Statistical optimization of medium for formate-driven bio-hydrogen production by the hyperthermophilic archaeon, thermococus onnurineus

Abstract

Medium compositions for the hyperthermophilic archaeon, Thermococcus onnurineus NA1 was statistically optimized to enhance formate-driven hydrogen (H 2 ) production by using response surface methodology. From the Plackett-Burman design-based experiment, it was confirmed that among the minor components of medium such as KCl, MgSO 4 , NH 4 Cl, Cystein-HCl, trace elements, Fe-EDTA and CaCl 2 , the trace elements were screened as the only positively effective components with respect to H 2 production. Subsequently, the optimal concentrations of the trace elements and the major components of a medium such as NaCl, yeast extract and sodium formate were determined from the five-level central composite design (CCD)-based experiment. The resulting quadratic model predicted the maximum H 2 production of 46.6 mmol/L in serum bottle and it was validated experimentally using the optimal medium initially supplemented with 26.70 g/L of NaCl, 9.81 g/L of sodium formate, 3.50 g/L of yeast extract and 4.59 mL/L of trace elements. From the duplicate batch cultivations in the fermentor using the optimized medium, the a maximum H 2 production rate up to 71.8 mmol/L/h could be obtained, which was a 65% enhanced value compared with that obtained using the control medium, showing the high efficiency of the optimized medium. © 2018, Korea Ocean Research and Development Institute. All rights reserved.