产自Cladosporium sp. F39的嗜酸耐盐纤维素酶及其酶学性质研究

Acidophilic and Halophilic Cellulase Produced by Cladosporium sp. F39 and Its Enzymatic Properties

摘要: 极端环境来源纤维素酶在造纸、纺织和纤维素乙醇生产等工业领域有巨大的运用潜力，因而备受关注。本研究以小麦秸秆为唯一碳源，从青海茶卡盐湖土壤中分离到一株具有降解纤维素功能的真菌菌株，命名为F39，通过形态学和ITS rRNA分子生物学鉴定，菌株F39被鉴定为Cladosporium sp. (GenBank登录号：ON318388)。用小麦秸秆发酵培养基进行诱导，发现该菌株所产纤维素酶的最适pH为5.0，最适温度为50℃，最适盐度为0.2 g/mL，在最适温度和pH条件下测得活性为0.237 U/mL；在pH 4.0~6.0或35℃~65℃或盐浓度低于2.5 g/mL时保持60%以上活性。在大多数金属离子件下活性表现稳定。金属离子Mn2+能激其强烈活性。酶抑制剂DTT和SDS低浓度存在的条件下活性表现强促进作用。菌株在小麦渣发酵培养基中发酵培养312 h后的上清纤维素酶活力(底物为羧甲基纤维素钠(CMC-Na))最高，为0.223 U/mL。以上结果表明该菌株所产纤维素酶有嗜酸、耐盐和耐热的特点，在饲料加工、生物乙醇生产等行业具有良好的运用潜力。

Abstract: The discovery of enzymes with high activity and special activity in extreme environments is of great significance to the development of new materials. In this study, sodium carboxymethyl cellulose and rice straw were used as the only carbon source, and a cellulose-degrading strain F39 was isolated from Chaka Salt Lake in Qinghai Province, China. After morphological observation and ITS sequence comparison analysis, the strain was preliminarily identified as Cladosporium sp. (ON318388) Using wheat residue fermentation medium for induction, the optimum pH and temperature of cellulase production were 5.0 and 50˚C, and the highest activity was 0.237 U/mL under the optimum conditions. Keep at pH 4.0~6.0 or 45˚C~65˚C, or keep more than 60% activity when the salt concentration is low of 2.5 g/mL. The activity is stable under most metal ions. The metal ion Mn2+ can stimulate its strong activity. The activity of enzyme inhibitor DTT and SDS was strongly promoted in the presence of low concentration. The supernatant of the strains fermented in wheat residue fermentation medium for 312 hours had the highest activity towards carboxymethyl cellulose sodium (CMC-Na) which was 0.223 U/mL. The Cladosporium sp. has acid and salt tolerance, good performance and great economic value.