【作者】 吕晓霞；

【导师】 黄克瀛；

【作者基本信息】 中南林学院 ， 林产化学加工工程， 2004， 硕士

【摘要】 进行了以富含纤维素和半纤维素的农副产物玉米芯为发酵底物，以绿色木霉为产酶菌种纤维素、木聚糖复合水解酶的诱导合成，将此酶对10％氨水处理后的玉米芯进行酶水解，以水解液为底物培养真菌(黑曲霉、绿色木霉、米根霉和戴尔根霉)，从真菌菌丝体中提取壳聚糖的研究。 纤维素、木聚糖复合水解酶的诱导合成研究表明：碳源和氮源种类、浓度及碳氮比、培养温度、pH等因素对纤维素酶和木聚糖酶的合成都有一定的影响。以经过1％NaOH预处理的玉米芯为主要碳源和诱导物，碳源浓度为20g/L，利用蛋白胨+硫酸铵+尿素为复合氮源，控制碳氮比为5.6，初始pH值为4.8，培养温度28℃时，纤维素酶活力(以CMC酶活计)和木聚糖酶活力分别达到了40.71U/mL和141.32U/mL。 利用所做复合水解酶对预处理玉米芯进行酶水解，当底物浓度为15％(W/V)，pH值为4.8，温度为50℃，酶用量30U/g底物时水解效果最好，水解24h后还原糖浓度可达62.3g/L并趋于恒定。 以预处理玉米芯的酶水解产物为碳源，分别对黑曲霉、绿色木霉、米根霉和戴尔根霉进行菌丝体培养提取壳聚糖的研究结果表明：省略浓碱处理过程时，可以从真菌菌丝体中提取壳聚糖，在同样的菌丝体培养和壳聚糖提取条件下，壳聚糖产量以黑曲霉最多。 以酶水解玉米芯为发酵底物，黑曲霉为菌种制备壳聚糖的研究结果表明：当培养液中还原糖浓度为20g/L时，菌丝体培养温度30℃，pH7.0，摇床转速150r/min，培养48h后壳聚糖产量最高，壳聚糖浓度为0.69g/L培养液，此时，菌丝体浓度为8.11g/L培养液，壳聚糖在菌丝体中的含量为8.51％，产品得率为34.5mg壳聚糖/g还原糖。更多还原

【Abstract】 Corn-cob is a kind of cellulose and xylan-riched agriculture byproduct.The synthesis of cellulase and xylanase with pretreated corn-cob as carbon source by Trichoderma viride and the hydrolysis with this enzyme pretreated corn-cob are studied in this thesis. Then using hydrolysates as carbon source to cultivate fungi (Aspergillus niger, Trichoderma viride, Rhizopus delemar, Rhizopus oryzae) and extracting chitosan from mycelia are studied.The result of cellulase and xylanase synthesis shows that the kind and concentration of carbon source, the kind of nitrogen source, and the C/N, the initial pH value, the culture temperature,etc all have some effects.The better preducing enzyme term is using 20g/L 1% NaOH pretreated corn-cob as carbon source and the peptone+ammonium sulfate+urea as nitrogen source, regulating C/N 5.6, initial pH value 4.8, ulture temperature28眑癈, 150r/min.The cellulase and xylanase activity reached 40.7IU/mL (CMC-ase activity) and 141.32U/mL respectively after 120 hours cultibvation.Enzyme hydrolysis result shows that the better substrate is 10% NH3 H2O pretreated corn-cob. And when substrate concentration is 15%(W /V), the optical hydrolysis condition is pH 4. 8, 50 C, enzyme quantity 30U/g substrate.After 24 hours the reducing sugars concentration reached 62.3g/L and almost kept constantly.The result shows that the yield of chitosan from Aspergillus niger is larger than Trichoderma viride, Rhizopus delemar and Rhizopus oryzae. The optimum conditions of cultiviating Aspergillus niger to produce chitosan using enzymatic hydrolysate as substrate is as follows: reducing sugars concentration 20g/L, culture temperature 30癈, initial pH value 7. 0, 150r/min. In this condition , mycelia and chitosan concentration reached 8. llg/L and 0.69g/L respectively. The content of chitosan in mycelia is 8.51% . Chitosan yield is 34. 5mg/(g reducing sugars) .更多还原