Feeding of a Freshwater Flagellate, Bodo saltans, on Diverse Bacteria¹

Bodo saltans was isolated from a chalk stream and fed with pure cultures of seven bacteria obtained from the same river. The flagellates were allowed to migrate into suspensions of either of two bacterial species in a T‐maze at 20–22°C. There was a significant difference ( P < 0.01) between the numbers of flagellates which migrated into suspensions of different bacteria, which were subsequently arranged in an order of “attractiveness” to the flagellate. Bodo saltans grew successfully in monoxenic suspensions of all seven bacterial strains, but more rapid growth occurred with non‐flagellated than with flagellated bacteria; this may be because while feeding, B. saltans tends to associate with surfaces where non‐flagellated bacteria may also congregate. The efficiency with which B. saltans is able to utilize different bacteria may be influenced by the motility or secretory activities of the bacteria. There was no incontrovertible evidence that B. saltans responds to specific bacterial attractants.