Effect of stress factors associated with postharvest citrus conditions on the viability and biocontrol activity of Clavispora lusitaniae strain 146

PEREYRA, MARTINA MARÍA; DIB, JULIÁN RAFAEL; MEINHARDT, FRIEDHELM; MEINHARDT, FRIEDHELM; DÍAZ, MARIANA ANDREA; DÍAZ, MARIANA ANDREA; PEREYRA, MARTINA MARÍA; DIB, JULIÁN RAFAEL

PLOS ONE

PUBLIC LIBRARY SCIENCE

Año: 2020 vol. 15

1932-6203

Only quite recently, we have shown that yeast strains Clavispora lusitaniae 146 and Pichiafermentans 27 can act as efficient biocontrol agents for combating postharvest fungal diseasesin lemons. During postharvest and storage conditions, microorganisms are subject todifferent stress factors that could affect both their survival and their protective capacity.Understanding the tolerance of yeasts to environmental stress factors could support thefuture development and commercial application of biological control formulations based onsuch organisms. Thus, the impact of different stressors on the viability and protection efficiencyof C. lusitaniae strain 146 and P. fermentans strain 27 was evaluated, and the yeastswere subjected to oxidative stress, thermal treatments, exposure to NaOCl, osmotic stress,and ultraviolet irradiation. Candida oleophila strain O served as the reference control. C.lusitaniae 146 was more resistant to H2O2 in plate assays; however, in liquid media therewas no significant difference to the other strains. Strain 146 was less affected by NaOCl,being able to survive with 300 ppm. P. fermentans 27 was the strain most heavily affectedby osmotic pressure, while strains 146 and strain O showed a similar adaptation. UV-B irradiationseverely affected C. oleophila and P. fermentans, while C. lusitaniae was the mostresistant. Strains 146 and 27 were similarly tolerant to thermal shocks, compared to the referencestrain, which was less viable. In in vivo tests, exposure to 10 mM H2O2, 45˚C or200 ppm NaOCl prior to fruit inoculation, reduced the antagonistic activity against the pathogenPenicillium digitatum. However, in no case was the biocontrol efficiency reduced to lessthan 50%. As C. lusitaniae 146 demonstrated a great potential to combat P. digitatum undera wide range of conditions, the organism is a promising candidate as an effective and valuablealternative to toxic fungicides.