title: Response of a three-stage process for PHA production by mixed microbial cultures to feedstock shift: impact on polymer composition.
abstract: Polyhydroxyalkanoates (PHA) can be produced by mixed microbial cultures (MMC) using a three-stage process. An attractive feature of MMC for PHA production is the ability to use waste/surplus feedstocks. In this study, the effect of a feedstock shift, mimicking a seasonal feedstock scenario and/or as a strategy for controlling polymer composition, on a MMC PHA production process was assessed using cheese whey (CW) and sugar cane molasses (SCM) as model feedstocks. The acidogenic stage responded immediately to the feedstock shift by changing the fermented products profile, with acetate and butyrate being the main acids produced from CW, while for SCM propionate and valerate were the dominant products. The fermentation process was then quite stable during long term operation. The PHA culture selection stage also responded quickly to the fermented feestocks shift, generating a polymer whose composition was linearly dependent on the concentration of HV and HB precursors produced in the acidogenic stage. The selected culture reached a maximum PHA content of 56% and 65% with fermented SCM and CW, respectively. Mixing fermented CW and SCM, in equal volume proportions, demonstrated the possibility of using different fermented feedstocks for tailoring polymer composition.
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Anouk F
authors.initials: AF
authors.lastname: Duque
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Catarina S S
authors.initials: CS
authors.lastname: Oliveira
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Inês T D
authors.initials: IT
authors.lastname: Carmo
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Gouveia
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Filipa
authors.initials: F
authors.lastname: Pardelha
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Ramos
authors.affiliation: CQFB-REQUIMTE, Departamento de Química, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. Electronic address: amr@dq.fct.unl.pt.
authors.forename: Maria A M
authors.initials: MA
authors.lastname: Reis
mesh_terms: D000143:Acids / Q000378:metabolism; D000693:Anaerobiosis / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D005285:Fermentation / Q000187:drug effects; D010100:Oxygen / Q000494:pharmacology; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis*; D031786:Saccharum / Q000187:drug effects / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014631:Valerates / Q000378:metabolism
chemical_list: D000143:Acids; D054813:Polyhydroxyalkanoates; D014631:Valerates; D010100:Oxygen