Box plot of the number of attached bacteria cells per frustule or capsule in stationary, xenic A. minutissimum cultures.

Dark grey boxes represent first and third quartile. White lines in box centres represent medians. Diamond symbols represent means. Dots represent individual counts of attached bacteria per diatom (larger dots are outliers). Bacteria were counted, if they were in direct, visible contact with the valve face of either a frustule, or a completely encapsulated diatom cell (see figures 2B and 3A for illustration). More capsules than frustules were counted, because more encapsulated diatom cells were present in our samples.