Biofouling Control by Quorum Quenching 15.4 Applications 437
Part B | 15.4
pathogen Aggregatibacter actinomycetemcomitans is
a b-hexosaminidase that exhibits a biofilm detachment
ability. A combination of DspB with antiseptics (triclosan or chlorhexidine) has given a synergistic broadspectrum antibiofilm and shown antimicrobial activity
against S. aureus, S. epidermidis, and E. coli [15.38].
15.4.2 The Pulp and Paper Industry
Eight commercial enzymatic preparations were evaluated for biofilm reduction in the paper industry. These
preparations contained proteases (pepsin, trypsin, Savinase1, and Alcalase1), glycosidases (dextranase and
pectinase), and lipases (from Candida rugosa and Lipolase1). Savinase1 was the most efficient protease when
used at concentrations of 40:5%. Cellulase is another
enzyme that was successful in degrading mature biofilm
formed by P. aeruginosa. It is possible to use this enzyme in combination with other treatments to increase
the effectiveness to attack the mixture of polysaccharides in the EPS [15.39].
15.4.3 Deterrents/Biocides
Naturally produced AF biocide compounds have been
divided into two categories: (i) non-polar metabolites
which remain on the surface of an organism and may
repel larvae exploring its surface, and (ii) polar metabolites, which are liberated into overlying water and may
be detected by larval receptors to trigger avoidance behavior. Such AF compounds are classified as deterrents
rather than toxins, since their mode of action may or
may not be related to toxic effects. Glucose oxidase,
hexose oxidase, and haloperoxidase are examples of oxidoreductases that can generate deterrents [15.36]. The
oxidases and haloperoxidases catalyze the production
of H 2 O 2 and hypohalogenic acids, respectively. H 2 O 2 ,
like other reactive oxygen species (ROS), can cause oxidative damage in living cells. Hypohalogenic acids,
e.g., HOBr or HOCl, being highly reactive, are thus
used as oxidants for the treatment of water as disinfecting agents [15.36]. The oxidative damage of cells by
H 2 O 2 finds many applications. H 2 O 2 has been used to
reduce macrofouling in marine cooling water systems,
particularly as Fenton’s reagent when combined with
ferrous ions [15.36].
15.4.4 Antifoulants
Hydrolases have been shown to abolish adhesion and
biofilm formation by Pseudoalteromonas sp. D41 in
natural seawater at 20
ı C. This antibiofilm effect is
due to the hydrolysis of extracellular polysaccharide
(EPS), QS molecules, and adhesions as the substrates
involved in bacterial adhesion. For example, hydrolysis of mutan and dextran EPS by mutanase and
dextranase enzymes inhibits the formation of dental biofilms by Streptococcus mutans and S. sobrinicus, respectively [15.40]. Proteases, for example, Savinase, are very effective enzymes that prevent adhesion and biofilm formation by marine organisms.
Savinase was effective and stable against biofilm formation, even when bacteria were allowed to adhere
for 24 h [15.40]. Commercial protease (subtilisin) enzymes like Savinase or Alcalase are very effective
when applied during the initial stages of bacterial adhesion. This can be done by conditioning the surface,
e.g., by immobilizing the enzyme directly onto the
surface or by applying the enzyme through an AF
paint [15.40].
Lysostaphin, a Staphylococcus simulans metalloendopeptidase, degrades pentaglycine cross links in the
cell wall and is effective against S. aureus, S. epidermidis. This enzyme can also detach biofilms, which
suggests a potential contribution of cell wall-associated
components to the matrix. Subtilisins, the serine proteases, cleave proteins in which serine serves as the
nucleophilic amino acid. Such proteases are easily
available as they are produced and secreted in large
measures by many Bacillus species [15.41]. Subtilisins
work on different biofilms, including those produced
by industrially significant problematic species such as
Pseudomonas fluorescens and Pseudoalteromonas.
DNA plays an important function in the stability
of biofilms. This has been shown by the addition of
deoxyribonuclease (DNaseI) leading to the dissolution
of biofilms. Addition of bovine DNaseI to established
biofilms can disrupt S. aureus biofilms formed on glass,
plastic, and titanium surfaces. Studies have demonstrated that inducing expression of S. aureus endogenous nuclease prevents biofilm formation on abiotic
surfaces. The use of DNase as a treatment for staphylococcal biofilm infections has not been attempted,
although recombinant human DNase (also called Pulmozyme Dornase alfa) is approved as a treatment to
reduce the viscosity of mucous in the lungs of cystic
fibrosis (CF) patients. It is postulated that Dornase alfa
plays a role in clearing bacterial infections that develop
in the CF lung and P. aeruginosa is known to form
a biofilm in this state. DNaseI also sensitizes biofilm
bacteria to killing by various biocides and also to detachment by anionic detergents.
Part B | 15.4
pathogen Aggregatibacter actinomycetemcomitans is
a b-hexosaminidase that exhibits a biofilm detachment
ability. A combination of DspB with antiseptics (triclosan or chlorhexidine) has given a synergistic broadspectrum antibiofilm and shown antimicrobial activity
against S. aureus, S. epidermidis, and E. coli [15.38].
15.4.2 The Pulp and Paper Industry
Eight commercial enzymatic preparations were evaluated for biofilm reduction in the paper industry. These
preparations contained proteases (pepsin, trypsin, Savinase1, and Alcalase1), glycosidases (dextranase and
pectinase), and lipases (from Candida rugosa and Lipolase1). Savinase1 was the most efficient protease when
used at concentrations of 40:5%. Cellulase is another
enzyme that was successful in degrading mature biofilm
formed by P. aeruginosa. It is possible to use this enzyme in combination with other treatments to increase
the effectiveness to attack the mixture of polysaccharides in the EPS [15.39].
15.4.3 Deterrents/Biocides
Naturally produced AF biocide compounds have been
divided into two categories: (i) non-polar metabolites
which remain on the surface of an organism and may
repel larvae exploring its surface, and (ii) polar metabolites, which are liberated into overlying water and may
be detected by larval receptors to trigger avoidance behavior. Such AF compounds are classified as deterrents
rather than toxins, since their mode of action may or
may not be related to toxic effects. Glucose oxidase,
hexose oxidase, and haloperoxidase are examples of oxidoreductases that can generate deterrents [15.36]. The
oxidases and haloperoxidases catalyze the production
of H 2 O 2 and hypohalogenic acids, respectively. H 2 O 2 ,
like other reactive oxygen species (ROS), can cause oxidative damage in living cells. Hypohalogenic acids,
e.g., HOBr or HOCl, being highly reactive, are thus
used as oxidants for the treatment of water as disinfecting agents [15.36]. The oxidative damage of cells by
H 2 O 2 finds many applications. H 2 O 2 has been used to
reduce macrofouling in marine cooling water systems,
particularly as Fenton’s reagent when combined with
ferrous ions [15.36].
15.4.4 Antifoulants
Hydrolases have been shown to abolish adhesion and
biofilm formation by Pseudoalteromonas sp. D41 in
natural seawater at 20
ı C. This antibiofilm effect is
due to the hydrolysis of extracellular polysaccharide
(EPS), QS molecules, and adhesions as the substrates
involved in bacterial adhesion. For example, hydrolysis of mutan and dextran EPS by mutanase and
dextranase enzymes inhibits the formation of dental biofilms by Streptococcus mutans and S. sobrinicus, respectively [15.40]. Proteases, for example, Savinase, are very effective enzymes that prevent adhesion and biofilm formation by marine organisms.
Savinase was effective and stable against biofilm formation, even when bacteria were allowed to adhere
for 24 h [15.40]. Commercial protease (subtilisin) enzymes like Savinase or Alcalase are very effective
when applied during the initial stages of bacterial adhesion. This can be done by conditioning the surface,
e.g., by immobilizing the enzyme directly onto the
surface or by applying the enzyme through an AF
paint [15.40].
Lysostaphin, a Staphylococcus simulans metalloendopeptidase, degrades pentaglycine cross links in the
cell wall and is effective against S. aureus, S. epidermidis. This enzyme can also detach biofilms, which
suggests a potential contribution of cell wall-associated
components to the matrix. Subtilisins, the serine proteases, cleave proteins in which serine serves as the
nucleophilic amino acid. Such proteases are easily
available as they are produced and secreted in large
measures by many Bacillus species [15.41]. Subtilisins
work on different biofilms, including those produced
by industrially significant problematic species such as
Pseudomonas fluorescens and Pseudoalteromonas.
DNA plays an important function in the stability
of biofilms. This has been shown by the addition of
deoxyribonuclease (DNaseI) leading to the dissolution
of biofilms. Addition of bovine DNaseI to established
biofilms can disrupt S. aureus biofilms formed on glass,
plastic, and titanium surfaces. Studies have demonstrated that inducing expression of S. aureus endogenous nuclease prevents biofilm formation on abiotic
surfaces. The use of DNase as a treatment for staphylococcal biofilm infections has not been attempted,
although recombinant human DNase (also called Pulmozyme Dornase alfa) is approved as a treatment to
reduce the viscosity of mucous in the lungs of cystic
fibrosis (CF) patients. It is postulated that Dornase alfa
plays a role in clearing bacterial infections that develop
in the CF lung and P. aeruginosa is known to form
a biofilm in this state. DNaseI also sensitizes biofilm
bacteria to killing by various biocides and also to detachment by anionic detergents.