The Spice of Life: Antimicrobial Properties of Spices

Kathy Winnett-Murraywinnetmurray@hope.eduHope College
Maria Burnatowska-Hledin hledin@hope.eduHope College
Sasha Balcazarsasha.balcazar@gmail.comHolland High School

Project Location

Undergraduate students test self-generated hypotheses concerning the potential antimicrobial properties of spices commonly used in ethnic cooking. A common technique, the Kirby-Bauer disc method, is used so that students can evaluate their hypotheses in a similar manner while allowing for experiments that will have unknown outcomes to both students and instructors.

Student Audience

Introductory, Major, Non-major

Scientific Domain

  • Evolution
  • Human health and nutrition
  • Microbiology

Nature of the Research

  • Wet lab/bench research
  • Basic research

Core Concepts

  • Evolution: The diversity of life evolved over time by process of mutation, selection, and genetic change.
  • Information Flow and Exchange: The growth and behavior of organisms are activated through the expression of genetic information in context.
  • Pathways and Transformation of Energy: Biological systems grow and change by processes based on chemical transformation pathways and are governed by the laws of thermodynamics.
  • Systems: Living systems are interconnected and interacting.

Core Competencies

  • Applying the process of science
  • Using quantitative reasoning
  • Tapping into the interdisciplinary nature of science
  • Communicating and collaborating
  • Understanding the relationship between science and society

Guiding Questions

  • Do common spices inhibit the growth of selected microbes?
  • Is the inhibition of microbial growth affected by origin/preparation of the spice (e.g. what part of the plant is used, fresh vs. frozen or dried, country of origin, etc.).
  • Is the inhibition of microbial growth affected by the type of extract (water or methanol) used to prepare the spice?
  • Do different microbial species respond to the same spice extract differently? Are some microbes more sensitive to certain spices?
  • Do microbes respond to spices by evolving resistance in a manner similar to their response to common pharmaceutical antibiotics?

Learning Objectives

  • design of experiments
  • identification of test variable characteristics and controlled variables
  • analyze data
  • become responsible for project
  • evaluating outcomes that are unknown at the start, relative to hypotheses formulated before the beginning of the experiment


Spices have been used for centuries to make food taste better, add nutrients, and retard spoilage. Scientists have recently proposed that spices may also kill micro-organisms, inhibit their growth, or suppress their production of toxins, implying that the development of spice use in ethnic cuisines may have been used historically to protect consumers from illness caused by pathogens (Sherman and Flaxman 2001). A variety of laboratory exercises designed to test spices for antimicrobial effects have been developed. Few of these emphasize evolutionary themes, and even fewer capitalize on the rich potential that a multitude of unique combinations of spices, microbes, solvents, and preparations can provide for an array of student-directed hypothesis-testing. Worldwide, there is tremendous variability in the use of different spices. This suggests that, if there is a relationship between spice use and antimicrobial benefits, this relationship has been realized multiple times in different cultures in the development of ethnic cuisines. This theme is inherently intriguing to many undergraduates, who may be curious about “who” uses what types of spices, and why. In this lab, we allow students to construct an investigation, including submission of a group research proposal, arising from their own personal interest in certain spices. We equip students with a standard protocol (the Kirby-Bauer disc method) to test their own unique hypotheses; the shared protocol facilitates lab management, resource use, and interpretation of outcomes, while allowing for a significant range of student-generated experiments. Students are also encouraged to compare the effectiveness of their spice extracts with other antibiotics (e.g. penicillin, erythromycin) on a target microbe (either Escherichia coli or Staphylococcus epidermidis). An extension allows students to document evidence of the microbial response through mutations - evidence of the evolution of antimicrobial resistance.


Antibiotic Properties of Spices Sasha Balcazar, Maria Burnatowska-Hledin, Kathy Winnett-Murray, & Lori Hertel

Winnett-Murray, Kathy Hope College
Burnatowska-Hledin, Maria Hope College
Balcazar, Sasha Holland High School