Isolation of a novel Aggregatibacter actinomycetemcomitans serotype b bacteriophage capable of lysing bacteria within a biofilm

Abstract

A bacteriophage specific for Aggregatibacter actinomycetemcomitans serotype b, able to kill the bacterium within a biofilm, was isolated. Random mutagenesis of this phage rendered a bacteriophage able to kill 99% of the bacteria within a biofilm. This is the first report of a biocontrol experiment against A. actinomycetemcomitans.

Fig. 1.

Infection of an A. actinomycetemcomitans biofilm with phages Aabφ01 and Aabφ01-1. A biofilm of A. actinomycetemcomitans cultured during 24 h under capnophilic conditions was infected with Aabφ01 or Aabφ01-1 at different MOIs. The results are expressed as percentages of CFU/ml recovered 24 h postinfection compared with the CFU/ml recovered before infection (a) or from quantified biofilm at 595 nm (b). As a control, we used a biofilm of A. actinomycetemcomitans without infection (Aa). Bars depict the average values from three independent experiments. An asterisk represents significance in relation to the control (P < 0.05).

Fig. 2.

Confocal microscopy of a biofilm of A. actinomycetemcomitans after infection with Aabφ01 or Aabφ01-1. A biofilm of A. actinomycetemcomitans serotype b or serotype c cultured during 24 h under capnophilic conditions was infected with Aabφ01 or Aabφ01-1 and was stained with the LIVE/DEAD BacLight bacterial viability kit. As a control, we used an A. actinomycetemcomitans biofilm without infection. Green indicates live bacteria, and red indicates dead or dying bacteria.