Isolation, identification and selection of antagonistic yeast against Alternaria alternata infection and tenuazonic acid production in wine grapes from Argentina

PRENDES, LUCIANA P.; MERÍN, MARÍA G.; FONTANA, ARIEL R.; BOTTINI, RUBÉN A.; RAMIREZ, MARÍA L.; MORATA DE AMBROSINI, VILMA I.

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Año: 2018 vol. 266 p. 14 - 20

0168-1605

Epiphytic isolates with yeast characteristics from grapes of the Malbec cultivar were obtained in order to find antagonists against Alternaria alternata. From a total of 111 isolates, 82% corresponded to the yeast-like organism Aureobasidium pullulans and the rest to the non-Saccharomyces yeasts Hanseniaspora uvarum (6.3 %), Metschnikowia pulcherrima or spp. (5.4 %), Cryptoccocus laurentti II (2.7 %), Starmerella bacilaris or Candida zemplinina (2.7 %) and Rhodotorula spp. (0.9 %). The 22.4% (15 out of 67) of epiphytic yeasts and yeast-like organisms evaluated were able to reduce A. alternata infection to a range from 0.0 to 4.4% when applied 2 hours previous to pathogen inoculation on wounds of grape berries. From these selected strains, 14 out of 15 completely prevented A. alternata infection (0.0%), which implies potential for field application. All Metschnikowia (pulcherrima or spp.), S. bacillaris and almost all H. uvarum evaluated strains showed antagonist capability against A. alternata. Meanwhile, none of the lesser nutritional requirement strains belonging to A. pullulans, Cr. laurenti II and Rhodotorula spp. did. All the yeasts with capacity to prevent A. alternata infection also reduced tenuazonic acid production by 81.2 to 99.8 %, founding TA levels similar to negative controls. Therefore, the epiphytic yeasts selected are promising as biological control agents against Alternaria infection in grapes for winemaking.