Oxalic Acid Production by Aspergillus Niger

Oxalic acid produced by Aspergillus niger under submerged conditions in this work. Optimization done with different sources of carbon, nitrogen, minerals and at different pH then biomass production done of Aspergillus niger under submerged conditions for 7 days at room temperature. Further supernatant taken for titration and mycelium for oxaloacetate acetylhydrolase determination by SDS-PAGE. KEY WORD: Oxalic acid, Aspergillus niger,Submerged fermentation, SDS-PAGE *Corresponding author MANISH KUMAR Department of Biochemistry & Biochemical Engineering Sam Higginbottom Institute of Agriculture, Technology & Sciences Allahabad-211007, India Int J Pharm Bio Sci 2013 Jan; 4(1): (B) 828 834 This article can be downloaded from www.ijpbs.net B 829 INTRODUCTION Oxalic acid is produced by a variety of fungi, including saprophytic and phytopathogenic species. In phytopathogenic fungi it is believed to play a role in pathogenesis, facilitating plant cell wall degradation. In saprophytic Species, such as Aspergillus niger, the role of oxalic acid production is less clear, but may also be related to mobilizing substrates from plant cell wall polysaccharides, e.g. pectin. In Aspergillus niger and in a number of other fungi, as well as in some Streptomyces species, the current evidence favours production of oxalic acid by a Mn dependent enzyme, oxaloacetate acetylhydrolase (EC 3.7.1.1). In Aspergillus niger this enzyme is localized in the cytoplasm, where it catalyses the following reaction: Oxaloacetate oxalate + acetate. Second pathway should exist in Aspergillus niger which generates oxalate from pentoses via glycolate and glyoxylate as intermediates. This route requires operation of glyoxylate dehydrogenase as the final step to oxidize glyoxylate to oxalate, but attempts to measure glyoxylate oxidizing enzymes in extracts of Aspergillus niger that produced oxalate were unsuccessful. The biosynthesis of oxalic acid seems to fit the general strategy of Aspergillus niger and other fungi to acidify their environment via an extracellular process involving glucose oxidase, by secreting organic acids which first accumulate intracellularly or by a combination of these processes. Aspergillus niger is a very efficient oxalic acid producer. Production of 13 g oxalic acid/l from 20 g sugar/l in 45h . Production of 38 g oxalic acid. Which is close to the solubility of sodium oxalate using a fedbatch process at pH 6 with sucrose as the carbon source. Oxalic acid produced by this pathogenic fungus played an essential role in its pathogenic capabilities, another pathogenic fungus infecting a wide range of plant species is Sclerotinia sclerotiorum. During infection, the fungus produces high levels of a necrosis phytotoxin identified as oxalic acid. The role of oxalic acid in the pathogenicity process is still unclear. However, oxalic acid may have a number of functions in the infection process including chelating calcium from the cell was thus making the pectic fraction more available to fungal hydrolases, and providing an acid pH needed for maximum activity of the wall degrading enzymes released by the pathogenic fungus.