Polyhydroxyalkanoate synthesis from primitive components of organic solid waste: Comparison of dominant strains and improvement of metabolic pathways

Abstract

The production of polyhydroxyalkanoate (PHA) from organic solid waste is a research hotspot. However, the allocation and conversion mechanism of different carbon resources between precursor routes and PHA metabolism remains unclear. We compared the PHA synthesis of dominant functional bacteria, Cupriavidus necator (C. necator) and Bacillus cereus (B. cereus), and replenished the metabolic pathways of primitive components (glucose, glycerin, lactic acid and propionic acid). The results showed that the PHA accumulation ability of C. necator (11.8%∼36.5%) was better than that of B. cereus (10.1%∼24.5%). C. necator had a faster rate of cell growth and PHA synthesis than B. cereus, which showed advantages in production efficiency. Most of the carbon of glucose flowed to the direct poly-3-hydroxybutyrate synthesis pathway. The carbon competition inhibited the PHA production from glycerin in C. necator, and cysteine metabolism was an effective pathway for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in B. cereus. There were active amino acid pathway and aminobutyric acid pathway in the utilization of lactic acid in C. necator and B. cereus, respectively. The yield of copolymer was limited by acetyl-CoA in propionic acid system. This study laid the foundation for exploring the PHA synthesis from the components of organic solid waste.