Microbially-mediated glass dissolution and sorption of metals by Pseudomonas aeruginosa cells and biofilm

A basaltic glass and a vitrified bottom ash were incubated at 25 °C in a growth medium (based on casaminoacids) inoculated with Pseudomonas aeruginosa. Bacterial growth and mineral concentrations in different compartments (bacterial cells, growth medium and biofilm) were monitored in short-term (3 days), and long-term experiments involving repeated renewals of the culture medium during 174 days.In short-term experiments, while the concentration of iron increased in the presence of bacteria, a decrease in Ni and Zn was observed in the growth medium compared to the sterile condition. During long-term experiments, such differences gradually decreased and disappeared after 78 days. On the contrary, iron concentration remained higher in the biotic condition compared to the sterile one. Bacterial growth resulted within a few days in the formation of a biofilm, which lead to the cementation of the altered glass grains. Most of the constituents of the glass (Si, Mg, Fe, Ti, Ba, Co, Zn, Cu, Ni and Cr) were found in the biofilm, while the chemical composition of the bacterial cells was very different.