Bacteriophage attacking bacteria

Novel way for bacteria to share biosynthetic gene clusters

Wednesday 30 Jun 21
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Mikael Lenz Strube
Associate Professor
DTU Bioengineering

In a collaborative effort of computational biology, microbiology and chemistry, researchers at CeMiSt have found a novel way for bacteria to share biosynthetic gene clusters (BGCs).

Such BGCs typically encode compounds with a range of biological activities. The CeMiSt team went through thousands of bacterial genomes, searching first for viruses that infect bacteria, the so-called bacteriophages. Next, these prophages were investigated for BGCs and it turns out that small subset of these phages carry genes encoding bacteriocins, a class of BGCs acting as bactericidal weapons. They then repeated the analysis in free-living bacterial viruses, and observed the same phenomena.

The team then went to the lab to confirm the findings, using the model bacteria and natural target of a bacteriocin-carrying phage, Bacillus subtilis. They competed non-infected bacteria with infected bacteria and observed a clear fitness advantage in latter, in which the infected bacteria would outcompete the non-infected.

Two strains of bacteria

Figure: Two strains of bacteria (red and green) only differing in their susceptibility to phage infection can peacefully co-exist in a bacterial colony as evident by the homogenous mixing. When a phage carrying a bacteriocin is added to the middle, however, the susceptible bacterium (green) can use the bacteriocin as a chemical weapon and eradicate the non-susceptible 

As the proliferation of a bacteriophage is dependent on eventually killing its host, it appears paradoxical to arm it with chemical weapons. In evolutionary terms, however, it appears that improving the fitness of the host will increase its proliferation, and hence, the proliferation of the phage as well.

Read the full article: 
Phages carry interbacterial weapons encoded by biosynthetic gene clusters
Dragoš A, Andersen AJC, Lozano-Andrade CN, Kempen PJ, Kovacs AT, Strube ML.
In Current Biology, 2021, 1–11.

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