Screening Of Disease-resistant Provibrio Strains From Marine Fungi And Study On Secondary Metabolites Of P. Chrysogenum UJNBHMF0648

In recent years,due to the extensive use of antibiotics in aquaculture,the ecological balance of the water environment has been seriously damaged and the aquaculture environment has been polluted,leading to the rapid increase of drug resistance of aquatic pathogens,and it is necessary to screen more new antimicrobial agents to suppress it.Fungi from the Marine environment is an important resource,Marine fungi species richness and diversity of secondary metabolites,diversity,biological activity,therefore,will come from Marine fungi used in aquaculture disease control is a very promising direction,can overcome the disadvantages of antibiotics,reduce the drug residues in water,improve the quality of aquatic products.In this paper,eight samples were collected from the Dongzhai Port Mangrove Nature Reserve in Hainan and the Beibu Gulf of the South China Sea.A total of 102 strains of fungi were isolated from the leaves,flowers,female leaves,fruits,rhizosphere soil of Kandelia candel,Dongsha sea mud and Dongsha sea water.Combining morphological and molecular methods,the fungal r DNA-ITS sequence was submitted to NCBI for Blast.In the end,102 fungi were successfully identified and belonged to 2 phyla,6 classes,11 orders,and 30 genera.They are Acarosporina,Hypocreales,Fusarium,Lecanicillium,Sarocladium,Simplicillium,Trichoderma,Neopestalotiopsis,Pestalotiopsis,Pseudopestalotiopsis,Xylaria,Hyphopichia,Alternaria,Curvularia,Massarina,Massa Rina,Nigrograna,Paraconiothyrium,Posidoniomyces,Stagonospora,Zasmidium,Cladosporium,Setomelanomma,Stagonospora,Rhytidhysteron,Bionectriaceae,Toxicocladosporium,Talaromyces,Penicillium,Aspergillus,Quam Balaria.The phylogenetic tree was established based on ITS-r DNA sequence homologous symphytic fungi,which belonged to 1 phylum,7 orders and 21 genera.The phylogenetic tree was constructed by N-J method with MEGA5.0 software.Then,the 102 strains of fungi were screened for their anti-vibrio activity.A total of 37 strains of fungi showed different antibacterial effects to Vibrio vulnificus,Vibrio parahaemolyticus,Vibrio alginolyticus and Vibrio brilliant.Based on the richness,yield and anti-Vibrio activity of the secondary metabolites,the fungus P.chrysogenum isolated from the rhizosphere soil of the mangrove plant Kandelia candel was selected for fermentation.A total of 22 compounds were isolated,including 3 New compounds,and the isolated compounds were tested for biological activity against pathogenic Vibrios,Five compounds showed a 40-60% inhibition rate against four pathogenic vibrios at the initial screening concentration of 50μM,and showed weak activity against pathogenic vibrios.