Leaching with Penicillium simplicissimum: Influence of metals and buffers on proton extrusion and citric acid production

Journal Article · Fri Mar 01 00:00:00 EST 1991 · Applied and Environmental Microbiology; (United States)

OSTI ID:5380207

Franz, A; Burgstaller, W; Schinner, F ^[1]

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1. Univ. of Innsbruck, (Austria)

In the presence of insoluble metal oxides (industrial filter dust, zinc oxide, synthetic mixture of metal oxides), Penicillium simplicissimum developed the ability to excrete considerable amounts of citric acid (>100 mM). Parallel with the increase of citric acid concentration in the culture broth, zinc was solubilized from zinc oxide. The adsorption of filter dust onto the mycelium (the pellets formed were less than 1 mm in diameter) was required for not only the citric acid excretion but also the leaching of zinc. When the filter dust was replaced with a synthetic mixture of metal oxides or with zinc oxide in combination with trace elements, levels of adsorption and citric acid production were observed to be similar to those in experiments where industrial filter dust was used. The two most important properties of the filter dust were its heavy-metal content and its buffering capacity. These properties were simulated by adding heavy metals in soluble form (as chlorides, sulfates, or nitrates) or soluble buffers to the medium. Both heavy metals and buffers were not able to induce a citric acid efflux. As with citric acid production by Aspergillus niger, the addition of manganese lowered citric acid excretion (by 40% with metal oxide-induced citric acid efflux and by 100% with urea-induced citric acid efflux). Copper antagonized the effect of manganese. The mechanism for the bulk of citric acid excretion by P. simplicissimum, however, seemed to be different from that described for citric acid accumulation by A. niger. Because of the inefficiency of metals in solubilized form and of soluble buffers to induce a strong citric acid efflux, adsorption of an insoluble metal compound (zinc oxide) turned out to be essential.

• OSTI ID: 5380207
• Journal Information: Applied and Environmental Microbiology; (United States), Vol. 57:3; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
METALS
LEACHING
PENICILLIUM
PHYSIOLOGY
ATP-ASE
BUFFERS
CITRIC ACID
COPPER
DUSTS
EXCRETION
FILTERS
MANGANESE
ZINC
ACID ANHYDRASES
CARBOXYLIC ACIDS
CLEARANCE
DISSOLUTION
ELEMENTS
ENZYMES
EUMYCOTA
FUNGI
HYDROLASES
HYDROXY ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHOHYDROLASES
PLANTS
SEPARATION PROCESSES
TRANSITION ELEMENTS
560300* - Chemicals Metabolism & Toxicology