Mutagenicity of Alternaria alternata and Penicillium cyclopium isolated from grains in an area of high incidence of oesophageal cancer--Linxian, China.

In order to study the relationship between daily consumption of mouldy food and the incidence of oesophageal cancer, we examined the mutagenicity of Alternaria alternata and Penicillium cyclopium, which seriously contaminate grain in Linxian county, China. We first examined extracts of cultured strains of A. alternata. In the reverse mutation test, positive results were obtained in 85% of strains; positive results were seen in 84% of 19/20 strains in the rec assay. Eight of ten strains induced sister chromatid exchange, and two of eight strains induced chromatid breaks. Six of seven strains induced unscheduled DNA synthesis and DNA synthesis inhibition. One extract induced a higher frequency of sister chromatid exchange in lymphocytes from normal persons than in those from patients with oesophageal cancer, and the spontaneous break-points in patients were related to fragile sites and neoplasia-associated break-points. The toxins alternariol and its monomethyl ether, produced by A. alternata, were examined in the reverse mutation assay and for unscheduled DNA synthesis. The results were similar to those obtained with extracts of the different strains. Alternariol had a four to eight times greater effect than its monomethyl ether. Of 24 strains of P. cyclopium isolated from cereals in Linxian, four were cultured with rice and 19 in Raulin-Thom medium. Cultures in Raulin-Thorn medium, solution and hyphae were then extracted. The strains cultured with rice induced sister chromatid exchange, unscheduled DNA synthesis and DNA synthesis inhibition. The solution extracts of 14 strains were positive in the rec assay, and five strains were positive in the reverse mutation test.(ABSTRACT TRUNCATED AT 250 WORDS)