Hsu’s Lactobacillus Pediococcus Medium

Hsu’s Lactobacillus Pediococcus Medium is a selective semi-solid medium that allows for the detection of Lactobacillus and Pediococcus species, while restricting the growth of culture yeast. The inclusion of agar at 2% makes it a semisolid medium, which offers a means of identifying lactic acid bacteria to the genus level on the basis of colony morphology. There is a choice of 3 sizes - 500g, 2kg, and 10kg.

PREPARATION: Mix 7 grams of the medium in 100 mL of purified water until evenly dispersed. Heat with repeated stirring and boil for 2-3 minutes to dissolve completely. Autoclaving is not necessary. Cool medium to approx. 45-50°C in a water bath and transfer aliquots of 17 mL to sterile 16x150mm test tubes, leaving ~ 1 cm (or equivalent to desired sample volume) of headspace. Apply caps and screw tightly. Alternatively, 1.5 to 2.0 grams of agar may be added in addition to the 7 grams of medium in order to produce solid media. If this is the desired application, pour the prepared medium into sterile petri dishes and test according to desired protocol.