Diversity And Bioactivities Of Filamentous Fungi Isolated From The Dianchi Lake Of Yunnan Plateau

Dianchi Lake is one of the important plateau lakes,it is a typical eutrophic lake.The research of Dianchi Lake is mainly focused on the pollution control,such as the distribution of nitrogen and phosphorus,the analysis of pollution characteristics,the application of aquatic higher plants,but about the distribution pattern or characteristics of the culturable aquatic filamentous fungal diversity,the spatial distribution characteristics of filamentous fungal diversity were not reported in the relationship between Dianchi aquatic ecosystem and surrounding human activities.In this study,we conducted a systematic study on the culturable filamentous fungi in water and sediment in Dianchi Lake.The pure culture method was used to isolate filamentous fungi from water samples and sediments in Dianchi,Yunnan.Traditional classical identification method to reveal culturable filamentous fungal diversity in Dianchi Lake,through the experimental data of ecological factors comprehensive analysis to explore the correlation culturable filamentous fungal colony number,diversity with environmental factors;at the same time,strains with enzyme-producing activities and antibacterial activities were screened and evaluated about their activities.According to related literature data,the distribution characteristics of the abiotic factors in the aquatic ecosystem of Dianchi Lake were analysed.The spatial distribution pattern of culturable filamentous fungal diversity and the spatial distribution of enzyme-producing and antimicrobial activities were correlated with the spatial distribution characteristics of environmental non-biological factors.In addition,the ecological factor comprehensive analysis method was used to explore the correlation between the spatial distribution characteristics and the human life,production activities in Dianchi Lake.(1)The basic information of each sample site,the environmental factors of water and sediments samples show that the environmental factors such as temperature,depth,pH,electrical conductivity and total hardness are evenly distributed in the respective regions.The abiotic factors such as total phosphorus,total nitrogen,organic carbon,NH4+-N,N03--N and other abiotic factors in Dianchi Lake were significantly different from each other with a certain spatial distribution.There is a gradual decline from north to south trend.(2)837 filamentous fungi(788 strains of surface water and 49 strains of sediments)were isolated from 17 samples of surface water and sediments in Dianchi Lake.Morphological identification was carried out,and the results showed that 837 strains belonged to 2 phyla/5 classes/15 orders/40 families/61 genera,and the dominant species were Cladosporium and Penicillium in water samples,the dominant species were Penicillium and Talaromyces in sediments.In Dianchi,the filamentous fungi is more abundant in the coast than the center,and compared to caohai,the diversity of filamentous fungal is more higher in Waihai.(3)Screening of 11 extracellular enzymes by plate screening at two temperatures.The results showed that there were 812 strains of 67 genera filamentous fungi with enzyme activities at 28 ?,763 strains of water and 49 strains of sediments,Production of amylase,inulinase and phytase strains are more,the minimum production of chitinase;There were 780 strains of 59 genera filamentous fungi with enzyme activities at 5 ?,734 strains of water and 46 strains of sediments,Production of amylase,pectinase,inulinase strains are more,the minimum production of laccase;At two temperatures,the strains producing cellulase were gradually decreasing from north to south in the distribution of Dianchi Lake,the strains producing lipaseand laccase were gradually increasing from north to south,other strains of extracellular enzyme strains were distributed irregularly.At the same time,the antibacterial activities of 14 pathogens was screened by filter paper and oxford cup method.The results showed that 553 strains of 59 genera filamentous fungi had antibacterial activities,504 strains of water and 39 strains of sediments,and the most strains resistant to skin pathogens,followed by plant pathogens and bacteria.The strains with antimicrobial effect on the Lasiodiplodia theobromae?Fusarium graminearum and Alternaria brassicae have a tendency to decline gradually from north to south,other strains with antimicrobial were distributed irregularly.(4)SPSS software was used to analyze the diversity,activity about filamentous fungi and environmental factors in Dianchi Lake.The correlation analysis of diversity,activity and environmental factors was carried out.The results showed that the diversity of filamentous fungi in each region was different,and it was significantly correlated with environmental factors,such as TN,TP and TOC.(5)26 filamentous fungi with high activity of enzyme activities were selected for quantitative experiments with seven extracellular enzymes.Every extracellular enzyme was identified by two kinds of media A and B.The results showed that the enzyme production of cellulase,laccase and amylase was relatively high,and other enzyme production was generally low,especially the chitinase;The strain of laccase from the above strains are screened and cultured at 30?,150 r/min for 7 days,the results showed that the laccase of medium A was better,and the enzyme activity unit reached 7189U/L,which was developed and applied.This strain is closest to the Periconia of Ascomycetesby the combination of morphological and phylogenetic analysis.The results show that there are a variety of culturable filamentous fungi in Dianchi Lake,Yunnan Plateau,and the fungal diversity and bioactivities exist a certain distribution characteristics in the Dianchi Lake region,there is a gradual decline from north to south trend,and they are related to environmental factors.