title: Effect of volatile fatty acids mixtures on the simultaneous photofermentative production of hydrogen and polyhydroxybutyrate.
abstract: Purple non-sulfur bacteria generate hydrogen and polyhydroxybutyrate (PHB) as a mechanism for disposing of reducing equivalents generated during substrate consumption. However, both pathways compete for the reducing equivalents released from bacteria growing under certain substrates, thus the formation of hydrogen or PHB is detrimental to the formation of each other. The effect of mixtures of acetic, propionic and butyric acids on the formation of H2and PHB was evaluated using Box-Behnken design. A bacterial community mainly constituted by Rhodopseudomonas palustris was used as inoculum. It was observed that the three volatile fatty acids had a significant effect on the specific PHB production. However, only the propionic acid had a significant effect on the specific H2production activity and the highest value was observed when acetate was the main component in the mixture. The maximum values for the specific PHB and hydrogen production rates were 16.4 mg-PHB/g-TSS/day and 391 mL-H2/g-TSS/day, respectively.
authors.affiliation: Laboratory for Research on Advanced Processes for Water Treatment, Instituto de Ingeniería, Unidad Académica Juriquilla, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, 76230, Querétaro, QRO, Mexico.
authors.forename: René
authors.initials: R
authors.lastname: Cardeña
authors.affiliation: Laboratory for Research on Advanced Processes for Water Treatment, Instituto de Ingeniería, Unidad Académica Juriquilla, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, 76230, Querétaro, QRO, Mexico.
authors.forename: Idania
authors.initials: I
authors.lastname: Valdez-Vazquez
authors.affiliation: Laboratory for Research on Advanced Processes for Water Treatment, Instituto de Ingeniería, Unidad Académica Juriquilla, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, 76230, Querétaro, QRO, Mexico. gbuitronm@ii.unam.mx.
authors.forename: Germán
authors.identifier: http://orcid.org/0000-0003-3975-7644
authors.initials: G
authors.lastname: Buitrón
mesh_terms: D005232:Fatty Acids, Volatile / Q000494:pharmacology*; D006859:Hydrogen / Q000378:metabolism*; D011091:Polyesters / Q000378:metabolism*; D012241:Rhodopseudomonas / Q000254:growth & development*
chemical_list: D005232:Fatty Acids, Volatile; D011091:Polyesters; D006859:Hydrogen
keywords: Hydrogen; Photofermentation; Polyhydroxybutyrate; Purple non-sulfur bacteria