The expansion of aquaculture has promoted the search for more effective prophylactic strategies and biosecurity measures, specifically targeting the control of bacterial pathogens that compromise the health and productivity of cultured organisms. Therefore, new products for disinfection in aquaculture must be tested.
The aim of this study was to evaluate the antimicrobial activity of a commercial disinfectant against Lactococcus petauri . The antimicrobial activity test was performed using the microdilution method, as described by Assane et al. ( 2019). The product tested was a disinfectant based on pentapotassium bisulfate peroxymonosulfate .
The L . petauri strain was exposed to serial dilutions of the commercial disinfectant, with a concentration range from 1% to 0.007%. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined according to The Clinical and Laboratory Standard Institute (CLSI, 2020) guidelines. The bacterial suspension (1 × 10⁶ CFU/mL⁻¹) was inoculated into the test wells (100 µL), the assays were conducted in duplicate. Quality control - QC (antimicrobial activity of oxytetracycline – OTC for Escherichia coli ) was performed using the same procedures and materials used for the test. The plates were incubated at 28°C for 24 hours.
The MIC and MBC of the commercial disinfectant against L. petauri were both determined as 0.1%. These results indicate that bacterial growth inhibition and bactericidal activity occur at the same concentration, suggesting a strong bactericidal effect. However, the relatively high MIC and MB C values also demonstrate that L. petauri requires elevated concentrations of the compound to achieve antimicrobial activity, reflecting a low susceptibility of this pathogen.