Killer Toxins of Ascomycete Yeast Suppressing Phytopathogenic Fungi Botrytis cinerea

Introduction: The problem of contamination of agricultural crops and plant raw materials by spoilage microorganisms is urgent — the damage caused by them to agriculture is growing from year to year. The use of pesticides can negatively affect the quality of raw materials and the health of consumers. A unilateral approach to solving this issue does not lead to positive results. Yeast killer toxins (KT) are of considerable interest for biotechnology as drugs that suppress the activity of pathogens.

Purpose: The purpose of this study is to screen ascomycete yeast strains from the collection of the National Bioresource Center of the All-Russian Collection of Industrial Microorganisms of the Kurchatov Institute Research Center,which exhibit the greatest killer activity in relation to phytopathogenic fungi of the Botrytis cinerea species, as well as to determine the factors affecting its effectiveness.

Materials and Methods: KT activity was determined on a thin agar on a full yeast medium YPD with the addition of 0,5 ml / l of 88% lactic acid solution, pH = 4,5. The value of the hydrogen index 4,5 was chosen as optimal for most of the studied yeast species.

Results: The largest growth suppression zones of Botrytis cinerea were given by Schwanniomyces occidentalis strains Y1-627, Y-1628, Y-1629, Y-1638, Y 1640, Y-1641, Metschnikowia pulcherrima Y-3698. Also small suppression zones were observed in Cyberlindnera mrakii Y-1211, Wickerhamomyces anomalus Y-201, Y-3836, Y-4562, Y-1182, Debaryomyces hansenii Y-1681 strains. During the test on the remaining strains, the effect of CT was not revealed.

Conclusions: In this study, it was found that killer yeasts from the collection of the BRC VKPM are effective against Botrytis cinerea F-1006, which gives the potential for their development and use as means of biocontrol.

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