Degradation of Preformed Gram-Positive and Gram-Negative Bacterial Biofilms Using Disintegrated and Intact Phages.

Abstract

Introduction: Biofilm is a major challenge across several sectors and contributes to serious risks to public health. This study aimed to evaluate the antibiofilm efficacy of disintegrated phages, whose lytic activities have been eliminated, against bacterial biofilms.

Methods: A total of seven lytic phages were disintegrated by sonication and confirmed to have completely lost their lytic activities by the spot test. Subsequently, both the disintegrated and intact phages were tested on the biofilms produced by five different biofilm-producing bacteria. The effects of heat and proteinase K on the ability of disintegrated phages to disrupt biofilms were determined. Moreover, the structural proteins released after the disintegration of phages were screened for their presence of lipase, amylase, protease, and DNase activities. Genome analysis of all the seven phages were screened for the presence of genes encoding proteins with enzymatic activities.

Results: The disintegrated phages showed more effectiveness in degrading the bacterial biofilm when compared with intact phages. The amylase test results were positive for all the seven disintegrated phages tested, confirming the presence of starch-degrading enzymes. Genomic analysis of five phages revealed the presence of genes encoding transglycosylases, amidases, and glycosaminidases, which could contribute to biofilm degradation. However, only four of these proteins were also structural proteins of phages.

Conclusions: Our study demonstrated that disintegrated phages without lytic effects can still possess biofilm degrading ability, probably associated with the enzymatic activities of their structural proteins. This study showed that phages may have activities beyond lytic phage activities exhibited by their structural enzymes.