Chemical communication in microbial phytoplankton communities : allelopathy and algicidal bacteria

Phototrophic phytoplankton fuel the marine food web and play a role in all major biogeochemical cycles in our ecosystem. They are responsible for over half of the world’s CO2 fixation as well as the production of half the global oxygen supply annually. Though these communities are generally considered beneficial to living all living organisms, a subset of these phytoplankton can produce toxins which can harm other members of the local community and bioaccumulate through higher trophic levels, affecting larger marine animals and even humans. The over proliferation of these toxic and other non-toxic species can cause additional harm to the local environment by inducing anoxic conditions, suffocating the surrounding organisms, termed harmful algal blooms (HABs). Microbial communication in the form of allelopathic communication between phytoplankton species and lysis or inhibition of phytoplankton by algicidal bacteria is thought to be key elements in the determination of species succession and bloom control within phytoplankton communities.