The difference in microbial growth on organic bread when exposed to different surfaces


  • Genoise Etman
  • Puneet Khosa
  • Remy Sanghe
  • Simran Sidhu


Organic bread, which contains a limited amount of preservatives, provides an optimal
growth medium for microbes. The purpose of this study was to determine the amount of
microbial growth on organic bread exposed to different surfaces. To conduct this experiment,
organic bread samples were dropped onto 3 different surfaces: cafeteria table, cafeteria floor and
bathroom floor. The bread samples were immediately sealed in ziploc bags and stored in a warm,
dark room to allow for microbial growth. After a 20-day period, microbial growth on each bread
sample was measured and extrapolated to percent cover of microbial growth. We hypothesized
that the different surfaces (cafeteria table, floor, and bathroom floor) contain varying amounts of
microbes. We predicted that the bathroom floor would house the most microbes compared to the
other treatment groups and the control. Therefore, the bread exposed to this surface would have
the greatest percent cover of microbial growth. However, we found there was no statistically
significant difference in percent cover of microbial growth between the different treatment
groups (p-value > 0.2001). Overall, our study does not support our hypothesis that bread exposed
to surfaces with varying levels of microbes will result in differences in percent cover of
microbial growth between the treatment groups. Some sources of error that may have contributed
to our results include increased indoor sanitization measures due to the COVID-19 pandemic,
lack of moisture in food samples and on surfaces, and counting microbial growth with the naked