Study On Inhibitory Effects Of Allicin On Pathogenic Fungi Live On Bombyx Mori L. And Its Mechanism

In order to solve the problem of enviroment pollution caused by prevention and cure against silkworm fungal disease,and to develop the herbal medicament of silkworm,the fungistasis of allicin was researched in this thesis,we isolated Beauveria bassiana of high virulent strains against Bombyx mori L.firstly.Then we investigated the fungistasis of allicin for Beauveria bassiana which had high virulent against Bombyx mori L..Next, we studied the influence on stability of allicin caused by external conditions.Finally,we investigated how fungistasis of allicin influenced the function of fungal membrane.1.The isolation of Beauveria bassiana of high virulent strains against Bombyx mori L.Five Beauveria bassiana strains were isolated and their growth rate,spore production and pathogenicity were tested.The results were as follows:the growth rate and spore production of B07-2 were the best in all strains.In 10 days,the mortality to silkworm was the highest(98.18%).Its LT₅₀ for Bombyx mori L.was 5.09d and its LC₅₀ was 2.69×10⁶ spore/mL.2.The fungistasis of allicin for the fungous disease of Bombyx mori L.The allicin effect on the spore sprouting and colony spreading of silkworm Beauveria bassiana(B07-2),the result showed that the allicin inhibitory action at Beauveria bassiana of Bombyx mori L.increased as the concentration power-up but strengthened.The inhibitory action was strongest when the concentration of allicin was at 10μL/mL.3d's restraint rates were 92.67%and 91.07%respectively.Its LC₅₀ were 2.79μL/mL and 1.41μL/mL respectively.Via mensurating the Minimal Inhibitory Concentration(MIC) and Minimal Lethal Concentration(MLC),the result showed that the MIC and MLC of allicin for Beauveria bassiana were 5.00μL/mL and 7.50μL/mL respectively.3.Impact of the external condition upon the effect of fungistasis of allicinThe fungistasis of allicin was stable in the condition that pH≦7 and the temperature was lower than 60℃.The effect of fungistasis of allicin reduced obviously when pH＞7 or the temperature＞80℃.All results showed that the allicin was a kind of unstable substance to the alkali and heat.4.The influence of allicin on fungal membrane function of silkworm Beauveria bassiana For investigating and discussing the influence of allicin on fungal membrane function,the influence of the rate of absorbing and making use of nutrient substance of fungus in its growth process,the relationship between the allicin thickness and the hurt of bioplasm membrane and the influence of ion transport and ion gradient maintenance ability of Beauveria bassiana cell that caused by allicin were tested,the results showed that:the rate of absorbing and making use of protein and sugar of Beauveria bassiana worked by allicin reduced 64.83%and 69.64%respectively in its growth process than contrast;The hurt of outward infiltrating rate of electrolyte of Beauveria bassiana cell that caused by allicin increased following the allicin thickness power-up,changing another word,the hurt of bioplasm membrane increaseed following the allicin thickness power-up;The result about mensurating of ATPase vigour between disposal team and contrast team revealed that all ATPase vigour in Beauveria bassiana cell had by a wide margin lessening.The N_a⁺K⁺-ATPase vigour reduced 84.36%,and C_a⁺⁺M_g⁺⁺-ATPase vigour reduced 75.35%.To sum up,allicin can damnify the cytomembrane function of Beauveria bassiana,and can influence the growth of Beauveria bassiana consequently.Based on this study,the results might be useful on allicin as herbal fungicides to controll silkworm diseases.