论文部分内容阅读
为了获得高效降解秸秆纤维素的微生物菌株,采用滤纸降解法和刚果红染色法从含纤维素类物质的土壤中筛选到一株产纤维素酶菌株QSH3-3,通过形态观察和ITS序列分析,鉴定为草酸青霉Penicillium oxalicum QSH3-3。摇瓶产酶试验结果表明,该菌株的最佳产酶条件为:碳源为0.5%的碱处理过的玉米秸秆粉,氮源为0.2%硫酸铵,起始pH为7,接种量为5%,产酶温度为30℃,培养时间为4 d。最佳产酶条件下,滤纸酶(FPase)、内切酶(CMCase)和木聚糖酶(Xylanase)分别为12 U、33 U、605 U(U为酶活性单位);在15℃,其残余酶活力可达70%～80%;在起始pH 4～9范围内,其残余酶活力可达70%以上。酶学稳定性研究表明,FPase、CMCase和Xyla-nase在起始pH 4～9范围残余酶活力达85%以上,具有较强的酸碱适应能力;FPase、CMCase和Xylanase在45℃以上酶活力迅速下降,耐热性较差。该菌株具有较高的木聚糖酶活力以及较强的低温、pH的耐受力,因而该菌株在田间温差大、土壤偏碱性等复杂条件下对秸秆纤维素类物质的降解具有较高的应用潜力。
In order to obtain microbial strains which can effectively degrade stalks cellulose, a cellulase producing strain QSH3-3 was screened from the soil containing cellulosic materials by filter paper degradation and Congo red staining. Through morphological observation and ITS sequence analysis, It was identified as Penicillium oxalicum QSH3-3. The results of shake flask fermentation showed that the optimal conditions for the enzyme production were as follows: alkali-treated corn stalks with carbon source of 0.5%, nitrogen source of 0.2% ammonium sulfate, initial pH of 7, inoculum size of 5 %, Enzyme production temperature is 30 ℃, incubation time is 4 d. Under the optimal conditions, the enzyme activity of FPase, CMCase and Xylanase were 12 U, 33 U and 605 U, respectively (U is the unit of enzyme activity); at 15 ℃, Residual enzyme activity up to 70% to 80%; in the initial pH range of 4 to 9, the residual enzyme activity up to 70%. The results of enzymatic stability showed that the residual enzyme activity of FPase, CMCase and Xyla-nase was more than 85% in the initial pH range of 4 ~ 9, and had strong acid-base adaptability. The activity of FPase, CMCase and Xylanase at 45 ℃ Rapid decline, poor heat resistance. The strain has high xylanase activity and strong low temperature, pH tolerance, so the strains in the field temperature, soil alkaline conditions and other complex conditions on the degradation of straw cellulose substances have a higher Application potential.