Peptone water pw

This investigation used three L. monocytogenes (ATCC 15313, ATCC 19115, and ATCC 1917) strains. In a 50 mL conical tube (SPL Life Sciences Co., Ltd., Gyeonggi-do, Republic of Korea), 100 µL of aliquot cultures (10⁸ to 10⁹ CFU/mL) was inoculated into 10 mL of tryptic soy broth (TSB; BD Difco, Sparks, NV, USA) at 30 °C for 24 h at 220 rpm in a shaking incubator (VS-8480, Vision Scientific, Gyeonggi-do, Republic of Korea). A portion of the cultured culture (100 µL) was placed in 10 mL TSB for another 24 h. After centrifuging at 10,000× g for 10 min at 4 °C, the samples were washed with Dulbecco’s phosphate-buffered saline (DPBS; Sigma-Aldrich, St Louis, MO, USA), and then diluted in peptone water (PW; BD Diagnostics, Franklin Lakes, NJ, USA). The mixed culture was made by mixing equal quantities of each strain. The mixed culture was used to make a suspension of 10⁵ CFU/mL and cultured on PALCAM agar (Oxoid, Hampshire, UK) medium at 30 °C for 24 h.

With slight adjustments, the procedure was carried out as previously described [37 (link)]. The MIC in this study was 220 µg/mL, and the inhibiting effect of biofilm was seen at sub-MIC levels, which may not have killed the bacteria but affected their virulence factor. Control, 1/8, 1/4, and 1/2 MIC concentrations were used in this study. In a 50 mL conical tube with 10 mL TSB (adjusted with quercetin and bacterial suspension), quercetin, and 100 µL of bacterial suspension (10⁵ log CFU/mL), the prepared samples were placed. They were then thoroughly combined with a vortex mixer (Scientific Industries, SI-0256, Bohemia, NY, USA) before being incubated for 24 h at 30 °C. After the biofilm formation, the coupons were washed twice with distilled water (DW) [37 (link),45 (link)]. After washed, the coupons were placed in 10 mL peptone water (PW; BD Diagnostics, Franklin Lakes, NJ, USA) 50 mL Falcon tube, which contained 10 glass beads [11 (link),37 (link)]. This bacterial suspension sample was serially diluted before being placed into Vibrio CHROMagar plates as an inoculum. The number of colonies on the plates was counted after they had been kept in a 30 °C incubator for 24 h. After subtracting the populations of each concentration (0, 1/8, 1/4, and 1/2 MIC) from the populations of each group, we were able to calculate the inhibition values and measured as log CFU/cm².