ACIB GmbH, Petersgasse 14, 8010, Graz, Austria.
Institute of Environmental Biotechnology, Graz University of Technology, Petersgasse 12, 8010, Graz, Austria.
Sci Rep. 2019 Feb 27;9(1):2864. doi: 10.1038/s41598-019-39673-6.
Large-scale microalgae cultivations are increasingly used for the production of animal feed, nutritional supplements and various high-value bioproducts. Due to the process size and other limitations, contaminations of microalgae fermentations with other photoautotrophic microorganism are frequently observed. In the present study, we explored the applicability of 5-isobutyl-2,3-dimethylpyrazine for the removal of contaminating microalgae from industrial photobioreactors. In order to select a representative microbial population for susceptibility experiments, reactor samples were obtained from a multi-stage cultivation process. Assignments of 18S rRNA gene fragment amplicons indicated that Haematococcus, Chlorella, and Scenedesmus were the three most frequently occurring microalgae genera in the selected reactors. Following the isolation of representative algae cultures, susceptibility tests were conducted with the antimicrobial pyrazine. It was demonstrated that all isolated contaminants are highly susceptible to the bioactive compound. The highest tolerance towards the alkylpyrazine was observed with Scenedesmus vacuolatus; solutions with 1.66% (v/v) of the active compound were required for its deactivation. Further tests with the vaporized pyrazine showed consistent reductions in the viability of treated microalgae. This pilot study provides evidence for the applicability of a novel, nature-based alternative for bioreactor decontaminations.
大规模的微藻培养越来越多地用于生产动物饲料、营养补充剂和各种高价值的生物制品。由于工艺规模和其他限制，微藻发酵经常会受到其他光能自养微生物的污染。在本研究中，我们探索了 5-异丁基-2,3-二甲基吡嗪去除工业光生物反应器中污染微藻的适用性。为了选择具有敏感性实验代表性的微生物种群，从多阶段培养过程中获得了反应器样品。18S rRNA 基因片段扩增子的分配表明，红球藻、绿藻和栅藻是所选反应器中最常见的三种微藻属。在分离出代表性的藻类培养物后，用抗菌吡嗪进行了敏感性测试。结果表明，所有分离出的污染物对生物活性化合物高度敏感。Scenedesmus vacuolatus 对烷基吡嗪的耐受性最高，需要 1.66%（v/v）的活性化合物溶液才能使其失活。用汽化吡嗪进行的进一步测试显示，处理后的微藻的存活率持续下降。这项初步研究为生物反应器净化的新型天然替代方案的适用性提供了证据。
