Spectramax m2 device

For MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) determination, P. aeruginosa PAO1 was grown on 24-well microplates with 1 mL of LB broth, in presence of P. guajava L. fruit extracts or fractions or purified compounds in different concentrations (from 31.25 to 2000 µg/mL), at 37 °C for 24 h. The MIC was defined as the lowest antimicrobial concentration that completely inhibited growth as detected by the naked eye. The culture of the strains is completed by the microdilution method on a 96-well microplate as previously described [50 (link)]. All inhibited growth cultures were then sub-cultured onto LB agar plate and incubated at 37 °C for 24 h to determine the MBC, which was defined as the lowest concentration that yielded negative sub-cultures [50 (link)]. Tobramycin, an antibiotic widely used to treat P. aeruginosa lung infection in cystic fibrosis patients was selected as positive control [29 (link)]. Additionally, the effect of P. guajava L. fruit extracts or active compounds on P. aeruginosa PAO1 growth kinetic was assessed by evaluating PAO1 cell density at A_600nm with a SpectraMax M2 device (Molecular Devices, Silicon Valley, CA, USA) over 22 h culture.

One thousand OA-MSCs or chondrocyte suspensions (100 μl/well) were seeded in a 96-well plate and then incubated in the humidified incubator. A 10 μl cell counting kit-8 solution (Cat#96992, Sigma-Aldrich) were added into each well and the plate was incubated for 4 h at 37°C, 5% CO₂ prior to detecting absorbance. Measurement of the absorbance at 450 nm was detected by a microplate reader (Spectramax M2 device; Molecular Devices, San Jose, CA, United States).