Alginate encapsulated nanobio-hybrid system enables improvement of photocatalytic biohydrogen production in the presence of oxygen

Abstract

Bacterial encapsulation for the generation of fuels and other valuable chemicals through fermentation emerges as a novel biotechnological strategy that provides significant advantages over the use of free cells. In the present study, we established an optimal alginate encapsulated TiO2/Escherichia coli hybrid system by varying the initial concentrations of alginate (2–5%) and initial inoculum concentration (OD600 0.5–2.5) to form the hydrogel beads for efficient production of hydrogen in the presence of oxygen with the given visible-light intensity of 2000 W m−2. The maximum hydrogen production of 2.8 mmol H2/mmol glucose was obtained with hydrogel beads consisting of 4% sodium alginate and initial inoculum with a cell density of 1.5 OD600. Natural sunlight could also be used to produce hydrogen under the same optimized condition. The optimization of the encapsulated nano bio-hybrid system with respect to alginate and inoculum concentration allows for the enhancement of hydrogen production even in the presence of oxygen.