Production of biological pest control agents on hydrolysates of switchgrass

Authors: Slininger, Patricia - Pat; SCHOEPKE, ANDREW - Orise Fellow; Dien, Bruce

Submitted to: Bioresource Technology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2022
Publication Date: 12/16/2022
Citation: Slininger, P.J., Schoepke, A.R., Dien, B.S. 2022. Production of biological pest control agents on hydrolysates of switchgrass. Bioresource Technology Reports. 21. Article 101312. https://doi.org/10.1016/j.biteb.2022.101312.
DOI: https://doi.org/10.1016/j.biteb.2022.101312

Interpretive Summary: Many of the chemicals used to protect crops from major plant diseases are no longer effective because the pathogens have built up immunity. For example, Fusarium dry rot is a fungal disease that was once kept in check using the chemical thiabendazole. Dry rot affects potatoes in storage and transit and costs the US potato industry approximately $500 million in annual losses. Global losses for potatoes are more than ten times this because potatoes are among the top four food crops. ARS scientists have developed a biological product derived from beneficial bacteria found in potato fields. Plant diseases find it hard to build up resistance to biological-based products because they attack the disease in multiple ways unlike chemical ones. Biological products are also preferred over chemicals because they are better for the environment. Although the introduction of biologicals to the agricultural market is outpacing that of new chemicals, production cost is still limiting their application. Biological products are typically produced by growing them on refined corn sugar. We propose to solve this problem by using inexpensive unrefined cellulosic sugars. Likewise, finding more uses for cellulosic sugars helps the nascent cellulosic sugar / biofuel industry by introducing a new product. Here, we demonstrate the feasibility of this approach using unrefined sugars generated from switchgrass, a bioenergy crop being developed by ARS. We are now applying the newly formulated biological control product in large pilot study that simulates commercial potato storages. This technology has multiple benefits: it gives potato producers a new effective and green product to attack a major disease and the offers possibility of increased profits for cellulose-based refiners.

Technical Abstract: Recently, biological products have outpaced chemicals for pest control because they are more compatible with the environment, and they offer multiple modes of action not easily overcome by resistance mechanisms. Pseudomonas spp. have been developed as biocontrol agents (BCAs) to replace chemicals no longer effective against dry rot disease and other maladies of postharvest potatoes, including sprouting, late-blight, pink rot and Pythium leak. It is proposed that Pseudomonas spp., which can use the diverse carbon sources in lignocellulosic hydrolysates, have aptitude as valuable coproducts compatible with lignocellulosic biorefining. Our results showed that three Pseudomonas strains could rapidly consume all sugars, including the pentoses, as well as the acetic acid, furfural, and hydroxymethyl furfural. High yields of efficacious BCAs could be obtained on xylose- or glucose-rich fractions and the combined fractions from switchgrass hydrolysis, provided pH was controlled near neutral and sugar concentrations were kept near 10 g/L to prevent osmotic inhibition.