Industrial Streptomyces with Capability to Grow on Cheap and Abundant Cellulose
Many species of Streptomyces are used industrially in the production of medicines, proteins and other fine commodity chemicals. However, the vast majority must be grown on high-cost glucose feedstock because they are unable to use cellulosic biomass as a source of nutrition.
One notable exception is a strain called ActE, recently isolated and extensively studied by UW–Madison researchers. The researchers have identified a series of genes that enable the organism to survive on cellulose and other types of biomass, and constructed expression plasmids comprising the most useful genes for producing cellulose-degrading enzymes.
Building on their work, the researchers have developed an optimized set of enzymes useful to create Streptomyces with the capability to grow on cellulosic polysaccharide substrates. The method enables industrially relevant strains to grow on cellulose as the sole carbon source.
Using an engineered plasmid expression system derived from the ActE strain, the researchers transformed two commercial species (S. lividans and S. venezuelae) and showed that they were able to grow on filter paper as the sole carbon source. Other suitable host stains include S. coelicolor, S. griseus, S. clavuligerus, S. hygroscopicus, S. viridochromogenes and S. avermitilis.
- Relevance to industrialized strains
- Lower cost feedstocks
- Modified Streptomyces for the production of high value chemicals and antibiotics
- Could enable other bacterial species to convert cellulosic biomass into a feedstock for eventual ethanol production
Optimization of the plasmid expression system is ongoing.
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