One-pot strategy for co-production of microbial biomass and polyhydroxyalkanoates under salinity stress and high organic load

Using mixed microbial culture (MMC) to produce polyhydroxyalkanoates (PHA) from waste streams is cost-effective and sustainable. However, low biomass and PHA accumulation under certain conditions limit PHA yield. This study developed a one-pot synthesis process for both biomass and intracellular PHA content of MMC under salinity and high organic load, without nitrogen limitation, ensuring long-term operation and high PHA yield. After 18hours of cultivation with the substrate chemical oxygen demand (COD) of 20000±100mg/L, 20% inoculation amount, 0.8% substrate salinity and initial pH 8.0, the mixed liquor volatile suspended solids (MLVSS) increased from 0.69 to 6.64g/L, achieving a PHA content of 0.56±0.01g PHA/g VSS and volumetric productivity of 0.21±0.01g/(L•h). Real food waste fermentation leachate (FWFL) verification showed a higher MLVSS (7.10g/L) but a 10% reduced PHA content and productivity. Microbial analysis revealed that PHA-producers dominated throughout the 18-hour cultivation, with the continuous high relative abundance of phaC. This process simultaneously boosted biomass and PHA accumulation, enhanced the PHA yield and offered industrial potential.