title: Response surface optimization of a method for extracting extracellular polymeric substances (EPS) from subaerial biofilms on rocky substrata.
abstract: The aim of the present study was to optimize a protocol for extracting extracellular polymeric substances (EPS) from biofilms on rocky substrata, as the EPS matrix is considered key to understanding the biofilm mode of life. For this purpose, we tested the extraction efficacy of NaOH and H2SO4 at different concentrations, temperatures and times for obtaining EPS from multi-species subaerial biofilms grown on granite blocks under laboratory conditions. Two experimental designs (Box-Behnken design and full factorial design) were used in testing each extractant. The extraction efficiency was determined by analysing the carbohydrate, protein and DNA contents of the extracts obtained. H2SO4 proved unsuitable as an extractant as it caused excessive cell lysis. However, response surface optimization of NaOH-mediated extraction enabled cell lysis to be minimized. Confirmation experiments were performed under the optimal conditions established and a protocol for extracting EPS is proposed, yielding the first quantitative data on EPS extracted from subaerial biofilms developed on rocky substrata. Graphical abstract Development of a method for extracting EPS from subaerial biofilms on rocky substrata.
authors.affiliation: Departamento de Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain. daniel.vazquez@usc.es.
authors.forename: Daniel
authors.identifier: http://orcid.org/0000-0002-6726-4890
authors.initials: D
authors.lastname: Vázquez-Nion
authors.affiliation: Departamento de Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Echeverri
authors.affiliation: Departamento de Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain.
authors.forename: Benita
authors.initials: B
authors.lastname: Silva
authors.affiliation: Departamento de Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Prieto
mesh_terms: D018441:Biofilms / Q000254:growth & development; D002241:Carbohydrates / Q000302:isolation & purification*; D005591:Chemical Fractionation / Q000379:methods*; D000460:Chlorophyta / Q000737:chemistry* / Q000502:physiology; D000458:Cyanobacteria / Q000737:chemistry* / Q000502:physiology; D004247:DNA / Q000302:isolation & purification*; D019015:Geologic Sediments / Q000382:microbiology; D011108:Polymers / Q000302:isolation & purification; D011506:Proteins / Q000302:isolation & purification*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D002241:Carbohydrates; D011108:Polymers; D011506:Proteins; C007886:granite; D012822:Silicon Dioxide; D004247:DNA
keywords: Extracellular polymeric substances (EPS); Extraction protocol; Response surface methodology; Subaerial biofilms