what is the purpose of a lactose fermentation test
A useful test to identify bacteria is a carbohydrate fermentation test. Fermentation is defined as an ATP generating process where organic compounds, in this case lactose, acts as both an electron donor and acceptor.A phenol red medium, with sucrose as the sole carbohydrate source, is used to detect fermentation.Phenol red indicator gives the medium a red-orange appearance. As lactose is fermented, acidic products are generated that causes the indicator to change from red-orange to yellow.An inverted tube (Durham tube) is sometimes placed in the medium to capture gas formed as a result of fermentation.henol red indicator gives the medium a red-orange appearance. As lactose is fermented, acidic products are generated that causes the indicator to change from red-orange to yellow. An inverted tube (Durham tube) is sometimes placed in the medium to capture gas formed as a result of fermentation.