Biohydrogenation of fumarate using Desulfovibrio desulfuricans: experimental results and kinetic rate modelling

Abstract

:The biological hydrogenation of organic compounds using sulphatereducing bacteria was investigated. A high pressure stainless steel bioreactor and an atmospheric pressure reactor were constructed so that identical reactions at di †erent pressures could be compared. The mesophillic sulphate-reducing bacteria Desulfovibrio desulfuricans (ATCC 7757) were used. Qualitative tests showed that Desulfovibrio desulfuricans was able to retain its viability at hydrogen pressures up to 35 atmospheres at a temperature of 37¡C when exposed to fumarate. Evidence of fumarate dismutation was observed since half of the fumarate was converted to succinate. The e †ect of bacterial cell concentration was also studied under hydrogen gas. For a doubling of the bacterial cell (reactivated) concentration, the conversion of fumarate doubled from 40% to 80% in 12 h. A Ðrst-order reaction rate model was Ðt to the fumarate concentration data. The Ðrst-order reaction rate constant was found to be a linear function of the bacterial cell concentration.

Estimating microbial growth and hydrogen consumption in hydrogen storage in porous media

“…shown not to change in response to different pH2 of 0.1-3.5 MPa [4,202], indicating neither stimulation nor toxicity at different levels of excess H2. The comparison to limiting H2 conditions was not made.…”

“…Only few studies investigated microbial H2 turnover at high pH2 of up to 1.5-24.8 MPa [4,201,202]. Methanogens (M. jannaschii) showed a strong inhibitory effect at high pH2 [201].…”

Enabling large-scale hydrogen storage in porous media – the scientific challenges

“…Although several studies have looked at hydrogen utilization under natural concentrations [65][66][67] , little is known about the effects that high hydrogen pressures expected in UHSP will have on the subsurface microbial system. A limited number of studies indicate that once microorganisms are exposed to excess hydrogen, hydrogen turnover will not further increase with increasing hydrogen pressure 68,69 , indicating that hydrogen turnover rates determined at excess hydrogen and standard conditions may be representative and applicable to estimate subsurface hydrogen rates, providing realistic nutrient, temperature, pressure, and salinity regimes are applied. A number of classes of microorganisms, including methanogens, sulphate-reducers, homo-acetogenic bacteria and iron(III)-reducers are considered as major hydrogen consumers and are frequently present in subsurface formations 70 .…”

¬Estimating Microbial Hydrogen Consumption in Hydrogen Storage in Porous Media as a Basis for Site Selection

“…Hence it is not clear whether H2 or CO2 performed the toxic action. For homoacetogens and SSRM, the H2 consumption was shown not to change in response to different pH2 of 0.1-3.5 MPa [4,195], indicating neither stimulation nor toxicity at different levels of excess H2. The comparison to limiting H2…”

“…Only few studies investigated microbial H2 turnover at high pH2 of up to 1.5-24.8 MPa [4,194,195]. Methanogens (M. jannaschii) showed a strong inhibitory effect at high pH2 [194].…”