Phylogenetic Diversities of Dominant Culturable Bacillus, Pseudomonas and Pantoea Species on Tomato Leaves and Their Possibility as Biological Control Agents

We have demonstrated the phylogenetic diversity and antagonistic activities of three genera of dominant culturable bacteria (Bacillus, Pseudomonas and Pantoea) on tomato leaves. A total of 133 Bacillus isolates that were dominant on greenhouse plants and 109 Pseudomonas and 48 Pantoea isolates that were dominant on field-grown plants were analyzed based on their 16S rRNA gene sequences. Bacillus pumilus (38%), Pseudomonas monteilii (76%) and Pantoea agglomerans (90%) were the most predominant of their genera, respectively. In the genus Bacillus, effective biological control agents (BCAs) against tomato leaf mould were interspersed among its phylogenetic tree as minority groups, while the effective BCAs of Pseudomonas and Pantoea were in majority groups that showed consistent suppressive activities. The results suggest that isolating Pseudomonas and Pantoea species from field-grown tomato plants may be preferable for BCA-candidate screening than isolating species of Bacillus from greenhouse.