Biocide-degrading enzymes

However, microorganisms may adapt to biocides in different ways including the production of biocide-degrading enzymes or changes in... 

Bacteria within a biofilm may be less sensitive to antibacterial compounds than planktonic cells (reviewed in [150]). Several possible reasons (Table 4.9) can be put forward to account for this, notably reduced access of drug or biocide to cells within a biofilm, chemical reaction with the glycocalyx and modulation of the micro-environment [147], In addition, the attached cells may produce degradative enzymes although the significance of this... 

Another way to control the release of biocides is to entrap them into a matrix that is slowly hydrolyzed, e.g., into polylactic acid or other polyesters [104, 105] or degradable polyelectrolyte multilayers [106], By choosing a matrix that is degradable by a specific enzyme, the location of release in the body can be controlled. An example of this approach, which is very common for drug release but rarely used for biocides, is fluoroquinolone-modified biodegradable polyurethane that releases the antibiotic ciprofloxazin upon degradation catalyzed by the enzyme cholesterol esterase [107],... 

All release systems that liberate an immobilized biocide into the surroundings will exhaust rather quickly. Furthermore, the constant release is an environmental issue and supports the building of biocide-resistance in microbial strains. If a release system is the only possible option, then it would be desirable to release the biocide on demand, e.g., in cases of infection or the start of biofilm formation. This can be achieved by either degrading or swelling the matrix with an infection-specific enzyme or metabolite, or by cleaving the linker between biocide and surface with a biochemical factor. 

Intrinsic resistance to biocides as a consequence of bacterial degradative activities is thus not a major mechanism of insusceptibility. There are, of course, examples of plasmid-mediated enzymes that confer resistance to inorganic (and sometimes organic) mercurials and these will be discussed later... 

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