Small interfering RNA are used in gene silencing to study gene function, treatment of cancer and other diseases. To produce a recombinant small interfering RNAs in Escherichia coli, a research was carried out in the City University of Hong Kong. They achieved milligram scale production of pro‐siRNA in MINIFOR bioreactor and a yield improvement by over 200‐fold compared with the traditional shake flask culture method.

Different recombinant pro‐siRNA clones of E.coli were cultivated in the MINIFOR Fermenter to study the production efficiency. High cell density fermentation was performed in Batch fermentation followed by the Fed-batch cultivation. Results obtained in fed‐batch process showed that the optical density at 600nm for an average culture were 39.8 and 41.7 g/L biomass (wet cell weight). With a high–cell density fed‐batch fermentation method in the MINIFOR Bioreactor, the optimized clone produced a yield of ~10 mg purified pro‐siRNA/liter of bacterial culture.