Impact of temperature on the survival and the biocontrol efficacy of Lysobacter capsici AZ78 against Phytophthora infestans

Temperature can strongly influence the biocontrol efficacy of Lysobacter strains when used against phytopathogens. We investigated the influence of temperature on physiological characteristics of Lysobacter capsici AZ78 in a biocontrol situation. L. capsici AZ78 effectively colonized tomato leaves at 15 and 25 °C while exposure to 35 and 37 °C was highly detrimental. Accordingly, Phytophthora infestans attacks on tomato leaves were controlled when L. capsici AZ78 was pre-exposed to 15 and 25 °C for 24 h. Conversely, exposure to 35 °C drastically reduced the biocontrol efficacy of L. capsici AZ78 probably by impairing anti-oomycete and proteolytic activity. Furthermore, the exposure to 15 °C made the L. capsici AZ78 cells more resistant to UV light and copper ions compared to 25 and 35 °C. These findings give an indication on the best temperature range for the future use of biofungicides based on L. capsici AZ78 cells.