Effects of growth medium composition, iron sources and atmospheric oxygen concentrations on production of luciferase-bacterial magnetic particle complex by a recombinant Magnetospirillum magneticum AMB-1

Growth conditions for mass production of luciferase-bacterial magnetic part icles (BMPs) by a recombinant Magnetospirillum magneticum AMB-1 were invest igated in a pH-regulated fed-batch culture system. Enrichment of growth med ium with L-cysteine, yeast extract and polypeptone enhanced both bacterial growth and BMP production. The presence of L-cysteine in the medium was use ful for induction of cell growth. Strict anaerobic conditions led to a prol onged lag phase and limited the final cell density. Trace oxygen enhanced c ell growth with increasing BMP production. As iron sources, ferrous sulfate and ferric gallate dramatically enhanced BMP yield as compared with ferric quinate, an iron chelate conventionally used. The optimized conditions inc reased cell density to 0.59 +/- 0.03 g cell dry weight/liter and BMP produc tion to 14.8 +/- 0.5 mg dry weight/liter in fed-batch culture for four days . (C) 2001 Elsevier Science Inc. All rights reserved.