Gram-Positive

Structure and Physiology

Structure and Physiology

Listeria monocytogenes is a Gram-positive, rod-shaped, motile, facultative anaerobic bacterium that has the ability to survive with or without oxygen. Contrary to most non-spore forming bacterium, L. monocytogenes can survive the effects of freezing, drying, high pH, and high temperatures. It has the ability to grow at temperatures as low as 0°C that permits proliferation in refrigerated foods.

Structure and Physiology

Bacillus cereus is a Gram-positive, rod-shaped, endopore-forming facultative aerobe bacterium related to Bacillus anthracis and Bacillus thuringiensis.

Transmission and Disease

Although B. cereus is commonly associated with food-borne illnesses, this microbe can also be responsible for several local and systemic infections.

Disinfection

Due to this bacterium's ability to sporulate, B. cereus is often relatively challenging to disinfect.

Structure and Physiology

Bacillus subtilis is a spore forming, motile, rod-shaped, Gram-positive, facultative aerobe. It is mostly found in soil and vegetation with an optimal growth temperature from 25-35 degrees Celsius. B. subtilis has the ability to produce and secrete antibiotics. The genomic structure of this microorganism contains five signal peptidase genes that are important for the secretion of these antibiotics. B.subtilis has shown to be capable of secreting polymyxin, difficidin, subtilin, and mycobacillin.

Structure and Physiology

Staphylococcus aureus is a Gram-positive, coccal-shaped, facultative anaerobic bacterium. During binary fission, the two daughter cells that are produced do not completely separate. Incomplete separations of the cells result in the cluster formation. S. aureus is a catalase-positive bacterium that is able to combat the electronegative oxidizing effects of reactive oxygen species (ROS).

Structure and Physiology

This bacteria is a Gram-positive, rod shaped, endospore generating obligate anaerobe. Clostridium species are part of the normal human gut flora that produce spores which are highly resistant to chemical and environmental conditions.

Transmission and Disease

C. difficile is commonly associated with hospital acquired infections and is known to cause antibiotic assisted colitis.

Structure and Physiology

This bacteria is a Gram positive, rod shaped aerobe. C. xerosis is referred to as a diptheriod because of its relation to C. diptheriae, the bacterium which causes diptheria.

Transmission and Disease

Mostly inocuous, C. xerosis is commonly found on human skin and has been known to cause opportunistic skin infections and endocarditis.

Disinfection

Because of its natural occurance on human skin, this bacteria is an excellent model for a variety of disinfectant and treated article testing.