초록
Aiming at maximizing the production of transmembrane rabies virus glycoprotein (rRVGP), the influence of hypothermic temperature on a recombinant Drosophila melanogaster S2 cell culture in Sf-900II medium was investigated. Cell growth and rRVGP production were assessed at 4 culture temperatures in Schott flasks: 16, 20, 24 and 28<SUP>o</SUP>C. The maximum specific growth rates μ<SUB>max</SUB> were, respectively: 0.009, 0.019, 0.038 and 0.035h<SUP>-1</SUP>, while the maximum rRVGP levels C<SUB>max</SUB><SUP>rRVGP</SUP> were: 0.075, 2.973, 0.480 and 1.404mgL<SUP>-1</SUP>. The best production temperature (20<SUP>o</SUP>C) was then tested in a bioreactor with control of pH and dissolved oxygen in batch and fed-batch modes. In the batch culture, μ<SUB>max</SUB> and C<SUB>max</SUB><SUP>rRVGP</SUP> were 0.060h<SUP>-1</SUP> and 0.149mgL<SUP>-1</SUP> at 28<SUP>o</SUP>C and 0.026h<SUP>-1</SUP> and 0.354mgL<SUP>-1</SUP> at 20<SUP>o</SUP>C, respectively. One batch-culture experiment was carried out with adaptation of the cells by the temperature falling in steps from 20<SUP>o</SUP>C to 16<SUP>o</SUP>C, so that μ<SUB>max</SUB> fell from 0.023 to 0.013h<SUP>-1</SUP>, while C<SUB>max</SUB><SUP>rRVGP</SUP> was improved to 0.567mgL<SUP>-1</SUP>. In the fed-batch mode at 20<SUP>o</SUP>C, μ<SUB>max</SUB> was 0.025h<SUP>-1</SUP> and C<SUB>max</SUB><SUP>rRVGP</SUP> was 1.155mgL<SUP>-1</SUP>. Taken together, these results indicate that the best strategy for optimized rRVGP production is the culture at hypothermic temperature of 20<SUP>o</SUP>C, when μ<SUB>max</SUB> is kept low and with feeding of limitant aminoacids.