Publicação
Pseudomonas fluorescens: the effect of evolution on the effectiveness of lytic phage as a control agent
| Resumo: | Antibiotic resistance in pathogenic bacteria is an increasing concern in health programs, and a number of alternatives are currently under investigation. One promising alternative is phage therapy, the use of specific bacteriophages to control or eradicate pathogenic bacteria. Despite having many advantages, the use of phages still presents some limitations and requires experimental investigation. Phage therapy benefits from the abilities of phages to multiply in situ and evolve, but bacteria can also evolve resistance to phages, in a process called antagonistic coevolution. Through the coevolution and evolution of wild type and mutator strains of Pseudomonas fluorescens and its lytic phage φ2, this study sought to determine how the nature of selection affects phage killing efficiency. Phages were sequentially transferred either with bacteria (coevolution) or passaged on the ancestral bacteria (evolution). The efficiency of phages from three time points (transfers 1, 4 and 8) was estimated by plating on ancestral and allopatric coevolved bacteria. The results indicate that the coevolution treatment leads to a greater increase in phage efficiency than the evolution treatment. This is specially seen when phage populations are confronted with mutator coevolved bacteria, which may be due to a specialization cost to the evolved phage populations. Wild type coevolved bacteria were resistant to all allopatric phages, whether from the past, present or future. Phage infectivity to ancestral bacteria peaked early in the transfer regime. Further studies are necessary to confirm these results and should consider the effects of phage dose. |
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| Autores principais: | Santos, Renata Isabel Lino dos, 1989- |
| Assunto: | Resistência a antibióticos Bactérias Microbiologia Teses de mestrado - 2012 |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Antibiotic resistance in pathogenic bacteria is an increasing concern in health programs, and a number of alternatives are currently under investigation. One promising alternative is phage therapy, the use of specific bacteriophages to control or eradicate pathogenic bacteria. Despite having many advantages, the use of phages still presents some limitations and requires experimental investigation. Phage therapy benefits from the abilities of phages to multiply in situ and evolve, but bacteria can also evolve resistance to phages, in a process called antagonistic coevolution. Through the coevolution and evolution of wild type and mutator strains of Pseudomonas fluorescens and its lytic phage φ2, this study sought to determine how the nature of selection affects phage killing efficiency. Phages were sequentially transferred either with bacteria (coevolution) or passaged on the ancestral bacteria (evolution). The efficiency of phages from three time points (transfers 1, 4 and 8) was estimated by plating on ancestral and allopatric coevolved bacteria. The results indicate that the coevolution treatment leads to a greater increase in phage efficiency than the evolution treatment. This is specially seen when phage populations are confronted with mutator coevolved bacteria, which may be due to a specialization cost to the evolved phage populations. Wild type coevolved bacteria were resistant to all allopatric phages, whether from the past, present or future. Phage infectivity to ancestral bacteria peaked early in the transfer regime. Further studies are necessary to confirm these results and should consider the effects of phage dose. |
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