Mechanisms of Bacillus subtilis spore resistance to and killing by aqueous ozone

Abstract

Aims: To determine the mechanisms of Bacillus subtilis spore killing by and resistance to aqueous ozone. Methods and Results: Killing of B. subtilis spores by aqueous ozone was not due to damage to the spore's DNA, as wild-type spores were not mutagenized by ozone and wild-type and recA spores exhibited very similar ozone sensitivity. Spores (termed a ) b ) ) lacking the two major DNA protective a ⁄ b-type small, acid-soluble spore proteins exhibited decreased ozone resistance but were also not mutagenized by ozone, and a ) b ) and a ) b ) recA spores exhibited identical ozone sensitivity. Killing of spores by ozone was greatly increased if spores were chemically decoated or carried a mutation in a gene encoding a protein essential for assembly of the spore coat. Ozone killing did not cause release of the spore core's large depot of dipicolinic acid (DPA), but these killed spores released all of their DPA after a subsequent normally sublethal heat treatment and also released DPA much more readily when germinated in dodecylamine than did untreated spores. However, ozone-killed spores did not germinate with either nutrients or Ca 2+ -DPA and could not be recovered by lysozyme treatment. Conclusions: Ozone does not kill spores by DNA damage, and the major factor in spore resistance to this agent appears to be the spore coat. Spore killing by ozone seems to render the spores defective in germination, perhaps because of damage to the spore's inner membrane. Significance and Impact of the Study: These results provide information on the mechanisms of spore killing by and resistance to ozone.

Ozone: an emerging technology for the seafood industry

“…About this form, an ozone treatment in organic wastes can be considered an effective and faster form, that other treatments with chlorine or hydrogen peroxide (Glaze;Kang and Chapin, 1987;King, 2001;Campos et al, 2006). In addition, the treatment with ozone is not exclusive and can be combined with the use of hydrogen peroxide or ultraviolet radiation, harnessing therefore the results by a synergic effect (King, 2001;Young and Setlow, 2004). Another property of ozone is the capacity of absorption of flavors and strange smells in the water.…”

“…At lowest pH, the mechanism of ionic reaction predominates (ozonolisys) and generates the peroxide production (Seafish, 1997;Guzel-Seydim et al, 2004;Bocci, 2006). Ozone technology has several significant advantages over its chemical alternatives i) Ozone can be generated on-site; ii) Ozone is one of the most active, readily available oxidizing agents; iii) Ozone rapidly decomposes to oxygen leaving no traces; iv) Reactions do not produce toxic halogenated compounds; v) Ozone acts more rapidly, and more completely than other common disinfecting agents do; vi) Ozone reacts swiftly and effectively on all strains of viruses (Brooks and Pierce, 1990;Ibanoglu, 2002;Tapp and Sopher, 2002;Young and Setlow, 2004;Chawla, Bell and Marlene, 2007). Ozone has a longer half-life in the gaseous state than in aqueous solution (Table 5).…”

“…Unlike other biocides agents such as chlorine, the time necessary to make the disinfection is lower. For this reason, it's very effective in destruction of chlorine resistant microorganisms due to a power of reaction of three thousand times superior to the chlorine, which turns it is a possible biocide agent, as much for the water treatment, like for the treatment of air and closed atmospheres (Brooks and Pierce, 1990;Duguet, 2004;Young and Setlow, 2004). On the other hand, its strong oxidizing capacity (Table 2) makes very appropriate for the water treatment with high organic content.…”

Characterization of Spores of Bacillus subtilis That Lack Most Coat Layers

“…Previous work has shown that coat proteins are important in protecting spores against a number of chemicals, including sodium hypochlorite, chlorine dioxide, and ozone, and cotE or chemically decoated wild-type spores are much more sensitive to these agents than are intact wild-type spores (37,40,41). This was also seen in the current work when extremely dilute sodium hypochlorite was used, as cotE spores were more sensitive than wild-type spores, and gerE spores were even more sensitive (Fig.…”

Alteration in Escherichia coli and Streptococcus faecalis cells induced by ozone

“…Researchers have found that it can damage cell membranes (Scott & Lesher, 1963;Murray et al, 1965;Kim et al, 1999;GuzelSeydim et al, 2004;Cho et al, 2010), facilitate protein denaturation and enzyme activity decrease (Hinze et al, 1987;Mehlman et al, 1987;Takamoto et al, 1992;Komanapalli & Lau, 1996), as well as destroy the nucleic acids of microbes (Scott & Lesher, 1963;Roy et al, 1981;Mura & Chung, 1990; Hunt & Mariñas, 1999). Other studies have investigated the effect of ozone on the spore inner membrane of Bacillus subtilis (Young & Setlow, 2004;Cortezzo et al, 2004), and on the spore morphologies of Bacillus atrophaeus as well as Geobacillus stearothermophilus (Mahfoudh et al, 2010). It was also showed that ozone inactivated Pseudomonas aeruginosa ATCC27853 by the combined results of increased cytoplasmic membrane permeability and cytoplasm coagulation, rather than by severe membrane disruption and cell lysis (Zhang et al, 2011).…”