An innovative multi-enzymatic system for gluconic acid production from starch using Aspergillus niger whole-cells

The use of multi-enzymatic systems for the industrial production of chemical compounds is currently considered an important green tool in synthetic organic chemistry. Gluconic acid is a multi-functional organic acid widely used in the chemical, pharmaceutical, food, textile, and construction industries. Its industrial production from glucose by fermentation using Aspergillus niger has drawbacks including high costs related to cell growth and maintenance of cell viability. This study presents an innovative one-step multi-enzymatic system for gluconic acid production from starch using Aspergillus niger whole-cells in association with amylolytic enzymes. Using soluble starch as substrate, the following results were achieved for 96 h of reaction: 134.5 ± 4.3 g/L gluconic acid concentration, 98.2 ± 1.3 % gluconic acid yield, and 44.8 ± 1.4 gGA/gwhole-cells biocatalyst yield. Although the process has been developed using starch as raw material, the approach is feasible for any substrate or residue that can be hydrolyzed to glucose.