Abstract Title

Bloom capacity of various Microcystis strains, are they all the same?

Start Date

26-5-2022 12:15 PM

End Date

26-5-2022 12:30 PM

Abstract

Microcystis is a well-known toxic cyanobacterium that blooms in freshwater ecosystems around the word. At the PCC collection (France), we maintain about 30 pure Microcystis strains originating from various blooms on all continents isolated from the 1970s to this century and kept alive since by successive transfer at 22-25°C.

Using a high-density culture system (CellDEG, Germany), we tested these Microcystis to form rapid bloom-like cell development within a week. Light, CO2 and nutrients were provided to 10-mL stirred cultures to allow the cell development over 80 h at 30°C.

We were surprised to observe so many different behaviors within Microcystis strains that resemble each other in low-density culture (DO~2). Depending on the light and shade, they all formed more abundant mucilage. Some challenged strains reached DO >10 and presented high metabolism while other never bloomed in such conditions. For certain, the blooming capacity was in function of age inoculum or ability to form colonial aggregation. We concluded that Microcystis is far from fully understood, and that it is best to characterize the growth of the Microcystis model in your laboratory before undertaking experiments based on what you think of its behavior.

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May 26th, 12:15 PM May 26th, 12:30 PM

Bloom capacity of various Microcystis strains, are they all the same?

Microcystis is a well-known toxic cyanobacterium that blooms in freshwater ecosystems around the word. At the PCC collection (France), we maintain about 30 pure Microcystis strains originating from various blooms on all continents isolated from the 1970s to this century and kept alive since by successive transfer at 22-25°C.

Using a high-density culture system (CellDEG, Germany), we tested these Microcystis to form rapid bloom-like cell development within a week. Light, CO2 and nutrients were provided to 10-mL stirred cultures to allow the cell development over 80 h at 30°C.

We were surprised to observe so many different behaviors within Microcystis strains that resemble each other in low-density culture (DO~2). Depending on the light and shade, they all formed more abundant mucilage. Some challenged strains reached DO >10 and presented high metabolism while other never bloomed in such conditions. For certain, the blooming capacity was in function of age inoculum or ability to form colonial aggregation. We concluded that Microcystis is far from fully understood, and that it is best to characterize the growth of the Microcystis model in your laboratory before undertaking experiments based on what you think of its behavior.