Protection of Erwinia amylovora bacteriophage Y2 from UV-induced damage by natural compounds
Bacteriophages have regained much attention as biocontrol agents against bacterial pathogens. However, with respect to stability, phages are biomolecules and are therefore sensitive to a number of environmental influences. UV-irradiation can readily inactivate phage infectivity, which impedes their potential application in the plant phyllosphere. Therefore, phages for control of Erwinia amylovora, the causative agent of fire blight, need to be protected from UV-damage by adequate measures. We here investigated the protective effect of different light-absorbing substances on phage particles exposed to UV-light. For this, natural extracts from carrot, red pepper, and beetroot were prepared and tested as a natural sunscreen for phage. All compounds were found to significantly increase half-life of UV-irradiated phage particles, due to their high concentration of light absorbing carotenoids and betalaines. Pure astaxanthin, a carotenoid, also offered a significant UV-protection. The extracts themselves did not negatively affect phage viability or infectivity. Altogether, a range of readily available, natural, environmentally-safe and inexpensive substances are suitable as UV-protectants to prevent phage particles from UV-light damage.