IngentaConnect Mechanisms of Bacillus subtilis spore killing by and resistance t...

Abstract:

Aims:

To determine the mechanisms of Bacillus subtilis spore killing by and resistance to an acidic solution containing Fe³⁺, EDTA, KI and ethanol termed the KMT reagent. Methods and Results:

Wild-type B. subtilis spores were not mutagenized by the KMT reagent but the wild-type and recA spores were killed at the same rate. Spores (α⁻β⁻) lacking most DNA-protective α/β-type small, acid-soluble spore proteins were less resistant to the KMT reagent than wild-type spores but were also not mutagenized, and α⁻β⁻ and α⁻β⁻recA spores exhibited nearly identical resistance. Spore resistance to the KMT reagent was greatly decreased if spores had defective coats. However, the level of unsaturated fatty acids in the inner membrane did not determine spore sensitivity to the KMT reagent. Survivors in spore populations killed by the KMT reagent were sensitized to killing by wet heat or nitrous acid and to high salt in plating medium. KMT reagent-killed spores had not released their dipicolinic acid (DPA), although these killed spores released their DPA more readily when germinated with dodecylamine than did untreated spores. However, KMT reagent-killed spores did not germinate with nutrients or Ca²⁺-DPA and were recovered only poorly by lysozyme treatment in a hypertonic medium. Conclusions:

The KMT reagent does not kill spores by DNA damage and a major factor in spore resistance to this reagent is the spore coat. KMT reagent treatment damages the spore's ability to germinate, perhaps by damaging the spore's inner membrane. However, this damage is not oxidation of unsaturated fatty acids. Significance and Impact of the Study:

These results provide information on the mechanism of spore resistance to and killing by the KMT reagent developed for killing Bacillus spores.

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Mechanisms of Bacillus subtilis spore killing by and resistance to an acidic Fe3+–EDTA–iodide–ethanol formulation

Mechanisms of Bacillus subtilis spore killing by and resistance to an acidic Fe³⁺–EDTA–iodide–ethanol formulation