Osmotic tolerance response of biocontrol agent Yarrowia lipolytica m18/3b under pre- and postharvest conditions

ABSTRACT

A pre-adaptation approach to osmotic stress was used to improve the colonisation and biocontrol capacity of Yarrowia lipolytica M18/3b on the apple under pre- and postharvest conditions. For this, M18/3b strain was cultured in an unmodified NYDB medium (0.996a_w) or in different media with water stress (0.950–0.970a_w) produced by the addition of NaCl, sorbitol, or glycerol and the impact on the growth rate in them was evaluated. Furthermore, the population dynamic of the yeast was evaluated on the apple surface under field and storage conditions. Treated fruits were also inoculated with Penicillium expansum and the disease incidence and severity were measured. Finally, the content of intracellular sugars and polyols on pre-adapted M18/3b cells was determined. The results showed that development of the M18/3b strain in the modified media was affected by the solute used to reduce the a_w. The cells adapted with glycerol (0.960a_w) reached higher population levels on the apple surface, both in pre- and postharvest conditions. Furthermore, an increase in the antagonistic activity of M18/3b pre-adapted with glycerol was obtained in the field application. In contrast, pre-adaptation with sorbitol had adverse effects on the colonisation capacity of the antagonist. Additionally, pre-adapted cells with NaCl and sorbitol showed an accumulation of erythritol and a significant decrease of trehalose compared with non-adapted cells. In conclusion, the osmotic treatment with glycerol at 0.960a_w increased the survival of Y. lipolytica M18/3b cells on the fruit surface and enhanced the antagonistic activity to control blue mould when apples were treated in pre-harvest.

KEYWORDS:

• Antagonist
• a_w
• field
• intracellular sugar
• polyols
• storage

Acknowledgements

The authors would like to thank the National Council of Science and Technology of Mexico (CONACYT) for M. Burgos-Zazueta grant 781116.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors would like to thank the National Council of Science and Technology of Mexico (CONACYT) for M. Burgos-Zazueta grant [781116].