Mac Agar Lab Report

In the first experiment to investigate how E. coli survives in food, bacterial growth significantly differed between my group’s nutrient agar and MAC agar plates. In courgette, there was moderate growth in nutrient agar while it was heavy in Mac agar. In beef broth, there was slight growth in nutrient agar while it was negative in MAC agar. In fresh basil, growth was heavy in nutrient agar while it was heavy in MAC agar. Where cottage cheese was the ingredient, both plates had heavy growth. For walnut, growth was slight in nutrient agar while it was negative in MAC agar.
Generally, the slight difference in bacterial concentration between the two plates could be because MAC agar inhibits growth of gram positive-bacteria and grows gram-positive bacteria while nutrient agar supports growth of fastidious microorganisms. The red color in the MAC agar plate indicates the presence of E. coli. Results from group A’s nutrient agar plate indicate that courgette, fresh basil, and cottage cheese appear to be contaminated with bacteria. Group A’s MAC agar plate indicates that courgette, and fresh basil may have had bacterial contamination with bacteria. Group B’s nutrient agar plate indicates that courgette, fresh basil, and cottage cheese appear to have bacterial contamination while courgette, fresh basil, and cottage cheese appear to be contaminated in
coli. In part one of the experiment to investigate the effect of hand-washing using different soaps, Hibiscrub had the best results with the least microbial growth after hand-washing. This is because the soap contains chlorhexidine gluconatem which is an antimicrobial agent (Netdoctor, 2014). Some students may have found microbial growth after hand-washing because of the paper towels they used to clean themselves with. In another way, microbial growth could be as a result of soap