Control of Aliivibrio fischeri Luminescence and Decrease in Bioluminescence by Fungicides.

Studies have reported that cell density, ultraviolet (UV) irradiation, and redox reactions, can induce bioluminescence in bacteria. Conversely, the relationship between seawater components and luminescence is not well understood. The efficacy of marine luminous bacteria as biosensors, and their reactivity to fungicides (for example postharvest pesticides) are also unknown. Therefore, we studied the relationship between the luminescence of Aliivibrio fischeri and the composition of artificial seawater media and analyzed the toxicity of fungicides using A. fischeri grown only with the elements essential to induce luminescence. Luminescence was activated in the presence of KCl, NaHCO3, and MgSO4. In addition, we cultivated A. fischeri with other compounds, including K+, HCO3-, and SO42- ions. These results suggested that A. fischeri requires K+, HCO3-, and SO42- ions to activate cell density-independent luminescence. Additionally, A. fischeri cultured in 2.81% NaCl solutions containing KCl, NaHCO3, and MgSO4 exhibited a decrease in luminescence in the presence of sodium orthophenylphenol at >10 ppm. This result suggests that A. fischeri can be used as a biosensor to detect the presence of sodium ortho-phenylphenol.