Laboratorio de Ecología Microbiana Medioambiental, Microbiología, Facultad de Química, Universidad de la República, Montevideo, Uruguay.
Laboratorio de Microbiología, Unidad Asociada del Instituto de Química Biológica, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Antonie Van Leeuwenhoek. 2023 Jul;116(7):721-738. doi: 10.1007/s10482-023-01840-1. Epub 2023 May 25.
Global warming has a strong impact on the polar regions, in particular, the Antarctic Peninsula and nearby islands. Methane (CH) is a major factor in climate change and mitigation of CH emissions can be accomplished through microbial oxidation by methanotrophic bacteria. Understanding this biological process is crucial given the shortage of research carried out in this geographical area. The aim of this study was to characterise psychrophilic enrichment cultures of aerobic methanotrophs obtained from lake sediments of the Fildes Peninsula (King George Island, South Shetland Islands) and revealing the distribution of the genus Methylobacter in different lake sediments of the peninsula. Four stable methanotrophic enrichment cultures were obtained and analysed by metagenome-assembled genomes (MAGs). The phylogeny of methanotroph MAGs recovered from these enrichment cultures based on the 16S rRNA gene showed that K-2018 MAG008 and D1-2020 MAG004 clustered within the Methylobacter clade 2, with high similarity to Methylobacter tundripaludum SV96 (97.88 and 98.56% respectively). However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values with M. tundripaludum were < 95% (84.8 and 85.0%, respectively) and < 70% (30.2 and 30.3%, respectively), suggesting that they represent a putative novel species for which the name 'Ca. Methylobacter titanis' is proposed. This is the first species of clade 2 of the genus Methylobacter obtained from Antarctica. The bacterial diversity assessed by 16S rRNA gene sequencing of 21 samples of different lakes (water column and sediments) revealed 54 ASVs associated with methanotrophs and the genus Methylobacter as the most abundant. These results suggest that aerobic methanotrophs belonging to the Methylobacter clade 2 would be the main responsible for CH oxidation in these sediments.
全球变暖对极地地区有强烈影响，特别是南极半岛和附近岛屿。甲烷（CH）是气候变化的一个主要因素，通过甲烷营养型细菌的微生物氧化可以减少 CH 排放。鉴于在该地理区域进行的研究很少，因此了解这一生物过程至关重要。本研究的目的是从福尔德斯半岛（南设得兰群岛的乔治王岛）的湖泊沉积物中获得好氧甲烷营养菌的嗜冷富集培养物，并揭示该半岛不同湖泊沉积物中甲基杆菌属的分布。获得了四个稳定的甲烷营养富集培养物，并通过宏基因组组装基因组（MAGs）进行了分析。基于 16S rRNA 基因从这些富集培养物中回收的甲烷营养菌 MAG 的系统发育表明，K-2018 MAG008 和 D1-2020 MAG004 聚类在甲基杆菌属 2 群内，与甲基杆菌 tundripaludum SV96 的相似度很高（分别为 97.88%和 98.56%）。然而，与 M. tundripaludum 的平均核苷酸同一性（ANI）和数字 DNA-DNA 杂交（dDDH）值均<95%（分别为 84.8%和 85.0%）和<70%（分别为 30.2%和 30.3%），表明它们代表了一个假定的新种，建议命名为“Ca. Methylobacter titanis”。这是从南极洲获得的甲基杆菌属 2 群的第一个物种。对 21 个不同湖泊（水柱和沉积物）样本的 16S rRNA 基因测序评估的细菌多样性揭示了与甲烷营养菌和甲基杆菌属相关的 54 个 ASVs，其中甲基杆菌属最为丰富。这些结果表明，属于甲基杆菌属 2 群的好氧甲烷营养菌将是这些沉积物中 CH 氧化的主要责任人。
