Kinetic modelling and optimisation of antimicrobial compound production by <i>Candida pyralidae</i> KU736785 for control of <i>Candida guilliermondii</i>

Abstract

Biological antimicrobial compounds from yeast can be used to address the critical need for safer preservatives in food, fruit and beverages. The inhibition of Candida guilliermondii, a common fermented beverage spoilage organism, was achieved using antimicrobial compounds produced by Candida pyralidae KU736785. The antimicrobial production system was modelled and optimised using response surface methodology, with 22.5 ℃ and pH of 5.0 being the optimum conditions. A new concept for quantifying spoilage organism inhibition was developed. The inhibition activity of the antimicrobial compounds was observed to be at a maximum after 17–23 h of fermentation, with C. pyralidae concentration being between 0.40 and 1.25 × 10 9 CFU ml −1 , while its maximum specific growth rate was 0.31–0.54 h −1 . The maximum inhibitory activity was between 0.19 and 1.08 l contaminated solidified media per millilitre of antimicrobial compound used. Furthermore, the antimicrobial compound formation rate was 0.037–0.086 l VZI ml −1 ACU h −1 , respectively. The response surface methodology analysis showed that the model developed sufficiently described the antimicrobial compound formation rate 1.08 l VZI ml −1 ACU, as 1.17 l VZI ml −1 ACU, predicted under the optimum production conditions.