Effects of culture conditions on expression of the ice nucleation phenotype of<i>Pseudomonas syringae</i>

Abstract

Pseudomonas syringae 1105 was grown under a variety of culture conditions and the effects on ice nucleation determined. Growth in a defined medium, Koser citrate broth, resulted in a greater number of more active ice nuclei than growth in either of three complex media. The ice nucleation phenotype was not expressed uniformly during the growth cycle in broth culture. Instead a maximal level of ice nucleation was observed during the middle to exponential phase and the phenotype was not expressed in stationary phase. Cells grown on agar plates expressed the phenotype to a much greater extent than cells from broth cultures.