Wegner Carl-Eric, Gorniak Linda, Riedel Stefan, Westermann Martin, Küsel Kirsten
Institute of Biodiversity, Aquatic Geomicrobiology, Friedrich Schiller University, Jena, Germany
Institute of Biodiversity, Aquatic Geomicrobiology, Friedrich Schiller University, Jena, Germany.
Appl Environ Microbiol. 2019 Dec 13;86(1). doi: 10.1128/AEM.01830-19.
Methylotrophic bacteria use methanol and related C compounds as carbon and energy sources. Methanol dehydrogenases are essential for methanol oxidation, while lanthanides are important cofactors of many pyrroloquinoline quinone-dependent methanol dehydrogenases and related alcohol dehydrogenases. We describe here the physiological and genomic characterization of newly isolated bacteria that rely on lanthanides for methanol oxidation. A broad physiological diversity was indicated by the ability to metabolize a wide range of multicarbon substrates, including various sugars, and organic acids, as well as diverse C substrates such as methylated amines and methylated sulfur compounds. Methanol oxidation was possible only in the presence of low-mass lanthanides (La, Ce, and Nd) at submicromolar concentrations (>100 nM). In a comparison with other , genomic and transcriptomic analyses revealed the usage of a glutathione- and tetrahydrofolate-dependent pathway for formaldehyde oxidation and channeling methyl groups into the serine cycle for carbon assimilation. Besides a single gene, we identified two additional genes for lanthanide-dependent alcohol dehydrogenases, including one coding for an ExaF-type alcohol dehydrogenase, which was so far not known in Homologs for most of the gene products of the recently postulated gene cluster linked to lanthanide utilization and transport could be detected, but for now it remains unanswered how lanthanides are sensed and taken up by our strains. Studying physiological responses to lanthanides under nonmethylotrophic conditions in these isolates as well as other organisms is necessary to gain a more complete understanding of lanthanide-dependent metabolism as a whole. We supplemented knowledge of the broad metabolic diversity of the by characterizing new members of this family that rely on lanthanides for methanol oxidation and that possess additional lanthanide-dependent enzymes. Considering that lanthanides are critical resources for many modern applications and that recovering them is expensive and puts a heavy burden on the environment, lanthanide-dependent metabolism in microorganisms is an exploding field of research. Further research into how isolated and other microbes utilize lanthanides is needed to increase our understanding of lanthanide-dependent metabolism. The diversity and widespread occurrence of lanthanide-dependent enzymes make it likely that lanthanide utilization varies in different taxonomic groups and is dependent on the habitat of the microbes.
甲基营养型细菌利用甲醇及相关含碳化合物作为碳源和能源。甲醇脱氢酶对于甲醇氧化至关重要，而镧系元素是许多吡咯喹啉醌依赖性甲醇脱氢酶及相关醇脱氢酶的重要辅因子。我们在此描述了新分离出的依赖镧系元素进行甲醇氧化的细菌的生理和基因组特征。这些细菌能够代谢多种多碳底物，包括各种糖类、有机酸以及多种含碳底物，如甲基化胺和甲基化硫化合物，这表明它们具有广泛的生理多样性。只有在亚微摩尔浓度（>100 nM）的低质量镧系元素（镧、铈和钕）存在时，甲醇氧化才有可能发生。与其他细菌相比，基因组和转录组分析揭示了其利用谷胱甘肽和四氢叶酸依赖性途径进行甲醛氧化，并将甲基导入丝氨酸循环进行碳同化。除了一个单一的基因外，我们还鉴定出另外两个与镧系元素依赖性醇脱氢酶相关的基因，其中一个编码ExaF型醇脱氢酶，该酶在细菌中迄今尚未被发现。对于最近推测的与镧系元素利用和转运相关的基因簇的大多数基因产物，都能检测到其同源物，但目前我们的菌株如何感知和摄取镧系元素仍未得到解答。研究这些分离菌株以及其他生物体在非甲基营养条件下对镧系元素的生理反应，对于更全面地理解整个镧系元素依赖性代谢是必要的。我们通过表征该家族中依赖镧系元素进行甲醇氧化且拥有额外镧系元素依赖性酶的新成员，补充了对该细菌广泛代谢多样性的认识。鉴于镧系元素是许多现代应用的关键资源，且回收它们成本高昂并给环境带来沉重负担，微生物中的镧系元素依赖性代谢是一个迅速发展的研究领域。需要进一步研究分离出的细菌和其他微生物如何利用镧系元素，以增进我们对镧系元素依赖性代谢的理解。镧系元素依赖性酶的多样性和广泛存在使得不同分类群中镧系元素的利用情况可能有所不同，并且依赖于微生物的栖息地。
