Method and compositions for improved lignocellulosic material hydrolysis
Inventors
Fox, Brian Grant • Takasuka, Taichi • Book, Adam Joel • Currie, Cameron Robert
Assignees
US Department of Energy • Wisconsin Alumni Research Foundation
Publication Number
US-10214758-B2
Publication Date
2019-02-26
Expiration Date
2032-12-10
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Abstract
A method of digesting a lignocellulosic material is disclosed. In one embodiment, the method comprises the step of exposing the material to an effective amount of Streptomyces sp. ActE secretome such that at least partial lignocellulosic digestion occurs.
Core Innovation
The invention relates to methods and compositions for digesting lignocellulosic material by exposing the material to an effective amount of Streptomyces sp. ActE secretome, resulting in at least partial lignocellulosic digestion. The secretome is preferably obtained as a supernatant from a Streptomyces sp. ActE culture grown on substrates comprising cellulose, hemicellulose, xylan, chitin, or biomass (wood or non-wood), with at least 40%, preferably 85%, of the carbon source derived from these materials.
The secretome composition varies depending on the growth substrate, yielding specialized enzymatic profiles that efficiently degrade cellulose, xylan, hemicellulose, chitin, and biomass. Compositions comprising individual or combinations of ActE genes or their expression products, such as SActE_0237 (GH6), SActE_0236 (GH48), SActE_3159 (CBM33), SActE_0482 (GH5), and others, are useful for optimized digestion of specific polysaccharides.
The problem addressed is the challenge of efficient hydrolysis of lignocellulosic materials due to their recalcitrant crystalline cellulose structure and structurally diverse hemicellulose, which limits utilization for renewable energy and biofuels. Existing cellulolytic organisms and enzymes have limitations in activity, specificity, or growth characteristics, especially concerning multi-enzyme synergies and production of enzyme mixtures effective at neutral pH and moderate temperatures.
The invention solves this problem by providing Streptomyces sp. ActE secretomes and compositions that secrete a well-defined set of enzymes, including hydrolytic and oxidative enzymes, that cooperate efficiently to deconstruct lignocellulosic biomass into fermentable sugars. The ActE secretomes show high cellulolytic capacities comparable to commercial enzyme mixtures and exhibit substrate-dependent enzyme expression, optimized reaction conditions compatible with fermentation hosts, and genetic amenability for overexpression or heterologous expression of key enzymes.
Claims Coverage
The patent discloses fifteen independent claims focusing on methods and compositions involving Streptomyces sp. ActE secretomes and specific gene products for lignocellulosic material digestion.
Method of digesting lignocellulosic material with Streptomyces sp. ActE secretome
Exposing lignocellulosic material to an effective amount of a secretome preparation from Streptomyces sp. ActE cultured on substrates with significant carbon content from cellulose, hemicellulose, xylan, biomass, or chitin to achieve partial digestion.
Purified preparation comprising Streptomyces sp. ActE secretome
Obtaining purified secretome preparations from Streptomyces sp. ActE cultured on carbon sources derived mainly from cellulose, hemicellulose, xylan, biomass, or chitin.
Compositions containing specific ActE genes or expression products for lignocellulosic digestion
Use of compositions comprising one or more genes or their expression products selected from SActE_0237 (GH6), SActE_0236 (GH48), SActE_3159 (CBM33), SActE_0482 (GH5), SActE_0265 (GH10), and SActE_2347 (GH5), optionally combined with others for optimized cellulose, xylan, chitin, biomass, mannan, beta-1,3-glucan, pectin, alginate, or galactose cleavage.
Method for digesting lignocellulosic material with compositions of ActE genes or expression products
Exposing lignocellulosic material to amounts of compositions comprising combinations of the specified ActE genes or expression products to achieve at least partial digestion.
Purified preparation of Streptomyces sp. ActE grown on specific carbon sources
Preparation of ActE grown on substrates where at least 40%, preferably 85%, of the carbon source is derived from cellulose, hemicellulose, xylan, non-wood biomass, wood biomass, chitin, or pretreated lignocellulosic material using various pretreatments.
The claims cover methods and compositions utilizing purified Streptomyces sp. ActE secretomes or specific genes and their products for efficient partial digestion of lignocellulosic materials, with substrate-dependent optimizations and genetic modifications to enhance enzyme production and activity.
Stated Advantages
Provides high cellulolytic capacity comparable to established industrial fungi preparations.
Enables substrate-specific secretome compositions tailored for efficient hydrolysis of cellulose, xylan, chitin, mannan, and mixed biomass.
Exhibits enzyme activity optima at neutral to slightly alkaline pH and moderate temperatures, compatible with fermentation organisms.
Secretomes produce primarily cellobiose as a product, facilitating targeted fermentation strategies.
ActE produces antibiotics that may reduce culture contamination during biomass processing.
Genetic tractability allows overexpression or heterologous expression of key enzymes to improve production and activity.
Enzymes demonstrate size minimization leading to increased specific activity.
Compositions can be combined synergistically with other enzyme preparations to enhance lignocellulosic degradation.
Documented Applications
Hydrolysis of lignocellulosic biomass for production of fermentable sugars for biofuels.
Pretreatment of agricultural crop materials to improve digestibility for ruminant animal feed.
Processing of paper waste to convert cellulose to fermentable sugars.
Improvement of biomass digestibility in animal feeds to promote growth.
Treatment of cotton-based textiles for smoothing or refinement.
Conversion of chitin-containing waste, such as shrimp industry waste, into soluble products.
Production of cellobiose and xylose from biomass for fermentation using engineered organisms capable of cellobiose uptake.
Combination with other cellulases or enzymes to improve the hydrolysis rate and yield in lignocellulosic conversion.
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