A microbiologist investigated the antimicrobial efficacy of a newly synthesized polypeptide, PMX-500, against a clinical isolate of Pseudomonas aeruginosa. They prepared agar plates inoculated with the bacterium and placed filter paper discs infused with PMX-500 onto the agar surface.
State one method the microbiologist could use to increase the reliability of the determined zone of inhibition for each concentration.
