Gluconic acid production by Aspergillus terreus

• Published in: Letters in applied microbiology Vol. 51; no. 3; pp. 252 - 257
• Main Authors: Dowdells, C, Jones, R.L, Mattey, M, Benčina, M, Legiša, M, Mousdale, D.M
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.09.2010; Blackwell Publishing Ltd; Blackwell
• Subjects: Aspergillus - metabolism; Aspergillus niger; Aspergillus terreus; Biological and medical sciences; Biotechnology - methods; Carbon - metabolism; Culture Media - chemistry; Fermentation; Fundamental and applied biological sciences. Psychology; Gluconates - metabolism; gluconic acid; Glucose - metabolism; glucose oxidase; Hydrogen-Ion Concentration; Industrial Microbiology; Microbiology; Phosphofructokinase-1 - genetics; Phosphofructokinase-1 - metabolism; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Fungi; Gluconic acid; Glucose oxidase; Enzyme; Applied microbiology; Production; Fungi Imperfecti; Oxidoreductases; Aspergillus terreus; Fermentation
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1111/j.1472-765X.2010.02890.x

Aspergillus terreus produces itaconic acid at low pH but lovastatin and other secondary metabolites at higher pH in the fermentation. The utilization of glucose as a carbon substrate was investigated for secondary metabolite production by A. terreus. With a starting pH of 6·5, glucose was rapidly metabolized to gluconic acid by the wild-type strain and by transformants harbouring Aspergillus niger genes encoding 6-phosphofructo-1-kinases with superior kinetic and regulatory properties for bioproduction of metabolites from glucose. On exhaustion of the glucose in batch fermentations, the accumulated gluconic acid was utilized as a carbon source. A novel pathway of glucose catabolism was demonstrated in A. terreus, a species whose wild type is, without any strain development, capable of producing gluconic acid at high molar conversion efficiency (up to 0·7 mol mol⁻¹ glucose consumed). Aspergillus terreus is a potential novel producer organism for gluconic acid, a compound with many uses as a bulk chemical. With a new knowledge of glucose catabolism by A. terreus, fermentation strategies for secondary metabolite production can be devised with glucose feeding using feedback regulation by pH.