Abstract

The cost of fermentable sugars added as a substrate is one major problem for economic lactic acid (LA) production. Old oil palm trunks (OPT) squeezed sap, the agricultural wastes on replanting and pruning of oil palm (Elaeis guineensis), contained mainly glucose and fructose as a potential feedstock to use as a vast carbon source for LA production. To improve the LA yield and productivity, various fermentation modes were performed by Lactobacillus rhamnosus ATCC 10863 using OPT sap as a basal medium. A modified constant feed mode of fed-batch and repeated fed-batch fermentation using undiluted OPT sap feed medium can achieve a high average LA concentration of 95.94 g/L, yield of 1.04 g/g, and productivity of 6.40 g/L/h) at 11 h cultivation time. It can also provide open and open repeated batch fermentation with an average LA concentration of 91.30 g/L, yield of 0.87 g/g, and productivity of 3.88 g/L/h at 21 h fermentation time.