The effect of P. betle extract on biofilm formation of each representative strain, S. mutans ATCC 25175 and A. actinomycetemcomitans ATCC 33384, was examined by using the modified microdilution method.16 Briefly, two-fold serial dilutions of P. betleextract were prepared, with final concentration ranged from 0.02 to 25 mg/mL. A cell suspension of the tested strains was prepared as described in the MIC assay, and 100 μL (1 × 106 CFU/mL) were inoculated in each of a 96-well plate. A 0.1% CHX, phosphate buffered saline (PBS) and extract free medium were used as the positive controls, non-treated and blank controls, respectively. After incubation at 37 °C for 24 h, supernatants were discarded and washed 3 times with PBS. Biofilm formation was quantified by using a 3-[4,5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium-bromide (MTT) assay. The numbers of surviving bacteria were determined by measuring their ability to reduce the yellow tetrazolium salt to a purple formazan product at 570 nm. Higher OD values indicate an increased number of surviving microorganisms in the biofilm. Percentage inhibition was calculated by using the equation [1 − (A570 of the test/A570 of non-treated control)] × 100. The minimum biofilm inhibition concentration (MBIC) was defined as the lowest concentration that showed 50% and 90% inhibition of biofilm formation (MBIC50 and MBIC90).
Article Screening for antibacterial and antibiofilm activity in Thai...
The effect of P. betle extract on biofilm formation of each representative strain, S. mutans ATCC 25175 and A. actinomycetemcomitans ATCC 33384, was examined by using the modified microdilution method.16 Briefly, two-fold serial dilutions of P. betleextract were prepared, with final concentration ranged from 0.02 to 25 mg/mL. A cell suspension of the tested strains was prepared as described in the MIC assay, and 100 μL (1 × 106 CFU/mL) were inoculated in each of a 96-well plate. A 0.1% CHX, phosphate buffered saline (PBS) and extract free medium were used as the positive controls, non-treated and blank controls, respectively. After incubation at 37 °C for 24 h, supernatants were discarded and washed 3 times with PBS. Biofilm formation was quantified by using a 3-[4,5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium-bromide (MTT) assay. The numbers of surviving bacteria were determined by measuring their ability to reduce the yellow tetrazolium salt to a purple formazan product at 570 nm. Higher OD values indicate an increased number of surviving microorganisms in the biofilm. Percentage inhibition was calculated by using the equation [1 − (A570 of the test/A570 of non-treated control)] × 100. The minimum biofilm inhibition concentration (MBIC) was defined as the lowest concentration that showed 50% and 90% inhibition of biofilm formation (MBIC50 and MBIC90).
Article Screening for antibacterial and antibiofilm activity in Thai...