Because of the global human aging, sarcopenia has become a major health problem, associated with high quality-of-life and financial costs for both patient and society. Unfortunately, pathophysiological processes are poorly understood; hence, the disease is largely undertreated. Recent studies indicate an association between sarcopenia and the gut microbiome. However, the central actors of the microbiome are still unknown. Based on previous research from our group, we found that quorum sensing peptides (QSP), produced by gut bacteria, can play a role in the gut microbiome - sarcopenia axis. Therefore, in this research proposal, we will further elaborate these findings by measuring the presence of microbial QSP in human biofluids in association with (muscle) phenotype of 250 care home residents. Moreover, causality of QSP on sarcopenia, and the potential to develop novel sarcopenia therapeutics such as probiotics/live biotherapeutics will be explored using mice models and muscle cells. Overall, this project will uncover new insights in the role of the gut microbiome in sarcopenia, translationally aiming to offer personalized therapies in order to extend independent living of older people.