Dr. Hassan Ahmed Barakat Mohamed :: Publications:

During this work, AFP was purified from A. giganteus with modified procedure after adaptation of the fermentation conditions. The antifungal activities as well as the mode of action against some plant and human pathogenic fungi were tested. Among three different A. giganteus strains A. giganteus IfGB0902V secreted the highest AFP amount on Olson medium than YPG medium. A positive relationship between pH and AFP concentration was recorded. Results illustrated that A. giganteus is able to secrete about 36.26±1.25 mg AFP/l Olson medium. The employed cation exchange chromatography with subsequent separation of the basic proteins by two gel filtrations yielded about 15-19 mg pure AFP per litre culture supernatant with general mean of 16.22±1.22 mg/l. The loss amount of AFP during purification using the two gel filtration steps is about 50% thus, purification procedure must be further improved. The antifungal activity of AFP was clearly increased with increasing of AFP concentration against all strains when comparing the lowest to the highest concentrations. The concentration of AFP as low as 80µg/ml still displayed obvious inhibitory effect against all tested Fusarium strains applying hyphal extension inhibition precdure with different AFP concentrations as 0, 80, 125, 250 and 500 µg/ml. The minimal inhibitory concentration (MIC) values for tested strains were ranged from 1 to 15 µg/ml. Microbiological shape analysis showed short, thick and highly septated hyphae with damaged constricted apical regions extruding from condensed mycelium aggregates in treated culture compared to the untreated culture for tested strains. No DNA-SYTOX-Green fluorescence was detected when all Fusarium spp. were incubated with SYTOX-Green in the absence of AFP. In contrast, strong DNA-SYTOX-Green fluorescent related to the uptake of the SYTOX-Green fluorogenic dye was observed when all strains were incubated with SYTOX-Green and 50 µg AFP/ml. Quantification the membrane permeability potential of AFP against all Fusarium strains could exude a positive relation with concentration and exposure time. While, no effect on P. chrysogenum even at a concentration of 100 µg/ml was observed. Results were associated together indicated that AFP has highly antifungal activity against Fusarium spp. Finally, the modified AFP purification method was established to purify simultaneously AFP which is very economically on large. AFP is considering as an attractive alternative for food antifungal preservatives and suggests several technological uses such as food bio-preservatives and development of antifungal agents.