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Competition for nutritional resources masks the true frequency of bacterial mutants.
Neves, Henrique Iglesias; Machado, Gabriella Trombini; Ramos, Taíssa Cristina Dos Santos; Yang, Hyun Mo; Yagil, Ezra; Spira, Beny.
Afiliação
  • Neves HI; Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil.
  • Machado GT; Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil.
  • Ramos TCDS; Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil.
  • Yang HM; Departamento de Matemática Aplicada, Instituto de Matemática, Estatística e Computação Científica, Campinas, SP, Brazil.
  • Yagil E; Departament of Biochemistry and Molecular Biology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel.
  • Spira B; Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil. benys@usp.br.
BMC Biol ; 18(1): 194, 2020 12 14.
Article em En | MEDLINE | ID: mdl-33317515
BACKGROUND: It is widely assumed that all mutant microorganisms present in a culture are able to grow and form colonies, provided that they express the features required for selection. Unlike wild-type Escherichia coli, PHO-constitutive mutants overexpress alkaline phosphatase and hence can hydrolyze glycerol-2-phosphate (G2P) to glycerol and form colonies on plates having G2P as the sole carbon source. These mutations mostly occur in the pst operon. However, the frequency of PHO-constitutive colonies on the G2P selective plate is exceptionally low. RESULTS: We show that the rate in which spontaneous PHO-constitutive mutations emerge is about 8.0 × 10-6/generation, a relatively high rate, but the growth of most existing mutants is inhibited by their neighboring wild-type cells. This inhibition is elicited only by non-mutant viable bacteria that can take up and metabolize glycerol formed by the mutants. Evidence indicates that the few mutants that do form colonies derive from microclusters of mutants on the selective plate. A mathematical model that describes the fate of the wild-type and mutant populations under these circumstances supports these results. CONCLUSION: This scenario in which neither the wild-type nor the majority of the mutants are able to grow resembles an unavoidable "tragedy of the commons" case which results in the collapse of the majority of the population. Cooperation between rare adjacent mutants enables them to overcome the competition and eventually form mutant colonies. The inhibition of PHO-constitutive mutants provides an example of mutant frequency masked by orders of magnitude due to a competition between mutants and their ancestral wild-type cells. Similar "tragedy of the commons-like" cases may occur in other settings and should be taken into consideration while estimating true mutant frequencies and mutation rates.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Escherichia coli / Interações Microbianas / Mutação Idioma: En Revista: BMC Biol Assunto da revista: BIOLOGIA Ano de publicação: 2020 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Escherichia coli / Interações Microbianas / Mutação Idioma: En Revista: BMC Biol Assunto da revista: BIOLOGIA Ano de publicação: 2020 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido