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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%。
In order to accelerate the enzymatic hydrolysis of wheat straw lignocellulose and improve the utilization rate of wheat straw resources, the enzymatic activity of a group of wheat straw aerobic decomposing bacteria was studied. The composite system can effectively decompose straw, the decomposition rate of cellulose reaches 80.0%, and the enzymatic activity of the enzyme secreted by the composite system is measured by the DNS method. The results showed that 0.78 g of cellulose was decomposed and 0.16 g of hemicellulose was decomposed within 0-10 d of the compound system decomposition. The enzyme secreted by the complex system was a group of enzyme complex system capable of degrading different substrates. The highest cellulase activity (endonuclease, exonuclease, β-glucosidase and total cellulase) was 0.17 U / mL; the highest xylanase activity appeared on the second day, reaching 2.82 U / mL; The optimal reaction temperature of xylanase was 50 ℃, the highest temperature was 60 ℃, the optimum pH of xylanase was 7, and pH≤5 strongly inhibited the enzyme activity. When the reaction time was 6 ~ 20 min, The activity of enzyme decreased sharply, and the enzymatic activity decreased slowly till 120 min after enzyme reaction. On the third day, 0.5 mL of centrifuged supernatant was enzymatically hydrolyzed for 2 h under optimal enzyme reaction conditions. The xylan substrate was hydrolyzed 6.76 mg with a conversion rate of 33.8%.