1株产甘露聚糖酶嗜热真菌的鉴定、酶学性质表征及转录组学分析

Identification,Enzymatic Characterization and Transcriptomic Analysis of a Mannanase-Producing Thermophilic Fungus

从大曲中筛选出一株产嗜热甘露聚糖酶的嗜热真菌GZFH7,经鉴定该菌为微小根毛霉(Rhizomucor pusillus),接菌至魔芋发酵培养基诱导产生的甘露聚糖酶的最适反应温度为70℃。在50~80℃范围内可保留50%以上的酶活力。在最适反应温度处理1 h,酶活力基本保持不变。该酶pH 2.0~12.0范围内均具有一定耐受性,其最适反应pH值为5.0。经转录组学测定分析,共有几丁质酶、半乳糖苷酶、甘露糖基转移酶等253个碳水化合物活性酶基因表达,其中糖基转移酶表达最为丰富,约占41.1%;其次为糖苷水解酶,约占37.5%。微小根毛霉R.pusillus GZFH7是嗜热真菌,其诱导的嗜热甘露聚糖酶热稳定性良好。同菌株GZFH7高效的产碳水化合物活性酶能力使其在酶制剂的开发与应用方面有较大的研究价值。

In this study,a thermophilic fungus,designated GZFH7,that can produce thermophilic mannanase was isolated from Maotai-flavor Daqu,a traditional fermentation starter for the production of Maotai-flavor Baijiu.The fungus was identified as Rhizomucor pusillus,and the optimal reaction temperature of mannanase produced from konjac gum by this strain was 70℃.At temperatures ranging from 50 to 80℃,the enzyme retained more than 50%of its activity,and kept its activity almost unchanged for 1 h at the optimal reaction temperature.The optimal reaction pH of the enzyme was 5.0,and it was tolerant to pH 2.0 to 12.0.Transcriptomic analysis showed that 253 carbohydrate-active enzymes(CAZyme)genes such as chitinase,galactosidase,and mannosyltransferase were expressed.Among them,glycosyltransferase was most abundantly expressed,accounting for 41.1%of the total,followed by glycoside hydrolase,about 37.5%.The mannanase produced by R.pusillus GZFH7 had good thermal stability.Furthermore,this strain could efficiently produce CAZymes,proving its great potential for the development and application of enzyme preparations.