Dataset Information

Aerobic deconstruction of cellulosic biomass by an insect-associated Streptomyces.

ABSTRACT: 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.

SUBMITTER: Takasuka TE

PROVIDER: S-EPMC3538285 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Aerobic deconstruction of cellulosic biomass by an insect-associated Streptomyces.

Takasuka Taichi E TE Book Adam J AJ Lewin Gina R GR Currie Cameron R CR Fox Brian G BG

Scientific reports 20130107

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 ...[more]

PMID: 23301151

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Project description:The cellulolytic insect symbiont bacterium, Streptomyces sp. SirexAA-E (SirexAA-E), is known to secrete a suite of Carbohydrate Active enZymes (CAZymes) for plant cell wall degradation in response to the available carbon sources. In this study, we sought to examine a poorly understood response of this bacterium to mannan, one of the major components of the plant cell wall, particularly in pine trees, the preferred host for SirexAA-E. SirexAA-E grew well on glucose, mannose, carboxymethyl cellulose (CMC), and locust bean gum (LBG) as sole carbon sources in the culture medium. The secreted proteins from each culture supernatant were tested for the polysaccharide-degrading ability, and the composition of secreted CAZymes in each culture supernatant were determined by LC-MS/MS. The results indicated that mannose, LBG, and CMC induced the secretion of mannan and cellulose-degrading enzymes. We found two α-1,2-mannosidases that were secreted during growth on mannose and LBG. By genomic analysis, we found a unique 12 bp palindromic sequence motif (5’-GACAACGTTGTC-3’) at 4 locations in the SirexAA-E genome, two of which were found upstream of genes encoding the above-mentioned α-1,2-mannosidases, along with a newly identified novel mannose and mannobiose responsive transcriptional regulator, SsManR. Furthermore, a transcriptional repressor that we previously showed was responsive to cellobiose, SsCebR, was determined to also use mannobiose as an effector ligand by in vitro binding assays. To test whether mannobiose induces the sets of genes under control of the two regulators, SsManR and SsCebR, SirexAA-E was grown on mannobiose, and the secretome composition was analyzed. As hypothesized, the composition of the mannobiose secretome combined sets of CAZymes found in both LBG and CMC secretomes, and so are likely under the regulation of both SsManR and SsCebR. To summarize, our findings support a transcriptional network that regulates mannose and LBG utilizing genes in SirexAA-E. Overall, this study defines a novel mannose regulatory transcriptional network that enables SirexAA-E to aggressively hydrolyze mannan-containing wood materials.

Dataset Information

Aerobic deconstruction of cellulosic biomass by an insect-associated Streptomyces.

Publications

Aerobic deconstruction of cellulosic biomass by an insect-associated Streptomyces.

Similar Datasets

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