Production of Hydrogen by Thermophilic Cyanobacterium Synechococcus sp. strain H-1

Abstract

The production of molecular hydrogen (H₂) from water by hydrogenase of thermophilic cyanobacterium Synechococcus sp. strain H-1 has been studied by following the time courses of hydrogen concentration in gas-phase, cell mass concentration and cellular content of D-glucose in dark batch reactions at temperatures ranging from 313 to 333 K. The anaerobic, dark, NO₃- starvation, neutral or alkaline pH and shaking condition were found to be a prerequisite for H₂ production. Strain H-1 could multiply and produce hydrogen at all temperature studied. The linear relation between hydrogen production and glucose consumption was observed and the yield coefficient of hydrogen in terms of D-glucose consumption was 71, 115 and 146 at initial concentration of cell mass of 0.75, 2.5 and 9.5 g·L^-1, respectively. The activation energies for the maximum specific rates of cell mass growth, D-glucose consumption and hydrogen production are found to be 62, 12.6 and 122 kJ·mol^-1, respectively. The maximum specific hydrogen production rate is found to be 0.09 μmol·mg-chl a^-1·h^-1 at 328 K and comparable to that reported in non-nitrogen-fixing unicellular cyanobacteria. It is concluded that utilization of thermophilic Synechococcus sp. strain H-1 for hydrogen production is beneficial since contamination risk of mesophilic bacteria is low.