Role of the competitive microbial flora in the radiation-induced enhancement of ochratoxin production by Aspergillus alutaceus var. alutaceus NRRL 3174

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Applied and Environmental Microbiology; (United States)

OSTI ID:5864178

Chelack, W S; Borsa, J ^[1]; Marquardt, R R; Frohlich, A A ^[2]

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1. Whiteshell Labs., Pinawa, Manitoba (Canada)
2. Univ. of Manitoba, Winnipeg (Canada)

The radiation sensitivity and the toxigenic potential of conidiospores of the fungus Aspergillus alutaceus var alutaceus were determined after irradiation with {sup 60}Co gamma rays and high-energy electrons. Over the pH range of 3.6 to 8.8, the doses required for a 1 log{sup 10} reduction in viability based on the exponential portion of the survival curve ranged from 0.21 to 0.22 kGy, with extrapolation numbers (extrapolation of the exponential portion of the survival curve to zero dose) of 1.01 to 1.33, for electron irradiation, and from 0.24 to 0.27 kGy, with extrapolation numbers of 2.26 to 5.13, for gamma irradiation. Nonsterile barley that was inoculated with conidia of the fungus and then irradiated with either electrons or gamma rays and incubated for prolonged periods at 28C and at a moisture content of 25% produced less ochratoxin levels compared with unirradiated controls. In these experiments, inoculation with 10{sup 2} spores per g produced greater radiation-induced enhancement than inoculation with 10{sup 5} spores per g. There was no radiation-induced enhancement when the barley was surface sterilized by chemical means prior to irradiation. These results are consistent with the hypothesis that a reduction in the competing microbial flora by irradiation is responsible for the enhanced mycotoxin production observed when nonsterile barley is inoculated with the toxigenic fungus A. alutaceus var. alutaceus after irradiation.

• OSTI ID: 5864178
• Journal Information: Applied and Environmental Microbiology; (United States), Vol. 57:9; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ASPERGILLUS
BIOLOGICAL RADIATION EFFECTS
TOXINS
BIOSYNTHESIS
BARLEY
ELECTRON BEAMS
GAMMA RADIATION
MOISTURE
RADIOSENSITIVITY
SPORES
SURVIVAL CURVES
TEMPERATURE EFFECTS
ANTIGENS
BEAMS
BIOLOGICAL EFFECTS
CEREALS
ELECTROMAGNETIC RADIATION
EUMYCOTA
FUNGI
GRAMINEAE
HAZARDOUS MATERIALS
IONIZING RADIATIONS
LEPTON BEAMS
LILIOPSIDA
MAGNOLIOPHYTA
MATERIALS
PARTICLE BEAMS
PLANTS
RADIATION EFFECTS
RADIATIONS
SYNTHESIS
TOXIC MATERIALS
560130* - Radiation Effects on Microorganisms