2,3-Dichloro-1-propanol is more chemically stable than its isomer, 1,3-dichloro-2-propanol, and is therefore more difficult to degrade. The isolation of bacteria capable of complete mineralization of 2,3-dichloro-1-propanol was successful only from enrichments at high pH. The bacteria thus isolated were found to be members of the ␣ division of the Proteobacteria in the Rhizobium subdivision, most likely Agrobacterium sp. They could utilize both dihaloalcohol substrates and 2-chloropropionic acid. The growth of these strains in the presence of 2,3-dichloro-1-propanol was strongly affected by the pH and buffer strength of the medium. Under certain conditions, a ladder of four active dehalogenase bands could be visualized from this strain in activity gels. The enzyme involved in the complete mineralization of 2,3-dichloro-1-propanol was shown to have a native molecular weight of 114,000 and consisted of four subunits of similar molecular weights.Epichlorohydrin (1-chloro-2,3-epoxypropane) and its precursors (1,3-dichloro-2-propanol [1,3-DCP], 2,3-dichloro-1-propanol [2,, and 3-chloro-1,2-propanediol [3-CPD]) are halohydrins used widely as solvents and as starting materials for resins, polymers, agrochemicals, and pharmaceuticals. 2,3-DCP, 1,3-DCP, and epichlorohydrin are carcinogenic, mutagenic, and genotoxic. According to a U.S. Environmental Protection Agency assessment (available at http://www.epa.gov /ngispgm3/iris/), 2,3-DCP showed significant effects on rats dosed with 35 mg of 2,3-DCP/kg of body weight/day. The resulting mortality is attributed to myocardial degeneration and kidney and liver malfunction. 2,3-DCP has been shown to be more toxic than 1,3-DCP to the testes and kidneys, though it is less hepatotoxic (7, 16). The Environmental Protection Agency Prioritized Chemical List showed that the overall score (as the sum of the persistence, bioaccumulation, and toxicity scores for human health risk potential added to the corresponding scores for ecological risk) for 1,3-DCP and epichlorohydrin were 11 out of 18 each. Both epichlorohydrin and 1,3-DCP have a high risk factor for animal and human toxicity with regards to the environment. No information was available for 2,3-DCP. However, due to its greater stability, 2,3-DCP is likely to be more persistent than 1,3-DCP and may pose a substantial environmental threat.To date, few bacteria capable of the complete degradation of 2,3-DCP have been isolated. A single Pseudomonas strain capable of growth on 2,3-DCP was isolated from 300 samples of contaminated soil (9). The same group later isolated 13 isolates from a further 1,000 similar samples, suggesting 2,3-DCP-degrading bacteria to be quite rare (10). These bacteria were shown to degrade only the S enantiomer of 2,3-DCP and were of use in enantiospecific preparation of (R)-2,3-DCP and (S)-epichlorohydrin. Haloalcohol dehalogenases with activity against 1,3-DCP have either no activity or only fractional activity (Ͻ50%) against racemic 2,3-DCP (2,10,15,21,22).The initial aim of this study was to isolate and ch...
Asporogenous and oligosporogenous mutants of Bacillus subtilis blocked at stages 111, IV and V and carrying mutations at 18 different genetic loci have been tested for complementation. This was done by preparing protoplasts 3 h after induction of sporulation (t3) and fusing them with wild-type protoplasts prepared in parallel. After incubation to t,, the suspension was assayed for heat-resistant (80 OC, 40 min) colony-forming units. Mutations in 9 of the 18 loci were complemented, i.e. the spore count was increased > 1000-fold. All of the complemented mutants, except for one stage V mutant, were blocked at stage IV. Spomutants that were complementable by wild-type were also complementable by other Spomutants provided that they did not carry the same spo mutation. Complementation analysis was applied to three alleles in the spoZVC locus. The complementation pattern suggests that there are at least two cistrons in the locus and this agrees with the mapping data.
Spores of Bacillus subtilis NCTC 8236 were exposed to 2% alkaline glutaraldehyde and subsequently subjected to various treatments in an attempt to revive injured spores. Treatment with alkali (sodium or potassium hydroxide or, to a lesser extent, sodium bicarbonate) proved to be most successful. Some revival was achieved after thermal treatment. No revival was obtained with lysozyme or with various types of coat-removing agents. Experiments designed to distinguish between germination and outgrowth in the revival process established that sodium hydroxide (optimum concentration, 20 mmol/l) added to glutaraldehyde-treated spores increased the potential for germination. In contrast, spores which had been allowed to germinate before exposure to low concentrations of glutaraldehyde and then to sodium hydroxide were inhibited at the outgrowth phase to a much greater extent than germinated spores treated with the dialdehyde without subsequent alkali exposure. The results overall are discussed in terms of the possible mechanism and site of action of glutaraldehyde and the practical implications and significance of its use as a sporicide.
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