Gram positive anaerobic, spore forming bacilli.
Spores are refractile, oval or spherical and usually wider than the parent
cell. They may be terminal, subterminal or central within the cell. Most
clostridia possess flagella and motile but C. perfringens not. In
48 hour cultures, many of the bacilli may be Gram negative.
Clostridia
lack the cytochromes required for electron transport to oxygen. They contain
flavoprotein enzymes that reduce oxygen to H2O2 and to
superoxide, and they lack the catalase, peroxidases and superoxide dismutase
that destroy these toxic products. Therefore, they can grow only under
anaerobic conditions. Some are found in animal, human intestines. Many species
are pathogenic, but most saprophytes found in soil and water decomposing plant
and animal matter. Some are of industrial importance for the production of
chemical such as acetone and butanol. They are highly pleomorphic, rod shaped,
motile. They are obligate anaerobes. The optimum temperature is 370C,
pH 7-7.4, growth relatively slow. The characteristic media is Robertson’s
cooked meat broth- contains unsaturated fatty acids which take up oxygen.
Clostridia can produce disease only when the conditions are appropriate.
