Fruit bat.

Biology 230

Research Project


The use of higher plants in the treatment of disease is as old as the art of healing itself. Isaiah of Biblical times suggested that a plaster of figs be placed on boils as a treatment of this form of infection. The Chinese have used plants and herbs for centuries in the treatment of many diseases. Thousands of phytochemicals have been isolated and several serve as plant defenses against microbial infection (3). Preliminary studies showed that plants have antibacterial properties but these studies were done over 60 years ago (2). The idea of using plants was abandoned with the discovery of antibiotics from soil bacteria. The widespread resistance of bacterial pathogens to conventional antibiotics has prompted renewed interest in the use of alternative natural microbial inhibitors such as amtimicrobial peptides (AMPs). AMPs, termed bacteriocins, are ribosomally synthesised polypeptides, which have bactericidal or bacteriostatic effect. A variety of antimicrobial peptides have been discovered in recent years including defensins, found in human skin, magainin, found in frog skin, and squalamine, from the spiny dogfish shark.. Additionally, the rise in foodborne infections has prompted renewed interest in the use of alternative natural microbial inhibitors.
Possible test organisms:

-Effects on bacterial/fungal growth of sublethal concentration(s) of an extract of berries, leaves, etc.
-Determine the Minimal inhibitory concentration (MIC) and/or minimal lethal concentration (MLC) of an extract.
-The presence of lysozyme against gram-positive cells. Gram-negative cells.
-What is your control?

Possible plants:

Cynara scolymus
Heracleum maximum
Anaphalis margaritacea 
Eriophyllum staechadifolium
Baccharis douglasii
Conium (or Daucus)
Delairea odorata

Cultures available:
Aspergillus sp.
Candida spp.
Escherichia coli
Micrococcus luteus
Salmonella enterica
Shigella sonnei
Staphylococcus aureus
Saccharomyces cerevisiae
Pseudomonas aeruginosa
Streptococcus pneumoniae
Streptococcus pyogenes
Streptococcus mutans