Study Of Hydroden Production By Photofermentation From Different Organic ACID As Substrate

Hydrogen presents itself as an alternative fuel in the search for clean energy. One of the biological routes for hydrogen production is the photofermentation by purple non-sulfur photosynthetic bacteria. In general, these cells are able to synthesize hydrogen from organic acids. In this study, the potential of the H₂ production of Rhodopseudomonas palustris and Rhodobacter capsulatus strains was evaluated. The influence of organic acids (butyric, malic, lactic, propionic and acetic) as substrate was also studied at fixed ration of C/N of 35 mM : 1 mM, using sodium glutamate as nitrogen source. The results obtained from the fractional factorial design 2^5-1, based on variance analysis (ANOVA), showed that only the variables statistically significant at 90% confidence were malic acid and lactic acid for Rhodopseudomonas palustris and malic acid, lactic acid and acetic acid for Rhodobacter capsulatus. The results showed that Rhodopseudomonas palustris presented higher productivity (26.01 μmol/L.h) when malic, lactic and butyric acids were combined as substrate resulting in a conversion of 0.1151 (mol of H₂/mol substrate). For Rhodobacter capsulatus, the higher hydrogen production was verified when malic, lactic and propionic acids were combined (19.09 μmol/L.h) as substrate resulting in a conversion efficiency of 0.0068 (mol of H₂/mol substrate).

Acknowledgments: FAPEMIG, CNPq, CAPES and Vale S.A. by financial support.