Question

How would I distinguish Enterococcus faecalis and Bacillus thuriengensis? What Test would I use to differentiate the two.

Answer 1

1. Morphologically, After staining Enterococcus faecalis forms colonies that occur as cocci singly or in pairs while Bacillus thuriengensis are bacilli in appearence.

2. Chemically, Antibiotic-based exclusion test can also be done.

i.e. Bacillus thuriengensis is resistant to the action of the beta-lactam antibiotics while E. faecalis is susceptible for the same. This helps in selecting one by exclusion method.

3. Mass spectrometry is the ideal test to differentiate between the Enterococcus faecalis and Bacillus thuriengensis based on their genetic sequence. It will give accurate read-outs for the type of organism present.