Question

Suppose some organisms ferment lactose but can't use citric acid for all their carbon needs. These organisms must be A) Shigella. B) Salmonella. C) Escherichia. D) Citrobacter.

Answer 1

The right answer is Escherichia coli

These four bacteria are from the family Enterobacteriaceae. They are bacillus gram negative bacteia.

E. coli ferments lactose and does not use citrate as a carbon source.

Shigella does not use both lactose and citrate.

Salmonella and citrobacter can use citrate as a carbon source.