A cost-effective, temperature dependent, control of H2 production period by Escherichia coli and using waste culture to detoxify the carcinogenic Cr6+

196Temperature dependency of the rate of hydrogen gas production by E. coli (Panel A) at 15 °C (closed triangles), 20 °C (open triangles), 25 °C (closed cubes), 30 °C (open squares), 35 °C (closed circles), 40 °C (open circles) and 45 °C (open cubes). Panel (B) shows the efficiency of hydrogen formation (columns I) and the maximum rate (columns II) at the log phase. Columns followed by the same letter (small letters are used for data columns of the hydrogen production efficiency while capital letters for columns of the maximum hydrogen formation rate) are not significantly different at LSD (P < 0.05). Panel (C) shows the total fermentation period at 30, 35 and 40 °C. Mean values and standard errors from three independent experiments are shown.