一株产木聚糖酶放线菌的液体发酵条件优化及水解特性研究

Optimization of Liquid Fermentation Conditions for Xylanase Production by a Actinomyces and Characterization of the Enzyme

以木聚糖为唯一碳源制作选择培养基,利用透明圈法筛选高产木聚糖酶菌株,对其中一株产酶较高的菌株L10608进行液体发酵条件优化并对所产木聚糖酶的水解特性进行研究。结果表明:菌株L10608最佳产酶条件为以质量浓度25g/L、80目的水不溶性玉米芯木聚糖为碳源,10g/L大豆蛋白胨和5g/L酵母浸膏为复合氮源,初始pH6.0、培养温度40℃、转速200r/min、表面活性剂吐温-80质量浓度4g/L,最佳产酶条件下木聚糖酶活力达1074.8U/mL。以桦木木聚糖、榉木木聚糖和燕麦木聚糖为底物研究菌株L10608所产木聚糖酶的水解特性,结果表明该木聚糖酶为内切型木聚糖酶,水解主要产物为木二糖和木三糖。表明菌株L10608有望作为功能性低聚木糖的生产菌株。

In the current study, high-xylanase-producing strain was screened from different soil samples by transparent circle method, using xylan as the only carbon source in medium. The cultural condition for xylanase production by strain L10608 was optimized and the hydrolysis property of the enzyme was further investigated. The results indicated that the optimum fermentation medium contained a carbon source of water-insoluble xylan （80 mesh） of 25 g/L, compound nitrogen source of soya peptone of 25 g/L and yeast extract of 5 g/L, initial pH 6.0, cultural temperature 40 ℃, rotational speed of 200 r/min, surfactant polysorbate 80 of 4 g/L. Under the optimized condition, the enzyme activity reached 1074.8 U/mL. The xylanase utilized all birch wood xylan, beech wood xylan and oat xylan as the substrate, exhibiting that xylanase produced by L10608 was endo-xylanase with xylobiose and xylotriose as the major hydrates. These results showed that strain L10608 could hopefully be used for industrial production of functional xyloolygosaccharides.