Mechanical Evaluation of Solvent Casted Poly(3-hydroxybutyrate) Films Derived from the Storage Polyesters Produced by Halomonas elongata DSM 2581T

Poly(3-hydroxybutyrate) (PHB) is a natural and biodegradable polyester which represents an alternative to replace conventional plastics in the packaging field. PHB production is currently limited owing to the high production costs. Early reports point to halotolerant and halophilic bacteria as feasible candidates for cost-effective production of PHB. Therefore, this work aimed at the synthesis of PHB using the extremely halotolerant Halomonas elongata DSM 2581T in nonsterile conditions and further mechanical evaluation of generated PHB films. H. elongata produced 2.96 g/L PHB after 72 h of incubation in a nonsterile medium supplemented with 1% w/v D-glucose and 0.1% w/v yeast extract at high salinity (8% w/v NaCl). The crotonic acid assay and 1H-NMR confirmed that the extracted polyester was PHB. The 2.7-µm thick 1% w/v PHB films generated using the polyester extracted from H. elongata indicated a higher hardness (43.78 MPa), Young`s Modulus (1.28 GPa), tensile stress (9.99 MPa) and tensile strain 1.39% than those measured for the films fabricated from commercially available PHB and poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Overall, this study is the first report on the mechanical evaluation of a PHB film generated from the polyester recovered from H. elongata cultured at high salinity combined with nonsterile settings. In perspective, by producing PHB films from polyesters synthesized by H. elongata under nonsterile conditions it is possible to achieve mechanical properties required for the development of eco-friendly packaging products.