| In this thesis, nutrient factors that affect the growth of D. Salina were studied systematically for the purpose of increasing the biomass of strain A1 in liquid culture, the correlation among four best nutrient factors of every nutrient factors were considered, and how to get Act resistant mutant of D. Salina by the EMS was also studied. Effects of nutrient factors on the growth of strain A1 were of hormones,bases,amino acids,vitamins,trace elements and propagation extractive fluid. The results showed the six hormones,2,4-D,6-BA,GA,IBA,NAA and IAA with suitable concentrations could accelerate the growth of strain A1 at different degrees. In these six hormones, IBA(0.5 mg·L-1),2,4-D(0.5mg·L-1),6-BA(1.0mg·L-1) and GA(0.1mg·L-1) had comparatively distinct improvement. Orthogonal test with these four hormones indicated that IBA,2,4-D,6-BA and GA had significant effects on biomass at 95% level, and the optimum combination of hormones was 2,4-D(0.1mg·L-1) IBA(1.0mg·L-1) 6-BA(0.5mg·L-1) GA (0.5mg·L-1). The most suitable concentrations of five bases A,C,U,T and G were 0.5 mg·L-1,1.0mg·L-1,1.0mg·L-1,10mg·L-1 and 0.5mg·L-1, respectively, and A,C,U and T had comparatively distinct improvement effects. Orthogonal test with these four bases indicated that A,C,U and T had significant effects on biomass at 95% level, and the optimum combination of bases was C(0.5mg·L-1)A (1.0mg·L-1)T(15mg·L-1)U(1.0mg·L-1). Thirteen amino acids were Val,Lys,Pro,Trp,Gly,Glu,Arg,His,Phe,Ser,Met,Cys and Thr. The effects of the suitable concentrations of Pro,Gly,Arg and Phe were more better than that of the other amino acids. Orthogonal test with these four amino acids indicated that Pro,Gly,Arg and Phe had significant effects on biomass at 95% level, and the optimum combination of amino acids was Phe(25mg·L-1)Arg(15mg·L-1)Pro(20mg·L-1) and Gly(15mg·L-1). VH and folacin inhibited the growth of D. Salina at the set concentration, and the higher concentration the strengther inhibition. The suitable concentrations of VB1,VB12,VB6 and VC could advance the growth of D. Salina respectively. Orthogonal test with these four vitamins indicated that VB1,VB12,VC and VB6 had significant effects on biomass at 95% level, and the optimum combination of vitamins was VB1(80μg·L-1)VB6(40μg·L-1)VB12 (10μg·L-1)VC(160μg·L-1) . The kinds of trace elements in experiments were same as those of the Johnson medium, and the effects of the trace elements to the growth of D. Salina were studied. The six trace elements were Cu,Zn,Mu,Mn and B. The results showed that the both higher and lower concentration than that of Johnson medium could prevent the growth of D. Salina. The suitable concentrations of the Cu,Zn,Mu,Mn and B were 6μg·L-1,1.0μg·L-1,3.8μg·L-1,2.55 μg·L-1,8.2μg·L-1 and 61μg·L-1 respectively. Five organic complex nutrient factors potato extract,bean sprout extract,peptone,yeast and dashi advanced distinctively the growth of the D. Salina. The suitable concentration of this five nutrient factors were 10%, 6%,4 g·L-1,2g·L-1 and 8%, respectively. EMS is a chemistry mutant, which was used to mutant breeding for the biology. The 95% lethatal dose was 6% of EMS and the dose was suitable for the isolation of mutant of D. Salina. The resistance to the Act of the originality D. Salina was 0.05mg·L-1, the mutant strain could resistant Act at the dose of 0.4mg·L-1.
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