Non-conventional therapeutic technique to replace CRISPR bacteria from biofilm by inducible lysogen.

Bacteriophage can be an effective means of regulating bacterial populations when conditions allow phage invasion of bacterial colonies. Phage can either infect and lyse a host cell, or insert their DNA into the host cell genome; the latter process is called lysogeny. The clustered regularly interspaced short palindromic repeat (CRISPR) system, linked with CRISPR-associated (Cas) genes, is a regulatory system present in a variety of bacteria which confers immunity against bacteriophage. Studies of the group behaviour of bacteria with CRISPR/Cas systems have provided evidence that CRISPR in lysogenized bacteria can cause an inability to form biofilm. This allows CRISPR-immune bacteria in biofilms to effectively resist phage therapy. Our recent work has described a potential therapeutic technique to eradicate CRISPR-immune bacteria from a biofilm by a continuous influx of lysogens carrying an identical phage sequence. However, this model predicted that the CRISPR-immune population could persist for long times before eradication. Our current focus is on the use of diverse lysogens against CRISPR-capable bacterial populations. The goal of this work is to find a suitable strategy which can eradicate bacteria with a CRISPR system through the influx of finite amounts of distinct lysogens over fixed intervals.