PHENOTYPIC CHARACTERIZATION OF PSEUDOMONAS AVELLANAE PSALLIDAS JANSE ET AL AND OCCURRENCE OF COLONY VARIANTS
M. Scortichini , L. Angelucci
Thirty-seven strains of Pseudomonas avellanae from northern Greece, northern Italy and two different areas of central Italy were assessed for some morphological and physiological properties. Whole-cell protein profile analysis was performed by means of UPGMA. The occurrence and induction of transparent colonies of P. avellanae sometimes observed on nutrient sucrose agar (NSA) isolation plates, is described. P. avellanae strains showed variability in morphological characteristics, gelatin liquefaction and maximum temperature of growth. Cluster analysis of whole-cell protein profiles indicated that strains from northern Italy differ from those from northern Greece and central Italy and that strains from the provinces of Viterbo and Rome clustered in the same group. All strains were negative in icenucleation activity and accumulation of poly-b-hydroxybutyrate, and positive in production acid from sucrose. All strains were copper-sensitive. The production of fluorescent pigments on media was influenced by subculture on NSA, and strains from Italy lost this feature after a number of transfers. The existence of populations of the pathogen seems possible. Transparent colonies of P. avellanae were also frequently obtained by incubation for three days at supraoptimal growth temperature, by adding 7% sucrose to the nutrient agar and by subculturing 30 day-old colonies on NSA. Such P. avellanae colony variants were encapsulated and did not induce hypersensitivity in tobacco leaves.