What is the Difference Between Lactose Fermenting and Non-lactose Fermenting Bacteria?

The main difference between lactose-fermenting and non-lactose fermenting bacteria lies in their ability to convert glucose into cellular energy and lactic acid. Lactose-fermenting bacteria can convert glucose into cellular energy and lactic acid through lactic acid fermentation, which is an anaerobic fermentation reaction. In contrast, non-lactose fermenting bacteria are unable to convert glucose into cellular energy and lactic acid.

Lactose-fermenting bacteria typically form pink colonies on MacConkey medium, an agar that differentiates bacteria based on their lactose metabolism. Examples of lactose-fermenting species include Escherichia coli, Enterobacteria, and Klebsiella. On the other hand, non-lactose fermenting bacteria, such as Salmonella, Proteus, Yersinia, and Pseudomonas, form off-white opaque colonies on MacConkey medium.

In general, lactose-fermenting bacteria can be either Gram-positive or negative, while non-lactose-fermenting bacteria are predominantly Gram-negative.

Comparative Table: Lactose Fermenting vs Non-lactose Fermenting Bacteria

The main difference between lactose-fermenting and non-lactose-fermenting bacteria lies in their ability to convert glucose into cellular energy and lactic acid. Here is a comparison table highlighting the key differences between the two types of bacteria:

Lactose-fermenting bacteria can be identified on MacConkey agar, where they form pink colonies due to lactose fermentation, while non-lactose-fermenting bacteria form off-white opaque colonies.