Bioremoval of graffiti using novel commercial strains of bacteria

Previous studies have provided evidence that bioremediation deals a novel approach to graffiti removal, thereby overcoming well-known limitations of current cleaning methods. In the present study eight bacteria aerobic, mesophilic and culturable from the American ATCC and the German DSMZ collections of microorganisms, some isolated from car paint waste, colored deposits in a pulp dryer and wastewater from dye works, were tested in the removal of silver and black graffiti spray paints using immersion strategies with glass slides. Absorbance at 600 nm and live/dead assays were performed to estimate bacterial density and activity in all samples. Also, pH and dissolved organic carbon (DOC) and inorganic carbon (DIC) measurements in the liquid media were made, as well as, thickness, colorimetric and infrared (FTIR) spectroscopy measurements in graffiti paint layers were used to evaluate the presence of the selected bacteria in the samples and the graffiti bioremoval capacity of bacteria. Data demonstrated that of the eight bacteria studied, Enterobacter aerogenes, Comamonas sp. and a mixture of Bacillus sp., Delliia lacustris, Sphingobaclerium caeni, and Ochrobactrum anthropi were the most promising for bioremoval of graffiti. According to significant changes in FTIR spectra, indicating an alteration of the paint polymeric structure, coupled with the presence of a consistent quantity of live bacteria in the medium as well as a significant increase of DIC (a measure of metabolic activity) and a change in paint color. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the capability of eight bacteria in the removal of silver and black graffiti spray paints, and found that Enterobacter aerogenes, Comamonas sp., and a mixture of Bacillus sp., Delliia lacustris, Sphingobaclerium caeni, and Ochrobactrum anthropi were the most promising for bioremoval of graffiti. The results showed significant changes in FTIR spectra, indicating alterations in the paint structure, along with the presence of live bacteria and an increase in DIC, demonstrating metabolic activity and changes in paint color.