Optimization Of Culture Conditions Of Destruxins A And Preparation Of Emulsion In Water

Destruxins are produced mainly by entomopathogenic fungus,such as Metarihizium anisopliae,over 40 different destruxins or destruxin analogs were indentified,which are composed of a α-hydroxy acid and five amino acid residues.Some destruxins,especially destruxin A,B and E exhibited insecticidal activity.The destruxins are important virulence factors because they accelerate the deaths of infected insects.Destruxins showed wide variety of biological activities,such as insecticidal,phytotoxic activities,anti-viral,immunosuppressant,and cytotoxic.However,the yield of destruxins is low,so it is very necessary to optimize the culture condition to improve the destruxins production.In addition,emulsifiable concentrate,wettable powder and other traditional formulations in C hina’s pesticide market still occupy a large market share.As one of the alternative varieties,emulsion in water has the advantages of using safe,low cost and low environmental pollution,etc.the promotion and application of new formulations,is in line with the pesticide reduction efficiency of the Ministry of Agriculture.In this paper,we studied the optimization of the liquid fermentation medium of Metarhizium anisopliae produce destruxin A,the combined virulence of the crude toxin and pesticides on Spodoptera litura,and the preparation of 10% crude toxin · deltamethrin of emulsion in water.The results were shown as following:1.Application of response surface method to determine the factors of effects Metarhizium anisopliaefermentation: sucrose(C source),peptone(N source)and fermentation time,and using central composite design to design,obtain a high degree of fitting,lower testing error model.Predicted by the model of destruxin A concentration is 6.90μ g/m L,optimal culture conditions was 2.27% sucrose and 1.34% peptone,0.20% beta alanine,distilled water 100 m L,p H=7-8;fermentation conditions optimized was: 9.14 days of incubation time,temperature 28 ℃,rotational speed in 220 r/min,and liquid volume 300 m L/L.2.The Spodoptera litura as tests insect to screening combined with synergistic effect:deltamethrin and crude toxin(c.f=28.69),chlorpyrifos and crude toxin(c.f=22.60);chlorantraniliprole and crude toxin(c.f=20.42).Study on the reasonable ratio with crude toxin and deltamethrin showed that the ratio of 6.25: 1(active ingredient)toxicity ratio was 1.71,the ratio of toxicity when 14.05 :1(active ingredient)ratio is 1.35,and the ratio of the other the toxicity ratio is less than 1.Crude toxin and deltamethrin at 6.25: 1(active ingredient)mixed with the co-toxicity coefficient of 238.47,showed a significant synergistic effect.3.Under the experimental conditions,the pseudo-ternary phase diagram showed that the anionic surfactant 500# and nonionic surfactant OP-10,NP-10,tween 80 and tween 60 can form emulsion separately.When the ratio of 500# to tween 80 and tween 60 was mixed with 1:3,the area of emulsion area was the largest.The stability test showed that T80: 500 #(3:1)was more stable in the case of 6%.4.Three kinds of composite emulsion in water were obtained by experiment screening:(1)10% crude toxin·deltamethrin,20% toluene and 6% emulsifier(tween 80:500# = 3:1),5% isopropyl alcohol,5% glycerin,deionized water added to 100%.(2)10% crude toxin·deltamethrin,20% toluene and 6% emulsifier(tween 80:500# = 3:1),5% ethanol,5% ethandial,deionized water added to 100%.(3)10% crude toxin·deltamethrin,20% toluene and 6% emulsifier(tween 80:500# = 3:1),5% ethanol,5% ethandial,distilled water added to 100%.After determination of emulsion stability,the three combinations of the indicators have reached the eligibility requirements.