Diversity Analyses And Antimicrobial Screening Of Fungi Isolated From Bamboo Forest

Three parts were included in this thesis:1) Fungi isolates from rhizosphere of Moso bamboo were screened for their antimicrobial activity and tentatively analyzed for the active components;2) Antimicrobial activity screen was employed on the endophyte strains from Moso bamboo seeds;3) Molecular identification and phylogenic analyses were made on fungi associated with fruiting body of Shiraia bambusicola.1 In order to find the fungi with activity of anti-microbe,40 strains were isolated from rhizosphere of Moso Bamboos in several counties of southern Anhui,such as Guangde and Huoshan.23 strains with significantly morphological differences were analyzed by means of molecular phylogenetics.Except for one strain of Basidiomycota,the other were belonged to Ascomycota,including 16 strains of Hypocreales,5 strains of Eurotiales,and two strains incertae sedis.Ten bacteria and fungi(E.coli,Pestalotiopsis microspora and so on) were employed as indicator strains to screen strains with activity of inhibitory.14 strains were screend out,which contains 11 strains against gram-positive bacteria,8 strains against gram-negative bacteria,4 strains of against fungi and 8 strains of multiple resistance.Phylogenetic analyses showed that the primarily screened strain L-521 was identified as Linkosia fusiformis(ascomycota,Hypocreales).The optimum fermentation conditions were studied by single factor tests combined with orthogonal tests,which were:based on liquid PDA medium as fermentation medium,with pH=6.0 and NaNO₃=0.5g/L in initial broth,cultured at 20℃and inoculating amount 10%.The characters of compounds against microbe for strain L-521 were as followed:1) ethyl acetate was considered the best extraction solvent for active components,2) the order of dissolution in solvent is methanol＞ethyl acetate,acetone and ethanol＞H₂O＞dichloromethane＞benzene＞petroleum ether,3) they were well thermal stable, even in 100℃still remained active,4) they were well acid stable but unstable in alkali with a large mounts of floccule produced,5) they had two ultraviolet absorption peaks at 220nm and 281nm,6) the molecular weight of one active component was determined to be 305 by LC-MS.2 E.coli and other six indicators were used to screen antimicrobial activity for endophytic fungi from the bamboo seeds,and 6 strains were screened out from 18 endophytic fungi with remarkably morphological differences,which had antimicrobial activity at different level, including B01,B02,B12,B19,B28 and 1735.3 In order to identify the related fungi associated with fruiting body of Shiraia bambusicola collected from south Anhui,50 fungal strains were isolated from fruiting bodies of Shiraia bambusicola.Strains with significantly morphological differences were characterized by 18S rDNA and ITS rDNA sequence analyses.Phylogenetic analyses showed that two strains belonged to the Zygomycota,and the other fungal 48 strains belonged to Ascomycota,in which the members of the Hypocreales and Apiosporaceae were dominant groups,secondly including the Pleosporales,Trichosphaeriales and Xylariales.