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[Establishment of genetic transformation system of Schizochytrium sp. by homologous recombination].

OBJECTIVE
Schizochytrium sp. is a marine fungus that can produce DHA efficiently. Genetic engineering has been successfully used in industrial strain improvement and metabolic studies. In order to use genetic engineering to modified Schizochytrium sp., we established an genetic transformation system of Schizochytrium sp.


METHODS
A genetic transformation system of Schizochytrium sp. was established by 18S rDNA-targeted homologous recombination. The targeting vector contained a part of 18S rDNA from Schizochytrium sp. and the ble gene. This targeting vector was transformed into Schizochytrium sp. by electroporation and then selected by Zeocin-containing plates. The incorporation of exogenous ble gene into the genome of Schizochytrium was inspected by PCR amplification.


RESULTS
Fermentation results show that the transformants had similar cell dry weight, lipid yield, DHA content, and composition of other fatty acids to the wild type strain.


CONCLUSION
Our results show that the introduction of resistance gene did not affect the cell growth and lipid metabolism. This system could be used to introduce new functional genes into Schizochytrium sp.