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Curiously, their interaction is reported as competitive under laboratory conditions. Selecting appropriate methodologies is therefore critical to analyse multi-species communities. Herein, we demonstrated the major biases associated with qPCR quantification of bacterial populations and optimized a RNA-based qPCR able not only to quantify but also to characterize microbial interactions within dual-species biofilms composed by <jats:italic>P<\/jats:italic>. <jats:italic>aeruginosa<\/jats:italic> and <jats:italic>S<\/jats:italic>. <jats:italic>aureus<\/jats:italic>, as assessed by gene expression quantification. qPCR quantification was compared with flow-cytometry and culture-based quantification. Discrepancies between culture independent and culture dependent methods could be the result of the presence of viable but not-cultivable bacteria within the biofilm. Fluorescence microscopy confirmed this. A higher sensitivity to detect viable cells further highlights the potentialities of qPCR approach to quantify biofilm communities. By using bacterial RNA and an exogenous mRNA control, it was also possible to characterize bacterial transcriptomic profile, being this a major advantage of this method.<\/jats:p>","DOI":"10.1038\/s41598-019-50094-3","type":"journal-article","created":{"date-parts":[[2019,9,20]],"date-time":"2019-09-20T10:15:48Z","timestamp":1568974548000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":42,"title":["RNA-based qPCR as a tool to quantify and to characterize dual-species biofilms"],"prefix":"10.1038","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2049-0185","authenticated-orcid":false,"given":"Andreia Patr\u00edcia","family":"Magalh\u00e3es","sequence":"first","affiliation":[]},{"given":"\u00c2ngela","family":"Fran\u00e7a","sequence":"additional","affiliation":[]},{"given":"Maria Ol\u00edvia","family":"Pereira","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3365-3537","authenticated-orcid":false,"given":"Nuno","family":"Cerca","sequence":"additional","affiliation":[]}],"member":"297","published-online":{"date-parts":[[2019,9,20]]},"reference":[{"key":"50094_CR1","doi-asserted-by":"publisher","first-page":"95","DOI":"10.1038\/nrmicro821","volume":"2","author":"L Hall-Stoodley","year":"2004","unstructured":"Hall-Stoodley, L., Costerton, J. 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