The Influence of Manganese Ions on Aspergillus niger Biomass and Citric Acid Biosynthesis in Repeated Fed Batch Fermentation

M. Berovič, M. Vodopivec and S. Milicic

Abstract
In citric acid technology absence of manganese ions in fermentation substrate is one of the most relevant requests. Presence of manganese ions higher than 1 μgl–1 could completely ruin citric acid biosynthesis initiating unproductive filamentous growth morphology and promoting isocitrate dehydrogenase activity in Tricarboxylic Acid Cycle. Running repeated fed batch process it was for the first time found that if fermentation process reach in batch fermentation its stationary growth phase in further continuation, as a repeated fed batch process, even feeding with a such high concentrations of manganese ions up to 200 μgl–1 does not effect any changes in fungal morphology either in cumulative biomass Xc or in cumulative citric acid Cc production.

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Keywords
Aspergillus niger, manganese ions, repeated fed batch, citric acid fermentation