일산화탄소 이용 초고온성 고세균의 연속배양을 통한 바이오수소생산

Abstract

The hyperthermophilic archaeon, Thermococcus onnurineus NA1 was known for a good bio-hydrogen producer through the water-gas shift (WGS) reaction (CO + H2O → CO2 + H2). Recently, we reported that H2 productivity from carbon monoxide (CO) of the metabolically engineered T. onnurineus NA1, MC01, was enhanced significantly (at least 2-fold increase), compared to that of wild-type strain. In this study, we assessed kinetic parameters for cell growth and bio-H2 production from CO by conducting the continuous cultivation of MC01 with varying dilution rate, CO supply rate, or agitation speed. Practically, the CSTR fermentation of MC01 using CO as a sole carbon could be performed over a month without any technical problem, implicating that the process is feasible to produce hydrogen continuously for a long-term basis. Based on the results, both cell growth and H2 productivity were linearly correlated with dilution rate unless CO was not limited. At a fixed dilution rate of 0.3 h-1, H2 production rate was linearly increased depending on CO supply rate up to 240 ml/min, which is corresponded to 0.12 vvm. However, at CO rate of 300 ml/min, both cell growth and H2 production rate considerably decreased, indicating CO inhibition toward cell growth and H2 production. Additionally, the increase in agitation speed was also effective in enhancing H2 production. It is considered that enhancing mass transfer by increasing CO supply f the metabolically engineered T. onnurineus NA1, MC01, was enhanced significantly (at least 2-fold increase), compared to that of wild-type strain. In this study, we assessed kinetic parameters for cell growth and bio-H2 production from CO by conducting the continuous cultivation of MC01 with varying dilution rate, CO supply rate, or agitation speed. Practically, the CSTR fermentation of MC01 using CO as a sole carbon could be performed over a month without any technical problem, implicating that the process is feasible to produce hydrogen continuously for a long-term basis. Based on the results, both cell growth and H2 productivity were linearly correlated with dilution rate unless CO was not limited. At a fixed dilution rate of 0.3 h-1, H2 production rate was linearly increased depending on CO supply rate up to 240 ml/min, which is corresponded to 0.12 vvm. However, at CO rate of 300 ml/min, both cell growth and H2 production rate considerably decreased, indicating CO inhibition toward cell growth and H2 production. Additionally, the increase in agitation speed was also effective in enhancing H2 production. It is considered that enhancing mass transfer by increasing CO supply