Vibrio gazogenes

Gram negative, rod-shaped Gammaproteobacteria

Vibrio gazogenes isolated from Little Sippewissett salt marsh Cape Cod, MA on a salt water medium during summer 2013. The red pigment observed is the compound prodigiosin. Prodigiosin is a secondary metabolite that has been show to have antibacterial, antifungal and even anticancer properties.

Vibriogazogenes ProdigiosinColumn

Janthinobacterium lividum

Gram negative, rod-shaped Betaproteobacteria

Janthinobacterium lividum was isolated from soil in Cape Cod, MA summer 2013. The soil was sprinkled on rice that was amended with cycloheximide to prevent fungal growth. The rice is used as a bait to induce this purple-pigmented bacterium. Janthinus is Latin for violet-colored and once isolated on nutrient agar it is clear to see that these colonies are purple. The pigment is called violacein which is known for its antibiotic activity. It is currently being studied as a potential anti-cancer drug because of its cytotoxic capabilities.

ViolaceinRice1 ViolaceinRice2 Janthinobacterium


Escherichia coli O157:H7

Gram negative, rod-shaped Gammaproteobacteria

The bacterium Escherichia coli O157:H7 (E. coli) is an enterohemorrhagic serotype that can cause abdominal cramps, diarrhea and kidney failure. A serotype describes the antigens that cause an immune response in the host. In E. coli there is the O antigen (lipopolysaccharide layer), K antigen (capsule) and H antigen (flagellin). The O157:H7 serotype produce a Shiga-toxin that is responsible for causing illness. The genes encoding the toxin are on an extrachromosomal plasmid which can be 'cured' or removed rendering the bacterium avirulent. Its natural environment is in the intestinal tract of animals where it may or may not cause disease. Both deer and cattle have been shown to be a natural reservoir for the bacterium as these animals do not have toxin receptors and are asymptomatic hosts. Fecal contamination of agricultural crops has been a major issue in the United States in the last few decades with as many as 73,000 illnesses in the United States annually.

Learn more:

Center for Disease Control

California Department of Public Health 

Food Safety News



GFP and dsRed labeled attenuated E. coli  O157:H7