论文部分内容阅读
Locoweeds are toxic plants of the genera Astragalus and Oxytropis containing swainsonine.Swainsonine is the principal agent responsible for locoism in animals.Recently, the fungal endophytes are isolated frequently from locoweeds, Undifilum spp, are believed that responsible for the production of swanisonine in locoweeds.If the swainsonine production in Undifilum spp is inhibited, the locoweeds toxicity would be reduced or eliminate.Currently, the mechanism was few known about the biosynthesis of swainsonine in Locoweeds endophytic fungi.The research about influence of different factors on swainsonine production in Undifilum oxytropis will be benefit for building the important basis for further to elucidate the swainsonine biosynthetic pathways and molecular regulation mechanism.U.oxytropis were inoclated in liquid medium of different pH or containing different concentration of PEG, L-pipecolic acid, L-lysine and α-ketoglutaric acid, respectively.To estimate the influence of different factors on swainsonine production in U.oxytropis, the swainsonine of cultured fungal mycelia and zymotic fluid were extracted and detected.after shaking culture.The results showed that is no significant difference about growth of different pH treatment of U.oxytropis groups.However, low pH (pH4.5) will inhibit the synthesis of swainsonine.PEG promoted the growth of U.oxytropis, but inhibited the synthesis of swainsonine.L-pipecolic acid could increase significantly the mycelial dry mass.When the initial concentration of L-pipecolic acid was 10-3 mol/L and 10-2 mol/L, the production of swainsonine in U.oxytropis was inhibited.However, when the initial concentration of L-pipecolic acid was 10-4mol/L, the production of swainsonine in U.oxytropis was increased significantly.When the initial concentration of L-lysine was 10-3 mol/L, the production of swainsonine in U.oxytropis was increased significantly.However,when the initial concentration of L-pipecolic acid was 10-1mol/L,10-2mol/L and 10-4mol/L, the production of swainsonine in U.oxytropis was inhibited significantly.When the initial concentration of a-ketoglutaric acid was 10-1 mol/L, 10-2mol/L and 10-3 mol/L, the growth of production of swainsonine in U.oxytropis was inhibited significantly.Low pH or PEG added to medium could significantly inhibit the production of swainsonine in U.oxytropis.It was significant that the influence of L-pipecolic acid, L-lysine and t-ketoglutaric acid on the swainsonine producing of fungal endophyte.However, the extent of influence on fungal swainsonine producing was highly correlated with the concentration of L-pipecolic acid, L-lysine and a-ketoglutaric in liquid media.