Biotransformation of palm oil wastewater to scl- and mcl-polyhydroxyalkanoates by mixed microbial consortia using different nitrogen and phosphorus sources

Polyhydroxyalkanoates (PHA) with short-chain-length (scl-PHA) and medium-chain-length (mcl-PHA) was accumulated by mixed microbial cultures (MMCs) using enzymatically pretreated palm oil wastewater as a feedstock. The effects of different nitrogen and phosphorus sources on the cell growth, PHA yield, monomer composition, and microbial communities were investigated. The results showed that NH4Cl and Na2HPO4 were the most suitable nitrogen and phosphorus sources for mcl-PHA from palm oil wastewater using MMCs. The monomer contents of PHA were significantly changed under different nitrogen and phosphorus sources. The maximum PHA yield of 805 mg COD/L was obtained under the C/N ratio of 33 and C/P ratio of 100. Moreover, 1.8 kg COD of palm oil waste was converted into 0.53 kg COD of PHA. Bacteria genera had no obvious effect on the microbial community under different phosphorus sources, but had an important effect on its relative abundance.