Valiolah Babaeipour - PhD student in chemical engineering-biotechnology
Seyed Abbas Shojaosadati - Prof. in industrial biotechnology
Rasoul Khalilzadeh - Assist. prof. in chemical engineering-biotechnology
Nader Maghsoudi - Assoc. prof. in molecular and cellular biology

The effect of various process parameters on over-expression of human interferon-γ sing an IPTG inducible expression system in recombinant Escherichia coli BL21 (DE3) [pET3a-ifnγ] was investigated. Process parameters include: i) type of cultivation process (batch and fed-batch), ii) feeding strategy (in fed-batch), iii) feed composition in postinduction feeding, and iv) induction conditions, were applied and then overall productivity of interferon-γ was examined. It was found that overall productivity of Interferon-γ was significantly affected by all of the studied parameters, but specific growth rate at both pre and post-induction, type of cultivation process and feeding strategy are more effective. By applying the fed-batch cultivation, feeding strategy with maximum attainable specific growth rate throughout the process, optimum induction conditions, and suitable composition in post-induction feeding basis of amino acid composition of recombinant protein and E.coli, overall productivity and concentration of rhIFN-γ was increased from 0.044 to 3 g l-1 h-1(interferon-γ), and 0.31 (at batch culture with LB medium) to 51 g l-1, (at f ed-batch culture with simple medium) respectively. Also overall productivity and concentration of biomass was increased of 0.14 to higher than 7.3 g l-1 h-1 (dry cell weight) and 0.95 to over than 127 g l-1 (dry cell weight), respectively. According to available data this is the highest specific yield and productivity that reported for recombinant proteins production yet.

Human Interferon-γ; Recombinant Escherichia coli; Productivity; Process parameters