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United States Department of Agriculture

Agricultural Research Service

Research Project: Technologies for Improving Industrial Biorefineries that Produce Marketable Biobased Products

Location: Bioproducts Research

Project Number: 2030-41000-054-00-D
Project Type: In-House Appropriated

Start Date: Oct 1, 2014
End Date: Sep 30, 2019

Objective:
This project provides technological solutions to the biofuels industry to help the U.S. meet its Congressionally mandated goal of doubling advanced biofuels production within the next decade. The overall goal is to develop optimal strategies for converting agricultural biomass to biofuels and to create value-added products (bioproducts) that improve the economics of biorefining processes. Specific emphasis is to develop strategies for biorefineries located in the Western United States by using regionally-specific feedstocks and crops, including sorghum, almond byproducts, citrus juicing wastes, pomace, municipal solid wastes (MSW), and food processing wastes. These feedstocks will be converted into biofuels, bioenergy and fine chemicals. Objective 1: Develop commercially-viable technologies for converting agriculturally-derived biomass, crop residues, biogas, and underutilized waste streams into marketable chemicals. Research on converting biogas will involve significant collaboration with one or more industrial partners. Sub-objective 1A: Provide data and process models for integrated biorefineries that utilize sorghum and available solid waste to produce ethanol, biogas and commercially-viable coproducts. Sub-objective 1B. Convert biogas from biorefining processes into polyhydroxyalkanoate plastics. Sub-objective 1C: Apply the latest tools in immobilized enzymes, nano-assemblies, to convert biomass to fermentable sugars, formaldehyde, and other fine chemicals. Objective 2: Develop commercially-viable fractionation, separation, de-construction, recovery and conversion technologies that enable the production of marketable products and co-products from the byproducts of large-scale food production and processing. Sub-objective 2A: Add value to almond byproducts. Sub-objective 2B: Apply bioenegineering of bacteria and yeast to produce diacids, ascorbic acid and other value-added products from pectin-rich citrus peel waste. Sub-objective 2C: Convert biomass into commercially-viable designer oligosaccharides using combinatorial enzyme technology.

Approach:
Objective 1, referred to by some as Gen 1.5 Biorefineries, involves development of processes that will generate advanced biofuels using the “cheapest source of carbons” within a given region. Sub-objective 1A provides data about the properties of grain, forage, and sweet sorghum grown in California. Compositional analysis of cellulose, lignin and hemicellulose for grain, forage, and sweet sorghum varieties grown in California provides growers information to decide whether sorghum will become a viable biofuels feedstock in integrated biorefineries that also include anaerobic digestion. Sub-objective 1B is goal-driven research toward improving methanotrophic bacteria for commercial production of commodity and fine chemicals. High throughput mutagenesis is employed to enrich production of polyhydroxyalkanoate, PHA, from mixed populations. Sub-objective 1C tests the hypothesis that bioconversion of biomass substrates into value-added products will be achieved more efficiently with enzymes anchored to nano-assemblies, compared with using the same enzymes free in solution. The basic nano-assembly building block, termed the Rosettasome, will spontaneously assemble into an 18-subunit, double-ring structure that holds up to 18 different enzymes. Proposed research involves developing optimized Rosettazymes for hydrolyzing various biomass substrates into value-added bioproducts using multiple tethered enzymes. Objective 2 will provide data and technology that will add value to food processing byproducts. Sub-objective 2A consists of a goal-driven series of engineering developments to recover value-added free sugars, hemicellulose, and gums from almond byproducts. Release and utilization of free sugar and sugar alcohol can be improved by optimizing extraction parameters (time, temperature, particle size of the hulls, etc.) during hot water isolation. This process releases fermentable sugars, hemicellulose molasses and gums from almond shells and hulls. Equations and their corresponding parameters will be developed into process models for recovery of water soluble sugars in almond hulls. The goal is to add increased value to all components of the almond processing industry. Research in sub-objective 2B is driven by the hypothesis that whole cells can be engineered to convert pectin and other specific oligosaccharides into value-added products more efficiently than using multi-step chemical or enzymatic reactions. This will be achieved by applying bioenegineering of bacteria and yeast to produce diacids, ascorbic acid, and other value-added products from pectin-rich citrus peel waste. The general hypothesis driving sub-objective 2C is that bioconversion research is that specific well-defined enzymes can be applied to "surgically" remove selective branching groups from individual polysaccharide substrates via controlled enzymatic debranching and cleavage of main chain polymers.

Last Modified: 06/24/2017
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