Biological Production of Succinic Acid Using Cull Peach Medium: Effects of Corn Steep Liquor Supplement and Hydrogen Sparging

Abstract. The feasibility of using cull peach, which is an agricultural waste generated in large quantities in the U.S. (13,000 MT in 2012), as a medium for the biological production of succinic acid by Escherichia coli AFP184 was investigated. The effects of corn steep liquor (CSL) supplement and exogenous hydrogen supply were also studied. Sucrose, the predominant but unmetabolizable sugar in cull peach medium, was converted to fermentable sugars (glucose and fructose) during sterilization and subsequently with invertase. Without CSL supplement, fructose consumption was incomplete and the final succinic acid concentration of 38.8 g L^-1 was achieved with a yield of 0.75 g g^-1 sugars consumed and a succinic acid:acetic acid molar ratio of 5.1:1. When CSL was supplemented to the medium, the final succinic acid concentration increased to 47.0 g L^-1 and the yield increased to 0.85 g g^-1 sugars consumed, but the succinic acid:acetic acid molar ratio remained at 5.6:1. With hydrogen sparging into the unsupplemented medium, the final succinic acid concentration increased to 45.5 g L^-1, the yield increased to 0.84 g g^-1 sugars consumed, and the succinic acid:acetic acid molar ratio increased to 7.7:1.