Biodeterioration of cinematographic cellulose triacetate by Sphingomonas paucimobilis using indirect impedance and chemiluminescence techniques

The bacterium Sphingomonas paucimobilis, isolated from cinematographic films in an earlier project, was able to biodeteriorate the cellulose triacetate material (acetylation degree of 2.7). Film colonization was monitored by the indirect impedance technique and the production of carbon dioxide. The presence of ruggedness and irregularities on the surface of the film, produced when the plasticizer was extracted, accelerated the biodeterioration of the material. In contrast, cinematographic films with their layered structure made of photographic gelatine emulsion were protected and no colonization was observed. The cinematographic film without photographic emulsion reached a 5% level of biodeterioration after six weeks of incubation, confirming the possibility of biodeterioration of archival cinematographic materials if conservation conditions are not adequate. Through viscosity measurements, a decrease in relative viscosity was observed on the biodeteriorated sample, with respect to the original material, confirming a lower molecular weight as a result of enzymatic activity of S. paucimobilis. Also, using chemiluminescence, the film surface oxidation on the biodeteriorated sample was observed. This technique was very sensitive in detecting material oxidation by reactive oxygen species generated by bacteria, and could be useful to study microbiological biodeterioration in polymeric materials.