裂褶菌-长枝木霉耦合发酵制备裂褶寡糖

Synthesis of branched oligoβ-1,3-glucan by co-cultivation of Trichoderma longibrachiatum and Schizophyllum commune

裂褶菌多糖是一类具有β-1,6支链的β-1,3-葡聚糖,具有很好的抗肿瘤、益生元等多种生理活性,但其过大的分子质量和水不溶性影响其功能和应用。该研究以食品安全的长枝木霉为出发菌株,通过常压室温等离子体(atmospheric room temperature plasma,ARTP)诱变筛选后得到高产内切β-1,3-葡聚糖酶的突变株T-6,所产内切β-1,3-葡聚糖酶对热凝胶和茯苓多糖具有较好的水解能力。此外,对发酵得到的突变株T-6粗酶液进行了部分的酶学性质研究,结果表明内切β-1,3-葡聚糖酶的动力学参数K_(m)=4.005 g/L,最适反应pH和温度分别为6.0、50℃,在pH 5.0~6.5,45~60℃酶活力较高,相对酶活力在85%以上;有严格的底物专一性,只水解含β-1,3-键的热凝胶、茯苓多糖和小核菌多糖。将裂褶菌与突变株T-6进行混合培养,获得裂褶寡糖。结构分析表明该寡糖都是由葡萄糖组成,聚合度为4~15。另外,裂褶寡糖具有良好的DPPH和超氧阴离子(·O_(2)^(-))清除能力。该研究通过真菌耦合发酵制备的裂褶寡糖在食品领域具有潜在的应用价值。

Schizophyllan is a type ofβ-1,3-glucan withβ-1,6-branched chain from Schizophyllum commune,which has great anti-tumor,prebiotic and other physiological activities.However,high molecular weight and low water solubility affect their function and applica-tions.In this work,the General Recognized as Safe(GRAS)Trichoderma longibrachiatum was used as the starting strain for ARTP muta-genesis and a mutant strain T-6 with higher endoβ-1,3-glucanase activity was obtained.The obtained endoβ-1,3-glucanase was capable of hydrolyzing curdlan and pachymaran.In addition,the enzymatic properties of endo-β-1,3-glucanase were studied.The results showed that the kinetic parameter K_(m) was 4.005 g/L,and its optimum reaction pH and temperature was 6.0 and 50℃,respectively.It could maintain more than 85%relative enzyme activity in the range of pH 5.0-6.5 and 45-60℃.It had strict substrate specificity and only hydrolyzeβ-1,3-bonds in curdlan,pachyman and scleroglucan.A co-cultivation system with S.commune and T-6 was established to prepare schizophyl-lan oligosaccharides.Structural analysis showed that the schizophyllan oligosaccharides were composed of glucose,and the degree of poly-merization was 4-15.In addition,the schizophyllan oligosaccharides had good DPPH and·O_(2)^(-) radical scavenging capabilities.The schizophyllan oligosaccharides prepared by fungi co-cultivation in this work would have potential application in the food industry.