Medium optimization for enhancement of formate-driven bio-hydrogen production by the hyperthemophilic archaeon, Thermococcus onnurineus NA1

Abstract

The hyperthermophilic archaeon, Thermococcus onnurineus NA1 which was isolated from deep-sea hydrothermal vent area has been reported to be able to grow on formate evolving hydrogen (H2) in a growth-associated manner. In this study, we optimized the composition of medium to enhance the formate-driven H2 production by T. onnurineus NA1 by using response surface methodology (RSM). Of the minor components of medium including potassium, magnesium, vitamin and trace elements, based on the Plackett-Burman design, trace elements was selected as the only positively effective component affecting H2 production. Subsequently, the optimal concentrations of the trace elements and the major components of medium such as NaCl, yeast extract and sodium formate were determined by the five-level central composite design. As a result, the maximum H2 concentration of 31.7%, which was 20% enhanced value compared with that obtained using control medium, was predicted when the concentrations of sodium formate, NaCl, yeast extract and trace elements were 11.31 g/L, 27.36 g/L, 4.01 g/L and 5.31 mL/L, respectively. In control medium, 10 g/L of sodium formate, 35 g/L of NaCl, 1 g/L of yeast extract and 1 mL/L of trace elements were included. The result was further verified by triplicate batch cultivation in serum bottle based on the optimized medium showing the practicability of this optimum strategy.mized the composition of medium to enhance the formate-driven H2 production by T. onnurineus NA1 by using response surface methodology (RSM). Of the minor components of medium including potassium, magnesium, vitamin and trace elements, based on the Plackett-Burman design, trace elements was selected as the only positively effective component affecting H2 production. Subsequently, the optimal concentrations of the trace elements and the major components of medium such as NaCl, yeast extract and sodium formate were determined by the five-level central composite design. As a result, the maximum H2 concentration of 31.7%, which was 20% enhanced value compared with that obtained using control medium, was predicted when the concentrations of sodium formate, NaCl, yeast extract and trace elements were 11.31 g/L, 27.36 g/L, 4.01 g/L and 5.31 mL/L, respectively. In control medium, 10 g/L of sodium formate, 35 g/L of NaCl, 1 g/L of yeast extract and 1 mL/L of trace elements were included. The result was further verified by triplicate batch cultivation in serum bottle based on the optimized medium showing the practicability of this optimum strategy.