Introduction: Single chain variable fragment (scFv) antibodies are reduced forms of the whole antibodies that could be regarded as an alternative tool for diagnostic and therapeutic purposes. The optimization of processes and environmental conditions is necessary to increase the production yields and enhance the productivity. This can result in a cost-effective process and respond to the high demand for these antibodies. Methods: In this research, physical and chemical factors influencing the batch fermentation was investigated in 50 mL batch tubes using minimum media to find the optimum conditions for production of a single chain variable fragment antibody in the Escherichia coli HB2151. Experimental designs were used to screen the effective parameters and to optimize the main factors. Results: Arabinose was used instead of IPTG as a cheaper and nontoxic inducer and its optimum concentration was determined 0.1% (w/w). Induction duration time and filling volume fraction were set on the relatively better states 24 hours and 1/10 respectively. Regarding our previous study, stationary phase of the cell growth was selected as induction start time that showed higher specific scFv production yields (YP/X) in the minimum media. Finally, a statistical experimental design was extended to a central composite design (CCD) and analysis was performed based on sucrose and sorbitol concentrations producing osmotic condition for induction. The optimum region in the contour plot for the periplasmic scFv production was an osmotic circle area with total sugar molarity 0.8 to 0.9. Conclusion: Sugars such as sucrose and sorbitol producing osmotic conditions could lead to periplasmic scFv concentrations up to 2.85 mg/L of culture media improving scFv concentration near to five times of the average of the screening step (0.59 mg/L).

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We propose this method to possibly be used for the large-scale production of recombinant proteins/peptides such as scFv and Fab antibodies.