P92: Production of succinate from soybean carbohydrates using engineered E. coli

Succinate produced by fermentation represents a potential route to the production of commodity chemicals from renewable feed stocks. Succinate is widely used in industry as additive in food and pharmaceuticals, as well as a precursor of biodegradable polymers, surfactants, and synthetic resin. Soybeans, an important agriculture feedstock, are a major ingredient in nonruminant animal diets which contain up to 35-40% carbohydrates. In this study, aerobic and anaerobic succinate production from soybean carbohydrates using engineered E. coli strains HL27659k (pKK313) (pRU600) and SBS550MG Cms243 (pHL413) (pRU600) is reported, respectively. The strain HL27659k (pKK313) (pRU600) produced 36 mM and 59 mM succinate from 11 mM and 21 mM raffinose with molar succinate yield of 3.25 and 2.74, respectively, in 24 hr under aerobic condition. The minor byproducts were formate (0-1.5 mM), fumarate (1.5-2 mM) and malate (1.5-2.6 mM). Soluble carbohydrates were extracted from soybean meal and hydrolyzed using dilute acid pretreatment. The hydrolysate containining 15 mM raffinose, 16 mM sucrose, 50 mM glucose, and 64 mM galactose was used to examine succinate production in shake flasks. The strain HL27659k (pKK313) (pRU600) consumed 130 mM of total hexose sugar and produced 98 mM succinate aerobically with 0.75 mol/mol succinate yield. The strain SBS550MG Cms243 (pHL413) (pRU600) anaerobically produced 165 mM succinate from 135 mM of total hexose sugar with 1.22 mol/mol succinate yield. The results of this study showed remarkable potential for large-scale aerobic and anaerobic succinate production using soybean feedstock. The project was supported by the United Soybean Board.