Primary Study Of Fungal Diversity And Antimicrobial And Enzyme Activities Of Culturable Fungi In Marine Sediments In The South China Sea

With the development and utilization of marine resources,the importance of marine microbes has attracted more and more attention.Fungi has become one of the hotspots in the research.Although diverse fungi have been found in deep-sea environment,the diversity of fungi and the role it plays have not been well characterized.To estimate the fungal community structure in the South China Sea sediments,we used a combination of high-throughput sequencing and traditional cultivation method.Sediments at four sites as well as three depths at each of the site(totally 12 sediment samples)were used in this study.A total of 1,272 OTUs were detected through high-throughput sequencing.387 OTUs from environmental DNA showed high divergence(unidentified)from the existing sequences in the GenBank.A total of 125fungi were isolated from the sediments.Based on the ITS sequence analysis and morphological characteristics,the isolates were grouped to 18fungal species and 12 genera within 2 phyla.Because of the particularity of the marine environment,marine-derived microbes have become an important resource for the study of new active substances(compounds,enzymes,etc.).In this study,the antibacterial activity of the crude extract of the fermentation broth was determined by the filter paper diffusion and growth rate methods.The results showed that the crude extracts of 10 fungi showed antibacterial activity,especially Alternaria tenuissima(DN09),Penicillium chrysogenum(DN16)and Alternaria alternata(DN14)showed inhibitory effects on G~+and G~-bacteria,while antifungal activity were not screened.At the same time,the potential of enzyme producting activity(protease,lipase,amylase,chitinase,cellulase and chitosanase)was determined by using the transparent circle method.Crude enzyme activity of the fermented broth was also determined.The results showed that 6 fungi produce protease,11 fungi produce amylase and 6 fungi produce lipase.In this study,using combined approaches including high-throughput sequencing and traditional culture method,the composition of fungal community of deep-sea sediments in the South China Sea was studied.The resluts reveal that the deep sea sediments of the South China Sea are rich in fungal resources.At the same time,a variety of cultivable fungi from the sediments of the South China Sea have the potential to produce antimicrobial substances and enzymes,indicating that deep-sea sediment-derived fungi are good source for bioactive substances.This study lays the foundation for the development and utilization of deep-sea derived fungi in the South China Sea.