胶质芽孢杆菌胞外多糖的制备及流变学特性

The preparation and rheological properties of the exopolysaccharides produced by Bacillus mucilaginous SM-01

以实验室保藏的胶质芽孢杆菌SM-01为研究对象,研究了其胞外多糖(EPS)在5 L发酵罐中的发酵过程及制备方法,并对EPS溶液的流变学特性进行了研究,主要分析了质量浓度、剪切速率、剪切时间、温度、pH、无机盐、外加多糖等对其黏度的影响。结果表明,发酵液中EPS的最大产量为23.46 g/L,经离心、醇沉、冷冻干燥后EPS的回收率为76.7%;EPS溶液是典型的非牛顿流体;溶液黏度随着质量浓度的增加而快速增大;25～100℃范围内EPS黏度变化不大;EPS溶液黏度受pH影响较大,其黏度值在pH 7时达到最大,pH>12时溶液成弱凝胶状;加入NaCl、KCl、MgCl2、CaCl2等无机盐后溶液黏度显著下降,Fe3+、Pb2+等高价阳离子使EPS沉淀;EPS与海藻酸钠、黄原胶、瓜尔胶、槐豆胶、阿拉伯胶均有协效性。

The fermentation,preparation and rheological properties of the exopolysaccharides（EPS） produced by Bacillus mucilaginosus（SM-01） were investigated.In addition,the effects of shearing rate,EPS concentration,shearing time,temperature,pH,inorganic salts and other polysaccharides on the viscosity of EPS were also studied.The results showed that the maximum yield of EPS in 5L fermentor was 23.46 g/L and the recovery of EPS was up to 76.7% through centrifugation,alcohol precipitation and freeze dehydration.The EPS solution showed a characteristic pseudoplastic non-Newtonian behavior.The viscosity of EPS solution was improved with the concentration increasing and had a good temperature resistance at temperatures from 25℃ to 100℃.The maximum viscosity was observed at pH7.0 and it would become a weak gel at pH12.0.The addition of NaCl,KCl,MgCl2 and CaCl2 remarkably decreased the viscosity.The precipitation in alkali was attained in the presence of high valence cation such as Fe3＋ and Pb2＋.The EPS had synergy with Sodium alginate,Locust bean gum,Carrageenan,Xanthan gum,Guar gum and Arabia gum.