Selective Isolation And Screening For Insecticide And Antifungal Activities Of Actinomycetes Ane Halophilic Bacteria From Inner Mongolia Desert Saline Soils

In this study,141actinomycetes and41halophilic bacteria has been selective isolatedfrom10soil samples collected from Inner Mongolia desert saline soils, meanwhile, theirinsecticide and antifungal activity were screening. The main results are showed as follow:1.Throughtout the choice of medium, the antibiotics added and soil pretreatment test, theresults suggestd that:①The nalidixic, out of five kinds of inhibition, nystatin, potassiumdichromate, nalidixic acid and cycloheximide, showed the best inhibition effect, followed bycycloheximide. The optimum combination was30mg/L nalidixic acid and30mg/Lcycloheximide.②Among six kinds of medium, TPA, HVA, HSG, CMKA, CA and DL,TPA showed the highest rate of actinomycetes, HSG medium followed.③After prtreatedwith phenol, phosphate buffer and the milk-CHES, the milk-CHES method effectivelyreduced the bacteria count, thus improved the actinomycetes rate. All of10soil samples havebeen soaked by the milk-CHES liquid, then were added with30mg/L nalidixic acid and30mg/L cycloheximide on TPA medium. In this paper,141actinomycetes was isolated, besides,41halophilic bacteria were isolated on starch casein and starch yeast medium.2.Fungicidal activities of141actinomycetes and41halophilic bacteria strains uponSclerotinia sclerotiorum were tested. Results showed that the aseptic filtrate of31strains hadsignificant antagonism to S.sclerotiorum on leaves after3days in vitro, and8of themreached90%inhibition rate;11-3-126、11-3-94、11-3-100and11-3-218exhibited highercontrol effects on S.sclerotiorum in the pots trails, and11-3-126showed71.97%inhibitionrate.3.The activities of182isolations against Botrytis cinerea were measured in vivo and theeffect of the target actinomycetes against hypha and spore of B.cinerea were tested.16strainsshown over60%in vivo antimicrobial activity against B.cinerea.4of above strains,11-3-195、11-3-199、11-3-84and11-3-126, with high research value showed highantimicrobial activity, more than90%; the protective effect of11-3-84and11-3-126reachedto98.92%and97.10%;the therapeutic effect of11-3-195and11-3-199were59.62%and57.28%, respectively.The fermentation broth of4strains showed certain inhibitory effect on the myceliumgrowth of B.cinerea, and the inhibition rates of11-3-126and11-3-195were93.89%and 82.25%. All the fermentation broth of4strains had better inhibition to B.cinerea sporegermination, and the inhibitory effect of11-3-126,11-3-199and11-3-84on sporegermination of B.cinerea were obvious. The inhibition effect of2times dilution still reachedto100%, and10times dilution of11-3-126,11-3-199were93.02%and89.48%after24h.4.Growth speed rate method was used for antimicrobial test in vitro. Results showed theantimicrobial spectrum of11-3-126was widely, and reached to91.67%、90.26%and88.89%inhibition rate against S.sclerotiorum, B.cinema and Alternaria solani, respectively.5.Among the182tested strains, the fermentation of17isolations indicated100%deathrate against Artemia salina L within24h, and2hours lethal rate of11-12-5and11-6-173was100%. Out of17active strains,11-3-145,11-12-5and11-12-8showed activities against the3rdlarva of Culex pipidens pallens, and24hours lethal rate of11-3-145was100%.