一组小麦秸秆好氧分解菌复合系的酶学特性研究

Enzymatic activity characteristics of a wheat straw aerobic degradation microbial community

为加快小麦秸秆木质纤维素酶解,提高小麦秸秆资源的利用率,探讨了一组小麦秸秆好氧分解菌复合系的酶活表达特性。该复合系能高效的分解秸秆,对纤维素的分解率达到80.0%,利用DNS法测定该复合系分泌的酶的酶活性。研究表明,在复合系分解的0~10 d内,0.78 g纤维素被分解,0.16 g半纤维素被分解;复合系分泌的酶是一组能够降解不同底物的酶复合系;复合系的最高纤维素酶活性（内切酶、外切酶、β-糖苷酶和总纤维素酶）为0.17 U/mL;最高木聚糖酶活性出现在第2天,其数值达到2.82 U/mL;最适木聚糖酶反应温度为50℃,最高耐受温度是60℃,最适木聚糖酶反应pH为7,pH≤5对酶活性产生强烈抑制;酶反应时间6~20 min时,酶活性急剧下降,以后至酶反应时间120 min时,酶活性下降缓慢。第3天的0.5 mL离心上清液在最适酶反应条件下酶解2h后,木聚糖底物被酶解6.76 mg,转化率为33.8%。

Enzyme activities from a wheat straw aerobic-degradation-microbial community were studied by using DNS method.These enzymes have stable and efficient capacity to decompose 80% of straw cellulose.Cellulose and hemicellulose lost 0.78 g and 0.16 g respectively 10 days after decomposition with these enzymes.The excreted enzymes of microbial community were a group of enzyme complex community with the capacity of zymohydrolyzing different substrates.The maximum cellulase activity was 0.17 U/mL.The maximum xylanase activity was found on the second day with a concentration of 2.82 U/mL.The optimum temperature for xylanase was 50 ℃,while the maximum tolerant temperature was 60 ℃.The optimum pH for xylanase was 7.0.At pH≤5 the xylanase activity was severely inhibited.Xylanase activity dropped quickly 6-20 min after initiation of the enzyme reaction.Afterwards until 120 min,xylanase enzyme activity dropped slowly.Zero point five milliliter centrifugal supernatant on the third day could saccharificate xylan substrate（22.5 mg/0.5 mL） of 6.76 mg with the transfer ratio of 33.8% in two hours under the optimum conditions of xylanase activity.