ICE NUCLEATION BY BACTERIA - PRODUCTION AND ACTIVITY

The ability of Pseudomonas syringae to catalyse ice formation at relat ively high temperatures from - 2 to - 5-degrees-C has received conside rable attention.A fermentation method was used in order to obtain a hi gh nucleation activity expressed in ice nuclei per cell. This was base d on the optimization of the medium composition and control of the fer mentation parameters. Meat peptone medium appeared to provide the best conditions for biomass production and ice nucleation activity. Moreov er, we observed a positive influence on the nucleation activity due to Mn2+ ion addition. The pH control of the culture seemed to influence negatively the bacterial nucleation activity.