Polyhydroxyalkanoates production from lactic acid fermentation broth of agricultural waste without extra purification: The effect of concentrations

Polyhydroxyalkanoates (PHAs) production can potentially realize the high-value utilization of agricultural wastes and reduce the cost of commercial PHA production. This study aimed to explore the feasibility of converting lactic acid (LA) fermentation broth from agricultural wastes into PHAs. The LA fermentation broth from the co-fermentation of swine manure and apple waste and the simulated LA solution were used as feedstock. Effects of different LA concentrations of these feedstocks were explored in the PHA production. Results showed that PHA content and PHA yield of LA fermentation broth decreased with increase of concentrations of both feedstocks. The LA fermentation broth with LA concentration of 2420.8 mg/L resulted in the highest PHA content (55.4% dry cell weight) and PHA yield (0.48 g PHA-COD/g CODini). In addition, LA fermentation broth with LA concentration of 25084.5 mg/L had the highest concentration of PHA (1.04 g/L). The dominant bacteria for PHA production using both feedstocks were recognized as P. aminovorans. Using swine manure and apple waste to synthesize PHA could have the potential high benefits of economy and environment.