Location: Bioproducts Research
2022 Annual Report
Objectives
Objective 1 encompasses processing technologies primarily for cellulosic feedstocks including hemp, a potential new specialty crop in the U.S. Research on objective 1 will focus on fiber-based packaging, particularly insulative and/or cushioning foam packaging and nanofiber films and composites. Objective 2 encompasses a broader range of feedstocks and includes starches and other carbohydrates beyond starch and cellulose as well as polyhydroxyalkanoates that are produced by bacteria. The primary objective is to utilize renewable polymers that are degradable in both garden compost and marine environments to make bioproducts designed for single-use food and packaging items. Objective 3 focuses on sustainable solutions for chemical products, particularly antibiotics, that are a growing health or environmental concern. The focus will be to use small molecules that bind or associate at critical concentrations to form active complexes with specific functions. Below the critical concentrations, the active complexes dissociate into benign molecules.
Objective 1: Enable new technologies to manufacture fiber/nanofiber-based bioproducts.
• Sub-objective 1A: Enable new technologies for making fiber-based foam products with moisture and grease/oil resistance.
• Sub-objective 1B: Create consumer products utilizing hemp fiber.
Objective 2: Enable new technologies for biopolymers and their blends.
• Sub-objective 2A: Develop plastics and composites for consumer products that are readily degraded in marine and soil environments.
• Sub-objective 2B: Develop microorganisms for novel biopolymer production.
• Sub-objective 2C: Develop new technologies to process biopolymers into industrially-relevant products.
Objective 3: Develop bioactive materials that are designed to minimize ecotoxicity and biocide resistance.
Approach
Hypothesis 1A: Fiber-based materials can be made into rigid, insulative foam products or non-foam composites with moisture and grease/oil resistance. Rigid foam samples will be made with agricultural fibers, foaming agent, and sizing agents. The rigid foam will be characterized by testing the mechanical and thermal properties of the foam. If the use of agricultural fibers is unsuccessful or too expensive, kraft fiber from wood pulp will be used in the study.
Hypothesis 1B: The hypothesis statement will be provided by the scientist who fills the vacant position in the CRIS. Biomass left over from CBD extraction from various industrial hemp cultivars will be pulped and used as a source of nanofibers. Water soluble film formulations will be provided by our CRADA partner and treated with nanofibers to evaluate their effect on mechanical properties. If nanofibers from hemp do not desired properties, biomass resources provided by our cooperators from Brazil.
Hypothesis 2A: Marine degradable polymers and composites can be processed into bioproducts including films, foams, and molded articles. We intend to promote crystallization of thermoplastic starch (TPS) during and after extrusion and molding as a means of enhancing moisture resistance and improving strength without reverting to chemical modification or blending. Commercial starches from various agricultural sources and with varying amylose:amylopectin ratios will be evaluated and formed into TPS using twin-screw extrusion. Blends of TPS and wood fiber, cellulose nanocrystals/nanofibrillar cellulose from hemp or corn stover will be prepared, processed by extrusion and/or film blowing, and characterized. Other biopolymers or mineral additives will be used in formulations if the properties of TSP are not acceptable.
Hypothesis 2B: Microorganisms that use methane (methanotrophs) or other carbon sources (Bacillus subtilis) can be engineered to improve production processes and generate valuable biopolymer additives. We will use overexpression of targeted proteins to increase cell hydrophobicity in methanotrophs. If this approach is unsuccessful, the membrane proteins that target proteins regulate will also be singled out to change their expression.
Hypothesis 2C: Active nutritional supplement can be produced at large scale by Bacillus megaterium.: B. megaterium strains within our own inventory will be used to produce poly-3-hydroxybutyrate (P(3HB)) trimers as active nutritional supplements. If insufficient quantities of 3HB trimer are produced, another strategy would be to isolate fungal or bacterial depolymerases for their ability to release trimers from P(3HB).
Hypothesis 3: Judicious use of reversible actives (e.g. antimicrobials) will minimize negative human health effects, ecotoxicity and biocide resistance. We will incorporate reversible bonds in traditionally persistent chemicals such as cationic guanylhydrazones to minimize environmental toxicity and biocide resistance. If activity is affected by anionic additives, we will utilize hydroxamic acids.
Progress Report
In support of Objective 1, research continued on the development of the fiber foam technology. Two more invention disclosures were submitted as a family of patent applications have been developed for different innovations in fiber foam. The fiber foam has many useful properties such as low density and low thermal conductivity. However, the foam is moisture sensitive. By adding small amounts of waxes during the foaming step, foams with moisture resistance were produced. The foam typically has low compressive strength relative to polystyrene foam. By incorporating paperboard reinforcing elements to the foam, compressive strength was improved while still maintaining low density and thermal conductivity. A compression molding process was developed that allowed the foam to be formed into shapes or articles. A compression molding process will be critical in manufacturing molded foam products. The Cooperative Research and Development Agreement with our industrial partner ended during the shutdown of our laboratory due to COVID restrictions. However, our industrial partner has assembled a research team that is working towards commercialization of the fiber foam technology.
In support of Sub-objective 2A, research continued on using starch/fiber blends in products and evaluating ways to make the composites moisture and oil resistant. Moisture and oil resistance are key properties for food containers. Various wax emulsions and sizing agents are being explored as useful additives for promoting moisture resistance.
In support of Sub-objective 2B, research continued on producing biodegradable copolymers in bacteria. Low cost, simple sugars are effective feedstocks in producing valuable copolymers that have promising commercial value.
In support of Sub-objective 2C, research continued in developing a process for making hydroxybutyrate oligomers. Progress has been made in making gram quantities of these materials. The products are currently being characterized in detail.
In support of Objective 3, a collaboration was established with ARS researchers in Ames, Iowa, to evaluate the use of reversible guanylhydrazone biocides as digital dermatitis treatments for sheep. Evaluations were conducted in FY21-22, representing the second field trial of these substances. These novel alternatives to antibiotics cleared these polybacterial infections within 1-2 weeks, matching current gold-standard tetracycline treatments at 1/30th the concentration.
In further work, preservative applications of guanylhydrazones were presented to an industry consortium organized by Green Chemistry and Commerce Council and attended by major chemical producers and brands in the home and personal care sector. Additional novel reversible biocides active against mold and bacteria were prepared from amino acid esters and hydrazides. Reversible antioxidants were synthesized and are currently under evaluation as alternatives to an ecotoxic tire antiozonant.
Accomplishments
1. New technology provides a way to make molded articles from biodegradable foam. Single-use plastic foam products found in the food and packaging sectors are an environmental concern. Replacement foam made from agricultural materials are less impactful on the environment but are difficult to mold into products. ARS researchers in Albany, California, have developed a process for molding plant fiber foam into shaped articles. This technology will help expand the use of plant fiber foam and help reduce the need for single-use plastic foam.
Review Publications
Nadeem, A., O'Keeffe, T.L., Cal, A.J., Palumbo, J.D., Arshad, R., Bibi, N., Lee, C.C. 2022. Isolation of endophytes that suppress pathogen growth of chickpea (Cicer arietinum L.). Pakistan Journal of Botany. 54(5):1813-1820. https://doi.org/10.30848/pjb2022-5(22).
Placido, D., Lee, C.C. 2022. Potential of industrial hemp for phytoremediation of heavy metals. Plants. 11(5). Article 595. https://doi.org/10.3390/plants11050595.
De Costa Farias, R., Leite Severo, L., Klamczynski, A.P., de Medeiros, E., de Lima Santana, L., de Araujo Neves, G., Glenn, G.M., Menezes, R. 2021. Solution blow spun silica nanofibers: Influence of polymeric additives on the physical properties and dye adsorption capacity. Nanomaterials. 11(11). Article 3135. https://doi.org/10.3390/nano11113135.
Gutiérrez-Jara, C., Bilbao-Sainz, C., McHugh, T.H., Chiou, B., Williams, T.G., Villalobos-Carvajal, R. 2021. Effect of cross-linked alginate/oil nanoemulsion coating on cracking and quality parameters of sweet cherries. Foods. 10(2). Article 449. https://doi.org/10.3390/foods10020449.
Gutierrez-Jara, C., Bilbao-Sainz, C., McHugh, T.H., Chiou, B., Williams, T.G., Villalobos-Carvajal, R. 2020. Physical, mechanical and transport properties of emulsified films based on alginate with soybean oil: Effects of soybean oil concentration, number of passes and degree of surface crosslinking. Food Hydrocolloids. 109. Article 106133. https://doi.org/10.1016/j.foodhyd.2020.106133.
