| Literature DB >> 9218559 |
A Netik1, N V Torres, J M Riol, C P Kubicek.
Abstract
The uptake as well as the export of citric acid by Aspergillus niger occur by active, deltapH-driven, H(+)-symport dependent systems. They are inhibited by nonmetabolizable tricarboxylic acid analogues and phthalic acid, and by several other mono-, di- and tribasic organic acids. However, citrate export could only be demonstrated in a mycelium cultivated under manganese-deficient growth conditions, whereas the uptake of citrate from the medium was only detectable upon precultivation of A. niger in a medium supplemented with Mn2+ ions. In addition, the uptake of citrate was dependent on the presence of Mn2+ ions in the assay, and inhibited by EDTA. This requirement for Mn2+ could also be partially fulfilled by Mg2+, Fe2+ or Zn2+, whereas Cu2+ ions inhibited citrate transport. The observed divergent effects of manganese ions on citrate uptake and citrate export may be a major reason for the well documented requirement for manganese deficiency of citric acid accumulation.Entities:
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Year: 1997 PMID： 9218559 DOI： 10.1016/s0005-2736(97)00032-1
Source DB: PubMed Journal: Biochim Biophys Acta ISSN： 0006-3002