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United States Department of Agriculture

Agricultural Research Service


Location: Foodborne Toxin Detection and Prevention Research

2012 Annual Report

1a. Objectives (from AD-416):
1. To explore improvements to formulation of biocontrol yeast for field application by growers. Types of formulations are wet formulations with additives (preservatives, nutritional supplements, surfactants for spreading) and dry formulations for delivery of viable yeast as a dry powder for tank mixing. 2. Evaluation of yeast longevity under different storage and application conditions: time and temperature. 3. Application for controlling l of other microbial pathogens: plant pathogenic fungi, microbial contaminants of crops (Salmonella, E. Coli)

1b. Approach (from AD-416):
Objective 1. Protective additives will be added to wet and dry yeast formulations and evaluated for improved shelf-life under lab conditions. Spray trials in the field may be used to evaluate effects on durability on plant leaves and fruits. Surfactants will be in the tank mix for even spreading. Objective 2. Yeast durability in a fully diluted mixture will be evaluated through time and temperatures series in lab so the upper threshold that might be expected under grower conditions. Objective 3. Ability to control fungi on agricultural crops. evaluations will be done using greenhouse tests on plants and pathogens of significance in tree fruit-nut and vegetable crops. Salmonella is a particular problem on almond. Initial experiments may involve field sprays on almond followed by collection of nuts and inoculation with Salmonella in lab-greenhouse and monitor Salmonella population Non-pathogenic E. Coli strains applied to lettuce and spinach in the greenhouse followed by yeast spray applications to determine whether potential control is possible. The effectiveness of the yeast against additional fungi of agricultural importance will initially be evaluated on tomato and potato. Documents SCA with UC-Davis.

3. Progress Report:
Aspergillus flavus as well as aflatoxin production. A wet formulation has been developed by adding certain compounds in the formulation of yeast cells for storage at 40C for up to one year with very little change in viability. Chitosan was evaluated for its activity to enhance the biocontrol efficacy of the yeast, Pichia anomala against target fungal pathogens such as Aspergillus flavus. Yeast cells grew well at low concentrations of chitosan. The research is on going. The ADODR monitored this project through site visits, emails and phone calls. The goal of the specific cooperative agreement is to develop practical applications of Pichia anomala to control pathogenic fungi and bacteria, which contributes directly to Objective 4 of the in-house project. The SCA has been extended to March 2013.

4. Accomplishments

Last Modified: 10/16/2017
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