*2.3.5.2 Nucleases enzymes*

*Microorganisms*

*2.3.3 Free fatty acids*

*2.3.4 Metal chelators*

*2.3.5 Enzymes*

(Tween-20) and ethoxylated p-tert-octyl phenol (Triton X-100), were demonstrated to cause biofilm detachment [100]. Certain biosurfactants, which are surface active molecules formed by microorganisms, were reported to have antibiofilm activity. For example, surfactin, obtained from *Bacillus subtilis*, was found to have antibiofilm activity in case of *Salmonella enterica* in polyvinyl chloride microtiter wells and urethral catheters [101]. Another example is Rhamnolipids, that are produced principally, by *P. aeruginosa*, were found to promote the dispersal of bacterial biofilm [99]. Additionally, biosurfactants from *P. fluorescens* prevent the

Free fatty acids obtained via hydrolysis of lipids by enzymes [103]. Certain members of free fatty acids are reported to exhibit antibiofilm activity [104]. For example, cis-2-decenoic acid from *P. aeruginosa* enhanced the dispersal of biofilms and inhibited its formation in different pathogens, such as *Klebsiella pneumoniae*, *E. coli*, *Proteus mirabilis*, *Streptococcus pyogenes*, *B. subtilis* and *S. aureus*, in addition to *C. albicans* [105]. Another example is *cis*-9-octadecenoic acid (oleic acid) that was reported to repress biofilm formation in *S. aureus* by interference with the initial attachment of bacterial cells [106]. The diffusible signal factor; *cis*-11-methyl-2-dodecenoic acid, from *Xanthomonas campestris* inhibits biofilm formation in case of *Bacillus cereus* [107]. This study showed also that diffusible signal factor or its structural analogs increased the antibiotic susceptibility of numerous bacterial

Removal of metals from the microbial environment via metal chelators renders bacteria more susceptible to antimicrobial agents, as metals are essential for different cellular processes [108]. Ethylenediaminetetraacetic acid (EDTA), the most-known metal chelator, has been reported to exhibit antibiofilm activity against *S. aureus*, and to eradicate the *in vivo* biofilm models on catheters [109]. Combination of EDTA with minocycline has effectively reduced the colonization of *S. epidermidis*, *S. aureus* and *C. albicans* on catheters [110]. Similarly, the combination of EDTA and flucon-

Based on their target, the antibiofilm enzymes are classified into three types:

Alpha amylase enzyme was found to inhibit biofilm formation by *S. aureus* through the detachment of biofilm and interfering with aggregation of cells [112]. Dispersion B, a bacterial glycoside hydrolase, degrades poly-N-acetylglucosamine (PNAG), a main matrix exopolysaccharide of *S. aureus* and *E. coli* [113]. Such polysaccharide is produced by many bacteria and fungi and plays an important role in surface adhesion, and biofilm formation. Furthermore, PNAG was reported to successfully disrupt the biofilm matrix of *S. epidermidis* [114]. Moreover, the combination of dispersion B and triclosan was reported to significantly reduce biofilm

attachment of *Listeria monocytogenes* to stainless steel surfaces [102].

pathogens, by inhibition of biofilm formation [107].

azole remarkably inhibited biofilm assembly in *C. albicans* [111].

polysaccharide-degrading enzymes, nucleases and proteases.

formation of *E. coli*, *S. aureus* and *S. epidermidis* [115].

*2.3.5.1 Polysaccharide-degrading enzymes*

**198**

Deoxyribonuclease I (DNase I) degrades DNA in biofilm matrix [104]. Moreover, it was shown to have antibiofilm activity and to detach the biofilms produced by different bacterial species [116]. Such nuclease can prevent the initial adherence of microbial cells to surfaces via the degradation of cell surface-associated nucleic acids that act as surface adhesins [117]. Furthermore, DNase I has been found to increase the sensitivity of bacterial cells in biofilm matrix to antibiotics, resulting in reduction of biofilm mass [118].
