Radiation resistance of a hemolytic micrococcus isolated from chicken meat

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5019876

Tan, S T

The effects of environmental factors on a highly radiation-resistant hemolytic micrococcus isolated from chicken meat were studied. NaCl tolerance and gamma radiation resistance of the cells were growth phase-related. The cells were resistant to injury from drying or freezing/thawing. Under certain conditions, cells in the frozen state required approximately 5 Mrad to inactivate 90% of the population; 0.2 Mrad injured an equivalent proportion. Survival curve of the cells heated at 60/sup 0/C showed a unique pattern which was in three distinct phases. Heat-stressed cells were much more sensitive to radiation inactivation than unheated cells. When suspended in fresh m-Plate Count Broth (PCB), the injured cells repaired without multiplication during incubation at 32/sup 0/C. The repair process in this bacterium, however, was slower compared to thermally injured organisms studied by other workers. An improved replica-plating technique, was devised for isolation of radiation-sensitive mutants of pigmented bacteria. A simple method to demonstrate radiation-inducible radiation resistance in microbial cells was developed. The new method required neither washing/centrifugation nor procedures for cell enumeration. Mutagenesis treatment of radiation-resistant micrococcal bacterium with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) followed by FPR and screening steps resulted in isolation of two radiation-sensitive mutants. The more sensitive mutant strain, designated as 702, was seven times as sensitive to gamma or UC radiation as the wild type. No apparent difference was observed between 702 and the wild type in (1) cell morphology, colonial morphology, and pigment production or (2) tolerance to NaCl, drying/storage, freezing/thawing, and heating. Sodium dodecyl sulfate treatment (for curing) of wild type did not result in isolation of a radiation-sensitive mutant.

• Research Organization: Nebraska Univ., Lincoln (USA)
• OSTI ID: 5019876
• Country of Publication: United States
• Language: English

Related Subjects

560132* -- Radiation Effects on Microorganisms-- Food Preservation-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALI METAL COMPOUNDS
ANIMALS
BACTERIA
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BIRDS
BODY TEMPERATURE
CARBONIC ACID DERIVATIVES
CHICKENS
CHLORIDES
CHLORINE COMPOUNDS
DATA
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
FOOD
FOWL
GAMMA RADIATION
GUANIDINES
HALIDES
HALOGEN COMPOUNDS
HYPERTHERMIA
INFORMATION
IONIZING RADIATIONS
LYOPHILIZATION
MEAT
MICROORGANISMS
MORPHOLOGY
MUTAGEN SCREENING
MUTAGENESIS
MUTANTS
NITROSO COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RADIATIONS
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
RECOVERY
REPAIR
SCREENING
SODIUM CHLORIDES
SODIUM COMPOUNDS
SURVIVAL CURVES
TOLERANCE
ULTRAVIOLET RADIATION
VERTEBRATES