Autotrophic production of polyhydroxyalkanoates using acidogenic-derived H2 and CO2 from fruit waste
Paolo Costa, Marina Basaglia, Sergio Casella, Christian Kennes, Lorenzo Favaro, María C. Veiga
Abstract
The environmental concerns regarding fossil plastics call for alternative biopolymers such as polyhydroxyalkanoates (PHAs) whose manufacturing costs are however still too elevated. Autotrophic microbes like Cupriavidus necator, able to convert CO2 and H2 into PHAs, offer an additional strategy. Typically, the preferred source for CO2 and H2 are expensive pure gases or syngas, which has toxic compounds for most PHAs-accumulating strains. In this work, for the first time, H2 and CO2 originating from an acetogenic reactor were converted autotrophically into poly(3-hydroxybutyrate) P(3HB). During the first stage, a mixed microbial community continuously catabolized melon waste into H2 (26.7 %) and CO2 (49.2 %) that were then used in a second bioreactor by C. necator DSM 545 to accumulate 1.7 g/L P(3HB). Additionally, the VFAs (13 gCOD/L) produced during acetogenesis were processed into 2.7 g/L of P(3HB-co-3HV). This is the first proof-of-concept of using acetogenic-derived H2 and CO2 from fruit waste to produce PHAs.