| In this paper, the tolerance and sensitivities of Spirulina to different antibiotics and L-canavanine sulphate (CS) was expounded. In the experiment, we extracted DNA anti-CS mutant A9c and transformed it into A9 strain, then we accepted some parameters to transform Spirulina. Also, we constructed the foreign vector p215t-spp which contains Spirulina promoter A9, and transformed it into Spirulina promoter A9. Thus, Green Fluorescent Protein (GFP) expressed successfully and stably in Spirulina. This research established a system for genetic transformation operation of Spirulina, and provided important reference to trans-gene technology of Spirulina.Spirulina was extremely sensitive to antibiotics such as Chl and Str. The lethal concentration of Chl and Str were 1.0μg·ml-1 and 3μg·ml-1 in liquid cultivating and1.2μg·ml-1 and 4μg·ml-1 in solid cultivating respectively. The Spirulina was relatively sensitive to Amp. The minimum inhibitory concentration (MIC) of Amp was 100μg·ml-1 in liquid situation and 200μg·ml-1 in solid situation. But 600μg·ml-1 Km showed no inhibition on the growth of A9 strain.Chl,Str and Amp might be suitable selection genetic markers for the Spirulina, and the selection concentrations were 1.2μg·ml-1,4μg·ml-1,200μg·ml-1 respectively.Extracted DNA of A9c strain which is the anti-CS mutant of A9 strain, screened by 30μg·ml-1 CS, then transformed it into A9 strain, we accepted a transformant and some parameters to transform Spirulina: cultured A9 strain at 24℃and treated with 2 mmol·L-1 EDTA for 24h before transformation; used ultrasonic treatment with power of 300w for 70s, used natural methods to screen transformants.In this experiment, both of original plasmid p215t and new constructed plasmid p215t-spp which contains gfp gene were used as vectors, used different method of ice bath and PEG fusion method separately to transform Spirulina A9 strains, the gfp gene were expressed in Spirulina successfully. We compared the transformation rate of different plasmid under the same conditions and methods. The data shows that, compared with p215t, p215t-spp can significantly improve transformation rate (α= 0.01). This proved that use Spirulina promoter to construct vectors can improve the transformation rate. We also compared the transformation rate of different methods. The data shows that use 1% PEG concentration in 30min can obtain a higher transformation rate (10.5‰). Observed by fluorescence microscope with 390nm as stimulation light, parts of the transformant filaments presented stable green fluorescence, and the foreign gfp gene has been effectively expressed in S. platensis.
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