What is the purpose of (presence/absence) P/A Broth and how is it used?
P/A Broth is used to screen drinking water for Total coliforms.
P/A Broth is ideal for screening drinking water samples for total coliforms. The method is a simple modification of the multiple-tube method. It uses lactose and lauryl tryptose broths with bromcresol puple, which detects acidity formed during lactose fermentation by the bacteria. Simply combine 100 mL of sample and P/A broth, indubate for 24 hours and check for a color change. A yellow color indicates the presence of total coliforms.