title: Effects of heavy metals on Cyanothece sp. CCY 0110 growth, extracellular polymeric substances (EPS) production, ultrastructure and protein profiles.
abstract: The effects of several heavy metals on the growth/survival, EPS production, ultrastructure and protein profiles of the highly efficient extracellular polymeric substances (EPS)-producer cyanobacterium Cyanothece sp. CCY 0110 were evaluated. Our results clearly show that each heavy metal affects the cells in a particular manner, triggering distinctive responses. Concerning chronic exposure, cells were more affected by Cu(2+) followed by Pb(2+), Cd(2+), and Li(+). The presence of metal leads to remarkable ultrastructural changes, mainly at the thylakoid level. The comparison of the proteomes (iTRAQ) allowed to follow the stress responses and to distinguish specific effects related to the time of exposure and/or the concentration of an essential (Cu(2+)) and a non-essential (Cd(2+)) metal. The majority of the proteins identified and with fold changes were associated with photosynthesis, CO2 fixation and carbohydrate metabolism, translation, and nitrogen and amino acid metabolism. Moreover, our results indicate that during chronic exposure to sub-lethal concentrations of Cu(2+), the cells tune down their metabolic rate to invest energy in the activation of detoxification mechanisms, which eventually result in a remarkable recovery. In contrast, the toxic effects of Cd(2+) are cumulative. Unexpectedly, the amount of released polysaccharides (RPS) was not enhanced by the presence of heavy metals.
  
  
  CONCLUSIONS
  This work shows the holistic effects of different heavy metals on the cells of the highly efficient EPS-producer the cyanobacterium Cyanothece sp. CCY 0110. The growth/survival, EPS production, ultrastructure, protein profiles and stress response were evaluated. The knowledge generated by this study will contribute to the implementation of heavy-metal removal systems based on cyanobacteria EPS or their isolated polymers.
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Porto, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Mota
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
authors.forename: Sara B
authors.initials: SB
authors.lastname: Pereira
authors.affiliation: Department of Agrifood Production and Environmental Sciences, University of Florence, Florence, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Meazzini
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
authors.forename: Rui
authors.initials: R
authors.lastname: Fernandes
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Porto, Portugal.
authors.forename: Arlete
authors.initials: A
authors.lastname: Santos
authors.affiliation: ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Evans
authors.affiliation: Department of Agrifood Production and Environmental Sciences, University of Florence, Florence, Italy; Institute of Ecosystem Study (ISE), National Research Council (CNR), Sesto Fiorentino (FI), Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: De Philippis
authors.affiliation: ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Wright
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Porto, Portugal. Electronic address: pmtamagn@ibmc.up.pt.
authors.forename: Paula
authors.initials: P
authors.lastname: Tamagnini
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology; D046889:Cyanothece / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000502:physiology; D019216:Metals, Heavy / Q000494:pharmacology*; D020543:Proteome / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D019216:Metals, Heavy; D020543:Proteome
keywords: Cyanobacteria; Cyanothece; Extracellular polymeric substances (EPS); Heavy metals; Proteome; iTRAQ