English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Penicillium simplicissimum excreted more than 100 mmol citric acid l-1 [2.9 mmol (g dry wt)-1; 9 d] if an industrial filter dust (&gt; 50% ZnO) providing a high extracellular buffering capacity was present in the medium. A similar specific [2 mmol (g dry wt)-1], but lower absolute (26 mmol l-1), citric acid excretion occurred in the absence of an extracellular buffer and if amino acids or urea were used as nitrogen source. P. simplicissimum excreted no citric acid under conditions where Aspergillus niger produces citric acid (deficiency of trace elements, low pH and reduced biomass formation). Citric acid excretion by P. simplicissimum always paralleled biomass formation and occurred in a pH range between 4 and 7. This indicated that different imbalances of metabolism were responsible for citric acid excretion in A. niger and P. simplicissimum. However, provided a high extracellular buffering capacity was present, the response of the Penicillium system to different carbon and nitrogen sources was similar to the Aspergillus system. In contrast, the metals iron and copper had virtually no effect on citric acid excretion compared with A. niger. Estimation of intracellular citric acid, as well as the effects of the uncoupler 2,4-dinitrophenol, and the H(+)-ATPase inhibitor sodium orthovanadate, led to the conclusion that the buffer-stimulated citric acid efflux was dependent on metabolic energy and an energized plasma membrane, respectively. Despite similarities to the Aspergillus system, a different mechanism for buffer-stimulated citric acid excretion by P. simplicissimum seems probable.

Influence of medium components and metabolic inhibitors on citric acid production by Penicillium simplicissimum