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Permeability of dormant spores of Bacillus subtilis to malachite green and crystal violet
Abstract
The permeability of dormant spores of Bacillus subtilis to malachite green (MG) and crystal violet (CV) was examined by using potassium trichloro(η2-ethylene)platinum(II) (KTPt) as an electron-opaque marker for the dyes. The spores were treated with the dyes and other substances at 30 °C for 30 min or at 80 °C for 5 min. When the spores were incubated in 50 mM-MG solution at 30 °C and in 50 mM-CV solution at 30 °C or 80 °C, many small electron-dense precipitates, which were chemical complexes of dyes and platinum, were seen, mainly around the boundary between the inner and outer coat regions. The spores treated under the above conditions were not stained. Treatment with 50 mM-MG alone or a mixture of 25 mM-oxalic acid and 50 mM-CV at 80 °C made the spores stainable and dye-TPt precipitates were observed mainly in the outer pericortex region. Pretreatment with 25 mM-oxalic acid and 5% (v/v) phenol at 80 °C followed by 50 mM-CV treatment at 30 °C gave the same results as above. It was considered from these results that the inner coat itself might function as the primary permeability barrier to MG and CV, and that a secondary barrier to the dyes might exist around the cortex region.
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© Society for General Microbiology 1991