High‐yield production of oxalic acid for metal leaching processes by Aspergillus niger

• Published in: FEMS microbiology letters 1994-06, Vol.119 (3), p.365-370
• Main Authors: Strasser, Hermann, Burgstaller, Wolfgang, Schinner, Franz
• Format: Article
• Language: English
• Subjects: Aspergillus niger; Aspergillus niger - metabolism; Biohydrometallurgy; Biohydrometallurgy. Microbial leaching; Biological and medical sciences; Biotechnology; Carbon source; Culture Media - chemistry; Fundamental and applied biological sciences. Psychology; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Hydrogen-Ion Concentration; Industrial applications and implications. Economical aspects; Industrial Microbiology - methods; Microbiology; Mycology; Oxalates - metabolism; Oxalic Acid; Speciation of Na‐oxalate; Stirred tank reactor; Sucrose
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.1994.tb06914.x

The complex‐forming compound oxalic acid can effectively solubilise metals such as aluminium, iron, lithium, and manganese. In order to produce high amounts of oxalic acid for biohydrometallurgical processes, it was the aim of this work to optimise oxalic acid production by Aspergillus niger, a fungus well known for its ability to produce oxalic acid. A. niger excreted 427 mmol oxalic acid 1−1 if it was cultivated in a pH‐controlled (pH 6.0) fed‐batch run in a 2‐1 stirred tank reactor. Sucrose and lactose permeate were suitable carbon sources for oxalic acid production. In sucrose medium, A. niger produced high amounts of gluconic and oxalic acids, whereas in lactose permeate medium only oxalic acid was produced. Cultivation in green syrup and molasses media lead to high yields of biomass, but low oxalic acid production (