Basic studies on the utilization of cellulosic biomass, unexploited natural resources, as fermentation raw materials, for the production of industrially useful products.

为了以纤维素生物质为发酵原料，培养能产生抗生素的链霉菌，我们从土壤中分离出了具有高纤维素水解能力的链霉菌C42菌株。我们构建了一个包含菌株携带的所有9个纤维素酶基因的基因表达盒，以创建链霉菌纤维素酶表达载体。与C42菌株相比，非纤维素水解链霉菌转化载体分泌纤维素酶，但不能降解纤维素和滤纸。我们还从另一种链霉菌中分离出与利用纤维素二糖相关的5个基因，构建了利用纤维素二糖的表达载体。纤维素二糖是纤维素酶消化的最终产物。纤维素酶的表达结果表明，提高纤维素酶基因的表达水平是产生载体的关键，使链霉菌能够诱导降解纤维素水解物质，用于发酵生产抗生素。

In order to breed streptomycetes that can produce antibiotics using cellulosic biomass as fermentation raw materials, we isolated highly cellulolytic Streptomyces strain C42 from soils. We constructed a gene expression cassette harboring all the nine cellulase genes that the strain carries to create a cellulase expression vector for streptomycetes. Non cellulolytic streptomycete transformed with the vector secreted cellulases but failed to degrade cellulose and filter paper in contrast to the C42 strain. We also isolated five genes encoding enzymes related to utilization of cellobiose, a final product of cellulose digested by cellulase, from another streptomycete to construct a cellobiose-utilizing expression vector. The results on the cellulase expression suggested that it is crucial to enhance the expression levels of the cellulase genes to generate vectors which enable streptomycetes to induce the degradation of cellulolytic materials for the fermentative production of antibiotics.