the herbi-cides Roundup and Avans as well as the fertilizers DAP and urea
(Tahedl and Häder, 2001; Pettersson and Ekelund, 2006; Azizullah
et al., 2010).
In the control cultures the cells showed a precise negative gravitaxis
(cells were swimming upward in the cuvette) which was
strongly impaired upon addition of the detergent.