose monomers occur in a molar ratio of 1 to 7. Succinate and pyruvate are commonly found as non-saccharidic substituents, whereas acetate might or might not be present, depending on the source of the polymer. Natural and chemically modified succinoglycans show high stability even under drastic operational conditions, such as high temperature and pressure, extreme salinity and pH values, or high shear rates. Microbial production of succinoglycan on an industrial scale has been traditionally restricted to Agrobacterium spp. Continuous fermentation processes have also been studied extensively by several authors.1