Inhibition of Biofilm Formation by T7 Bacteriophages Producing Quorum-Quenching Enzymes

Abstract

Bacterial growth in biofilms is the major cause of recalcitrant biofouling in industrial processes and of persistent infections in clinical settings. The use of bacteriophage treatment to lyse bacteria in biofilms has attracted growing interest. In particular, many natural or engineered phages produce depolymerases to degrade polysaccharides in the biofilm matrix and allow access to host bacteria. However, the phage-produced depolymerases are highly specific for only the host-derived polysaccharides and may have limited effects on natural multispecies biofilms. In this study, an engineered T7 bacteriophage was constructed to encode a lactonase enzyme with broad-range activity for quenching of quorum sensing, a form of bacterial cell-cell communication via small chemical molecules (acyl homoserine lactones [AHLs]) that is necessary for biofilm formation. Our results demonstrated that the engineered T7 phage expressed the AiiA lactonase to effectively degrade AHLs from many bacteria. Addition of the engineered T7 phage to mixed-species biofilms containing Pseudomonas aeruginosa and Escherichia coli resulted in inhibition of biofilm formation. Such quorum-quenching phages that can lyse host bacteria and express quorum-quenching enzymes to affect diverse bacteria in biofilm communities may become novel antifouling and antibiofilm agents in industrial and clinical settings.

Phage-Encoded Colanic Acid-Degrading Enzyme Permits Lytic Phage Infection of a Capsule-Forming Resistant Mutant Escherichia coli Strain

“…A thicker biofilm results. This is in accordance with a previous finding (36) that mucoid phage-resistant E. coli colonies appeared when a preformed biofilm was treated with phage T7 for 1 h. There is another report describing the successful suppression of E. coli biofilms by T7 infection (37). However, the authors did not observe biofilm formation long enough for the encapsulated mutants to become dominant; thus, they claimed that T7 was effective at inhibiting biofilm formation.…”

Current Research Approaches to Target Biofilm Infections.

“…Other studies have demonstrated T7 engineered phage expressing the EPS-degrading enzyme Dispersin B to be more efficient in killing E. coli biofilms than phages alone (46). A recent study utilizing a phage expressing a lactonase enzyme that degrades quorum sensing bacterial signaling molecules was shown to be effective in preventing biofilm formation in mixed cultures of P. aeruginosa and E. coli (47).…”

Using Phage’s to Exterminate Biofilms

“…The key intent behind this strategy is not to kill pathogens but to disarm them making them oversensitive to the normal antimicrobial treatments. Furthermore, the QS system is not contributing in any way in mechanisms which can be essential for the bacteria survival, but inhibiting this method won't be described as a reason behind producing a firm selective pressure suitable enough to cause resistance development [53,54]; showed that the engineered phage strain T7 that creates the metalloenzymes AiiA lactonase range of action against signalling molecules (acyl homoserine lactones) which are mixed up in bacterial quorum sensing is extremely wide that is and these molecules are important for the development of the biofilm.…”