Abstract
The effect of near UV- irradiation (320- 425, peak 366 nm) and far- UV (240-280, peak 254 nm) on biomass yield and on some metabolic activities in Aspergillus nidulans (anamorph of Emericella nidulans) and Fusarium oxysporum was investigated. Near-UV irradiation was found to retard biomass production; while short periods of far-UV irradiation (5 min) induced biomass yield but longer periods of irradiation reduced the biomass yield. Near UV–irradiation increased the total protein in A. nidulans, but slightly affect the protein content in F. oxysporum. On the other hand far-UV irradiation induced protein synthesis markedly in both fungi. The increase was pronounced in A. nidulans. DNA in A. nidulans was induced by near UV- irradiation after 40 and 80 min, while DNA synthesis in F. oxysporum was significantly inhibited to about 72% after 240 min of near- UV irradiation. RNA in A. nidulans was induced by 120 min near-UV irradiation while RNA in F. oxysporum was slightly affected. Short periods of far- UV irradiation (5 min) induced DNA synthesis in both fungi, however longer irradiation and incubation periods significantly increased DNA content especially in A. nidulans. RNA increased in A. nidulans and inhibited markedly in F. oxysporum.

Key words: F. oxysporum, A. nidulans, UV-irradiation, biomass yield, protein, nucleic acids