Organic Acids

Zidwick, Mary Jo

doi:10.1016/b978-0-7506-9115-4.50017-6

Cited by 8 publications

(13 citation statements)

References 136 publications

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“…No stimulating e¡ect of Cu 2þ on citrate production could be observed in the presence of Mn 2þ . Since manganese was found to disturb citric acid accumulating pathways at different levels [1] these results seemed logical. An inhibitory e¡ect of copper on lipid biosynthesis of the cells was observed both in the presence of Mg 2þ and Mg 2þ /Mn 2þ , yet much more reduced lipid levels were recorded in mycelium grown in the medium with magnesium as a sole metal cation.…”

Section: Discussionmentioning

confidence: 99%

“…Citric acid fermentation has historically been known as one that is di⁄cult to control [1] and fundamental progress in commercial citric acid production was achieved only after the profound e¡ect of metal ions on the fungal metabolism was discovered. It was often reported that low amounts of Mn 2þ severely interfered with metabolic pathways leading to acid accumulation [2], while on the other hand copper was stated to be particularly e¡ective if added at the beginning of fermentation [3,4].…”

Section: Introductionmentioning

confidence: 99%

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The influence of metal ions on malic enzyme activity and lipid synthesis in Aspergillus niger

Jernejc

2002

FEMS Microbiology Letters

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In the presence of copper significant induction of citric acid overflow was observed, while concomitantly lower levels of total lipids were detected in the cells. Its effect was more obvious in a medium with magnesium as sole divalent metal ions, while in a medium with magnesium and manganese the addition of copper had a less pronounced effect. Since the malic enzyme was recognised as a supplier of reducing power in the form of reduced nicotinamide adenine dinucleotide phosphate for lipid biosynthesis, its kinetic parameters with regard to different concentrations of metal ions were investigated. Some inhibition was found with Fe 2þ and Zn 2þ , while Cu 2þ ions in a concentration of 0.1 mM completely abolished malic enzyme activity. The same metal ions proportionally reduced the levels of total lipids in Aspergillus niger cells. A strong competitive inhibition of the enzyme by Cu 2þ was observed. It seemed that copper competes with Mg 2þ and Mn 2þ for the same binding site on the protein.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The influence of metal ions on malic enzyme activity and lipid synthesis in Aspergillus niger

Jernejc

2002

FEMS Microbiology Letters

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“…The widespread use of fungi in biotechnology stems from the unique ability of fungi to economically produce many different types of products, including some of the most important antibiotics (e.g., penicillins and cephalosporins; Masurekar, 1991;Rambosek, 1991), commodity chemicals (e.g., citric acid; Zidwick, 1991), and commercial enzymes (e.g., proteases and amylases; Bigelis, 1991;Arora et al, 1992). For the production of enzymes and therapeutic proteins, fungi offer several advantages over other types of cells.…”

Section: Introductionmentioning

confidence: 99%

Fungal morphology and fragmentation behavior in a fed-batchAspergillus oryzae fermentation at the production scale

Shukla

Fordyce

et al. 2000

Biotechnol. Bioeng.

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“…Zidwick (1992) reported that the major difference between citric and gluconic acid fermentation was associated with the pH of the fermentation. When the pH values were in the range of 2.5-3.5, citric acid was produced, and for pH values greater than 5, gluconic acid was produced.…”

Section: Column Studymentioning

confidence: 98%

Fungal Generation of Organic Acids for Removal of Lead from Contaminated Soil

Ousmanova

Parker

2006

Water Air Soil Pollut

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The use of solid-state fermentation (SFF) of low cost substrates by fungal species to generate organic acid solutions for washing of lead from a contaminated soil was evaluated in this study. SFF filtrates were generated by fermentation of four substrates (corn cobs, apple pomace, rice and hay) with three fungal species (Aspergillus niger NRRL 2001 (A. niger 1), Aspergillus niger ATCC 64065 (A. niger 2), Aspergillus foetidus NRRL 337) at three fermentation times. The concentration and speciation of organic acids of the filtrates was found to be a function of the substrate type, the fungal species and the fermentation time. Fermentation of rice resulted in the highest concentrations of citric acid while fermentation of corn cobs, apple pomace and hay tended to generate oxalic acid with an increasing fraction of this acid as the fermentation progressed. Batch extraction tests that employed the SSF filtrates revealed that soluble lead concentrations as high as 35 mg/l could be achieved. Filtrates containing elevated concentrations of citric acid resulted in the greatest lead extraction while oxalic acid inhibited solubilization. Due to the buffering of pH that was provided by the soil in the batch tests this factor did not appear to influence lead extraction. Lead extraction was observed over an extended period of time in a column test. Lead extraction was strongly influenced by the pH of the soil column and less strongly influenced by the organic acid content of the SSF filtrate. The speciation of organic acids was substantially modified from primarily citric acid in the SSF filtrate to gluconic acid in the soil column discharge.

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Organic Acids

Cited by 8 publications

References 136 publications

The influence of metal ions on malic enzyme activity and lipid synthesis in Aspergillus niger

The influence of metal ions on malic enzyme activity and lipid synthesis in Aspergillus niger

Fungal morphology and fragmentation behavior in a fed-batchAspergillus oryzae fermentation at the production scale

Fungal Generation of Organic Acids for Removal of Lead from Contaminated Soil

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