The Production of Organic Acids

Abstract

The production of organic acids covers two aspects: first, the metabolic pathways involved in the biosynthesis, and, second, the industrial process strategy adopted. The review seeks to show the underlying biochemical similarities in the biosynthesis of organic acids and the resulting similarities in the commercial processes. Two groups of acids are defined, those with a "long" biosynthetic path from glucose, involving much of the glycolytic pathway and the tricarboxylic acid cycle, and those acids with a "short pathway", essentially a biotransformation of glucose. The regulation of the pathways and the future developments in metabolic control theory and genetic manipulations relating to them are considered. The organisms used industrially are also limited, Aspergillus sp. and Candida yeasts; again the underlying metabolic similarities lead to similar strategies for all the acids discussed.

Overview of citric acid production from Aspergillus niger

“…Monosaccharides and disaccharides are the preferred carbon source as they are more rapidly metabolized by the fungus than polysaccharides, thus producing higher yield (Mattey 1992). Polysaccharides are not suitable as the raw material as the decomposition process takes too long to meet the rate of sugar catabolism necessary for the production of citric acid.…”

Organic Acid Production by Filamentous Fungi

“…The product is transported out of the mitochondrion and finally out of the cell. The mechanisms have been exhaustively reviewed Mattey, 1992;Ruijter et al, 2002). The accumulated evidence on the biochemistry of citric acid production in A. niger will be presented with attention to possible targets for improvement.…”

Oxalic acid production by Aspergillus niger: an oxalate-non-producing mutant produces citric acid at pH 5 and in the presence of manganese

“…), which is well above the concentration recommended in citric acid fermentation ( 1 p.p.b. ;Mattey, 1992). To test whether NW185 was sensitive to Mn# + we again performed fermentation in PM at pH 5 using sucrose, but 50 µM MnCl # (2n7 p.p.m.)…”