Question

One of the features that separates E. Coli from closely-related species is it’s ability to ferment lactose very efficiently. If the lactose in the EMB plate is replaced with glucose, will it affect the specificity or sensitivity of the media? What impact will the change have in terms of conclusions that can be drawn from the data?

Answer 1

If in the EMB plate, the lactose is replace by glucose, the media will definitely loss its specificity because it will not be able to differentiate between lactose fermenting and non-fermenting bacteria. There are many bacteria which are able to ferment glucose or use glucose as their sugar and hence it becomes difficult. It will affect the specificity and it will make it difficult to differentiate between the micro-organisms.

The conclusion that we can get from this data is that lactose if replaced with glucose will be able to promote growth of many micro-organism as it is easy to break down glucose as compared to lactose. This cannot differentiate between lactose fermenting and non-fermenting bacteria.