As CPS are thought to play a crucial role in phage evasion/infection (Porter et al., 2020), immune evasion (Fanning et al., 2012; Hsieh et al., 2020; Porter et al., 2017), and protection from other environmental stressors, we expected to see a decreased colonization probability for acapsular B. theta strains in all microbiota backgrounds. This evidence concerns the gene CAD and infection.