ENHANCED HYDROGEN-PRODUCTION FROM AROMATIC-ACIDS BY IMMOBILIZED CELLSOF RHODOPSEUDOMONAS-PALUSTRIS

Cells of the purple non-sulphur bacterium Rhodopseudomonas palustris D SM 131 were immobilized in agar, agarose, K-carrageenan or sodium algi nate gel. With alginate beads, prepared by an emulsion technique, and an optimal cell load of 10 mg dry weight/ml gel, the hydrogen producti on from aromatic acids was doubled as compared to that resulting from liquid cultures. Hydrogen yields of 60%, 57%, 86% or 88% of the maxima l theoretical value were obtained from mandelate, benzoylformate, cinn amate or benzoate respectively. Benzoate concentrations above 16.5 mM were inhibitory. During a period of 55 days the process of hydrogen ev olution with immobilized cells was repeated in five cycles with slowly decreasing efficiency.