Taxonomy Identification Of A Strain Of Unknown Filamentous Fungus And Analysis Of Its Characteristics

A strain of filamentous fungus named Mars was isolated in our laboratory.Morphological characteristics of Mars strain were compared with thestandard strain of Beauveria bassiana3.4428. Based on this analysis, somephysiological and biochemical characteristics such as spore output,extracellular protease production, chitinase activities and virulence of Marsstrain were studied and compared with 3.4428 strain. According to the resultsof morphological identification and physiological and biochemicalcharacteristics, the taxonomy position of Mars strain was identified.The colony and morphological characteristics of Mars and 3.4428 strainson potato dextrose agar (PDA), Czapek agar (CA), potato dextrose agaradded with peptone (PPDA) media were observed respectively. The resultsshowed that the colony of Mars strain was white or light yellow near round,and the edge of colony was regular, their shape transformed from villous ofearlier cultivation to blankets of later cultivation, microbial pool were higher.The colony of this strain on PPDA medium was wrinkle and radial branch.It's vegetal mycelia were colorless, smooth, 1.2μm～3.0μm crude, manyconidiogenous cells born on vegetal mycelia, sometimes as many as a dozen,a very small number were single. The base of conidiogenous cell wasenlarged and many of them were bottle-shaped or spherical. The upper ofconidiogenous cell extended into a conidiogenous axis of 1μm wide and 14μm length which was the knee-bending ("Z" like bending), there were small pectinae on the axis, conidium located on the small pectina. A few ofconidiogenous cells became into longer filaments infertility. In the late phaseof cultivation, many spherical conidiogenous cells group were seen inmicroscope. Conidia of Mars strain was transparent, smooth and many ofthem were spherical or near spherical. Based on these characteristics above,Mars strain was identified to Beauveria bassiana.The growth rate and spore output of Mars and 3.4428 strains on PDA,PPDA, CA media and PDA, PPDA, CA media respectively added with pestcarcasses were compared. The order of the growth rate of Mars strain on sixkinds of media was: PDA added with pest carcasses＞CA added with pestcarcasses＞CA＞PPDA＞PPDA added with pest carcasses＞PDA. The order ofthe growth rate of 3.4428 strain on six kinds of media was: PDA added withpest carcasses＞CA added with pest carcasses＞PDA＞PPDA＞PPDA addedwith pest carcasses＞CA. The order of spore output of Mars strain on thesemedia was: PPDA added with pest carcasses＞PPDA＞CA added with pestcarcasses＞PDA added with pest carcasses＞CA＞PDA. The order of sporeoutput of 3.4428 strain on these media was: PPDA added with pest carcasses＞PPDA＞CA added with pest carcasses＞CA＞PDA added with pestcarcasses＞PDA.The extracellular protease and chitinase activities of Mars and 3.4428strains were determined. The results showed that Mars strain in gelatin agarmedium could produce extracellular protease which was rarely less than that of 3.4428. In the chitinase induction medium, Mars strain could producechitinase, but the chitinase activities of 3.4428 were higher than that of Mars.At the beginning of cultivation, the chitinase activities were lower, and withprolong of cultivation, it began to increase and reached the highest activitiesafter 84 hour.Dendrolimus tabulaeformis were infected by the spore suspension of2×10~8/mL of Mars and 3.4428 strains respectively. The results indicated thatin different phase, the cumulative mortality of Dendrolirnus tabulaeformisinfected by Mars were lower than 3.4428, which meant the virulence of Marswas lower than that of 3.4428.