Host Exopolysaccharide Quantity and Composition Impacts Bacteriophage Pathogenesis of Erwinia amylovora.

Roach, D.R., Sjaarda, D.R., Castle, A.J., and Svircev, A.M. (2013). "Host Exopolysaccharide Quantity and Composition Impacts Bacteriophage Pathogenesis of Erwinia amylovora.", Applied and Environmental Microbiology, 79(10), pp. 3249-3256. doi : 10.1128/AEM.00067-13  Access to full text

Abstract

Erwinia amylovora bacteriophages (phages) belonging to Myoviridae and Podoviridae families demonstrated a preference for either high (HEP) or low (LEP) exopolysaccharide producing bacterial hosts when grown on artificial medium without or with sugar supplementation. Myoviridae phages produced clear plaques on LEP and turbid plaques on HEP hosts. The reverse preference was demonstrated by most Podoviridae phages, where clear plaques were seen on HEP hosts. Efficiency of plating (EOP) was determined by comparing phage growth on the original isolation host to the LEP or HEP host. Nine of ten Myoviridae phages showed the highest EOPs on LEP hosts and eight of eleven Podoviridae phages had the highest EOPs on HEP hosts. Increasing the production of EPS on sugar supplemented medium or decreasing production by knocking out the synthesis of amylovoran or levan, the two EPSs produced by E. amylovora, indicated that these components play crucial roles in phage infection. Amylovoran was virtually essential for proliferation of most Podoviridae phages when phage population growth was compared to the wild type. Decreased levan production resulted in a significant reduction of progeny from phages in the Myoviridae. Thus, Podoviridae phages are adapted to hosts that produce high levels of exopolysaccharides and are dependent on host-produced amylovoran for pathogenesis. Myoviridae phages are adapted to hosts that produce lower levels of exopolysaccharides and host-produced levan.

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