Afonso, Ana CristinaSimões, ManuelSaavedra, Maria Jose FelixSimões, LúciaLema Rodicio, Juan ManuelTrueba Santiso, Alba María2024-09-262024-09-262024-06-14Journal of Applied Microbiology 135 6 (2024) lxae143http://hdl.handle.net/10347/34880Aim Coaggregation, a highly specific cell–cell interaction mechanism, plays a pivotal role in multispecies biofilm formation. While it has been mostly studied in oral environments, its occurrence in aquatic systems is also acknowledged. Considering biofilm formation’s economic and health-related implications in engineered water systems, it is crucial to understand its mechanisms. Here, we hypothesized that traceable differences at the proteome level might determine coaggregation ability. Methods and Results Two strains of Delftia acidovorans, isolated from drinking water were studied. First, in vitro motility assays indicated more swarming and twitching motility for the coaggregating strain (C+) than non-coaggregating strain (C−). By transmission electronic microscopy, we confirmed the presence of flagella for both strains. By proteomics, we detected a significantly higher expression of type IV pilus twitching motility proteins in C+, in line with the motility assays. Moreover, flagellum ring proteins were more abundant in C+, while those involved in the formation of the flagellar hook (FlE and FilG) were only detected in C−. All the results combined suggested structural and conformational differences between stains in their cell appendages. Conclusion This study presents an alternative approach for identifying protein biomarkers to detect coaggregation abilities in uncharacterized strainsengAtribución 4.0 Internacional© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/)http://creativecommons.org/licenses/by/4.0/AggregationCell–cell interactionCellular appendagesMultispecies biofilmProteomicsTEMjournal article10.1093/jambio/lxae1431365-2672open access