This study evaluated linear alkylbenzene sulfonate removal in an expanded granular sludge bed reactor with hydraulic retention times of 26 h and 32 h. Sludge bed and separator phase biomass were phylogenetically characterized (sequencing 16S rRNA) and quantified (most probable number) to determine the total anaerobic bacteria and methanogenic Archaea. The reactor was fed with a mineral medium supplemented with 14 mg l(-1) LAS, ethanol and methanol. The stage I-32 h consisted of biomass adaptation (without LAS influent) until reactor stability was achieved (COD removal &gt;97%). In stage II-32 h, LAS removal was 74% due to factors such as dilution, degradation and adsorption. Higher HRT values increased the LAS removal (stage III: 26 h - 48% and stage IV: 32 h - 64%), probably due to increased contact time between the biomass and LAS. The clone libraries were different between samples from the sludge bed (Synergitetes and Proteobacteria) and the separator phase (Firmicutes and Proteobacteria) biomass. (C) 2011 Elsevier Ltd. All rights reserved.FAPESPFapespCNPqCNP

Delforno, Tiago Palladino

Okada, Dagoberto Yukio

Polizel, Juliana

Sakamoto, Isabel Kimiko

Varesche, Maria Bernadete Amancio

Universidade de São Paulo

Bioresource Technology

Microbial characterization and removal of anionic surfactant in an expanded granular sludge bed reactor

AbstractThis study evaluated linear alkylbenzene sulfonate removal in an expanded granular sludge bed reactor with hydraulic retention times of 26h and 32h. Sludge bed and separator phase biomass were phylogenetically characterized (sequencing 16S rRNA) and quantified (most probable number) to determine the total anaerobic bacteria and methanogenic Archaea. The reactor was fed with a mineral medium supplemented with 14mgl−1LAS, ethanol and methanol. The stage I-32h consisted of biomass adaptation (without LAS influent) until reactor stability was achieved (COD removal >97%). In stage II-32h, LAS removal was 74% due to factors such as dilution, degradation and adsorption. Higher HRT values increased the LAS removal (stage III: 26h – 48% and stage IV: 32h – 64%), probably due to increased contact time between the biomass and LAS. The clone libraries were different between samples from the sludge bed (Synergitetes and Proteobacteria) and the separator phase (Firmicutes and Proteobacteria) biomass

Delforno, T.P.

Okada, D.Y.

Polizel, J.

Sakamoto, I.K.

Varesche, M.B.A.

Elsevier - Publisher Connector 

Microbial characterization and removal of anionic surfactant in an expanded granular sludge bed reactor 

This study evaluated linear alkylbenzene sulfonate removal in an expanded granular sludge bed reactor with hydraulic retention times of 26 h and 32 h. Sludge bed and separator phase biomass were phylogenetically characterized (sequencing 16S rRNA) and quantified (most probable number) to determine the total anaerobic bacteria and methanogenic Archaea. The reactor was fed with a mineral medium supplemented with 14 mg l(-1) LAS, ethanol and methanol. The stage I-32 h consisted of biomass adaptation (without LAS influent) until reactor stability was achieved (COD removal &gt;97%). In stage II-32 h, LAS removal was 74% due to factors such as dilution, degradation and adsorption. Higher HRT values increased the LAS removal (stage III: 26 h - 48% and stage IV: 32 h - 64%), probably due to increased contact time between the biomass and LAS. The clone libraries were different between samples from the sludge bed (Synergitetes and Proteobacteria) and the separator phase (Firmicutes and Proteobacteria) biomass. (C) 2011 Elsevier Ltd. All rights reserved

RCAAP - Repositório Científico de Acesso Aberto de Portugal

T.P. Delforno

D.Y. Okada

J. Polizel

I.K. Sakamoto

M.B.A. Varesche

Crossref

The bacterial toxin pyolysin (PLO) belongs to the family of cholesterol-dependent cytolysins (CDCs), which form large, ring-shaped oligomeric pores in cholesterol-containing membranes. Monomeric CDC molecules have a structure of four domains, with domains 2 and 3 packed against each other. After binding to target membranes containing cholesterol, toxin monomers oligomerize into pre-pore complexes. Trans-membrane pores form when the pre-pores insert into the lipid bilayer. Membrane insertion requires each subunit in the pre-pore to undergo a significant change in conformation, including the separation of domains 2 and 3. We here characterize a pyolysin mutant with an engineered disulfide bond between domains 2 and 3. The disulfide-tethered mutant binds to membranes but does not form oligomers. When mixed with wild type PLO, the two proteins form hybrid oligomers, which are reduced in size and arc-shaped rather than ring-shaped. With equimolar mixtures or the disulfide mutant in slight excess, the hybrid oligomers retain pore-forming activity, while a larger excess of the mutant suppresses pore formation. These results support a “partially cooperative” mode of protein activity, in which a limited number of functional subunits within an oligomer have to cooperate to initiate membrane insertion and pore formation.</jats:p

Lisa Pokrajac

Clara Baik

J. Robin Harris

Naghmeh S. Sarraf

Michael Palmer

Biochemistry and Cell Biology

Partial oligomerization of pyolysin induced by a disulfide-tethered mutant

Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)

The bacterial toxin pyolysin (PLO) belongs to the family of cholesterol-dependent cytolysins (CDCs), which form large, ring-shaped oligomeric pores in cholesterol-containing membranes. Monomeric CDC molecules have a structure of four domains, with domains 2 and 3 packed against each other. After binding to target membranes containing cholesterol, toxin monomers oligomerize into pre-pore complexes. Trans-membrane pores form when the pre-pores insert into the lipid bilayer. Membrane insertion requires each subunit in the pre-pore to undergo a significant change in conformation, including the separation of domains 2 and 3. We here characterize a pyolysin mutant with an engineered disulfide bond between domains 2 and 3. The disulfide-tethered mutant binds to membranes but does not form oligomers. When mixed with wild type PLO, the two proteins form hybrid oligomers, which are reduced in size and arc-shaped rather than ring-shaped. With equimolar mixtures or the disulfide mutant in slight excess, the hybrid oligomers retain pore-forming activity, while a larger excess of the mutant suppresses pore formation. These results support a "partially cooperative" mode of protein activity, in which a limited number of functional subunits within an oligomer have to cooperate to initiate membrane insertion and pore formation. \ua9 2012 Published by NRC Research Press.Peer reviewed: YesNRC publication: Ye

Pokrajac, L.

Baik, C.

Harris, J.R.

Sarraf, N.S.

Palmer, M.

NRC Publications Archive

Publisher version available at: http://dx.doi.org/10.1139/O2012-029The bacterial toxin pyolysin (PLO) belongs to the family of cholesterol-dependent cytolysins (CDCs), which form large, ring-shaped oligomeric pores in cholesterol-containing membranes. Monomeric CDC molecules have a structure of four domains, with domains 2 and 3 packed against each other. After binding to target membranes containing cholesterol, toxin monomers oligomerize into pre-pore complexes. Trans-membrane pores form when the pre-pores insert into the lipid bilayer. Membrane insertion requires each subunit in the pre-pore to undergo a significant change in conformation, including the separation of domains 2 and 3. We here characterize a pyolysin mutant with an engineered disulfide bond between domains 2 and 3. The disulfide-tethered mutant binds to membranes but does not form oligomers. When mixed with wild type PLO, the two proteins form hybrid oligomers, which are reduced in size and arc-shaped rather than ring-shaped. With equimolar mixtures or the disulfide mutant in slight excess, the hybrid oligomers retain pore-forming activity, while a larger excess of the mutant suppresses pore formation. These results support a "partially cooperative" mode of protein activity, in which a limited number of functional subunits within an oligomer have to cooperate to initiate membrane insertion and pore formation.Natural Sciences and Engineering Research Council of Canad

Pokrajac, Lisa A.

Baik, Clara

Harris, J. Robin

Sarraf, Naghmeh S.

Palmer, Michael

University of Waterloo's Institutional Repository

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Microbial characterization and removal of anionic surfactant in an expanded granular sludge bed reactor

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Universidade de São Paulo

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RCAAP - Repositório Científico de Acesso Aberto de Portugal

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Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)

Elsevier - Publisher Connector

NRC Publications Archive

University of Waterloo's Institutional Repository