DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison , Madison, Wisconsin, United States of America.
Sci Rep. 2013;3:1030. doi: 10.1038/srep01030. Epub 2013 Jan 7.
Streptomyces are best known for producing antimicrobial secondary metabolites, but they are also recognized for their contributions to biomass utilization. Despite their importance to carbon cycling in terrestrial ecosystems, our understanding of the cellulolytic ability of Streptomyces is currently limited to a few soil-isolates. Here, we demonstrate the biomass-deconstructing capability of Streptomyces sp. SirexAA-E (ActE), an aerobic bacterium associated with the invasive pine-boring woodwasp Sirex noctilio. When grown on plant biomass, ActE secretes a suite of enzymes including endo- and exo-cellulases, CBM33 polysaccharide-monooxygenases, and hemicellulases. Genome-wide transcriptomic and proteomic analyses, and biochemical assays have revealed the key enzymes used to deconstruct crystalline cellulose, other pure polysaccharides, and biomass. The mixture of enzymes obtained from growth on biomass has biomass-degrading activity comparable to a cellulolytic enzyme cocktail from the fungus Trichoderma reesei, and thus provides a compelling example of high cellulolytic capacity in an aerobic bacterium.
链霉菌以产生抗菌次级代谢产物而闻名，但它们也因其对生物质利用的贡献而受到认可。尽管它们对陆地生态系统中的碳循环很重要，但我们目前对链霉菌的纤维素分解能力的理解仅限于少数土壤分离株。在这里，我们展示了与入侵的松蛀木蜂 Sirex noctilio 相关的需氧细菌链霉菌 sp. SirexAA-E (ActE) 的生物质解构能力。当在植物生物质上生长时，ActE 分泌了一系列酶，包括内切和外切纤维素酶、CBM33 多糖单加氧酶和半纤维素酶。全基因组转录组和蛋白质组学分析以及生化分析揭示了用于解构结晶纤维素、其他纯多糖和生物质的关键酶。从生物质生长获得的酶混合物具有与真菌里氏木霉的纤维素酶混合物相当的生物质降解活性，因此为需氧细菌中具有高纤维素分解能力提供了一个令人信服的例子。
