The present study investigates the production kinetics of recombinant human tumor necrosis factor alpha (TNF-α) in Escherichia coli under three different non-conventional inducible expression systems viz. salt, the thermal and auto-inducible system in batch culture in a bioreactor. A codon-optimized synthetic gene of human TNF-α was inserted into plasmid pET-14b under T7 promoter to obtain its plasmid based expression in E. coli. Very high specific yields were obtained with auto-inducible expression systems ~47% of total cellular protein (TCP). The thermal and salt-induced expression could yield up to ~30% and ~17 % of TCP respectively. Maximum specific productivities were reported to be 0.092 g/gDCW/h, 0.1 g/gDCW/h, 0.079 g/gDCW/h for auto-inducible, thermal inducible, salt inducible expression systems respectively.
Key words: TNF-α, Expression kinetics, Auto-induction, Thermal induction, Salt induction, Escherichia coli
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