Fermentative Synthesis of Gluconic and Xylonic Acids from Hydrolyzed Palm Fronds Using Gluconobacter oxydans

The escalating demand for sustainable and eco-friendly production processes has necessitated the exploration of renewable resources for the synthesis of valuable chemicals. This study investigated the fermentative synthesis of gluconic acid (GA) and xylonic acid (XA) from hydrolyzed palm fronds by using Gluconobacter oxydans. The key variables examined included agitation speed, inoculum ratio, and composition of fermentation media. In a synthetic medium, maximum GA concentration reached 52.82 ± 12.88 g/L at 65 h using 150 rpm agitation and 15% (v/v) inoculation, while maximum XA concentration achieved 2.31 ± 1.43 g/L at 96 h using 220 rpm agitation and 9% (v/v) inoculation. In the hydrolysate medium, the maximum GA concentration was 3.24 ± 0.66 g/L at fermentation onset using 220 rpm agitation and 15% (v/v) inoculation, while the maximum XA concentration reached 0.62 ± 0.04 g/L at 24 h using 190 rpm agitation and 5% (v/v) inoculation. These findings demonstrate the feasibility of utilizing palm fronds as a renewable feedstock for the sustainable synthesis of high-value biochemicals, promoting waste valorization, and contributing to the advancement of a circular bioeconomy.