Development of a glutaric acid production system equipped with stepwise feeding of monosodium glutamate by whole-cell bioconversion

In the bioproduction of glutaric acid, an emerging bioplastic monomer, α-ketoglutaric acid (α-KG) is required as an amine acceptor for 4-aminobutyrate aminotransferase (GabT)-driven conversion of 5-aminovalerate (5-AVA) to glutarate semialdehyde. Herein, instead of using expensive α-KG, an indirect α-KG supply system was developed using a relatively cheap alternative, monosodium glutamate (MSG), for L-glutamate oxidase (Gox)-based whole-cell conversion. Using 200 mM 5-AVA and 30 mM MSG initially with Gox, 67.1 mM of glutaric acid was produced. By applying the stepwise feeding strategy of MSG, the glutaric acid production capability was increased to 159.1 mM glutaric acid with a conversion yield of 79.6%. In addition, a buffer-free one-pot reaction from L-lysine was also applied in a 5 L bioreactor to evaluate its industrial applicability, resulting in a conversion yield of 54.2%. The system developed herein might have great potential for the large-scale, economically feasible production of glutaric acid by whole-cell conversion.