Remembering Pepe Casadesús.

On Tuesday, 2 August 2022, Josep (Pepe) Casadesús unexpectedly passed away while on vacation in his native Catalonia. Pepe was born on 11 September 1951, in his grandparents’ house, a small ‘masía’, in the municipality of Casserres, region of Catalonia, Spain. Pepe was trained as microbiologist at the ‘Estación Experimental del Zaidín-CSIC’ in Granada, Spain, working in the laboratory of José Olivares. He obtained his PhD degree in 1980 with a thesis on ‘Genetic studies in Rhizobium meliloti’. In 1983, after a 2year stay at the ‘Nitrogen Fixation Laboratory’ of Ray Dixon at the University of Sussex (to learn molecular biology), he moved to the laboratory of John Roth at the University of Utah, in Salt Lake City, for a second postdoctoral period. John Roth’s lab had pioneered the use of Salmonella enterica (serovar Typhimurium) as a model organism for bacterial genetic studies. The charm and power of Salmonella genetics combined with the intellectual liveness of the lab would have an ever-lasting impact on Pepe’s scientific life. Not only did he adopt Salmonella as a model system for his subsequent studies, but he was also strongly inspired by the spirit and practices of Roth’s lab when he started his own group at the University of Seville in 1985. He never imposed experiments on his students, but preferred experimental strategies to take shape during open and friendly discussions, only occasionally animated by his persuasive skills. He returned to Utah as a visiting professor for two extended periods of time, in 1988 and in 2000. Besides enjoying the company of some faculty at the Biology Department, he loved the magnificent decor of Salt Lake City mountains. He especially liked taking walks in Red Butte Canyon, at the eastern edge of the University campus, where colour changes in the fall can overwhelm your senses (Fig. 1). After two other stays as visiting professor at the Biozentrum, Universität Basel (Switzerland) and at the Università degli Studi di Sassari (Sardinia, Italy), in 1999, Pepe became full Professor of Genetics at the University of Seville, where he stayed for the rest of his career. He received many distinctions related to his academic activity, but undoubtedly what was most rewarding for him was the appreciation and respect he received from his former students and alumni. He trained many researchers in his lab and his lectures inspired many students to undertake a career in science. Pepe was the editor of several journals like PLoS Genetics (from 2011) and was the ambassador of the American Society for Microbiology in Europe. In 2018, he was elected fellow of the American Academy of Microbiology and in 2019 of the European Academy for Microbiology. He did extensive work as reviewer of papers and grant proposals for institutions in the USA, IberoAmerica, and the European Commission. In his nearly 40 years of activity, Pepe’s research covered various aspects of Salmonella biology. Early on, he became fascinated by the mechanisms that produce phenotypic heterogeneity in populations of genetically identical bacteria, a topic that constituted a leitmotif in his scientific career. This interest, which he developed long before the subject became trendy, led him to focus on epigenetic regulation, particularly the role of DNA methylation in the Figure 1. Pepe in Red Butte Canyon, UT, October 2014.