Contribution to determination of extracellular DNA origin in the biofilm matrix

Abstract

This study is focused on the analysis of extracellular DNA (eDNA) from a biofilm matrix formed by Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica. The presence of eDNA in the biofilm of all the studied strains was confirmed by confocal laser scanning microscopy using fluorescent dyes with high affinity to nucleic acid. The protocol for eDNA isolation from the biofilm matrix was established, and subsequent characterization of the eDNA was performed. The purified eDNA obtained from the biofilm matrix of all three microorganisms was compared to the genomic DNA (gDNA) isolated from relevant planktonic grown cells. The process of eDNA isolation consisted of biofilm cultivation, its collection, sonication, membrane filtration, dialysis, lyophilisation, and extraction of DNA separated from the biofilm matrix with cetyltrimethylammonium bromide. An amplified fragment length polymorphism (AFLP) was used for comparing eDNA and gDNA. AFLP profiles showed a significant similarity between eDNA and gDNA at the strain level. The highest similarity, with a profile concordance rate of 94.7% per strain, was observed for S. aureus, L. monocytogenes, and S. enterica exhibited lower profiles similarity (78% and 60%, respectively). The obtained results support the hypothesis that the eDNA of studied bacterial species has its origin in the gDNA.

Progress in the Prevalence, Classification and Drug Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus

“… 106 In addition, the chemical bonds among eDNA molecules lead to the tight connection of cells in biofilms, which increases the plasmid transfer through coupling and mobilization, and promotes the horizontal transfer of drug-resistant genes; 107 eDNA, negatively charged, acts as a chelating agent for cationic antibacterials and has been proved to participate in the resistance to cationic peptides. 108 Moreover, different concentrations of antibiotics are associated with drug resistance in biofilms. At subinhibitory concentrations, some antibiotics can act as signaling molecules to induce biofilm formation and increase the biomass of biofilms; at low concentration, antibiotics can accelerate the horizontal transfer of drug-resistant genes in the biofilms and promote the spread of drug-resistant genes.…”

“…106 In addition, the chemical bonds among eDNA molecules lead to the tight connection of cells in biofilms, which increases the plasmid transfer through coupling and mobilization, and promotes the horizontal transfer of drug-resistant genes; 107 eDNA, negatively charged, acts as a chelating agent for cationic antibacterials and has been proved to participate in the resistance to cationic peptides. 108 Moreover, different concentrations of antibiotics are associated with drug resistance in biofilms. At subinhibitory concentrations, some antibiotics can Notes: MSCRAMMs in S. aureus are Spa (Staphylococcus protein A), FnbpA and FnbpB (fibronectin binding proteins), ClfA and ClfB (clumping factors), Cna (collagen-binding protein), SdrC, SdrD and SdrE (serine aspartate repeat proteins), which play key roles in adhesion, colonization and evasion of innate immune defences.…”

Antibioflm effects of extracellular matrix degradative agents on the biofilm of different strains of multi-drug resistant Corynebacterium striatum

“…For some well-known gram-positive bacteria (including S. aureus , and Bacillus subtilis ), the bacterial extracellular matrix has been recognized to be an essential determinant in mediating biofilm formation and participating in the protection process from external insults [ 21 , 22 ]. The extracellular matrix composition was similar among different bacteria, including EPA, proteins, and eDNA, all of which participated in the process of biofilm formation in different manners [ 21 , 23 – 25 ]. Correspondingly, degradative agents directed against the above components were developed to deter biofilm formation, including dispersin B, proteinase K, and DNase I. Biofilm matrix degradation with enzymatic degradative agents toward polysaccharides, proteins, and nucleic acids paves an efficient way of controlling or treating infections caused by biofilm-producing bacterial pathogens [ 26 – 28 ].…”

pH-Responsive nanoplatform synergistic gas/photothermal therapy to eliminate biofilms in poly(l-lactic acid) scaffolds

“…50,51 Due to the similarity between biofilm eDNA and bacterial genomic DNA (gDNA), the gDNA was extracted by the bacterial DNA extraction kit for different treatments. 52,53 The band mapping images from agarose gel electrophoresis are shown in Fig. 8a.…”