Location: Crop Bioprotection Research
Title: Evaluation of osmoprotectants and carriers for formulating Gram-negative biocontrol agents active against potato dry rot in storage Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2014
Publication Date: August 9, 2014
Citation: Schisler, D.A., Slininger, P.J., Olsen, N.L., Shea Andersh, M.A., Woodell, L.K. 2014. Evaluation of osmoprotectants and carriers for formulating Gram-negative biocontrol agents active against potato dry rot in storage. Meeting Abstract. Technical Abstract: The production of a dry formulation containing viable cells of a Gram-negative biological control agent is a challenging yet vital step in developing the agent into a commercial product. <i>Pseudomonas fluorescens </i> strains S11:P:12, P22:Y:05, and S22:T:04 reduce Fusarium dry rot of potatoes (causal agent, <i>Gibberella pulicaris</i>) in storage. The strains were evaluated in a high-throughput microtiter plate assay for viability after drying in differing amounts of carbohydrate-based osmoprotectants applied after 24 h of cell growth in a liquid medium. Fructose and trehalose at 20g/L were the most effective at maintaining the viability of the strains. Different grades of diatomaceous earth, perlite, fumed silica and clay were then combined with high titer suspensions of washed cells of each strain. After being dried for 18-22 h in a controlled RH atmosphere, several DE products including Kenite 700 were superior in maintaining cell viability. Combining cells suspended in osmoprotectant with Kenite 700 resulted in dried products with up to 10X higher cell survival. In initial laboratory assays, most dried products containing P22:Y:05 and S22:T:04 reduced dry rot by more than 50% in laboratory assays (P<0.05, FPLSD) but dried products containing S11:P:12 were less effective. Results of a small pilot-scale trial testing dried biocontrol products for efficacy in reducing dry rot on potatoes in storage will also be reported.