利用青霉属简单种进行浸提：金属和缓冲液对质子排出和柠檬酸生产的影响。
Leaching with Penicillium simplicissimum: Influence of Metals and Buffers on Proton Extrusion and Citric Acid Production.
机构信息
Institute of Microbiology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
出版信息
Appl Environ Microbiol. 1991 Mar;57(3):769-74. doi: 10.1128/aem.57.3.769-774.1991.
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. Surface phenomena possibly involving the plasma membrane H-ATPase are thought to participate in the induction of citric acid excretion by P. simplicissimum in the presence of industrial filter dust.
在不溶性金属氧化物（工业滤尘、氧化锌、金属氧化物合成混合物）存在的情况下，青霉属简单种（Penicillium simplicissimum）发展出了大量分泌柠檬酸的能力（>100mM）。随着发酵液中柠檬酸浓度的增加，氧化锌中的锌被溶解。滤尘对菌丝的吸附（形成的小球直径小于 1 毫米）不仅是柠檬酸分泌的必要条件，也是锌浸出的必要条件。当滤尘被金属氧化物合成混合物或氧化锌与微量元素代替时，观察到吸附和柠檬酸产量与使用工业滤尘的实验相似。滤尘的两个最重要的特性是其重金属含量和缓冲能力。通过向培养基中添加可溶性形式的重金属（如氯化物、硫酸盐或硝酸盐）或可溶性缓冲剂来模拟这些特性。重金属和缓冲剂都不能诱导柠檬酸流出。与黑曲霉产生柠檬酸一样，添加锰会降低柠檬酸的排泄量（金属氧化物诱导的柠檬酸流出时降低 40%，尿素诱导的柠檬酸流出时降低 100%）。铜拮抗锰的作用。然而，青霉属简单种大量分泌柠檬酸的机制似乎与黑曲霉积累柠檬酸的机制不同。由于可溶性形式的金属和可溶性缓冲剂溶解效率低，不能诱导强烈的柠檬酸流出，因此吸附不溶性金属化合物（氧化锌）是必不可少的。可能涉及质膜 H+-ATP 酶的表面现象被认为参与了在工业滤尘存在下青霉属简单种柠檬酸分泌的诱导。
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