BPLS Agar (Brilliant-green Phenol-red Lactose Sucrose Agar)
This culture medium contains lactose, whose degradation to acid is indicated by the pH indicator phenol red, which changes its colour to yellow. The indicator exhibits a deep red colour in the alkaline range. The growth of the accompanying Gram-positive microbial flora, Salmonella typhi and Shigella is largely inhibited by brilliant green. The growth of Salmonella is, however, improved by the richer nutrient base. Increased growth of accompanying microorganisms is considerably prevented by raising the concentration of brilliant green. Salmonellae are not able to ferment either lactose or sucrose. Thus in contrast to BPL agar, the sucrose contained in this medium allows identification of accompanying, weakly lactose-positive or lactose-negative, but sucrose-positive microorganisms.
Formula:
Peptone from meat 5.0; peptone from casein 5.0; meat extract 5.0; sodium chloride 3.0; di-sodium hydrogen phosphate 2.0; lactose 10.0; sucrose 10.0; phenol red 0.08; brilliant green 0.0125; agar-agar 12.0.
Preparation
Suspend 57 g/litre, autoclave (15 min at 121 °C), pour plates. pH: 6.9 ± 0.2 at 25 °C. The plates are clear and red.