Optimization of a vacuum-drying protectants for the biocontrol agent Pichia membranifaciens and its influence on viability and efficacy

In this study, we focused on screening for an optimal protectant formula for vacuum-dried Pichia membranifaciens and compared the biocontrol efficacy of fresh P. membranifaciens and dried one on citrus fruit. We also used several techniques to test the viability of P. membranifaciens that were vacuum dried with the protectants. By performing an orthogonal experiment to optimize an appropriate protectants combination, which consisted of 20 % (w/v) trehalose, 2 % (w/v) sodium glutamate, 5 % (w/v) polyvinyl pyrrolidone (PVP) and 20 % (w/v) skim milk, the viability of the vacuum-dried P. membranifaciens cells was improved from 18.0 % ± 4.9 % when dried without protectants to 79.4 % ± 4.8 % when dried with the protectants formulation. The results of cell viability assays using live/dead staining with fluorescent dyes, conductivity determinations and intracellular nucleotide leakage determinations agreed with the observed cell viability values obtained by enumerating the colony-forming units (CFUs) on plates. For practical applications, there was no significant difference in the biocontrol effects between fresh and active dry yeast when applied to Citrus sinensis.

Source: Biological Control - November 26, 2019 Category: Biology Source Type: research