Effect of conditions and protectants on the survival of Penicillium bilaiae during storage

Abstract

Penicillium bilaiae is a fungal microorganism used to promote soil-bound phosphorous uptake in several crop species such as wheat, canola, and pulse crops. In this study, an air-dried granular starch-based form of the inoculant was studied for improved longevity. Experiments were performed to determine optimal water activity, packaging atmosphere, and the effects of several protective chemicals. Viable spore fractions were measured at 1, 3, and 6 months. Longevity of the microorganism was found to suffer at intermediate values of water activity and with the addition of glycerol. However, skim milk powder, sucrose, MSG, and proprietary PBX3000 were found to improve survival, with a maximum survival fraction of 15% at 6 months using the best formulation. Cell concentration was not found to influence shelf-life. High viability loss during storage in a nitrogen environment resulted in less than 1% survival.

Keywords:

• Stability
• Penicillium bilaiae
• water activity
• storage
• formulation
• Pesta

Acknowledgments

The authors would like to thank the Natural Sciences and Engineering Research Council of Canada (NSERC) CRD Program and Philom Bios for financial support and the technical assistance of Deanna Zimmerman and Jason Wiens.