Extraction of polyhydroxyalkanoates from mixed microbial cultures: Impact on polymer quality and recovery

•PHA-producing MMCs are more resistant than single strain cultures to cell breakage.•Standard PHA extraction protocols are ineffective on MMCs.•Total costs of PHA production could be affected by PHA extraction protocols.•PHA extraction protocols on MMCs are strictly connected to polymer properties.

Polyhydroxyalkanoates (PHAs) can be extracted from mixed microbial cultures (MMCs) by means of dimethyl carbonate (DMC) or combination of DMC and sodium hypochlorite (NaClO). The protocol based on DMC, a green solvent never used before for the extraction of PHAs from MMC, allows an overall polymer recovery of 63%; also the purity and the molecular weight of the recovered polymers are good (98% and 1.2 MDa, respectively). The use of NaClO pretreatment before DMC extraction increases the overall PHA recovery (82%) but lowers the mean molecular weight to 0.6–0.2 MDa. A double extraction with DMC results to be the method of choice for the recovery of high quality PHAs from attractive but challenging MMCs.