Institute for Microbiology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
Appl Environ Microbiol. 1989 May;55(5):1153-6. doi: 10.1128/aem.55.5.1153-1156.1989.
Zinc was extracted from a filter residue of a copper works (58.6% zinc) by a Penicillium sp. isolated from a metal-containing location. By isotachophoresis citric acid was identified as the leaching agent. Citrate was only formed when the leaching substrate was present. This production of citrate was different in several ways from that achieved by Aspergillus niger: glucose was utilized before fructose; the initial concentration of zinc was 50 to 500 times higher than usual in citrate fermentations with A. niger; citrate production stopped when 80 to 90% of the zinc was leached, although sufficient sugar for further synthesis was still present; and in synthetic media citrate production by A. niger needs an acidic environment (pH 2), while the formation of citric acid by Penicillium sp. occurred in a pH range of 7 to 4. Tests with different concentrations of waste material (0.5, 2.5, and 5%) showed that the highest yield of solubilized zinc occurred with a 2.5% substrate (93% zinc extracted after 13 days).
从一家含有金属的地点分离出的青霉属（Penicillium sp.）从一家铜厂的滤渣（含锌 58.6%）中提取了锌。通过等速电泳法鉴定出柠檬酸是浸出剂。只有在浸出底物存在的情况下才会形成柠檬酸盐。这种柠檬酸的产生在几个方面与黑曲霉（Aspergillus niger）的生产方式不同：葡萄糖在果糖之前被利用；锌的初始浓度比通常在柠檬酸发酵中用黑曲霉（A. niger）高 50 至 500 倍；当浸出 80%至 90%的锌时，柠檬酸的生产就停止了，尽管仍然存在足够的糖用于进一步合成；在合成培养基中，黑曲霉（A. niger）生产柠檬酸需要酸性环境（pH 2），而青霉属（Penicillium sp.）形成柠檬酸的 pH 值范围为 7 至 4。用不同浓度的废料（0.5%、2.5%和 5%）进行的测试表明，在 2.5%的底物下（13 天后提取 93%的锌），可溶锌的产量最高。
