Biohydrogen Production Using Immobilized Cells of Hyperthermophilic Eubacterium Thermotoga neapolitana on Porous Glass Beads

Biohydrogen fermentation using immobilized cells of Thermotoga neapolitana on porous glass beads was successfully performed in a continuously stirring anaerobic bioreactor (CSABR) system operated under the conditions of temperature 75 o C, pH 7.0 and 5.0 g/L pentose (xylose) and/or hexose (glucose). The results showed that both batch and fed-batch cultivations of the immobilized cells were effective for high-rate and high-yield H 2 production compared with those from the free cells. In the batch cultivation, the H 2 production rate and H 2 production yield of the immobilized cells, respectively achieved the highest values of 5.64 ± 0.19 mmol-H 2 L -1 h -1 and 1.84 ± 0.1 mol H 2 /mol xylose, which were almost 1.7-fold and 1.3-fold higher than those with free cells. The maximum H 2 production rate ­ (6.91 mmol L -1 h -1 ) in this proposed method was 1.5-fold higher than that of free cells in the fed-batch cultivation.