Lee Jessica A, Stolyar Sergey, Marx Christopher J
Department of Biological Sciences, University of Idaho, Moscow, ID, United States.
Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, ID, United States.
Front Microbiol. 2022 Mar 11;13:849573. doi: 10.3389/fmicb.2022.849573. eCollection 2022.
Pink-pigmented facultative methylotrophs have long been studied for their ability to grow on reduced single-carbon (C) compounds. The C groups that support methylotrophic growth may come from a variety of sources. Here, we describe a group of strains that can engage in methoxydotrophy: they can metabolize the methoxy groups from several aromatic compounds that are commonly the product of lignin depolymerization. Furthermore, these organisms can utilize the full aromatic ring as a growth substrate, a phenotype that has rarely been described in . We demonstrated growth on -hydroxybenzoate, protocatechuate, vanillate, and ferulate in laboratory culture conditions. We also used comparative genomics to explore the evolutionary history of this trait, finding that the capacity for aromatic catabolism is likely ancestral to two clades of , but has also been acquired horizontally by closely related organisms. In addition, we surveyed the published metagenome data to find that the most abundant group of aromatic-degrading in the environment is likely the group related to , and they are especially common in soil and root environments. The demethoxylation of lignin-derived aromatic monomers in aerobic environments releases formaldehyde, a metabolite that is a potent cellular toxin but that is also a growth substrate for methylotrophs. We found that, whereas some known lignin-degrading organisms excrete formaldehyde as a byproduct during growth on vanillate, do not. This observation is especially relevant to our understanding of the ecology and the bioengineering of lignin degradation.
粉红色色素兼性甲基营养菌长期以来因其在还原态单碳（C）化合物上生长的能力而受到研究。支持甲基营养生长的碳基团可能来自多种来源。在这里，我们描述了一组能够进行甲氧基营养的菌株：它们可以代谢几种芳香族化合物中的甲氧基，这些芳香族化合物通常是木质素解聚的产物。此外，这些生物体可以利用整个芳香环作为生长底物，这种表型在……中很少被描述。我们在实验室培养条件下证明了它们能在对羟基苯甲酸、原儿茶酸、香草酸和阿魏酸上生长。我们还利用比较基因组学来探索这一特性的进化历史，发现芳香族化合物分解代谢的能力可能是……两个进化枝的祖先特征，但也被密切相关的生物体通过水平基因转移获得。此外，我们调查了已发表的宏基因组数据，发现环境中最丰富的芳香族化合物降解……组可能是与……相关的组，它们在土壤和根际环境中尤其常见。在有氧环境中，木质素衍生的芳香族单体的脱甲氧基作用会释放甲醛，甲醛是一种代谢产物，既是一种强效细胞毒素，也是甲基营养菌的生长底物。我们发现，虽然一些已知的木质素降解生物体在香草酸上生长时会将甲醛作为副产物排出，但……不会。这一观察结果对于我们理解木质素降解的生态学和生物工程尤其重要。
