Some
Gram-positive bacteria produce endospores which are highly resistant to heating
and a variety of chemicals. These spores are found in the genera Bacillusand
Clostridium. The spores are difficult to stain using normal techniques,
but it is possible to drive the stain into them using heat. Once the stain has
been taken up by the spores, it is extremely difficult to decolourise them,
although the vegetative portion of the cell can be decolourised easily. Several
versions of the spore stain are used.
This is the
most important stain in bacteriology and is so central to identification that
it should be practised until the operator is fully competent. Anumber
of different variations are found, and the laboratory should standardise on
one method.
