Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) co-produced with l-isoleucine in Corynebacterium glutamicum WM001

Abstract

Co-production of polyhydroxyalkanoate (PHA) and amino acids makes bacteria effective microbial cell factories by secreting amino acids outside while accumulating PHA granules inside. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is one of the PHAs with biocompatibility and fine mechanical properties, but its production is limited by the low level of intracellular propionyl-CoA. l -Isoleucine producing Corynebacterium glutamicum strain WM001 were analyzed by genome and transcriptome sequencing. The results showed that the most over-expressed genes in WM001 are relevant not only to l -isoleucine production but also to propionyl-CoA accumulation. Compared to the wild-type C. glutamicum ATCC13869, the transcriptional levels of the genes prpC2, prpD2, and prpB2 , which are key genes relevant to propionyl-CoA accumulation, increased 2 6.7 , 2 5.8 , and 2 8.4 -folds in WM001, respectively; and the intracellular level of propionyl-CoA increased 16.9-fold in WM001. When the gene cluster phaCAB for PHA biosynthesis was introduced into WM001, the recombinant strain WM001/pDXW-8- phaCAB produced 15.0 g/L PHBV with high percentage of 3-hydroxyvalerate as well as 29.8 g/L l -isoleucine after fed-batch fermentation. The maximum 3-hydroxyvalerate fraction in PHBV produced by WM001/pDXW-8- phaCAB using glucose as the sole carbon source could reach 72.5%, which is the highest reported so far. Genome and transcriptome analysis showed that C. glutamicum WM001 has potential to accumulate l -isoleucine and propionyl-CoA pool. This was experimentally confirmed by introducing the phaCAB gene cluster into WM001. The recombinant strain WM001/pDXW-8- phaCAB produced high levels of PHBV with high 3-hydroxyvalerate fraction as well as l -isoleucine. Because of its high level of intracellular propionyl-CoA pool, WM001 might be used for producing other propionyl-CoA derivatives.