Pear to be disadvantageous, studies of another Gram-negative marine bacterium, Marinobacter, offer insights into a unique role for vibrioferrin. Vibrioferrin has been isolated from alga-associated subclades of Marinobacter, and it was proposed that its low affinity and photoreactivity are evolutionary adaptations to the bacterium-alga mutualism (74). The phototactic dinoflagellates form aggregates