Abstract The Role of Cyanobacteria in the Aquatic Resistome † Tânia Rosado 1 , Duarte Balata 2 , Rani de la Rivière 1,3 , Vera Manageiro 4,5,6 , Dina Carpinteiro 7 , Luís Vieira 7 , Francisco Pina-Martins 2 , Carina Menezes 1 , Octávio S. Paulo 2 , Manuela Caniça 4,5,6 and Elsa Dias 1,5,6, *,‡ 1 2 3 4 5 6 7 * † ‡ Citation: Rosado, T.; Balata, D.; de la Rivière, R.; Manageiro, V.; Carpinteiro, D.; Vieira, L.; Pina-Martins, F.; Menezes, C.; Paulo, O.S.; Caniça, M.; et al. The Role of Cyanobacteria in the Aquatic Resistome. Biol. Life Sci. Forum 2022, 14, 32. https://doi.org/10.3390/ blsf2022014032 Academic Editor: Vitor Gonçalves Published: 25 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in Laboratório de Biologia e Ecotoxicologia, Departamento de Saúde Ambiental, Instituto Nacional de Saúde Dr. Ricardo Jorge (INSA), Av. Padre Cruz, 1649-016 Lisboa, Portugal; tania.s.rosado@gmail.com (T.R.); raniriviere1404@gmail.com (R.d.l.R.); carina-menezes@insa.min-saude.pt (C.M.) Centro de Ecologia, Evolução e Alterações Ambientais, Faculdade de Ciências, Universidade de Lisboa (FCUL), Campo Grande 016, 1749-016 Lisboa, Portugal; duarte.balata@hotmail.com (D.B.); f.pinamartins@gmail.com (F.P.-M.); octavio.paulo@fc.ul.pt (O.S.P.) Faculdade de Ciências, Universidade de Lisboa (FCUL), Campo Grande 016, 1749-016 Lisboa, Portugal Laboratório Nacional de Referência. da Resistência aos Antibióticos, Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge (INSA), Av. Padre Cruz, 1649-016 Lisboa, Portugal; vera.manageiro@insa.min-saude.pt (V.M.); manuela.canica@insa.min-saude.pt (M.C.) Centro de Estudos de Ciência Animal (CECA), Instituto de Ciências, Tecnologias e Agroambiente (ICETA), Universidade do Porto, 4051-401 Porto, Portugal Laboratório Associado para Ciência Animal e Veterinária (AL4AnimalS), 4051-401 Porto, Portugal Unidade de Tecnologia e Inovação, Departamento de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge (INSA), Av. Padre Cruz, 1649-016 Lisboa, Portugal; dina.carpinteiro@insa.min-saude.pt (D.C.); luis.vieira@insa.min-saude.pt (L.V.) Correspondence: elsa.dias@insa.min-saude.pt Presented at the 7th Iberian Congress on Cyanotoxins/3rd Iberoamerican Congress on Cyanotoxins, Ponta Delgada, Portugal, 18–20 July 2022. Presenting author (oral communication). Abstract: The aquatic environment is a reservoir of antibiotics, pathogenic and native microorganisms, and antibiotic resistance genes (ARGs), constituting a key aspect of the One Health approach. Thus, the problem of antibiotic resistance is no longer restricted to bacterial pathogens but is a consequence of the interplay between distinct clinical and environmental drivers. In the project “ExplorAR— Exploring the Aquatic Resistome”, we investigated the putative role of cyanobacteria (CB) in the freshwater resistome, using a multidisciplinary approach based on phenotypic/genotypic/genomic tools. In this presentation, we disclose the main results of the project: (i) the development of a microdilution-based antibiotic susceptibility assay for CB; (ii) the establishment of an antibiotic susceptibility profile of CB genus/species; (iii) the identification of CB strains with reduced susceptibility to multiple antibiotic classes; (iv) the identification of ARGs in CB genomes; (v) the characterization of the antibiotic resistance profile of CB-associated bacteria; (vi) mapping the occurrence of CB and ARGs in surface freshwater reservoirs by high-throughput sequencing approaches. Overall, ExplorAR strongly supports the hypothesis that CB are environmental players in the emergence and dissemination of ARGs in water environments, contributing to the problem, and challenges, of antibiotic resistance. published maps and institutional affiliations. Keywords: antibiotic pollution; antibiotic resistance; aquatic resistome; cyanobacteria; minimum inhibitory concentration; next-generation sequencing Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Author Contributions: Conceptualization, E.D., M.C. and O.S.P.; methodology, D.B., T.R., R.d.l.R., V.M., D.C., L.V., F.P.-M., C.M., O.S.P., M.C. and E.D.; software D.B., D.C., L.V., F.P.-M. and O.S.P.; investigation, D.B., T.R., F.P.-M., V.M., C.M., O.S.P., M.C. and E.D.; resources, E.D. and M.C.; writing— original draft preparation, D.B., T.R. and E.D.; writing—review and editing, D.B., T.R., F.P.-M., V.M., C.M., O.S.P., M.C. and E.D.; visualization, D.B., T.R., C.M. and D.C.; supervision, O.S.P., M.C. and E.D.; project administration, E.D.; funding acquisition, E.D. and M.C. All authors have read and agreed to the published version of the manuscript. Biol. Life Sci. Forum 2022, 14, 32. https://doi.org/10.3390/blsf2022014032 https://www.mdpi.com/journal/blsf Biol. Life Sci. Forum 2022, 14, 32 2 of 2 Funding: This research was funded by the Portuguese Foundation for Science and Technology (FCT/MCTES), through national funds (PIDDAC), in the scope of the project “ExplorAR_Exploring the Aquatic Resistome” (PTDC/BIABMA/31451/2017). Financial support included the fellowship attributed to Duarte Balata and a research contract of Tânia Rosado. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Conflicts of Interest: The authors declare no conflict of interest.