Ecological studies on algal‐lysing bacteria in fresh waters

Publisher Website
Google Scholar
Abstract
Summary: Algal‐iysing bacteria are present in five lochs, two reservoirs, one sewage works and five alkaline soils whieh were examined. Nine out of thirty‐six isolates have been studied in detail and all are gram‐negative non‐fruiting myxobaeteria. All are aero‐philic, require a neutral or alkaline pH (optimum 7.0–9.0) for good growth, have temperature optima of 28–37°C, require contact with the host for lysis to oecur, and are so similar in morphology and host range that they all appear to be strains of a single genus. They lyse all bloom‐forming Cyanophyeeae on whieh they have been tested, including species of Anabaena, Aphanizomenon, Gloeotrichia, Microcystis and Oscillatoria. Their abundance is usually correlated direetly with the abundance of Cyanophyeeae in eutrophic waters and it is probable that in most ecosystems the algae and the bacteria co‐exist, although if the equilibrium changes markedly as a result of change in environmental conditions situations may arise where the bacteria may play an important role in the lysis of algal blooms. The available evidence suggests, however, that this is likely to be a rare occurrence in natural ecosystems.