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Flow Cytometry Research Group


Group Head



Flow Cytometry Research Group

PD Dr. Bernhard Fuchs

MPI for Marine Microbiology
Celsiusstr. 1
D-28359 Bremen




+49 421 2028-935

PD Dr. Bernhard Fuchs

About our Research

Flow cytometry complements the molecular biological toolbox to study microorganisms. Its capacity of fast analysis of thousands of cells per second and the simultaneous recording of multiple parameters makes flow cytometry a standard tool in plankton research. In addition flow cytometric cell sorting (FACS) enables the physical separation and enrichment of well-defined cell populations without prior cultivation. 

In our group we continuously improve our flow cytometry methods and combine them with new molecular biological approaches to gain deeper insights into the ecological role of microbes in a range of diverse marine habitats.

What is Flow Cytometry?

Gen­e­ral­ly, flow cy­to­metry is the mea­su­re­ment of sin­gle cells in a wa­ter jet.

We use flow cy­to­metry rou­ti­nely to quan­ti­fy cell numbers pi­co­plank­ton sam­ples and cell cul­tu­res. Fluorescent pig­ments like chlo­ro­phyll and ca­ro­te­no­ids cha­rac­te­ris­tic for ma­ri­ne cya­no­bac­te­ria and mi­cro­al­gae are de­tec­ted as well as fluo­re­scent dyes spe­ci­fic for DNA, pro­te­ins and other cel­lu­lar com­pounds of mi­cro­or­ga­nisms like cell membranes. Fur­ther, cells mee­ting pre­de­fi­ned pro­per­ties can be sor­ted with high speed in high purity for fur­ther molecular biological ana­ly­sis.

A sim­pli­fied il­lus­tra­ti­on of a Flow Cy­to­meter with a Sorting Unit is gi­ven be­low.

Principle of a Flow Cytometer
Principle of flow cytometric analysis and sorting
© B. Fuchs / MPI-MM

Briefly, cells suspended in the sample are injected into a sheath fluid (top). Through the nozzle cells are focused into the center of the water jet. After leaving the nozzle cells are passing by the laser beam in a single file like pearls on a string. The signals of the cells are focused through collection lenses (not shown) and re­cor­ded through detectors by a computing unit. Cells meeting defined parameters in the break-off point will be charged in their water droplet. The resulting charged droplet will be deflected into a vial. Depicted here is a two-way sort of two differently stained cell populations. Please refer to the literature for further details.

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