Impact of a Mn-oxidizing bacterial strain on the dissolution and browning of a Mn-bearing potash-lime silicate glass

Abstract This work aims to investigate the role played by a model Mn-oxidizing bacterial strain and its exudates on the alteration of Mn-bearing potash-lime silicate glasses representative of medieval stained glass windows. Two model glasses, with or without manganese, were prepared and used for abiotic and Pseudomonas putida inoculated dissolution experiments. Results show that the presence of P. putida slows down the dissolution kinetics while changing the dissolution stoichiometry. In biotic experiments, the acidification of the solution at the beginning of the experiment favors the release of K. After a few days, a drop in Mn and P in solution is observed, retained by bacterial cells. Reciprocally, the amount of glass influences bacterial behavior. The more glass, the faster the bacterial population increases in size and produces siderophore. In the presence of the Mn-bearing glass, siderophore production is followed by the formation of brown phases, identified as Mn oxides.