Genetic Basis of Acinetobacter sp. K1 Adaptation Mechanisms to Extreme Environmental Conditions

Abstract

Anthropogenic pollution often leads to the generation of technosols, technogenic soils with inhospitable conditions for all living organisms including microbiota. Aluminum production near Ziar nad Hronom (Slovakia) resulted in the creation of a highly alkaline and heavy-metal-rich brown mud landfill, from which a bacterial strain of a likely new species of the genus Acinetobacter, Acinetobacter sp. K1, was isolated. The whole-genome sequence analysis of this strain confirmed the presence of operon units enabling tolerance to the heavy metals copper, zinc, cobalt, cadmium, chromium, and metalloid arsenic, which are functionally active. Despite the predominance of plasmid-related sequences in the K1 genome, the results indicate that most of the resistance genes are chromosomally encoded. No significant alkali tolerance of Acinetobacter sp. K1 was observed in vitro, suggesting that community level mechanisms are responsible for the survival of this strain in the highly alkaline, brown mud bacterial community.

Genomic insights into the adaptation of Acinetobacter johnsonii RB2-047 to the heavy metal-contaminated subsurface mine environment

“…The high Pb tolerance of the RB2-047 isolate could be provided by non-specific efflux pumps (e.g., metal transporting ATPase) or other mechanisms, as we did not detect any genes in the RB2-047 genome that could participate in the development of Pb tolerance (e.g., pbr operon). Very similar genetic determinants were also found in the Acinetobacter species isolated from a brown mud created during aluminum production near Ziar nad Hronom (Slovakia), and the isolate showed a similarly high tolerance to the same metals (Petrová et al 2023 ). Similar findings reported Furlan et al ( 2019 ) in multi-drug resistant Acinetobacter seifertii obtained from soil of a corn crop field.…”

“…The identification of beta-lactamase genes and other antibiotic resistance determinants among Acinetobacter species demonstrates their potential to acquire and stably maintain resistance determinants in their genomes (Montaña et al 2016 ). Beta-lactamase genes appear to be linked to a similar profile of heavy-metal tolerance determinants as shown by the RB2-047 isolate (Furlan et al 2019 ; Petrová et al 2023 ). In silico comparative genomic analysis confirmed these findings also in other environmental Acinetobacter johnsonii species (this study).…”

“…with efflux pumps appearing to be the most prevalent adaptive mechanism to heavy metals, e.g. cop operon consisting of genes involving in copper ion efflux from the cell, mer operon involved in the transport of mercury ions out of the cell, chr operon with chrA and chrB genes encoding proteins involved in chromium tolerance, czc operon consisting of genes encoding CzcABCD proteins, which ensure efflux of cobalt, zinc and cadmium cations out of the cell or ars operon consisting of genes associated with the reduction of arsenate to arsenite and its efflux from the bacterial cell (Mindlin et al 2016 ; Marwa et al 2019 ; Bazzi et al 2020 ; Petrova et al 2023 ).…”

“…in heavy-metal contaminated environments, there are few studies addressing genetic determinants of antibiotic resistance induced by the presence of heavy metals in this genus. However, multiple resistance to heavy metals seems to be often linked with the presence of beta-lactamase genes (Furlan et al 2019 ; Jia et al 2021 ; Petrova et al 2023 ). From this point of view, it was also interesting to exam the antibiotic susceptibility and its genetic determinants of the Acinetobacter isolate obtained from an isolated mine environment.…”