Mutagenicity of 5,6-dihydropenicillic acid (DHPA) in Drosophila melanogaster and bacterial conversion of penicillic acid to DHPA

We studied the mutagenicity of 5,6-dihydropenicillic acid (DHPA) by means of the Drosophila wing-spot test. DHPA (10 mg/g of medium) significantly increased the number of small single and twin spots. Since twin spots were exclusively caused by mitotic crossing-over, the results demonstrated that DHPA can induce chromosome recombination in Drosophila somatic cells. Penicillic acid (PA) was converted to DHPA by an incubation with Agrobacterium radiobactor. The conversion occurred with other spoilage bacteria, such as Pseudomonas aeruginosa and P. cepacia. PA was completely converted to DHPA within a 24-h incubation with P. aeruginosa or P. cepacia in medium containing yeast extract. The results suggested that mutagenic DHPA is produced by environmental bacteria when foods are contaminated by fungi which produce PA