Gęsicka Aleksandra, Borkowska Monika, Białas Wojciech, Kaczmarek Paulina, Celińska Ewelina
Department of Biotechnology and Food Microbiology, Poznan University of Life Sciences, ul. Wojska Polskiego 48, 60-627 Poznan, Poland.
Microorganisms. 2020 May 12;8(5):717. doi: 10.3390/microorganisms8050717.
Sustainable economy drives increasing demand for raw biomass-decomposing enzymes. Microbial expression platforms exploited as cellular factories of such biocatalysts meet requirements of large-volume production. Previously, we developed recombinant strains able to grow on raw starch of different plant origin. In the present study, we used the most efficient amylolytic strain as a microbial cell factory of raw-starch-digesting (RSD) amylolytic preparation composed of two enzymes. The RSD-preparation was produced in fed-batch bioreactor cultures. Concentrated and partly purified preparation was then tested in simultaneous saccharification and fermentation (SSF) processes with thermotolerant for ethanol production and for production of lactic acid. These processes were conducted as a proof-of-concept that application of the novel RSD-preparation supports sufficient starch hydrolysis enabling microbial growth and production of targeted molecules, as the selected strains were confirmed to lack amylolytic activity. Doses of the preparation and thermal conditions were individually adjusted for the two processes. Additionally, ethanol production was tested under different aeration strategies; and lactic acid production process was tested in thermally pre-treated substrate, as well. Conducted studies demonstrated that the novel RSD-preparation provides satisfactory starch hydrolyzing activity for ethanol and lactic acid production from starch by non-amylolytic microorganisms.
可持续经济推动了对原始生物质分解酶的需求不断增加。作为此类生物催化剂细胞工厂的微生物表达平台满足了大规模生产的需求。此前，我们开发了能够在不同植物来源的生淀粉上生长的重组菌株。在本研究中，我们使用效率最高的淀粉分解菌株作为由两种酶组成的生淀粉消化（RSD）淀粉分解制剂的微生物细胞工厂。RSD制剂在分批补料生物反应器培养物中生产。然后，将浓缩并部分纯化的制剂在同步糖化发酵（SSF）过程中进行测试，用于生产乙醇的耐热菌株以及用于生产乳酸的菌株。进行这些过程是为了证明一个概念，即新型RSD制剂的应用能够支持充分的淀粉水解，从而使微生物生长并生产目标分子，因为所选菌株被证实缺乏淀粉分解活性。针对这两个过程分别调整了制剂的剂量和热条件。此外，还在不同的曝气策略下测试了乙醇生产；乳酸生产过程也在经过热预处理的底物中进行了测试。所进行的研究表明，新型RSD制剂为非淀粉分解微生物从淀粉生产乙醇和乳酸提供了令人满意的淀粉水解活性。
