Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Sci Total Environ. 2022 Mar 1;810:152003. doi: 10.1016/j.scitotenv.2021.152003. Epub 2021 Nov 29.
The rise of multiresistant bacterial pathogens is currently one of the most critical threats to global health, encouraging a better understanding of the evolution and spread of antimicrobial resistance. In this regard, the role of the environment as a source of resistance mechanisms remains poorly understood. Moreover, we still know a minimal part of the microbial diversity and resistome present in remote and extreme environments, hosting microbes that evolved to resist harsh conditions and thus a potentially rich source of novel resistance genes. This work demonstrated that the Antarctic Peninsula soils host a remarkable microbial diversity and a widespread presence of autochthonous antibiotic-resistant bacteria and resistance genes. We observed resistance to a wide array of antibiotics among isolates, including Pseudomonas resisting ten or more different compounds, with an overall increased resistance in bacteria from non-intervened areas. In addition, genome analysis of selected isolates showed several genes encoding efflux pumps, as well as a lack of known resistance genes for some of the resisted antibiotics, including colistin, suggesting novel uncharacterized mechanisms. By combining metagenomic approaches based on analyzing raw reads, assembled contigs, and metagenome-assembled genomes, we found hundreds of widely distributed genes potentially conferring resistance to different antibiotics (including an outstanding variety of inactivation enzymes), metals, and biocides, hosted mainly by Polaromonas, Pseudomonas, Streptomyces, Variovorax, and Burkholderia. Furthermore, a proportion of these genes were found inside predicted plasmids and other mobile elements, including a putative OXA-like carbapenemase from Polaromonas harboring conserved key residues and predicted structural features. All this evidence indicates that the Antarctic Peninsula soil microbiota has a broad natural resistome, part of which could be transferred horizontally to pathogenic bacteria, acting as a potential source of novel resistance genes.
多药耐药细菌病原体的出现是目前对全球健康的最严重威胁之一，这促使人们更好地了解抗菌药物耐药性的演变和传播。在这方面，环境作为耐药机制的来源的作用仍未被充分了解。此外，我们对偏远和极端环境中存在的微生物多样性和抗药基因库仍知之甚少，这些环境中存在着适应恶劣条件的微生物，因此是新型耐药基因的潜在丰富来源。这项工作表明，南极半岛土壤中存在着显著的微生物多样性和广泛存在的土著抗生素耐药细菌和耐药基因。我们观察到分离物中存在对多种抗生素的耐药性，包括对十种或更多种不同化合物具有耐药性的假单胞菌，并且未受干扰地区的细菌总体上的耐药性增加。此外，对选定分离物的基因组分析表明，有几个基因编码外排泵，并且一些被抵抗的抗生素（包括粘菌素）缺乏已知的耐药基因，这表明存在新的未被表征的机制。通过结合基于分析原始读数、组装的 contigs 和宏基因组组装基因组的宏基因组方法，我们发现了数百种广泛分布的基因，这些基因可能赋予对不同抗生素（包括各种失活酶）、金属和杀菌剂的抗性，主要由极地单胞菌、假单胞菌、链霉菌、鞘氨醇单胞菌和伯克霍尔德菌承载。此外，这些基因中有一部分位于预测的质粒和其他移动元件中，包括来自极地单胞菌的一种假定的 OXA 样碳青霉烯酶，该酶具有保守的关键残基和预测的结构特征。所有这些证据表明，南极半岛土壤微生物群具有广泛的天然抗药基因库，其中一部分可能通过水平转移到致病菌中，成为新型耐药基因的潜在来源。
