Bio-Prospecting for Improved Hydrogen-Producing Organisms

Abstract : The discovery of cyanobacteria that produce high amounts of hydrogen (H2) could lead to more efficient H2 production in engineered systems. H2 oxidizing chemolithotrophs (knallgas bacteria) utilize H2 as electron donor and oxygen as electron acceptor. The goal was to determine whether H2 exchange occurs between knallgas bacteria and cyanobacteria, and whether knallgas bacteria can be used to detect cyanobacteria that overproduce H2. Culture-dependent and -independent approaches were used to investigate interactions between knallgas bacteria and cyanobacteria. The techniques provided sensitive, reproducible assays for novel hydrogenases and knallgas bacteria and detected the H2 flux between cyanobacteria and knallgas bacteria. Application of the techniques to natural microbial mats has not yet yielded clear evidence of such interspecies exchange in natural ecosystems. The results suggest that H2 exchange between cyanobacteria and knallgas bacteria is possible, but the effectiveness of knallgas bacteria as indicators of H2 producing cyanobacteria may be limited because our understanding of H2 flux in microbial communities is incomplete. The potential for other bacteria and other hydrogenases to consume H2 suggests a wider net be cast to better understand H2 flux in microbial systems.