Perez María Florencia, Angelov Angel, Übelacker Maria, Torres Tejerizo Gonzalo Arturo, Farias María Eugenia, Liebl Wolfgang, Dib Julián Rafael
Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán, Tucumán, Argentina.
Chair of Microbiology, Technical University of Munich, Freising, Germany.
Environ Microbiol. 2025 Jan;27(1):e70020. doi: 10.1111/1462-2920.70020.
Actinobacteria have frequently been reported in the Andean Puna, including strains of the genus Micrococcus. These strains demonstrate resistance to high levels of UV radiation, arsenic, and multiple antibiotics, and possess large linear plasmids. A comparative analysis of the sequences and putative functions of these plasmids was conducted. The presence of large regions with high sequence identity (exceeding 30 kb in total) in all three studied Micrococcus megaplasmids indicates a clear evolutionary link among these elements. Genes related to essential plasmid functions were primarily found within these conserved regions, while genes associated with resistance to metals and antibiotics resided in accessory regions. Moreover, the abundance of open reading frames related to transposition and recombination, along with local deviations from the average GC content, provides evidence for the mosaic nature and considerable genetic plasticity of these plasmids. This study presents evidence of a common ancestor for linear plasmids in Micrococcus and suggests that horizontal gene transfer likely occurs frequently within Andean lakes, providing the native microbial community with a beneficial gene pool to withstand extreme conditions. Additionally, the successful transfer of the linear plasmid pLMA1 by a DNase-insensitive, conjugation-type mechanism and its potential use as a genetic vector is demonstrated.
放线菌在安第斯普纳地区经常被报道，包括微球菌属的菌株。这些菌株对高水平的紫外线辐射、砷和多种抗生素具有抗性，并拥有大型线性质粒。对这些质粒的序列和推定功能进行了比较分析。在所有三个研究的巨大微球菌大质粒中存在高序列同一性的大片段区域（总计超过30 kb），表明这些元件之间存在明显的进化联系。与必需质粒功能相关的基因主要在这些保守区域内发现，而与金属和抗生素抗性相关的基因位于辅助区域。此外，与转座和重组相关的开放阅读框的丰富性，以及与平均GC含量的局部偏差，为这些质粒的镶嵌性质和相当大的遗传可塑性提供了证据。这项研究提供了微球菌线性质粒存在共同祖先的证据，并表明水平基因转移可能在安第斯湖泊中频繁发生，为本地微生物群落提供了一个有益的基因库以抵御极端条件。此外，还证明了线性质粒pLMA1通过对DNase不敏感的接合型机制成功转移及其作为遗传载体的潜在用途。
