Enhancement of the biocontrol agent Candida oleophila (strain O) survival and control efficiency under extreme conditions of water activity and relative humidity

Plant Biology Research Institute, Department of Biological Sciences, Montreal University, 4101 Sherbrooke Est, Montréal, Que., H1X 2B2 Canada
Biological Control (Impact Factor: 1.64). 12/2009; 51(3):403-408. DOI: 10.1016/j.biocontrol.2009.07.014


The objective of this work is to evaluate the ability of some additive substances in protecting the biocontrol agent Candida oleophila (strain O) against the adverse effects of environmental factors, such as water activity (aw, 0.93 and 0.98) and relative humidity (75% and 98%). The protection obtained with various protectant substances, skimmed milk (SM), peptone, maltose, sucrose, sorbitol, lactose and polyethylene glycol was assayed under in vitro and in vivo conditions. The yeast cells with the highest level of protecting agents (1%) had higher viability than those with low protectant levels (0.1% and 0.5%). SM, sucrose and sorbitol improved significantly the C. oleophila survival on apple fruit surface by 80.8%, 42.26% and 37.27% and gave a significant protection (from 96% to 100%) against Penicillium expansum under dried conditions. The highest strain O density and efficacy was obtained with SM. Under experimental conditions reflecting practical conditions, SM applied in combination with the strain O resulted in improved biocontrol efficacy by 74.65%. Therefore, SM could be used as material substrate with the best sugar protectants during the formulation process of this antagonistic yeast for eventual pre-harvest application.

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    • "Thiabendazole (TBZ) and imazalil are the most commonly used chemicals for preventing and controlling postharvest infections caused by Penicillium spp. on apples and citrus fruits (Jijakli et al., 1993). Unlike preharvest treatments, these products are applied after harvesting by dipping or drenching (Lahlali et al., 2009). However, this practice attracts criticism because of the possibility of fungicide resistance development and other environmental effects. "
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