一株植物内生细菌促进香菇木腐菌糖化秸秆的研究

One Plant Endophytic Bacteria Promoting on Lentinus edodes Wood-rotting Fungi Saccharifying Rice Straw

香菇类木腐菌利用水稻秸秆的基本过程,包括清除果胶与木质素屏障、释放纤维素和半纤维素、降解纤维素和半纤维素、利用单糖等,其中清除屏障释放纤维素和半纤维素、降解纤维素和半纤维素为糖化过程。在香樟内生菌Bacillus spp WP7和香菇(Lentinus edodes)菌株SH2184共转化水稻秸秆体系中,在香菇菌的定植期,菌丝生长速度是对照组的279%;共转化体系的发酵物总还原糖释放量比对照组提高了185.0%,葡萄糖释放量比对照组提高了262.5%,非葡萄糖释放量比对照组提高了139.0%;共转化体系的发酵物中果胶酶活性是对照组的127.3%,纤维素酶活与对照组接近;木聚糖酶活是对照组的75%。根据结果分析,植物内生菌释放的果胶酶可能是共转化秸秆体系中葡萄糖和其它单糖释放量提高的原因之一,从而进一步促进香菇菌菌丝定植期的生长速度;另外,该植物内生菌本身可能产生抑制木糖酶活性的物质或抑制木糖酶表达的信号物质。

The process of Lentinus edodes wood-rotting fungi degrading and transforming rice straw was composed of breaking the straw barrier （such as pectin and lignin） to release cellulose and hemicellulose, saccharifying cellulose and hemicellulose to monose and oligosaccharide, and transforming monose to other substances. In the system of plant endophytic bacteria and L. edodes transforming rice straw, the growth rate of L. edodes mycelium during 6 d colonization was 279% of the control system. Compared with the control group, the release amount of the total reduction sugar, glucose and non-glucose from the system of plant endophytic bacteria and L. edodes was increased by 185.0%, 139.0% and 262.5%, respectively. The activity of pectinase and xylanase from the system of plant endophytic bacteria and L. edodes was 127.3% and 75% of that in the control group, and the cellulase activity was close to that of the control group. This results might implied that the pectin from the plant endophytic bacteria might be an important factor for promoting the release amount of glucose and other monosaccharide, which further pro- mote the growth rate of L. edodes mycelium during the colonization period. Additionally, plant endophytic bacteria might pro- duce one or more substance for inhibiting the activity of xylanase or for depressing the expression of xylanase genes.