(1) Endotoxins. Some parts of the cell structures of microorganisms are
toxins. These toxins are referred to as endotoxins because the substance is inside the
cell. An example of a microorganism that produces endotoxins is S. typhosa, the
organism that produces typhoid fever.
(2) Exotoxins. Some microorganisms produce toxins that are secreted or
diffused from the cell. Corynebacterium diphtheriae is a microorganism that produces
diphtheria by the production of an exotoxin.
(3) Enterotoxins. An enterotoxin is a toxin that is absorbed specifically in
the gastrointestinal tract. For example, Staphylococcus aureus produces an enterotoxin
when it rapidly grows in such foods as milk, salads, and sandwich fillings. When
ingested, this enterotoxin may cause the person to vomit, have diarrhea, and have
gastrointestinal cramps. This particular enterotoxin is resistant to destruction by heat.
l. Morphology. Morphology is the study of form and structure of organisms.
m. Physiology. Physiology is the study of the function of organisms.
n. Etiology. Etiology is the study of the cause or origin of disease.
o. Aerobic. Aerobic organisms require oxygen in order to live.
p. Anaerobic. Anaerobic organisms live in an environment in which there is no
q. Facultative Anaerobic. A microorganism that is a facultative anaerobe can
adapt to oxygenless environment if the need arises, but can live and grow where
oxygen is present.
r. Spore. A spore is a resting stage form of life some microorganisms are able
to produce. Spores are very hearty; they are able to endure great extremes in
temperature; hence, they are difficult to kill. Once spore encounters favorable
conditions for growth, the microbial cell breaks through the protective spore cell wall and
grows as a normal cell.
Since spores are so resistant to adverse conditions, you must use potent
chemicals or moist heat under pressure to kill them.
s. Micron. A micron is a unit of measure used to measure the size of
microorganisms. A micron is 1/25,400 (0.000039) of an inch or 0.0001 of a centimeter.