Sporicidal Action of Hydrogen Peroxide on Conidia From Toxigenic Strains of Aspergillus flavus and Aspergillus parasiticus

Abstract

Effectiveness of hydrogen peroxide was evaluated as a sporicidal agent aginst conidia of Aspergillus parasiticus NRRL 2999 and 3315, and Aspergillus flavus NRRL 3353. Conidia were harvested from 7-, 10-, and 14-day-old mold cultures grown on modified Moyer's agar, treated with hydrogen peroxide, and then were recovered with mycological agar. An initial spore concentration of 5 × 105 to 1 × 106 per ml was treated with 2, 4, and 6% (wt/vol) peroxide at 40, 30, and 20 C. Survival curves were not straight logarithmic but tended to tail off at the end. Time required for 99.9% reduction of spores ranged from minutes to an hour, and on rare occasions it took hours to achieve the first logarithmic reduction. Conidia of NRRL 3353 consistently were most resistant among the three strains tested. Conidia of NRRL 2999 and 3315 were equally sensitive to peroxide in most instances, although time required for 99.9% destruction of the latter was occasionally greater. Conidia from 14-, and 10-day-old cultures of NRRL 3315 and 3353, respectively, were more resistant than conidia from the other mold cultures. Resistance of conidia from NRRL 2999 was not affected by age of the culture.