How does the exposure duration (0 h, 1 h, 2 h, 3 h, 4 h) (± 0.1 s) of curcumin harvested from turmeric (Curcuma longa) to blue light- emitting diode (470 nm) from a distance of 0.5 cm affect its antibacterial activity measured through the number of colonies against Escherichia coli ATCC 25922 incubated at 28°C using the single plate-drop method?
