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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Bioenergy Research » Research » Research Project #436582

Research Project: Improved Biocontrol Agent Production and Delivery Technologies Compatible with Cellulosic Biorefining ... Potatoes in Storage

Location: Bioenergy Research

Project Number: 5010-41000-189-006-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Aug 1, 2019
End Date: Jul 31, 2021

1) Design rehydration conditions for most efficient reactivation of dry-stored co- cultures of Pseudomonas, and use laboratory bioassays to test recovery rate and efficacy against dry rot. 2) In flask and small fermentor studies, optimize efficient production of desiccation tolerant Pseudomonas co-cultures on low cost switchgrass hydrolyzate sugars consistent with biorefining, and test the recovery rate and efficacy of the dry biocontrol product against development of dry rot in laboratory assays. 3) Test top BCA treatments emerging from laboratory studies at varied rates with practical application methods available to growers (agitation, application volume, etc.), and at appropriate temperatures for wound healing and storage to control Fusarium dry rot on Clearwater Russet potatoes postharvest in small-pilot-scale bin studies. Additional cultural practices will be incorporated into the studies to optimize the use of the post-harvest treatments for control of Fusarium dry rot.

1) A practical rehydration technique consistent with treatment of a potato harvest will be sought by drying droplets of BCA cells in wells of microplates, storing at 25°C for 1-4 weeks, and then reconstituting in various rehydrating media. The timecourse of metabolic activity recovery will be tracked in microplates using an instrument which can monitor as many as 200 experimental treatments at a time. Statistical designs of experiments will be applied to efficiently optimize environment and nutrient composition (mineral, carbon, and nitrogen sources) supporting most rapid recovery of metabolic activity. Residual C and N sources following recovery of metabolism will also be monitored by high performance liquid chromatography to design the rehydration to minimize these. Efficacy of rehydrated BCAs will be assayed on wounded potatoes challenged with Fusarium. 2) Environmental, nutrient, and initial inocula conditions of the three desiccation- tolerant Pseudomonas strains will be optimized as necessary to produce co-cultures of strains having similar concentrations of all three strain populations on low cost switchgrass hydrolysate sugars, prepared in our laboratory to be consistent with those obtainable from a biorefinery . Optimizations will be carried out in microplates (48 or 96 x deep-well plates) and small shake flasks, and each of the three bacterial populations of the co-culture will be enumerated using selective and differential plating media techniques. The hydrolyzate-produced cell populations of fresh or dry-stored BCAs will be assayed for cell viability, recovery rate after rehydration, and efficacy in lab wounded potato bioassays. 3.) Application management studies of biocontrol agents will be emphasized to identify best methods to apply products to commercial potatoes post-harvest. Superior rehydration treatments of dried, co-cultured biological control products composed of dry-tolerant variants of three Pseudomonas sp. strains produced optimally on biorefinery hydrolyzates of switchgrass will be tested in small-pilot- scale bin studies for efficacy against dry rot at the Kimberly R & E Center, Kimberly, ID. Variables to be tested will be selected from the following: storage temperatures for process or seed tubers, combination with full and reduced strength chemicals, and best tank application methods and practices for growers. Final treatment selections will be prioritized based on current industry practices and needs.