This non-stimulated increase was also observed in cultures of 1 kDa oligo chitosan and 10 kDa fungal chitosan in concentrations of 5 and 25 ppm and in all cultures with 10 kDa chitosan.
In the media supplemented with 10 kDa shrimp chitosan a small brown precipitate was observed after two days of incubation. However the color and transparency of the liquid