摘要
微生物降解木质纤维素既是生物质资源化利用中的关键问题,也是亟需解决的难点问题.本文在前期获得木质素降解菌——解淀粉芽孢杆菌MN-8菌株的基础上,进一步研究该菌株对玉米秸秆木质纤维素的降解作用.研究利用玉米秸秆粉-MSM培养基对MN-8菌株进行固态发酵,监测发酵过程中木质纤维素酶活力和木质纤维素含量变化情况,并通过傅立叶红外光谱（FTIR）和气质联用色谱（GC/MS）对木质纤维素的降解情况及产物进行分析.结果表明：解淀粉芽孢杆菌MN-8菌株可产生木质素过氧化物酶、锰过氧化物酶、纤维素酶和半纤维素酶等木质纤维素降解酶,在发酵10~16 d陆续达到酶活力峰值,最高酶活力分别为55.0、16.7、45.4和60.5 U·g-1.发酵24 d后,玉米秸秆中木质素、纤维素和半纤维素的降解率可分别达到42.9%、40.6%和27.1%.FTIR光谱数据表明,玉米秸秆发酵后木质素、纤维素和半纤维素的特征吸收峰强度均有一定程度的下降,表明木质纤维素被部分降解.GC/MS分析结果也证实,解淀粉芽孢杆菌MN-8能有效降解秸秆木质纤维素.MN-8菌株可断裂玉米秸秆木质素单体之间的连接键β-O-4,将秸秆木质素解聚为苯丙胺、苯丙酮和苯丙酸等保留木质素苯丙烷结构的单体化合物,并将部分单体化合物进一步氧化为Cα羰基化合物,如2-氨基-1-苯丙酮和紫丁香基苯乙酮等.在对纤维素和半纤维素降解产物的GC/MS分析中发现,降解产物包含葡萄糖、甘露糖和半乳糖等多种单糖化合物以及甲酸、乙酸、丙酸、1,1-乙二醇和3-羟基丁酸等代谢产物.表明解淀粉芽孢杆菌MN-8对秸秆木质纤维素表现出强降解作用,且该作用依赖于菌株产木质纤维素降解酶的能力.
Microbial degradation of lignocellulose is one of the key problems that need to be solved urgently in the process of utilizing biomass resource. Bacillus amyloliquefaciens MN-8 is our previously isolated bacterium capable of degrading lignin. To determine the capability of strain MN-8 to degrade lignocellulose of corn straw,B. amyloliquefaciens MN-8 was inoculated and fermented with solid-state corn straw powder-MSM culture medium. The changes in the enzyme activity and degradation products of lignocellulose were monitored in the process of fermentation using the FTIR and GC / MS. The results showed that B. amyloliquefaciens MN-8 could produce lignin peroxidase,manganese peroxidase,cellulase and hemicellulase enzymes. The activities of all these enzymes reached the peak after being incubated for 10-16 days,and the highest enzyme activities were 55. 0,16. 7,45. 4 and 60. 5 U·g-1,respectively. After 24 d of incubation,the degradation percentages of lignin,cellulose and hemicellulose were up to 42. 9%,40. 6% and 27. 1%,respectively. The spectroscopic data by FTIR indicated that the intensities of characteristic absorption peaks of lignin,cellulose and hemicellulose of the corn straw were decreased,indicating that the lignocellulose was degraded partly after being fermented by B. amyloliquefaciens MN-8. GC / MS analysis also demonstrated that strain MN-8 could degrade lignocellulose efficiently. It could depolymerize lignin into some monomeric compounds with retention of phenylpropane structure unit,such as amphetamine,benzene acetone and benzene propanoic acids,by the rupture of β-O-4 bond connected between lignin monomer,and it further oxidized some monomer compounds into Cα carbonyl compounds,such as2-amino-1-benzeneacetone and 4-hydroxy-3,5-dimethoxy-acetophenone. The GC / MS analysis of the degradation products of cellulose and hemicellulose showed that there were not only monosaccharide compounds,such as glucose,mannose and galactose,but also some glycolysis products including formic acid,acetic acid,propion
出处
《应用生态学报》
CAS
CSCD
北大核心
2015年第5期1404-1410,共7页
Chinese Journal of Applied Ecology
基金
河北省农业科技成果转化项目(12820911D)
河北省科技支撑计划项目(12226605)资助
