Biological hydrogen production by extremely thermophilic novel bacterium Thermoanaerobacter mathranii A3N isolated from oil producing well

Hydrogen producing novel bacterial strain was isolated from formation water from oil producing well. It was identified as Thermoanaerobacter mathranii A3N by 16S rRNA gene sequencing. Hydrogen production by novel strain was pH and substrate dependent and favored pH 8.0 for starch, pH 7.5 for xylose and sucrose, pH 8.0–9.0 for glucose fermentation at 70 °C. The highest H2 yield was 2.64 ± 0.40 mol H2 mol glucose at 10 g/L, 5.36 ± 0.41 mol H2 mol – sucrose at 10 g/L, 17.91 ± 0.16 mmol H2 g – starch at 5 g/L and 2.09 ± 0.21 mol H2 mol xylose at 5 g/L. The maximum specific hydrogen production rates 6.29 (starch), 9.34 (sucrose), 5.76 (xylose) and 4.89 (glucose) mmol/g cell/h. Acetate-type fermentation pathway (approximately 97%) was found to be dominant in strain A3N, whereas butyrate formation was found in sucrose and xylose fermentation. Lactate production increased with high xylose concentrations above 10 g/L.

► A novel thermophilic strain identified as Thermoanaerobactermathranii A3N was isolated from oil well. ► The strain was characterized for hydrogen production under thermophilic conditions. ► The strain showed thermophilic hydrogen production from starch and sugars. ► The acetate-type fermentation pathway dominated for hydrogen production in the strain.