Abstract:

With the aim to further enhance lipoxygenase (LOX) activity produced by recombinant E. coli, response
surface methodology was used to optimize the fermentation conditions. First of all, we explored the effects of starting
time of induction, inducer concentration, induction duration, induction temperature, inoculum size, medium initial pH and
medium volume on LOX production by single factor tests. Three factors with significant impacts on LOX activity including
starting time of induction, induction time and medium initial pH were selected out of these seven factors by using Plackett-
Burman design. Simultaneously, the optimal conditions for LOX production were determined by Box-Behnken design and
response surface methodology as induction starting at OD600 nm of 1.6 and lasting for 34 h and medium initial pH of 7.0. The
LOX activity was (21 261.60 ± 264.03) U/mL under these conditions, which was improved by 56.87% than that before
optimization, (13 553.96 ± 46.64) U/mL.

Key words: lipoxygenase, fermentation conditions, response surface methodology, Plackett-Burman design