Submitted to: Federation of European Microbiological Societies Yeast Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2006
Publication Date: 1/18/2007
Citation: Dunlap, C.A., Evans, K.O., Theelen, B., Boekhout, T., Schisler, D.A. 2007. Osmotic shock tolerance and membrane fluidity of cold-adapted Cryptococcus flavescens OH 182.9, previously reported as Cr. nodaensis, a biocontrol agent of Fusarium head blight. Federation of European Microbiological Societies Yeast Research. 7:449-458.
Interpretive Summary: Biological control is the use of natural microorganisms to control unwanted pest and pathogens without the use of chemicals. While a large variety of microorganisms have been identified with the potential to control pests, several technical hurdles remain before they can be implemented on a commercial scale. The ability to dry microorganisms to improve ease of handling and storage stability without damaging the cells remains a challenging problem. The current study characterizes the cell wall properties of microorganisms produced under two different growth conditions, but with different drying tolerances. Understanding the cellular properties that give rise to improved drying tolerance should lead to better methods of producing drying tolerant cells.
Technical Abstract: Cryptococcus nodaensis (previously reported as Cr. nodaensis), a biological control agent of Fusarium head blight, has been previously shown to have improved desiccation tolerance after cold adaptation. The goal of the current study was to determine the effect of cold adaptation on the physicochemical properties of C. nodaensis that may be responsible for its improved desiccation tolerance. The results show cold adaptation improves liquid hyperosmotic shock tolerance and alters the temperature dependence of osmotic shock tolerance. Fluorescence anisotropy was used to characterize differences in the membrane fluidity of C. nodaensis with and without cold adaptation. Force curves from atomic force microscopy showed a significant increase in the cell wall spring constant after cold adaptation. Cold adaptation of C. nodaensis during culturing was shown to produce smaller cells and trended towards higher colony-forming unit yields. These results suggest cold adaptation significantly alters the membrane properties of C. nodaensis and may be an effective method of improving the desiccation tolerance of microorganisms. In addition, information is provided on the correct naming of the isolate as Cr. flavescens.