•Each different species of bacterium has a different molecule of DNA (i.e., DNA with a unique series of nucleotide bases). •Since DNA codes for protein synthesis, then different species of bacteria must, by way of their unique DNA, be able to synthesize different protein enzymes. •Enzymes catalyze all the various chemical reactions of which the organism is capable. This in turn means that different species of bacteria must carry out different and unique sets of biochemical reactions.•Each different species of bacterium has a different molecule of DNA (i.e., DNA with a unique series of nucleotide bases). •Since DNA codes for protein synthesis, then different species of bacteria must, by way of their unique DNA, be able to synthesize different protein enzymes. •Enzymes catalyze all the various chemical reactions of which the organism is capable. This in turn means that different species of bacteria must carry out different and unique sets of biochemical reactions