Bacterial communities of plum phyllosphere and characterization of indigenous antagonistic Bacillus thuringiensis R3/3 isolate.

Abstract

The characterization of bacterial communities diversity on four local plum cultivars in two phenological stages using culture-dependent and culture-independent methods and screening among culturable plum community for indigenous bacteria active against phytopathogens. The bacterial communities associated with leaves and fruits of four local Serbian plum cultivars (Požegača, Ranka, Čačanska Lepotica and Čačanska Rodna) were investigated in two phenological stages during early (May) and late (July) fruit maturation. Metagenomic approach revealed Methylobacterium, Sphingomonas and Hymenobacter as dominant genera. The most frequently isolated representatives with cultivable approach were pseudomonads with Pseudomonas syringae and Pseudomonas graminis, the most likely resident species of plum community. Antagonistic Bacillus thuringiensis R3/3 isolate from plum phyllosphere had ability to produce exoenzymes, reduce the growth of phytopathogenic bacteria in co-culture environment and show quorum quenching activity. Plum cultivar and growth season contribute to the structure of the bacterial community associated with plum. Plum phyllosphere is good source of antagonists effective against phytopathogens. Knowledge of bacterial communities on plum will have an impact on studies related to phyllosphere ecology and biocontrol. The indigenous antagonistic isolate, B. thuringiensis R3/3, from plum could be further investigated for its potential use in biological control of plum diseases.