Photofermentation of tequila vinasses by Rhodopseudomonas pseudopalustris to produce hydrogen

Hydrogen production by photofermentation of tequila vinasses (VT) was studied using Rhodopseudomonas pseudopalustris DSM 123. To the best of our knowledge this is the first report on hydrogen production by photofermentation on VT. Hydrogen production was doubled on VT (260 m$props_value{literPattern}/L) as compared to a synthetic medium. Storing VT changed its chemical composition; however, in photofermentations of a sixty-day old stock, growth and hydrogen production were similar to fresh VT. The periodic displacement of hydrogen with nitrogen resulted in a three-fold increase in both hydrogen and growth of R. pseudopalustris (860 mL H2/L and 4.5 g/L respectively) as compared to non-displaced headspace. Hydrogen almost doubled at a light intensity of 270 W/m2 (2249 mL H2) as compared to 68 W/m2. In dark-light cycles, biomass and hydrogen production were highest with continuous illumination. The potential of VT to produce hydrogen in high amounts using R. pseudopalustris has been demonstrated.