Enhancing biohydrogen production of the alkalithermophile Thermobrachium celere

摘要

In this study the effect of different buffering agents, pH control and N_2 sparging on biohydrogen production in Thermobrachium celere was investigated in batch cultivations. Among the tested buffers, none was able to prevent the medium acidification resulting in a premature interruption of the hydrogen production. Controlling the pH helped to sustain the growth, the complete substrate consumption and the H_2 production. However, in these conditions the increase of H_2 partial pressure induced a partial metabolic shift towards ethanol production resulting in a decreased H_2 yield. Analysis of formate accumulation during growth suggests that this compound might play a relevant role in the anabolic routes in T. celere. When frequent N_2 sparging was applied for H_2 removal, together with pH control, the H_2 yield was remarkably enhanced from 2.26 to 3.53 mol H_2/mol glucose, and the maximum H_2 production rate and specific H_2 production rate reached 41.5 mmol H_2/l/h and 142.3 mmol H_2/h/g, respectively. This result suggests that under proper conditions T. celere is able to produce hydrogen at high yield and production rate.