Abstract: Polyhydroxyalkanoates（PHAs）is a natural macromolecule biomaterial synthesized in microorganisms. It can be used as a reserve material of microbial carbon source under excessive carbon sources and the condition of insufficient nitrogen and phosphorus. PHA is the best substitute for traditional petrochemical plastics because of its fine biocompatibility,biodegradability and thermal processing properties. With the development of PHA industrialization,4 generations of commercially produced PHA products（PHB,PHBV,PHBHx,and P3HB4HB）have been used in medicine,industry,agriculture,chemical industry and other fields,and become one of the most active research hotspots in the field of biomaterials. However,the issues of high cost of fermentation substrates and sterilization,low production efficiency and low product performance have not been effectively solved,thus it is difficult to maintain a greater competitiveness to petroleum-based plastics,which makes it particularly important to explore a low-cost method of synthesizing PHA. The main types and characteristics of PHAs and the hot fields of its industrialization are introduced. The research and development advances in low-cost synthetic PHA are reviewed,i.e.,scientists around the world have adopted strategies of constructing low-cost metabolic pathways,transforming production strains,using cheap fermentation substrates and improving fermentation process. It is aimed to provide a theoretical basis for PHA to replace petrochemical plastics in a low-cost and large-scale way at an early date.

Key words: polyhydroxyalkanoates, production cost, metabolic pathway, PHA application