Enhancing Biocide Efficacy: Targeting Extracellular DNA for Marine Biofilm Disruption

Abstract

Biofilm formation is a global health, safety and economic concern. The extracellular composition of deleterious multispecies biofilms remains uncanvassed, leading to an absence of targeted biofilm mitigation strategies. Besides economic incentives, drive also exists from industry and research to develop and apply environmentally sustainable chemical treatments (biocides); especially in engineered systems associated with the marine environment. Recently, extracellular DNA (eDNA) was implicated as a critical structural polymer in marine biofilms. Additionally, an environmentally sustainable, multi-functional biocide was also introduced to manage corrosion and biofilm formation. To anticipate biofilm tolerance acquisition to chemical treatments and reduce biocide application quantities, the present research investigated eDNA as a target for biofilm dispersal and potential enhancement of biocide function. Results indicate that mature biofilm viability can be reduced by two-fold using reduced concentrations of the biocide alone (1 mM instead of the recommended 10 mM). Importantly, through the incorporation of an eDNA degradation stage, biocide function could be enhanced by a further ~90% (one further log reduction in viability). Biofilm architecture analysis post-treatment revealed that endonuclease targeting of the matrix allowed greater biocide penetration, leading to the observed viability reduction. Biofilm matrix eDNA is a promising target for biofilm dispersal and antimicrobial enhancement in clinical and engineered systems.

How biofilm changes our understanding of cleaning and disinfection

“…(i) “ Mechanical” quenching/neutralisation : extracellular polymeric substances (EPS) matrix and to some extend lysed bacteria effectively act as organic load and contribute to the production of an antimicrobial concentration gradient [ 28 ]. eDNA in the EPS matrix contributes to antimicrobial resistance [ 29 , 30 ] and horizontal resistance gene transfer [ 29 ]. (ii) Reduced metabolism and growth rate : the slow growth rate and metabolism of these bacteria lend themselves to the reduced efficacy of antibiotics in the treatment of biofilm infection, as many compounds rely on active metabolism to work [ 31 , 32 ].…”

Comprehensive Review on the Use of Biocides in Microbiologically Influenced Corrosion

“…Biofilm can relatively maintain the membrane’s internal environment stability and protect microorganisms from the toxicity of biocides. Therefore, sessile cells in biofilms are more difficult to eradicate than planktonic cells suspended in the liquid phase [ 112 ]. Killing sessile cells requires an increased concentration of biocide; it is difficult to achieve a good effect of killing microorganisms by using biocides alone [ 113 ].…”