Fed Batch Bioreactors: the proprietary FUJIFILM Diosynth Biotechnologies (FDB) CHO DG44-IgG-expressing cell line was cultured in FDB-MAP (Sigma) medium supplemented with 175 nM MTX (Sigma) and 8mM L-glutamine (Sigma). For maintenance culture the cell line was sub-cultured every 3-4 days in vented Erlenmeyer shake flasks (Corning, Amsterdam, Netherlands) at a seeding density of 0.5x10 6 cells/mL and maintained in a shaking cell culture incubator. Cultures were expanded to attain required numbers prior to seeding bioreactors.