白腐菌预处理对稻草化学组分及酶水解的影响

采用5株白腐菌预处理稻草,对预处理过程中产生的木质纤维素降解酶系以及稻草化学组分变化进行了分析,研究了预处理对后续纤维素酶水解效率的影响。研究结果表明,5株白腐菌在预处理期间(0~50天)均能检测到漆酶(Lac)、锰过氧化物酶(MnP)和纤维素酶(Cel)活性,但未检测到木质素过氧化物酶(LiP)活性。其中凤尾菇培养第20天Lac活性达到最高,为2244 U/L;平菇培养40天MnP活性最高,达771 U/L;凤尾菇和平菇的木质素降解选择性指数(SI)随着预处理时间延长呈上升趋势,培养至50天时平菇的SI达到1.87,比其它4株白腐菌表现出更好的选择性降解木质素能力。云芝4号、平菇和凤尾菇表现出良好的预处理效果,经此3菌株预处理50天的稻草粉,在每克底物20 FPU酶用量条件下用纤维素酶水解48 h,酶水解总糖转化率分别达到59.6%、56.3%和54.4%。

Effects of White Rot Fungi Pretreatment on Chemical Compositions and Enzymatic Hydrolysis of Rice Straw

The effect of biological pretreatment with 5 white rot fungi, Coriolus versicolor 4, 6, 9, Pleurotus ostreatus and Pleurotus sajor-caju on the ligninolytic enzyme and cellulase production, chemical composition and enzymatic hydrolysis efficiency of rice straw were evaluated. Laccase, Mn-peroxidase and cellulase were detected during the pretreatment （0-50 d）. The activity of Lingin-peroxidase was not detected. The highest Lac activity 2 244 U/L was obtained after 20 d cultivation by Pleurotus sajor-caju, and the highest MnP activity 771 U/L was obtained after 40 d cultivation by Pleurotus ostreatus. Lignin degrading selectivity index （SI） of Pleurotus ostreatus increased over the pretreatment time and went up to 1.87 （in 50 d）, and it showed better lignin selective degrading ability than other 4 white rot fungi. Coriolus versicolor 4, Pleurotus ostreatus and Pleurotus sajor-caju revealed a good pretreatment efficiency. After enzymatic hydrolysis, total sugar conversion of 59.6%, 56.3%, 54.4% can be achieved by using the substrate pretreated with Coriolus versicolor 4, Pleurotus ostreatus and Pleurotus sajor-caju under the condition of pretreatment time 50 d and cellulase loading of 20 FPU/g （substrate）, respectively.