有害有毒赤潮の生物学(16)殺藻細菌による赤潮プランクトンの殺藻機構一2

摘要

Predatory bacteria are important for material cycling and energy flow through killing live bacteria and other microorganisms in terrestrial and aquatic ecosystems. In case of predatory bacteria for microalgae, those are expected to control harmful algal bloom occurrences in the sea and land water. Predatory bacteria belong to wide and various taxonomic groups. They are categorized in for strategies (group or "wolfpack" predation, epiphytic attachment, direct invasion of the cytoplasm, and periplasmic invasion), and in two types of obligate and facultative predations. Bacteria that kill and utilize planktonic microalgae (phytoplankton) for growth are defined to be algi-cidal bacteria. The presence of easily utilizable organic substances such as peptone usually inhibits the algicidal activities of predatory bacteria. Predatory bacteria are sometimes inversely devoured by mixotrophic microalgae such as the dinoflagellate Cochlodinium polykrikoides. Bacteria of facultative predators and wide prey range preda-tors are thought to be ecologically advantageous for survival and growth in the sea. It is considered that predatory bacteria are substantial controlling agents of harmful algal blooms in the coastal ecosystems.