Under specially selected cultivation conditions, the life cycle of the
bacteria Bacillus cereus and Micrococcus luteus can culminate in the
formation of cystlike refractive cells (up to 60% of the total number)
that retain viability over a long time, are metabolically inactive an
d thermotolerant and possess specific ultrastructure. These properties
allow them to be attributed to a new type of resting forms of microor
ganisms.