Example of a difficult cultivation (Gyrosigma)

Diatoms of the genus Gyrosigma are often found in samples from brooks and lakes. It is noticeable that these diatoms usually move to and fro in flakes of detritus. Presumably, they absorb substances from the detritus.

Isolated diatoms of genus Gyrosigma usually did not multiply in our raw cultures. It proved successful to cultivate these diatoms with the detritus. Some detritus flakes together with green algae, ciliates, Gyrosigma sp. and other diatom species were pipetted into a petri dish containing nutrient solution and a favorable light exposure was selected. In Video 1 you can see a flake of detritus (from the brook "Schwarze Rot") in which Gyrosigma sp. developed well, first under the stereomicroscope and then under the inverse microscope at two different magnifications. This has nothing to do with a pure culture, but the conditions seem to be favorable.

Occasionally one can be lucky and the cultivation succeeds. A raw culture was inoculated with Nitzschia sigmoidea and some specimens of the genus Gyrosigma from a pond near Hohenheim (Stuttgart). Both reproduced well, as the subsequent video (Video 2) shows. It is very easy to separate the two species in the following culture and so the video below (Video 3) was created (4x time-lapse). Unfortunately, the culture proved to be unstable and after several successive cultures the growth came to a halt.

Sometimes I add Gyrosigma to a raw culture. Unfortunately the successful cultivation could not be repeated so far.

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