[2] Adler returned to the University of Wisconsin–Madison to join the faculty of the Departments of Biochemistry and Genetics as an assistant professor in 1960.
In 1880, Wilhelm Pfeffer, a famous German botanist, had used motile bacteria to study attraction and repulsion by various plant and animal extracts and chemicals.
Adler eventually discovered that E. coli contain several MCPs which play important roles in chemotaxis sensory transduction system.
Strains of bacteria without this protein, or lacking the ability to methylate and demethylate them were unable to respond to stimuli.
Bacteria swam more smoothly due to a counterclockwise rotation of their flagella in the presence of increasing attractant.
In a decreasing attractant gradient, there is an increase in bacterial tumbling, produced by a clockwise flagellar rotation.
Adler isolated bacterial envelopes and found that he could restore counterclockwise flagellar rotation by adding artificial electron donors and an energy source.