Institute of Microbiology, University of Innsbruck, Technikerstrasse 25, 6020, Innsbruck, Austria.
Institute of Pharmacy, Pharmacognosy, University of Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
Sci Rep. 2019 May 16;9(1):7496. doi: 10.1038/s41598-019-43976-z.
As one of the most frequently occurring monomers in the biosphere, glucosamine is a valuable metabolite for several applications. Although microbial glucosamine production is still in its infancy, it offers the possibility to circumvent problems associated with traditional production by hydrolysis. Of particular interest is a study with Aspergillus niger, which reports for the first time high glucosamine excretion in the early phase of citric acid production. These results have relevance for both the commercial glucosamine production and deeper insight into the regulation of organic acid excretion in fungi. To investigate glucosamine excretion, we performed bioreactor batch cultivations with Penicillium ochrochloron CBS123.824 and A. niger CBS120.49 using cultivation conditions which are known to trigger the production of citric acid. Glucosamine detection in culture filtrates was achieved by two photometric methods, High performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) and HPLC with mass spectrometry detection (HPLC-MS). Surprisingly, we detected no glucosamine at all. Based on a critical review of published data for A. niger, we conclude that the reported high levels of excreted glucosamine might be an experimental artifact. However, growth experiments with glucosamine as a combined or single source for carbon or nitrogen showed that both organisms are in principle able to transport glucosamine across their plasma membrane, which is a prerequisite for the excretion of glucosamine.
作为生物界中最常见的单体之一，氨基葡萄糖是几种应用的有价值的代谢物。虽然微生物氨基葡萄糖的生产仍处于起步阶段，但它提供了规避传统水解生产相关问题的可能性。特别值得关注的是一项关于黑曲霉的研究，该研究首次报道了在柠檬酸生产的早期阶段高浓度氨基葡萄糖的排泄。这些结果不仅对商业氨基葡萄糖生产具有重要意义，而且对真菌中有机酸排泄的调控也有更深入的了解。为了研究氨基葡萄糖的排泄，我们使用已知会触发柠檬酸生产的培养条件，对青霉菌 CBS123.824 和黑曲霉 CBS120.49 进行了生物反应器分批培养。通过两种光度法，即高效液相色谱蒸发光散射检测（HPLC-ELSD）和高效液相色谱质谱检测（HPLC-MS），在培养滤液中检测到氨基葡萄糖。令人惊讶的是，我们根本没有检测到氨基葡萄糖。基于对黑曲霉已发表数据的批判性回顾，我们得出结论，报告的高浓度排泄的氨基葡萄糖可能是一个实验性的假象。然而，以氨基葡萄糖作为碳源或氮源的组合或单一来源的生长实验表明，两种生物原则上都能够将氨基葡萄糖穿过它们的质膜运输，这是氨基葡萄糖排泄的前提条件。
