Production of citric acid by Aspergillus niger immobilized in Detarium microcarpum matrix

Abstract

Aims: This study investigated the potential use of Detarium microcarpum as a support matrix for the immobilization offungal cell and its subsequent use in the production of citric acid.Methodology and results: Conidia of Aspergillus niger were immobilized on Detarium microcarpum matrix crosslinkedwith glutaraldehyde (2.5% v/v). Effects of various immobilized conditions on citric acid yield were determined. Citric acidproduction was optimum at 9% gel concentration, 5.0 mm bead size and 400 mg spore load. Higher citric acid yield (82g/L) was obtained by immobilized cells while free cells gave (61 g/L). Immobilized gels were stable for 15 days in thefermentation medium and retained about 75% of initial yield after five repeated cycles.Conclusion, significance and impact of study: This study therefore shows that D. microcarpum is a novel matrix forcell immobilization and will enhance production of citric acid in batch system.

Keywords

• Detarium microcarpum
• Aspergillus niger
• Cassava whey