Downregulation of a CRISPR Cas3 system subtype I-F stands out as well when looking at differential expression of proteins in sessile Curvibacter, as it was furthermore upregulated in liquid culture and on Hydra. Since CRISPR systems are commonly known to protect bacteria from viral infection (Makarova and Koonin, 2015; Ishino et al., 2018), expression of this Cas3 subtype in liquid culture and on Hydra, together with downregulation in sessile Curvibacter could indicate a lack of defense in sessile Curvibacter that could result in its susceptibility to phages on solid medium. The gene discussed is EFS; the disease is viral infectious disease.