Isolation Of Antifungal Strain From Ocean Samples And Purification Of Antifungal Protein From An Aspergillus Sp.H075

Ocean is a very special environment. The marine microorganisms living in this special environment can produce natural active products with novel structure and function for they have unique metabolic pathway. To look for new drug resources from marine microorganisms now become hot research. Fungal diseases caused the reduce of economic crops every year. They even threaten the health of human and animals. Chemical pesticides already cause the problem of antibiotic resistance and environment pollution. It is needed to find out new drug resources to against fungal diseases. In this study, we tried to screen the marine microorganisms with anti-fungal activity and to purify its active protein.Samples used in the paper are from the Arctic and the India Ocean, they are sea water samples or marine sediment samples. Through the regular microorganism separation methods,22strains of actinomycetes,183strains of fungi and lots of marine bacteria were isolated, among which28strains with anti-fungal activity were further isolated, including1strain of bacteria,2strains of actinomycetes and25strains of fungi. Subsequently, the crude proteins from cultures of9strains were prepared by ammonium sulfate precipitation and tested for their anti-plant pathogenic fungi activities. The results indicated that6strains have anti-fungi activities, and one strain, named as H075, was identified as Aspergillus sp. by sequencing18SrDNA. Then the crude protein active gradient of H075was purified by ammonium sulfate precipitation and ion exchange chromatography. Its molecular weight was estimated about18KD in SDS-PAGE and the active protein was named as AFH1. Through the ESI mass spectra analysis, this AFH1was identified as a fungal RNase, belonging to microbial RNase superfamily. Our results showed that AFH1retains anti-plant pathogenic fungi activity well after heating, protease digestion and surfactant treatment. It also exhibits RNase activity and cytotoxic activity to some extent. The results suggested that AFH1may have a great potential application in medicin, agriculture and food preservation.