Aeromonas punctata derived depolymerase improves susceptibility of Klebsiella pneumoniae biofilm to gentamicin Microbial biochemistry, physiology and metabolism

Abstract

Background: To overcome antibiotic resistance in biofilms, enzymes aimed at biofilm dispersal are under investigation. In the present study, applicability of an Aeromonas punctata derived depolymerase capable of degrading the capsular polysaccharide (CPS) of Klebsiella pneumoniae, in disrupting its biofilm and increasing gentamicin efficacy against biofilm was investigated. Results: Intact biofilm of K. pneumoniae was recalcitrant to gentamicin due to lack of antibiotic penetration. On the other hand, gentamicin could not act on disrupted biofilm cells due to their presence in clusters. However, when depolymerase (20 units/ml) was used in combination with gentamicin (10 μg/ml), dispersal of CPS matrix by enzyme facilitated gentamicin penetration across biofilm. This resulted in significant reduction (p∈ m value) and high turnover number (indicated by K cat value) of the bacterial depolymerase (K m ∈=∈89.88 μM, K cat ∈=∈285 s -1) over the phage derived one (K m ∈=∈150 μM, K cat ∈=∈107 s -1). Conclusion: Overall the study indicated that, the A. punctata derived depolymerase possesses antibiofilm potential and improves gentamicin efficacy against K. pneumoniae. Moreover, it can serve as a potential substitute to phage borne depolymerases for treating biofilms formed by K. pneumoniae.