Separation of forms of Microcystis from Anabaena in mixed populations by the application of pressure

Abstract

Critical-pressure distributions of gas vesicles in Anabaena circinalis, Microcystis aeruginosa f. aeruginosa and M. a. f. flos-aquae were determined for suspensions both in hypertonic sucrose solutions and in reservoir water. The differences between the critical and apparent critical pressures of gas vesicles suggested that differential pressurization could be used to separate these taxa. Subsequent experiments successfully separated (>90%) the two formae of Microcystis by the application of 500 kPa and M. a. f. aeruginosa from A, circinalis by the application of 300 kPa. This technique has the potential to provide sufficiently pure material to distinguish the relative toxicity of the two formae of Microcystis in the presence of a neurotoxic A. circinalis.