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POSTERS: Biological control

Characteristics of Aureobasidium pullulans strains exhibiting biocontrol activity against fruit decay pathogens from different parts of the world
Wojciech Janisiewicz - USDA-ARS, Appalachian Fruit Research Station. Filippo De Curtis- Dep. of Agricultural, Environmental and Food Sciences, University of Molise, Anja ?ernoša- National Institute of Biology, Department of Biotechnology and System Biology, Giuseppe Lima- Dep. of Agricultural, Environmental and Food Scienc

The yeast-like fungus, A. pullulans, is a commonly occurring natural saprophyte on wide range of plants. This fungus, isolated from fruit and leaves in different parts of the world, exhibited strong biocontrol activity against postharvest decays on various fruit, and was developed into a few commercial products. Knowledge of common characteristics of these strains may be very useful in future selection of the best antagonists of this species. Thus, we obtained 20 of these strains and characterized them for growth at 37 and 0°C, tolerance to 50°C, osmotic tolerance, biofilm formation, activity of specific enzymes, and production of siderophores. All strains grew at 0°C, which is very important to control decays at low storage temperature, and none grew at 37°C, which eliminates concern for human safety. Only 2 strains survived for 24 h at 50°C, while 18 survived for 2 h. Osmotolerance varies; however, all strains grew on medium with 14% NaCl and 16 even with 18% NaCl. Tolerance to high temperature and osmoticum enables compatibility with postharvest practices. Small differences were observed in enzymatic activity, although some strains didn't produce chitinase (7), xylanase (10), or urease (10). Siderophore productions on CAS agar was generally low, except for one strain that was high and one that produced no detectable siderophores. Ability to form biofilm vary widely between the strains. Merits and demerits of the presented characteristics will be discussed.