[Biogenesis of 6-aminopenicillanic acid (6-APA) and penicillin in Penicillium chrysogenum: effect of the biocatalyst chrysin]. / Biogenez 6-aminopenitsillanovoi kisloty (6-APK) i penitsillina u Penicillium chrysogenum; éffekt biokatalizatora khrizina.

The investigations were concerned with the examination of the effect of chrysin, a biocatalyst on the 6-APA and penicillin biogenesis in Penicillium chrysogenum (Thom), Panlabs P-5 strain. Chrysin, a natural plant biocatalyst was used to increase the large scale production of penicillin. The experiments were conducted on chemically defined media under conditions determined for this strain in shake flask fermentations. The production of 6-APA and penicillin G was checked and confirmed by HPLC. The level of free 6-APA in the germinating culture increased 12 hours after the inoculation of the P. chrysogenum conidiospores. With the addition of chrysin to the germinating culture the biogenesis of penicillin started in 14 hours but in the experiments without the chrysin addition it was observed 21 hours after the conidiospore inoculation. The origin of free 6-APA in the fermentation broth could be explained solely by the involvement of an independent metabolic pathway of the 6-APA and penicillin biogenesis i.e. N-acylation of free 6-APA. In the fermentation broth of P. chrysogenum it is necessary to distinguish between the primary 6-APA which is a product of the biosynthesis via L-cystine/D-valine and the secondary 6-APA which originates from isopenicillin N.

Cytogenetics analysis of meiotic chromosomes of irradiated mice and their progeny after treatment with streptomycin and dihydrodeoxystreptomycin.

The purpose of this investigation is to find out whether streptomycin and the related compound dihydrodeoxystreptomycin have any mutagenic effect and whether they both are capable of recovering X-ray induced chromosomal translocations in mouse spermatogonia of directly treated animals and their progeny of the first generation. The cytological findings show the absence of any mutagenic effect in animals nonirradiated and treated with streptomycin and dihydrodeoxystreptomycin. The frequency of chromosomal translocation after total irradiation was 9,07%; in animals treated with streptomycin following irradiation 5.13%, and in those irradiated and treated with dihyrodeoxystreptomycin, 3.70%. Male offsprings, originated from parents treated only with antibiotics show no chromosomal translocations. However, offsprings originated from irradiated and treated parents gave birth to the male offspring with chromosomal translocations.