Early experiments which indicated that the spore coat layers are not important determinants of spore UV resistance 414445 were based on studies in which monochromatic nm UV-C radiation was used.
Collectively, our data indicate that in addition to lysozyme and H2O2 resistance, the intact spore coat contributes to the resistance of B.
Spore resistance to artificial UV-B radiation to nm was assayed by determining the average LD90 for each strain based on a minimum of three trials Fig. For solar UV radiation experiments, spore samples were exposed to sunlight on the roof of Building 90 at the University of Arizona during the daily period of maximal solar intensity, from 2 h before local noon to 2 h after local noon; local noon was calculated for the longitude of Tucson, Ariz.
The transcriptional regulator, Spo0A, serves as the master regulator of sporulation in all studied endospore-forming bacteria. The increased sensitivity of spores lacking a functional gerE gene product to UV-B and solar UV radiation suggests that resistance of spores to solar UV radiation may be a function of an intact inner spore coat layer.
In support of this hypothesis, it has been observed that chemical decoating causes the release of dipicolinic acid DPA and hexosamine from spores, which indicates that the cortex integrity may also be compromised 3 In all solar UV experiments, heat controls consisting of samples that were prepared as described above but were wrapped in aluminum foil were exposed in parallel in order to correct for the lethal effect of environmental heating.
DPA is produced by DPA synthetase in the mother cell and is transported into the core of the developing prespore. Colonies were enumerated from plates after a minimum of 36 h incubation.
Two hundred microliter culture was spread onto A normalized summary of the results of UV treatments is presented in Fig. In order to assess the contribution of the spore coat to solar radiation resistance in the field, we utilized an exposure system described in detail previously Spore resistance to UV-B radiation.
Spore resistance to artificial UV-C radiation. For exposure to oxygen, 2 ml culture was placed in a sterile petri dish, removed from the anaerobic chamber, sealed with parafilm to reduce evaporation and aliquots were removed after 30 min, 1, 3, 6, 9, 12, and 24 h incubation.
None of the types of wild-type or coat mutant spores were killed to a significant extent by solar heating in the control samples data not shown. Preparation of Spores Isolated spores were prepared as previously described Edwards et al. Erythromycin-resistant colonies were isolated and screened for the 2 kb insertion in the spo0A locus using primers oMC and oMC How this morphological change in the arrangement of the coat results in enhanced spore resistance to all UV wavelengths from to mn is frankly puzzling if the CotE protein simply acts as part of a matrix upon which the inner and outer coat layers are assembled and perhaps cross-linked 6 see above.
Spore resistance to artificial UV-B radiation. Regardless of the target of H2O2 in the spore core, in the absence of hard data which show that catalase and peroxidase activities are present in the dormant spore coat it appears that either the spore coat layers serve as a diffusion barrier to H2O2 or spore coat proteins act as oxidation targets which decrease the effective H2O2concentration before H2O2 reaches the target s in the spore core.
Spore suspensions were placed in flasks and exposed to oxygen at room temperature for 7—10 days to kill all vegetative cells.
UV doses are reported below in Joules per square meter. Assays for spore UV resistance.Impact of Spore Biology on the Rate of Kill and Suppression of Resistance in Bacillus Ordway Research Institute1 and Institute for B. ANTHRACIS SPORE BIOLOGY, KILL RATE, AND.
Heat resistance of Bacillus spores The research presented in this thesis was funded by TI Food and Nutrition (Wageningen, the Netherlands), a public-private partnership on pre-competitive research in food and nutrition.
The research was conducted at sporulation and spore resistance mechanisms (11, 55). The sporulation process is a. Chemical and Stress Resistances of Clostridium difficile Spores and Vegetative Cells. Adrianne N.
Edwards, Samiha T. Karim, Ricardo A To measure C. difficile spore resistance to ethanol, The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a.
Spore resistance to organic solvents and heat seems to be a function of the peptidoglycan cortex which underlies the coat (19, 29, 30), and protection of spore DNA from nm UV radiation and from free radical damage is associated with binding of spore DNA by small, acid-soluble spore proteins in the.
The radiation resistance of spores of 6 strains of Type E Clostridiunw botulinum was determined in a beef stew substrate. The results are evaluated in terms of the minimum dose showing no spoilage for a 2 billion total inoculum level (20 cans each with million spores per can) and in terms of a calculated radiation D value.
Effect of sporulation conditions on the resistance of Bacillus sporothermodurans spores to nisin and heat. Spore resistance decreases as the acidity of the medium increases. N. SandlerSpore research in historical perspective.
Hurst, G.W. Gould.Download