Cloning of the determinants for microcin D93 production and analysis of three different D-type microcin plasmids

Martínez, J L; Pérez-Díaz, JoséC.

doi:10.1016/0147-619x(90)90053-f

Cited by 14 publications

(5 citation statements)

References 33 publications

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“…In the course of this work and later on when we isolated five additional microcin-producing strains we did not detect the microcins of any other types, not even the A or D type. The incidence of these types among microcin producers was reported earlier to be more than 30% and 50%, respectively [10,11]. Under our conditions, the microcin producers of type B were the most widely distributed: nine out of the 12 microcinsynthesizing isolates produced this type of microcins, and three microcins were similar (by cross-immunity test) to microcin of type C.…”

Section: Microcin Nature and Activity Rangesupporting

confidence: 52%

Isolation and characterization of Escherichia coli strains producing microcins of B and C types

Khmel

1993

FEMS Microbiology Letters

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A screening of 11956 enterobacteria isolates resulted in selection of seven active microcin-producing strains. The microcins were shown to be peptides or their derivatives with a rather broad spectrum of activity, mainly against Gram-negative bacteria. According to cross-immunity criteria, the microcins studied belonged to two of the previously suggested types, B (five strains) and C (two strains). Those of type B could be further classified into two subtypes on the account of differences in the spectrum of antibacterial activity. In five cases out of seven the microcin-producing ability has been attributed to plasmids that the strains harboured. The effect of microcins on sensitive cells was shown to depend on ompR and ompF gene products.

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Section: Microcin Nature and Activity Rangesupporting

confidence: 52%

Isolation and characterization of Escherichia coli strains producing microcins of B and C types

Khmel

1993

FEMS Microbiology Letters

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“…, 2006) or to ecologically valuable determinants such as siderophores, toxins or microcins (Delgado‐Iribarren et al. , 1987; Martinez and Perez‐Diaz, 1990; Herrero et al. , 2008).…”

Section: Second‐order Selection Should Resistance Remain?mentioning

confidence: 99%

Ecology and evolution of antibiotic resistance

Baquero

Álvarez-Ortega

Martínez

2009

Environ Microbiol Rep

134

100

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The evolution of bacterial pathogens towards antibiotic resistance is not just a relevant problem for human health, but a fascinating example of evolution that can be studied in real time as well. Although most antibiotics are natural compounds produced by environmental microbiota, exposure of bacterial populations to high concentrations of these compounds as the consequence of their introduction for human therapy (and later on for farming) a few decades ago is a very recent situation in evolutionary terms. Resistance genes are originated in environmental bacteria, where they have evolved for millions of years to play different functions that include detoxification, signal trafficking or metabolic functions among others. However, as the consequence of the strong selective pressure exerted by antimicrobials at clinical settings, farms and antibiotic-contaminated natural ecosystems, the selective forces driving the evolution of these potential resistance determinants have changed in the last few decades. Natural ecosystems contain a large number of potential resistance genes; nevertheless, just a few of them are currently present in gene-transfer units and disseminated among pathogens. Along the review, the processes implied in this situation and the consequences for the future evolution of resistance and the environmental microbiota are discussed.

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“…This includes resistance to toxic compounds (e.g. antibiotics, heavy metals, biocides) and other elements, such as siderophores, microcins or toxins, which can favour the survival of bacteria in a given habitat (Delgado-Iribarren et al 1987;Martinez & Perez-Diaz 1990;Herrero et al 2008). Under these circumstances, resistance can be co-selected by its associated trait in the absence of antibiotics.…”

Section: Changes In Natural Ecosystems and Future Evolution Of Antibimentioning

confidence: 99%

The role of natural environments in the evolution of resistance traits in pathogenic bacteria

Martínez¹

2009

Proc. R. Soc. B.

419

313

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Antibiotics are among the most valuable compounds used for fighting human diseases. Unfortunately, pathogenic bacteria have evolved towards resistance. One important and frequently forgotten aspect of antibiotics and their resistance genes is that they evolved in non-clinical (natural) environments before the use of antibiotics by humans. Given that the biosphere is mainly formed by micro-organisms, learning the functional role of antibiotics and their resistance elements in nature has relevant implications both for human health and from an ecological perspective. Recent works have suggested that some antibiotics may serve for signalling purposes at the low concentrations probably found in natural ecosystems, whereas some antibiotic resistance genes were originally selected in their hosts for metabolic purposes or for signal trafficking. However, the high concentrations of antibiotics released in specific habitats (for instance, clinical settings) as a consequence of human activity can shift those functional roles. The pollution of natural ecosystems by antibiotics and resistance genes might have consequences for the evolution of the microbiosphere. Whereas antibiotics produce transient and usually local challenges in microbial communities, antibiotic resistance genes present in gene-transfer units can spread in nature with consequences for human health and the evolution of environmental microbiota that are largely ignored.

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Cloning of the determinants for microcin D93 production and analysis of three different D-type microcin plasmids

Cited by 14 publications

References 33 publications

Isolation and characterization of Escherichia coli strains producing microcins of B and C types

Isolation and characterization of Escherichia coli strains producing microcins of B and C types

Ecology and evolution of antibiotic resistance

The role of natural environments in the evolution of resistance traits in pathogenic bacteria

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