“…Cyclic di-AMP (c-di-AMP) plays a central role in the adaptation of bacteria to the environmental osmolarity (Witte et al, 2008;Commichau et al, 2015Commichau et al, , 2018Commichau et al, , 2019Fahmi et al, 2017;Stülke and Krüger, 2020). c-di-AMP is in fact essential for Bacillus subtilis, Lactococcus lactis, Listeria monocytogenes and other Gram-positive bacteria (Woodward et al, 2010;Corrigan et al, 2011;Luo and Helmann, 2012;Bai et al, 2013;Mehne et al, 2013;Witte et al, 2013;Whiteley et al, 2015;Rismondo et al, 2016) since the dinucleotide prevents the uptake of potassium and other osmolytes to toxic levels by direct binding to the respective transport systems Bai et al, 2014;Kim et al, 2015;Schuster et al, 2016;Blötz et al, 2017;Gundlach et al, 2017;Whiteley et al, 2017;Devaux et al, 2018;Pham et al, 2018;Zarella et al, 2018;Zeden et al, 2018;Gibhardt et al, 2019;Gundlach et al, 2019;Quintana et al, 2019). Recently, it has been shown that c-di-AMP is also involved in osmoadaptation of cyanobacteria and archaea (Rubin et al, 2018;Braun et al, 2019).…”