BUSCADOR RECOLECTA

© 2021 Dorado-Morales et al., Plasmids have largely contributed to the spread of antimicrobial resistance genes among Staphylococcus strains. Knowledge about the fitness cost that plasmids confer on clinical staphylococcal isolates and the coevolutionary dynamics that drive plasmid maintenance is still scarce. In this study, we aimed to analyze the initial fitness cost of plasmids in the bacterial pathogen Staphylococcus aureus and the plasmid-host adaptations that occur over time. For that, we first designed a CRISPR (clustered regularly interspaced palindromic repeats)-based tool that enables the removal of native S. aureus plasmids and then transferred three different plasmids isolated from clinical S. aureus strains to the same-background clinical cured strain. One of the plasmids, pUR2940, obtained from a livestock-associated methicillin-resistant S. aureus (LA-MRSA) ST398 strain, imposed a significant fitness cost on both its native and the new host. Experimental evolution in a nonselective medium resulted in a high rate pUR2940 loss and selected for clones with an alleviated fitness cost in which compensatory adaptation occurred via deletion of a 12.8-kb plasmid fragment, contained between two ISSau10 insertion sequences and harboring several antimicrobial resistance genes. Overall, our results describe the relevance of plasmid-borne insertion sequences in plasmid rearrangement and maintenance and suggest the potential benefits of reducing the use of antibiotics both in animal and clinical settings for the loss of clinical multidrug resistance plasmids., This work was financially supported by the Spanish Ministry of Science, Innovation and Universities grants BIO2014-53530-R and BIO2017-83035-R (Agencia Española de Investigación/Fondo Europeo de Desarrollo Regional, European Union) to I.L. and C.S. P.D.-M. was supported by an F.P.I. (BES-2015-072859) contract from the Spanish Ministry of Science, Innovation and Universities.

Incluye material complementario, Bacterial biofilms provide high cell density and a superior adaptation and protection from stress conditions compared to planktonic cultures, making them a very promising approach for bioremediation. Several Rhodococcus strains can desulfurize dibenzothiophene (DBT), a major sulphur pollutant in fuels, reducing air pollution from fuel combustion. Despite multiple efforts to increase Rhodococcus biodesulfurization activity, there is still an urgent need to develop better biocatalysts. Here, we implemented a new approach that consisted in promoting Rhodococcus erythropolis biofilm formation through the heterologous expression of a diguanylate cyclase that led to the synthesis of the biofilm trigger molecule cyclic di-GMP (c-di-GMP). R. erythropolis biofilm cells displayed a significantly increased DBT desulfurization activity when compared to their planktonic counterparts. The improved biocatalyst formed a biofilm both under batch and continuous flow conditions which turns it into a promising candidate for the development of an efficient bioreactor for the removal of sulphur heterocycles present in fossil fuels., This study was financially supported by the Spanish Ministry of Science, Innovation and Universities grants BIO2014‐53530‐R and BIO2017‐83035‐R (Agencia Española de Investigación/Fondo Europeo de Desarrollo Regional, European Union) to I. Lasa and C. Solano and grants BIO2016‐79736‐R, PCIN‐2014‐113 and PCI2019‐111833‐2 to E. Díaz. P. Dorado‐Morales was supported by a F.P.I. (BES‐2015‐072859) contract from the Spanish Ministry of Science, Innovation and Universities.

Plasmids have largely contributed to the spread of antimicrobial resistance genes among Staphylococcus strains. Knowledge about the fitness cost that plasmids confer on clinical staphylococcal isolates and the coevolutionary dynamics that drive plasmid maintenance is still scarce. In this study, we aimed to analyze the initial fitness cost of plasmids in the bacterial pathogen Staphylococcus aureus and the plasmid-host adaptations that occur over time. For that, we first designed a CRISPR (clustered regularly interspaced palindromic repeats)-based tool that enables the removal of native S. aureus plasmids and then transferred three different plasmids isolated from clinical S. aureus strains to the same-background clinical cured strain. One of the plasmids, pUR2940, obtained from a livestock-associated methicillin-resistant S. aureus (LA-MRSA) ST398 strain, imposed a significant fitness cost on both its native and the new host. Experimental evolution in a nonselective medium resulted in a high rate pUR2940 loss and selected for clones with an alleviated fitness cost in which compensatory adaptation occurred via deletion of a 12.8-kb plasmid fragment, contained between two ISSau10 insertion sequences and harboring several antimicrobial resistance genes. Overall, our results describe the relevance of plasmid-borne insertion sequences in plasmid rearrangement and maintenance and suggest the potential benefits of reducing the use of antibiotics both in animal and clinical settings for the loss of clinical multidrug resistance plasmids., This work was financially supported by the Spanish Ministry of Science, Innovationand Universities grants BIO2014-53530-R and BIO2017-83035-R (Agencia Española de Investigación/Fondo Europeo de Desarrollo Regional, European Union) to I.L. and C.S.
P.D.-M. was supported by an F.P.I. (BES-2015-072859) contract from the Spanish Ministry of Science, Innovation and Universities.