Efficiency of Phage phi 6 for Biocontrol of Pseudomonas syringae pv. syringae: An in Vitro Preliminary Study

Author(s)

Pinheiro, Larindja A. M. ^{[1, 2]} ; Pereira, Carla ^{[1, 2]} ; Frazao, Carolina ^{[1, 2]} ; Balcao, Victor M. ^{[1, 2, 3]} ; Almeida, Adelaide ^{[1, 2]}

Affiliation

^[1] Univ Aveiro, Dept Biol, Campus Univ Santiago, P-3810193 Aveiro - Portugal

^[2] Univ Aveiro, CESAM, Campus Univ Santiago, P-3810193 Aveiro - Portugal

^[3] Univ Sorocaba, PhageLab Lab Biofilms & Bacteriophages, BR-18023000 Sao Paulo - Brazil

• Document type: Journal article
• Source: MICROORGANISMS; v. 7, n. 9 SEP 2019.
• Web of Science Citations: 1

Abstract

Pseudomonas syringae is a plant-associated bacterial species that has been divided into more than 60 pathovars, with the Pseudomonas syringae pv. syringae being the main causative agent of diseases in a wide variety of fruit trees. The most common treatments for biocontrol of P. syringae pv. syringae infections has involved copper derivatives and/or antibiotics. However, these treatments should be avoided due to their high toxicity to the environment and promotion of bacterial resistance. Therefore, it is essential to search for new approaches for controlling P. syringae pv. syringae. Phage therapy can be a useful alternative tool to the conventional treatments to control P. syringae pv. syringae infections in plants. In the present study, the efficacy of bacteriophage (or phage) phi 6 (a commercially available phage) was evaluated in the control of P. syringae pv. syringae. As the plants are exposed to the natural variability of physical and chemical parameters, the influence of pH, temperature, solar radiation and UV-B irradiation on phage phi 6 viability was also evaluated in order to develop an effective phage therapy protocol. The host range analysis revealed that the phage, besides its host (P. syringae pv. syringae), also infects the Pseudomonas syringae pv. actinidiae CRA-FRU 12.54 and P. syringae pv. actinidiae CRA-FRU 14.10 strains, not infecting strains from the other tested species. Both multiplicities of infection (MOIs) tested, 1 and 100, were effective to inactivate the bacterium, but the MOI 1 (maximum reduction of 3.9 log CFU/mL) was more effective than MOI 100 (maximum reduction of 2.6 log CFU/mL). The viability of phage (1)6 was mostly affected by exposure to UV-B irradiation (decrease of 7.3 log PFU/mL after 8 h), exposure to solar radiation (maximum reduction of 2.1 PFU/mL after 6 h), and high temperatures (decrease of 8.5 PFU/mL after 6 days at 37 degrees C, but a decrease of only 2.0 log PFU/mL after 67 days at 15 degrees C and 25 degrees C). The host range, high bacterial control and low rates of development of phage-resistant bacterial clones (1.20 x 10(-3)) suggest that this phage can be used to control P. syringae pv. syringae infections in plants, but also to control infections by P. syringae pv. actinidiae, the causal agent of bacterial canker of kiwifruit. Although the stability of phage phi 6 was affected by UV-B and solar radiation, this can be overcome by the application of phage suspensions at the end of the day or at night. (AU)

• FAPESP's process: 18/05522-9 - PsaPhageKill - isolation, characterisation and use of lytic bacteriophages against Pseudomonas syringae PV. actinidiae to fight the cancer of kiwifruit: an efficient and ecofriendly alternative
• Grantee: Vitor Manuel Cardoso Figueiredo Balcão
• Support Opportunities: Scholarships abroad - Research