Institute of Microbiology and Biotechnology, Ulm University, 89069 Ulm, Germany.
Microbial Biotechnology, Campus Straubing for Biotechnology and Sustainability, Technical University of Munich, 94315 Straubing, Germany.
ACS Synth Biol. 2020 Jun 19;9(6):1426-1440. doi: 10.1021/acssynbio.0c00098. Epub 2020 May 19.
Due to climate change and worldwide pollution, development of highly sustainable routes for industrial production of basic and specialty chemicals is critical nowadays. One possible approach is the use of CO- and CO-utilizing microorganisms in biotechnological processes to produce value-added compounds from synthesis gas (mixtures of CO, CO, and H) or from C1-containing industrial waste gases. Such syngas fermentation processes have already been established, , biofuel production using strictly anaerobic acetogenic bacteria. However, aerobic processes may be favorable for the formation of more costly (ATP-intensive) products. strain OM5 is an aerobic carboxidotrophic bacterium and potentially a promising candidate for such processes. We here performed RNA-Seq analysis comparing cells of this organism grown heterotrophically with acetate or autotrophically with CO, CO, and H as carbon and energy source and found a variety of chromosomally and of native plasmid-encoded genes to be highly differentially expressed. In particular, genes and gene clusters encoding proteins required for autotrophic growth (CO fixation Calvin-Benson-Bassham cycle), for CO metabolism (CO dehydrogenase), and for H utilization (hydrogenase), all located on megaplasmid pHCG3, were much higher expressed during autotrophic growth with synthesis gas. Furthermore, we successfully established reproducible transformation of electroporation and developed gene deletion and gene exchange protocols two-step recombination, enabling inducible and stable expression of heterologous genes as well as construction of defined mutants of this organism. Thus, this study marks an important step toward metabolic engineering of and effective utilization of C1-containing gases with this organism.
由于气候变化和全球污染，现今开发高度可持续的基本和特种化学品工业生产路线至关重要。一种可能的方法是在生物技术过程中使用 CO 和 CO 利用微生物，从合成气（CO、CO 和 H 的混合物）或含 C1 的工业废气中生产增值化合物。已经建立了这样的合成气发酵工艺，例如，使用严格厌氧的产乙酸菌生产生物燃料。然而，好氧过程可能有利于形成更昂贵的（ATP 密集型）产品。OM5 菌株是一种好氧羧化细菌，是此类过程的有前途的候选者。我们在这里进行了 RNA-Seq 分析，比较了该生物体在异养生长时用乙酸盐或自养生长时用 CO、CO 和 H 作为碳和能源源的细胞，发现各种染色体和天然质粒编码的基因高度差异表达。特别是，编码用于自养生长（CO 固定卡尔文-本森-巴斯姆循环）、CO 代谢（CO 脱氢酶）和 H 利用（氢化酶）所需的蛋白质的基因和基因簇，所有这些都位于大质粒 pHCG3 上，在使用合成气的自养生长过程中表达更高。此外，我们成功地通过电穿孔建立了可重复的转化，并开发了基因缺失和基因交换协议——两步重组，能够诱导和稳定表达异源基因，并构建该生物体的定义突变体。因此，这项研究标志着朝着代谢工程和有效利用该生物体的含 C1 气体迈出了重要一步。
