以浸米水为原料生产细菌纤维素

Production of bacterial cellulose by Gluconacetobacter xylinus using rice milk

为提高黄酒生产过程中浸米水的利用率、减少其排放量,对比了浸米水与自然发酵椰子水的理化指标差异,分析各指标与细菌纤维素(BC)产量的相关性,继而优化浸米水培养基组分,并研究所得BC的理化性状。结果表明,浸米水中果糖、葡萄糖、蔗糖、乙酸、总蛋白含量显著(P<0.05)低于自然发酵椰子水,它们对BC产量均有显著(P<0.05)影响。以浸米水为原料生产BC的最适碳源为35.0 g·L^-1葡萄糖,最适氮源为酵母浸提物和胰蛋白胨混合物(各3.0 g·L^-1)。经优化后,BC产率(以干质量计)达到9.3 g·L^-1。以浸米水和自然发酵椰子水为原料生产的BC均具有纳米级多孔网状微结构,两者的含水量、持水力和硬度无显著差异,红外光谱和X-射线衍射分析结果显示,其化学组成均为β-型葡聚糖、Ⅰα型纤维素,结晶度分别为82.7%和84.6%。以浸米水和自然发酵椰子水为原料生产的BC理化性状基本相同,说明浸米水可用作BC的生产原料。

In order to utilize rice milk effectively and reduce its discharge amount,the differences in the physicochemical indexes between rice milk and naturally fermented coconut water were compared,and the correlation analysis within physicochemical indexes and bacterial cellulose(BC)yield was conducted.The BC production based on rice milk medium was optimized,and some physical properties and chemical composition of the produced BC were investigated.The results showed that the contents of fructose,glucose,sucrose,acetic acid and protein in rice milk were significantly(P<0.05)lower than those in the naturally fermented coconut water,and these substances affected BC yield significantly(P<0.05).The optimal fermentation condition for rice milk was as follows:35.0 g·L^-1 glucose as carbon source,and mixture of 3.0 g·L^-1 yeast extract and 3.0 g·L^-1 tryptone as nitrogen source.After optimization,the BC yield could reach 9.3 g·L^-1(dry weight).BCs produced from either rice milk or the naturally fermented coconut water had nano-porous microstructure,and there was no significant difference in the water content,water holding capacity and hardness between them.Infrared spectroscopy and X-ray diffraction analysis showed that BCs produced from either rice milk or the naturally fermented coconut water were composed of β-glucan and type Ⅰα cellulose,and the crystallinity was 82.7% and 84.6%,respectively,indicating that BCs produced from rice milk and the naturally fermented coconut water were almost the same.Therefore,rice milk would be a promising material to produce BC.