Effect of manganese and other heavy metals on submerged citric acid fermentation of molasses

Clark, Douglas S.; Ito, Katsumi; Horitsu, Hiroyuki

doi:10.1002/bit.260080402

Cited by 94 publications

(35 citation statements)

References 8 publications

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“…All the cic mutants produced citric acid in high amounts in the absence of Mn2+ ions (.60 g/liter), although some of the mutants did not achieve the titer of the parental strain (Table 2). In the presence of 20 ,uM Mn2+ ions, however, the yield of citric acid was drastically decreased, as previously reported (2,6,8). Mutant cic-7/3, however, accumulated 50%o of the amount produced under deficient conditions, i.e., twice the amount produced by the parent strain B60 under Mn2+-containing conditions (Table 2).…”

supporting

confidence: 83%

Inhibition of citric acid accumulation by manganese ions in Aspergillus niger mutants with reduced citrate control of phosphofructokinase

Schreferl¹,

Kubicek²,

Röhr³

1986

J Bacteriol

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Mutant strains of Aspergillus niger with reduced citrate control of carbohydrate catabolism (cic mutants) grow faster than the parent strain on media containing 5% (wt/vol) citrate. The mutants tolerated a higher intracellular citrate concentration than the parent strain. One mutant (cic-713) contained phosphofructokinase activity significantly less sensitive towards citrate than the enzyme from the parent strain. When this mutant was grown under citrate-accumulating conditions, acidogenesis was far less sensitive to inhibition by Mn2+ than in the parent strain. Some of the cic mutants also showed altered citrate inhibition of NADP-specific isocitrate dehydrogenase.The accumulation of large amounts of citrate by the filamentous fungus Aspergillus niger is known to depend on a variety of environmental factors, among which the level of Mn2+ ions in the nutrient medium plays a key role. Only when the Mn2+ concentration is below 0.02 mM (which does not yet affect growth rate or yield) will citrate accumulate in high amounts (17).A biochemical explanation of this manganese effect has been presented recently. Mn2+ deficiency leads to an increase in protein turnover, which ultimately leads to a high intracellular concentration of NH4+ (7, 9); this level of NH4+ is able to counteract the inhibition of phosphofructokinase by citrate (4, 5), thereby guaranteeing a high rate of glucose breakdown by the fructose biphosphate pathway, which is necessary for citric acid accumulation (17).According to this model, Mn2+ deficiency is mainly required for eliminating glycolytic feedback control by citrate. If this model is correct, mutants lacking citrate inhibition of phosphofructokinase should accumulate citrate even in the presence of Mn2+.To test this hypothesis, A. niger B60 (7) was propagated on potato dextrose agar for 7 days, and the conidia were harvested, diluted in sterile water containing 0.1% (wt/vol) Tween 80 to give a final density of 2 x 106 conidia per ml, and shaken vigorously to break clumps. Of this suspension, 10 ml was then placed in an open petri dish 14 cm below a germicidal UV lamp and stirred magnetically for 5 min. Subsequently, the suspension was covered with aluminium foil for 1 h and used for the isolation of potential mutants. Their identification was based on the assumption that mutants lacking citrate control of phosphofructokinase would grow faster on a sucrose medium containing citrate, as discussed below. For this reason, the diluted, mutagenized conidium suspensions were plated on solid medium containing 20% (wt/vol) sucrose and 5% (wt/vol) citrate as carbon sources. Other inorganic nutrients and nitrogen source were essentially as used in the citric acid production medium (8), except that the pH was adjusted to 3.5 with H2SO4. Oxgall (0.5% [wt/vol]; Sigma Chemical Co., St. Louis, Mo.) was added to the medium to restrict growth to small, defined * Corresponding author. colonies (15). The fastest-growing colonies were considered to be less affected in carbohydrate breakdown by citrate and thus we...

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supporting

confidence: 83%

Inhibition of citric acid accumulation by manganese ions in Aspergillus niger mutants with reduced citrate control of phosphofructokinase

Schreferl¹,

Kubicek²,

Röhr³

1986

J Bacteriol

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“…When A. niger was grown in such a medium, di¡er-ences between biomass increase, the amount of total lipids and citric acid accumulated were followed, due to the different concentrations of divalent metal ions present. In fact, it was carried out in a medium with Mg 2þ that was favouring citric acid accumulation as well as with Mg 2þ / Mn 2þ medium where citric acid over£ow was hindered due to the presence of Mn 2þ [2] (Fig. 1).…”

Section: E¡ect Of Copper On Growth Total Lipid Content and Citric Acmentioning

confidence: 99%

“…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]. A closer look at the A. niger mycelium, grown in the presence of copper, revealed reduced total lipid levels [4].…”

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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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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“…O teor de manganês apresentou valor em torno de 3,0 ppm, valor este também superior ao citado na literatura, que segundo CLARK et al (1986), deve ser de l ppm no meio de fermentação.…”

Section: Caracterização Físico-química Da Manipueira E Dos Meios Com unclassified

Manipueira como substrato na biossíntese de ácido cítrico por Aspergillus niger

Leonel

Cerada

1995

Sci. agric. (Piracicaba, Braz.)

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RESUMO: O trabalho teve por objetivo avaliar a viabilidade do uso da manipueira, residuo líquido resultante da prensagem da massa ralada de mandioca, como substrato na biossíntese de ácido cítrico por Aspergillus niger. Os meios de manipueira foram comparados nas mesmas condições de temperatura, a meios sintéticos, utilizados tradicionalmente. Em se tratando de proposta de um novo substrato, foi estudado o armazenamento do resíduo a temperatura ambiente por 72 horas, e realizada a caracterização físico-química da manipueira e dos meios elaborados com esse substrato. Foi avaliada a produção de ácido cítrico nos meios sintéticos e de manipueira. Verificou-se que a produção de ácido cítrico não diferiu quanto ao meio. Não foi observado crescimento do microrganismo nos meios de manipueira com concentra- INTRODUÇÃOAtualmente, o ácido cítrico é quase que exclusivamente obtido através de processos de biossíntese utilizando como agente biológico o fungo imperfeito Aspergillus niger. Dois processos são utilizados na biossíntese deste ácido, o de superfície e o submerso, que se diferenciam essencialmente pelo modo de crescimento do microrganismo.O ácido cítrico é utilizado em grande escala pelas indústrias de alimentos, refrigerantes, produtos farmacêuticos, além de outras em que o íon citrato propicia a formação de uma variedade de moléculas complexas que possuem a capacidade de seqüestrar e inativar íons metabólicos. Devido a isto, controlam efeitos indesejáveis numa reação, que poderiam ocasionar alterações de cor, aparência, estabilidade, etc., prejudicando o produto final (CABELLO, 1991).Um dos problemas enfrentados na produção de ácido cítrico por bolores é o custo do processo, onde o substrato representa um alto percentual. Na tentativa de diminuir esse custo no processo, temse utilizado resíduos industriais como componente do meio de cultivo para microrganismos.Estuda-se o uso da manipueira, resíduo lí-quido resultante do processo de fabricação da farinha de mandioca ou da extração da fécula, como substrato para biossíntese de ácido cítrico, visto que apresenta características físico-químicas favoráveis

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Effect of manganese and other heavy metals on submerged citric acid fermentation of molasses

Cited by 94 publications

References 8 publications

Inhibition of citric acid accumulation by manganese ions in Aspergillus niger mutants with reduced citrate control of phosphofructokinase

Inhibition of citric acid accumulation by manganese ions in Aspergillus niger mutants with reduced citrate control of phosphofructokinase

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

Manipueira como substrato na biossíntese de ácido cítrico por Aspergillus niger

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