Wood constructions are often protected with biocides. Thereby, the active substances can get into the environment and affect bacteria.
Source: Selina Schmidt, BAM FB 4.1
Materials are often protected from biological degradation with biocidal products. The active substances contained in such material preservatives can be introduced into soils or water bodies because protected materials are usually in close contact with the environment. A wide range of bacteria occur in the environment in different habitats, which are thus exposed to the biocides.
It has been known for a long time that bacteria respond to stress factors by growing more slowly or switching on genes that give them traits to better cope with stress. Recent studies have also shown that bacteria can acquire entirely new traits under stress by mutating existing genes or by increasing the transfer of genes between different bacterial cells (e.g. through a process called conjugation). Until now, it was not known whether active substances used in biocidal products also influence the rates at which mutation occurs or at which genes are transferred.
In a research project at BAM, in cooperation with partners from the FU Berlin, the influence of different biocides on mutation rates and gene transfer rates in bacteria has now been investigated. The results show that the following biocides increase mutation rates in the bacterium Escherichia coli used as a model: chlorhexidine digluconate, the quaternary ammonium substance didecyldimethylammonium chloride (DDAC), the heavy metal copper, the insecticide permethrin and the fungicide propiconazole. Furthermore, the study shows that the following substances increase the transfer of genes between bacteria: the quaternary ammonium substance benzalkonium chloride, chlorhexidine digluconate and permethrin.
Increased mutation rates and gene transfer rates may not only enable bacteria to adapt against biocides. Both processes are particularly important in the emergence and spread of resistance to antibiotics, which are used as drugs to fight bacterial infections. Future studies have to show now whether biocides also increase mutation rates and gene transfer rates outside the laboratory, in the natural environment, and whether this is relevant for the risk assessment of biocides with regard to the emergence and spread of antibiotic resistance.
Biocides Used as Material Preservatives Modify Rates of de novo Mutation and Horizontal Gene Transfer in Bacteria
Selina B. I. Schmidt, A. Rodríguez-Rojas, J. Rolff und Frank Schreiber
published in Journal of Hazardous Materials, Volume 437, 129280, 2022
BAM division Materials and the Environment
BAM department Biodeterioration and Reference Organisms