The occurrence of ice nucleation activity in pathogenic bacterial species

Abstract

We tested the nucleation activity (INA) of 122 strains of plant pathogenic bacteria (12 varieties and 15 subspecies) stored in collection of the University of Göttingen (GSPB). The strains are isolates from diverse host plants and different geographic regions. One-hundred and seven isolates belong to the Pseudomonads, nine to the genus Erwinia and six to the Xanthomonas. The INA was analysed by −3°, −5°, −7° and −9°C. The observed value of INA cells ranged from non-detectable to a maximum concentration of ice nuclei in a range from −7.85 at −5°C to −2.63 at −3°C in 1.82 × 10³ cfu to 3.3 × 10³ cfu per ml. The data indicated that 71 (58.2%) of the 122 strains had INA cells, and 51 (41.8%) were inactive. The highest amount of strains with INA cells we found in Pseudomonads (69). In comparison only one strain was active at Erwinia and at Xanthomonas, 46 strains were isolated from the genus Phaseolus vulgaris and 6 from the genus Beta vulgaris. The other isolates with ice active cells belonged to the 13 other plant species. The 51 inactive pathovars were isolated from 21 different culture plants. The pathogens under test were isolated in 16 different countries, mainly in Germany and USA.

Keywords:

• ice-nucleation-activity
• phytopathovars
• distribution in host plants and geographic regions
• phytopathogenic collection of bacteria (Göttingen)

Acknowledgements

This work was supported by the DFG, No. 506/3-1 and by the department of “Wissenschaft, Forschung und Kultur” of the State of Brandenburg (HSP III, 1.6). We thank Mr. K. Rudolph (Göttingen) for the friendly leaving of the pathogenic bacteria and Mr. Mavridis (Göttingen) for control the data in Table 1. Furthermore, we thank Mrs. Y. Franke and Mr. A. Schranz for technical assistance and also Prof. K. Naumann (Aschersleben) and G. Mittelstädt (Christchurch, NZ.) for critical control of the English text.