Identification of ice nucleation-active bacteria isolated from frost-damaged vegetable leaves.

Abstract

Ice nucleation-active bacteria isolated from frost-damaged vegetable leaves in Kagawa Prefecture, Japan were identified as Pseudomonas viridiflava (80.0% of total ice nucleation-active bacteria), P. syringae (12.0%), P. fluorescens (2.7%), and Erwinia ananas (5.3%). The dominance of P. viridiflava was remarkably different from the earlier data by Goto et al, in 1988 on the profile of ice nucleation-active bacteria detected in Shizuoka Prefecture on healthy plants such as tea buds, vegetable leaves, and Magnolia denudata flowers. Ice nucleation-active strains of P. syringae in this study were different from those in the previous one in biochemical properties such as pyoverdin production, gelatin liquefaction, and acid production from sucrose implying diversity of bacteriological characteristics in the strains of this epiphyte. Saprophytic bacteria not active as ice nuclei were isolated from 64 of 75 broccoli leaves with frost damage, whereas ice nucleation-active bacteria from only 10 similar leaf samples (13.3%). On these leaves, ice nucleation-active bacteria comprised 7.6 to 12.6% of the total population of epiphytic bacteria.