SANGORRIN marcela paula
Yeast biocontrol of fungal spoilage of pears stored at low temperature
ROBIGLIO, A.; SOSA, C.; LUTZ, C.; LOPES, C.A.; SANGORRIN, M.P.
INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
ELSEVIER SCIENCE BV
Año: 2011 vol. 147 p. 211 - 216
To reduce the use of fungicides, biological control with yeasts has been proposed in postharvest pears. Moststudies of antagonists selection have been carried out at room temperature. However, in regions like NorthPatagonia where fruits are stored at −1/0 °C during 57 months the selection of potential antagonist agentsmust be carried out at low temperature. In this study, 75 yeast cultures were isolated from healthy pears fromtwo Patagonian cold-storage packinghouses. Aureobasidium pullulans, Cryptococcus albidus, Cryptococcusdifluens, Pichia membranifaciens, Pichia philogaea, Rhodotorula mucilaginosa and Saccharomyces cerevisiae yeastspecies were identified. Additionally, 13 indigenous isolates of Penicillium expansum and 10 isolates of Botrytiscinerea were obtained from diseased pears, characterized by aggressiveness and tested for sensitivity topostharvest fungicides. The yeasts were pre-selected for their ability to grow at low temperature. In a firstbiocontrol assay using the most aggressive and the most sensitive isolate of each pathogen, two epiphyticisolates of A. pullulans and R. mucilaginosa were the most promising isolates to be used as biocontrol agents.They reduced the decay incidence by P. expansum to 33% and the lesion diameter in 88% after 60 days ofincubation in cold. Foreign commercial yeast used as a reference in assays, only reduced 30% of lesiondiameter in the same conditions. Yeasts were not able to reduce the incidence of B. cinerea decay. The controlactivity of the best two yeasts was compared with the control caused by the fungicides in a second bioassay,obtaining higher levels of protection against P. expansum by the yeasts. These two regional yeasts isolatescould be promising tools for the future development of commercial products for biological control