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Extracellular Polysaccharide by Bradyrhizobium japonicum: Production and CharacterizationDipartimento di Chimica Fisica ed Elettrochimica Universatà degli Studi Via Golgi 19, 20133 Milano, Italy
Dipartimento di Chimica Fisica ed Elettrochimica Universatà degli Studi Via Golgi 19, 20133 Milano, Italy
Dipartimento di Scienze e Technologie Alimentari e Microbiologiche Università degli Studi Via Celoria 2, 20133 Milano, Italy
Dipartimento di Scienze e Technologie Alimentari e Microbiologiche Università degli Studi Via Celoria 2, 20133 Milano, Italy An exopolysaccharide from Bradyrhizobium japonicum has been produced, purified and characterized. It is mainly composed of carbohydrates (86 ± 4.5%) and uronic acids (14 ± 1%). The relative proportions are: carbohy dratesglucose 84%, galactose 14%, mannose 2%; uronic acidsglucuronic 83%, galacturonic 10%, mannuronic 3%, arabinuronic 4%. The IR spectrum in dicates the presence of ether, ester, hydrogen bonds and a ß-type bond between the monomers. DSC analysis revealed the presence of two transition peaks: the first in the temperature range 117-153 ° C due to bound water and the second at 292°C due to thermal decomposition of the polymer. Viscosity measure ments of water solutions as a function of polymer concentration in the range 0.33-1% w/w allowed the determination of the consistency coefficient and be haviour index. Taking into account the dependence on temperature, a general relation of viscosity as a function of polymer concentration, temperature and shear rate has been proposed.
Journal of Bioactive and Compatible Polymers, Vol. 4, No. 4,
333-344 (1989) |
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