Application of Bacillus cereus for synthesis of polyhydroxyalkanoates from industrial corn starch residue

Starch hydrolysate from corn is typically employed as a carbon source for citric acid production by Aspergillus niger. Enzymatic or acid hydrolysis of corn starch generates a corn starch residue (CSR), which represents a potential bio-fermentation carbon source. In addition, polyhydroxyalkanoates (PHAs) can be used as an alternative to traditional petrochemical plastics. In this study, the potential applications of CSR in microbial PHA production were investigated. Two Bacillus cereus strains, MG1 and MQ1, were isolated based on their ability to grow with CSR as the sole carbon source and their capacity for PHA accumulation. After introducing key genes involved in the PHA synthesis pathway and optimizing fermentation conditions, the PHA content of MG2 reached 61.61 % of the cell dry weight (CDW), representing the highest PHA content (CDW%) in B. cereus. To the best of our knowledge, this is the first report of PHA synthesis from CSR in B. cereus and provides a novel approach for the rational utilization of CSR.