Figure 1.

Optical microscopy of Anabaena cylindrica cultures developing untreated as reference (a, f) and growing incubated with an overall concentration of 0.8 mM Au³⁺ (b–e). Images were taken before incubation (a), after six hours (b), eleven hours (c) and 24 hours (d) of gold salt incubation. After 190 hours (eight days) (e) no vital cells were found in the incubated culture anymore, while the reference at this time seems to be unaltered (f). Image (g) shows degraded Anabaena cylindrica after diluted HCl was added for comparison.