Characteristics of a new photosynthetic bacterial strain for hydrogen production and its application in wastewater treatment

The optimal conditions for ZX-5, a newly isolated PNS bacterial strain, to produce hydrogen and the potential for it to treat wastewater were investigated. The strain could grow and produce hydrogen at pH 5.5–9.5, and it was able to adjust the pH value to about 7 during photo-fermentation by itself. ZX-5 could use 22 tested carbon sources for growth, and 15 of these carbon sources to produce hydrogen. The hydrogen conversion efficiencies of ZX-5 from succinate, lactate, butyrate, malate, acetate, pyruvic acid, propionate, d-mannitol and glucose were 89.7, 81.5, 71.5, 78.8, 69.0, 72.6, 61.9, 64.5, and 52.6%, respectively. The highest hydrogen-producing rate of 118 ml/l h was observed when butyrate was used as a carbon source. Relatively high efficiencies for reducing chemical oxygen demand (>80%>80%) and hydrogen production were achieved when ZX-5 was used for photo-fermentation of succinate wastewater, or effluents from dark fermentation of wastewater from a fuel ethanol manufacturer or kitchen waste. The concentration of total fatty acids was <0.001%<0.001% after photo-fermentation by ZX-5. The above results suggest that ZX-5 would possess the potential for hydrogen production while treating wastewater.