Microbiology, genetics and evolution are the main areas of research that Nelson Frazão has embraced since graduating in Biology and Genetics from the University of Lisbon in 2002. His graduate studies were conducted both in the Tomasz lab at The Rockefeller University, USA, and Universidade Nova de Lisboa, Portugal, during which he disclosed the effectiveness of a vaccine against Streptococcus pneumoniae carriage in Portugal. He obtained his PhD degree in Biology and Molecular Biology in December 2010. During his early postdoctoral work, Nelson strengthened skills in animal models, this time using an infant mouse model of pneumococcal influenza virus coinfection at the Radboud University in the Netherlands. This allowed him to assess the virulence of pneumococcal isolates selected in vivo by the S. pneumoniae vaccine in humans. In 2014, he joined the Evolutionary Biology group at the Instituto Gulbenkian de Ciência (IGC) to establish a new mouse colonization model to study Escherichia coli adaptation to the mammalian gut. This resulted in several key discoveries, including that bacteriophage-driven adaptation to the intestine overrides the mutational process, bringing metabolic advantage (PNAS, 2019), and that the shaping of gut bacterial strain diversity is induced by two evolution modes (Nature Commun, 2022). Overall, Nelson Frazão has published 18 peer-reviewed articles, 9 as first and 4 as co-corresponding author, which have received an average of 58 citations each. He has (co-)reviewed manuscripts for major international journals (e.g., Nature Ecology & Evolution, PNAS, Cell Host & Microbe, Cell Reports, PLoS Biology), served as external examiner of a PhD thesis, supervised 10 undergraduate students, and has often been invited lecturer in different graduate and undergraduate programs (e.g., IGC PhD Program, Universidade de Aveiro, Faculdade de Ciências da Universidade de Lisboa). He is also strongly committed to promoting science to lay audiences, having delivered outreach talks at different events (e.g. International Biology Olympiad, Earth day and International Microorganism Day) and interviews to major national media outlets, such as radio stations Antena 1 and Antena 2 Ciência or the national TV channel RTP1. Nelson Frazão has secured funding for his salary on a competitive basis (fellowships/contracts) ever since completing his PhD. In 2020, he was awarded an FCT-funded project as Co-Principal Investigator (€249,720) and an IGC Bluesky Project grant (€10,000). The latter project enabled him to establish his own research group in 2024, focusing on E. coli evolution in the mammalian gut under pressures such as IAV infection and pregnancy at Católica Medical School.