Enhanced itaconic acid production in Aspergillus niger using genetic modification and medium optimization

BMC Biotechnology

Research Article

An Li¹  Nina Pfelzer¹  Robbert Zuijderwijk²  Peter Punt² 

[1]TNO Microbiology and Systems biology, PO Box 360, 3700 AJ, Zeist, The Netherlands

[2]TNO Microbiology and Systems biology, PO Box 360, 3700 AJ, Zeist, The Netherlands

[3]Molecular Microbiology & Biotechnology Leiden University, Universiteit Leiden, Postbus 9500, 2300 RA, Leiden, Netherlands

关键词: High Performance Liquid Chromatography;    Itaconic Acid;    Dissolve Oxygen Tension;    Citric Acid Production;    Reference Medium;   

DOI  :  10.1186/1472-6750-12-57

 received in 2012-01-13, accepted in 2012-08-20,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundAspergillus niger was selected as a host for producing itaconic acid due to its versatile and tolerant character in various growth environments, and its extremely high capacity of accumulating the precursor of itaconic acid: citric acid. Expressing the CAD gene from Aspergillus terreus opened the metabolic pathway towards itaconic acid in A. niger. In order to increase the production level, we continued by modifying its genome and optimizing cultivation media.ResultsBased on the results of previous transcriptomics studies and research from other groups, two genes : gpdA encoding the glyceraldehyde −3-dehydrogenase (GPD) and hbd1 encoding a flavohemoglobin domain (HBD) were overexpressed in A. niger. Besides, new media were designed based on a reference medium for A. terreus. To analyze large numbers of cultures, we developed an approach for screening both fungal transformants and various media in 96-well micro-titer plates. The hbd1 transformants (HBD 2.2/2.5) did not improve itaconic acid titer while the gpdA transformant (GPD 4.3) decreased the itaconic acid production. Using 20 different media, copper was discovered to have a positive influence on itaconic acid production. Effects observed in the micro-titer plate screening were confirmed in controlled batch fermentation.ConclusionsThe performance of gpdA and hbd1 transformants was found not to be beneficial for itaconic acid production using the tested cultivation conditions. Medium optimization showed that, copper was positively correlated with improved itaconic acid production. Interestingly, the optimal conditions for itaconic acid clearly differ from conditions optimal for citric- and oxalic acid production.

【 授权许可】

CC BY   
© Li et al.; licensee BioMed Central Ltd. 2012