The Effect of Outer Space and Other Environmental Cues on Bacterial Conjugation

Piscon, Bar; Esposito, Eliana Pia; Fichtman, Boris; Samburski, Guy; Efremushkin, Lihi; Amselem, Shimon; Harel, Amnon; Rahav, Galia; Zarrilli, Raffaele; Gal-Mor, Ohad

doi:10.1128/spectrum.03688-22

Cited by 6 publications

(2 citation statements)

References 67 publications

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“…In line with our observations, previous work has reported on substantial differences between levels of transcripts versus proteins of the T4SS, with higher transcription levels in poor media compared to rich media. In contrast, western blot of the corresponding proteins revealed elevated expression in rich media compared to the poor media 64 . Taken together, algal exudates may impact post-transcriptional regulation of genes involved in bacterial conjugation.…”

Section: Discussionmentioning

confidence: 71%

Algal Exudates Promote Conjugation in Marine Roseobacters

Rapp,

Lipsman,

Yuda

et al. 2023

Preprint

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Horizontal gene transfer (HGT) is a pivotal mechanism driving bacterial evolution, conferring adaptability within dynamic marine ecosystems. Among HGT mechanisms, conjugation mediated by Type IV secretion systems (T4SSs) plays a central role in the ecological success of marine bacteria. However, the triggers initiating conjugation events in the marine environment are not well understood. Roseobacters, abundant marine bacteria commonly associated with algae, possess a multitude of plasmids encoding T4SSs. Many Roseobacters are heterotrophic bacteria that rely on algal secreted compounds for supporting bacterial growth. Algal compounds therefore attract bacteria and promote colonization, including attachment to algal cells. Bacterial proximity, cell-to-cell contact, and attachment, can all foster HGT. Hence, we hypothesized that algal exudates, acting as chemoattractants for bacteria, may function as cues promoting bacterial HGT. Examination of various Roseobacters demonstrated that the genomic location of the T4SS impacts its functionality; a bacterial strain harboring a chromosomal-encoded T4SS does not perform conjugation, while a strain of the same species carrying a plasmid-encoded T4SS exhibits functional conjugation capability. Subsequently, we probed the influence of algal exudates on bacterial conjugation dynamics. Our findings revealed that algal exudates enhance plasmid transfer through conjugation but do not modulate the transcription of the conjugative machinery genes. These observations suggest that the bacterial responses to algal hosts evolved to correlate with an increased likelihood of encountering compatible partners for successful conjugation. Furthermore, since specific algae attract distinct bacterial populations, algae influence potential partners for genetic exchange and may shape the trajectory of bacterial evolution in the marine environment.

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Section: Discussionmentioning

confidence: 71%

Algal Exudates Promote Conjugation in Marine Roseobacters

Rapp,

Lipsman,

Yuda

et al. 2023

Preprint

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“…HGT is a powerful force that shapes the evolution, diversification, and adaptation of bacterial communities and provides, for instance, a platform for the spread and persistence of ARGs ( Piscon et al., 2023 ). Today, three canonical mechanisms of HGT are recognized, including transformation, transduction, and conjugation ( Dubnau and Blokesch, 2019 ).…”

Section: Discussionmentioning

confidence: 99%

Sporadic clone Escherichia coli ST615 as a vector and reservoir for dissemination of crucial antimicrobial resistance genes

Carrera Páez,

Olivier,

Gambino

et al. 2024

Front. Cell. Infect. Microbiol.

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There is scarce information concerning the role of sporadic clones in the dissemination of antimicrobial resistance genes (ARGs) within the nosocomial niche. We confirmed that the clinical Escherichia coli M19736 ST615 strain, one of the first isolates of Latin America that harbors a plasmid with an mcr-1 gene, could receive crucial ARG by transformation and conjugation using as donors critical plasmids that harbor blaCTX-M-15, blaKPC-2, blaNDM-5, blaNDM-1, or aadB genes. Escherichia coli M19736 acquired blaCTX-M-15, blaKPC-2, blaNDM-5, blaNDM-1, and aadB genes, being only blaNDM-1 maintained at 100% on the 10th day of subculture. In addition, when the evolved MDR-E. coli M19736 acquired sequentially blaCTX-M-15 and blaNDM-1 genes, the maintenance pattern of the plasmids changed. In addition, when the evolved XDR-E. coli M19736 acquired in an ulterior step the paadB plasmid, a different pattern of the plasmid’s maintenance was found. Interestingly, the evolved E. coli M19736 strains disseminated simultaneously the acquired conjugative plasmids in different combinations though selection was ceftazidime in all cases. Finally, we isolated and characterized the extracellular vesicles (EVs) from the native and evolved XDR-E. coli M19736 strains. Interestingly, EVs from the evolved XDR-E. coli M19736 harbored blaCTX-M-15 though the pDCAG1-CTX-M-15 was previously lost as shown by WGS and experiments, suggesting that EV could be a relevant reservoir of ARG for susceptible bacteria. These results evidenced the genetic plasticity of a sporadic clone of E. coli such as ST615 that could play a relevant transitional link in the clinical dynamics and evolution to multidrug/extensively/pandrug-resistant phenotypes of superbugs within the nosocomial niche by acting simultaneously as a vector and reservoir of multiple ARGs which later could be disseminated.

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