Radiation Protection of Foods, and Nature of Microbial Radiation Resistance
391
that contain –SH groups tend to be radioprotective,
14 but what role these play, if any, in the extreme
resistance of bacteria is still unclear.
One of the unusual things about D. radiodurans is that each cell in the stationary phase carries about
four genomes (i.e., about four copies of its chromosome). Actively dividing cells may contain four to
ten copies. Although this abundance of DNA may not be necessary for extreme radiation resistance,
it is conceivable that upon exposure to radiation the extra DNA makes it possible for the damaged
cell to synthesize a new genome. It has been found that upon exposure to radiation, these organisms
undergo an immediate and extensive breakdown of chromosomal DNA, and this appears to be a part
of the DNA repair process. For more on irradiation resistance in D. radiodurans, see reference 6.
Among the other unusual features of D. radiodurans is its possession of an outer membrane, which is
characteristic of Gram-negative bacteria. It may be noted from Table 15–8 that a number of other Grampositive radioresistant bacteria possess an outer membrane. Although it possesses an outer membrane,
it does not possess lipopolysaccharide or lipid A, as do the typical Gram-negative bacteria. Its outer
envelope consists of five layers outside the plasma membrane.
51 The genome of D. radiodurans is
unusual in that it has a tight and ordered packaging of its DNA that may facilitate repair.43
REFERENCES
1. Andrews, L.S., D.L. Marshall, and R.M. Grodner. 1995. Radiosensitivity of Listeria monocytogenes at various temperatures
and cell concentrations. J. Food Protect. 58:748–751.
2. Anellis, A., D. Berkowitz, and D. Kemper. 1973. Comparative resistance of nonsporogenic bacteria to low-temperature
gamma irradiation. Appl. Microbiol. 25:517–523.
3. Anellis, A., D. Berkowitz, W. Swantak, and C. Strojan. 1972. Radiation sterilization of prototype military foods: Lowtemperature irradiation of codfish cake, corned beef, and pork sausage. Appl. Microbiol. 24:453–462.
4. Anellis, A., E. Shattuck, D.B. Rowley, E.W. Ross, Jr., D.N. Whaley, and V.R. Dowell, Jr. 1975. Low-temperature irradiation
of beef and methods for evaluation of a radappertization process. Appl. Microbiol. 30:811–820.
5. Bacq, Z.M., and P. Alexander. 1961. Fundamentals of Radiobiology, 2nd ed. Oxford: Pergamon.
6. Battista, J.R. 1997. Against all odds: The survival strategies of Deinococcus radiodurans. Ann. Rev. Microbiol. 51:203–224.
7. Clavero, M.R.S., J.D. Monk, L.R. Beuchat, M.P. Doyle, and R.E. Brackett. 1994. Inactivation of Escherichia coli 0157:H7,
salmonellae, and Campylobacter jejuni in raw ground beef by gamma irradiation. Appl. Environ. Microbiol. 60:2069–
2075.
8. Clifford, W.J., and A. Anellis. 1975. Radiation resistance of spores of some Clostridium perfringens strains. Appl. Microbiol.
29:861–863.
9. Collins, M.D., and D. Jones. 1981. Distribution of isoprenoid quinone structural types in bacteria and their taxonomic
implications. Microbiol. Rev. 45:316–354.
10. Collins, C.I., E.A. Murano, and I.V. Wesley. 1996. Survival of Arcobacter butzleri and Campylobacter jejuni after irradiation
treatment in vacuum-packaged ground pork. J. Food Protect. 59:1164–1166.
11. Counsell, T.J., and R.G.E. Murray. 1986. Polar lipid profiles of the genus Deinococcus. Int. J. Syst. Bacteriol. 36:202–
206.
12. Dickson, J.S., and R.B. Maxcy. 1984. Effect of radiolytic products on bacteria in a food system. J. Food Sci. 49:577–580.
13. Doty, D.M. 1965. Chemical changes in irradiated meats. In Radiation Preservation of Foods, 121–125. Washington, DC:
National Research Council, National Academy of Sciences.
14. Duggan, D.E., A.W. Anderson, and P.R. Elliker. 1963. Inactivation of the radiation-resistant spoilage bacterium Micrococcus
radiodurans. II. Radiation inactivation rates as influenced by menstruum temperature, preirradiation heat treatment, and
certain reducing agents. Appl. Microbiol. 11:413–417.
15. Ehioba, R.M., A.A. Kraft, R.A. Molins, H.W. Walker, D.G. Olson, G. Subbaraman, and R.P. Skowronski. 1988. Identification
of microbial isolates from vacuum-packaged ground pork irradiated at 1 kGy. J. Food Sci. 53:278–279, 281.
16. EI-Zawahry, Y.A., and D.B. Rowley. 1979. Radiation resistance and injury of Yersinia enterocolitica. Appl. Environ.
Microbiol. 37:50–54.
391
that contain –SH groups tend to be radioprotective,
14 but what role these play, if any, in the extreme
resistance of bacteria is still unclear.
One of the unusual things about D. radiodurans is that each cell in the stationary phase carries about
four genomes (i.e., about four copies of its chromosome). Actively dividing cells may contain four to
ten copies. Although this abundance of DNA may not be necessary for extreme radiation resistance,
it is conceivable that upon exposure to radiation the extra DNA makes it possible for the damaged
cell to synthesize a new genome. It has been found that upon exposure to radiation, these organisms
undergo an immediate and extensive breakdown of chromosomal DNA, and this appears to be a part
of the DNA repair process. For more on irradiation resistance in D. radiodurans, see reference 6.
Among the other unusual features of D. radiodurans is its possession of an outer membrane, which is
characteristic of Gram-negative bacteria. It may be noted from Table 15–8 that a number of other Grampositive radioresistant bacteria possess an outer membrane. Although it possesses an outer membrane,
it does not possess lipopolysaccharide or lipid A, as do the typical Gram-negative bacteria. Its outer
envelope consists of five layers outside the plasma membrane.
51 The genome of D. radiodurans is
unusual in that it has a tight and ordered packaging of its DNA that may facilitate repair.43
REFERENCES
1. Andrews, L.S., D.L. Marshall, and R.M. Grodner. 1995. Radiosensitivity of Listeria monocytogenes at various temperatures
and cell concentrations. J. Food Protect. 58:748–751.
2. Anellis, A., D. Berkowitz, and D. Kemper. 1973. Comparative resistance of nonsporogenic bacteria to low-temperature
gamma irradiation. Appl. Microbiol. 25:517–523.
3. Anellis, A., D. Berkowitz, W. Swantak, and C. Strojan. 1972. Radiation sterilization of prototype military foods: Lowtemperature irradiation of codfish cake, corned beef, and pork sausage. Appl. Microbiol. 24:453–462.
4. Anellis, A., E. Shattuck, D.B. Rowley, E.W. Ross, Jr., D.N. Whaley, and V.R. Dowell, Jr. 1975. Low-temperature irradiation
of beef and methods for evaluation of a radappertization process. Appl. Microbiol. 30:811–820.
5. Bacq, Z.M., and P. Alexander. 1961. Fundamentals of Radiobiology, 2nd ed. Oxford: Pergamon.
6. Battista, J.R. 1997. Against all odds: The survival strategies of Deinococcus radiodurans. Ann. Rev. Microbiol. 51:203–224.
7. Clavero, M.R.S., J.D. Monk, L.R. Beuchat, M.P. Doyle, and R.E. Brackett. 1994. Inactivation of Escherichia coli 0157:H7,
salmonellae, and Campylobacter jejuni in raw ground beef by gamma irradiation. Appl. Environ. Microbiol. 60:2069–
2075.
8. Clifford, W.J., and A. Anellis. 1975. Radiation resistance of spores of some Clostridium perfringens strains. Appl. Microbiol.
29:861–863.
9. Collins, M.D., and D. Jones. 1981. Distribution of isoprenoid quinone structural types in bacteria and their taxonomic
implications. Microbiol. Rev. 45:316–354.
10. Collins, C.I., E.A. Murano, and I.V. Wesley. 1996. Survival of Arcobacter butzleri and Campylobacter jejuni after irradiation
treatment in vacuum-packaged ground pork. J. Food Protect. 59:1164–1166.
11. Counsell, T.J., and R.G.E. Murray. 1986. Polar lipid profiles of the genus Deinococcus. Int. J. Syst. Bacteriol. 36:202–
206.
12. Dickson, J.S., and R.B. Maxcy. 1984. Effect of radiolytic products on bacteria in a food system. J. Food Sci. 49:577–580.
13. Doty, D.M. 1965. Chemical changes in irradiated meats. In Radiation Preservation of Foods, 121–125. Washington, DC:
National Research Council, National Academy of Sciences.
14. Duggan, D.E., A.W. Anderson, and P.R. Elliker. 1963. Inactivation of the radiation-resistant spoilage bacterium Micrococcus
radiodurans. II. Radiation inactivation rates as influenced by menstruum temperature, preirradiation heat treatment, and
certain reducing agents. Appl. Microbiol. 11:413–417.
15. Ehioba, R.M., A.A. Kraft, R.A. Molins, H.W. Walker, D.G. Olson, G. Subbaraman, and R.P. Skowronski. 1988. Identification
of microbial isolates from vacuum-packaged ground pork irradiated at 1 kGy. J. Food Sci. 53:278–279, 281.
16. EI-Zawahry, Y.A., and D.B. Rowley. 1979. Radiation resistance and injury of Yersinia enterocolitica. Appl. Environ.
Microbiol. 37:50–54.