Listeriolysin S: A bacteriocin from epidemic Listeria monocytogenes strains that targets the gut microbiota Original paper

What was studied?

This study explored the role of listeriolysin S (LLS), a bacteriocin produced by Listeria monocytogenes, and its impact on the gut microbiota during infection. Specifically, it examined how LLS affects the microbial community composition in the host intestine and how it contributes to the virulence of Listeria during oral infection. The study focused on comparing the effects of LLS-producing Listeria strains and mutants lacking LLS on bacterial growth, colonization, and microbiota modulation.

Who was studied?

The study primarily investigated Listeria monocytogenes, particularly focusing on strains producing LLS and its effect on the gut microbiota in a mouse model of oral infection. It compared the wild-type LLS-producing strain (F2365, lineage I) to isogenic mutants deficient in LLS production (llsA and llsB mutants). The microbial community composition in infected mice was analyzed using high-throughput 16S rDNA sequencing to determine how LLS production influences the intestinal microbiota.

What were the most important findings?

The study found that LLS plays a crucial role in modulating the host’s gut microbiota during Listeria monocytogenes infection. The presence of LLS significantly altered the abundance of specific bacterial genera in the intestinal microbiota, particularly decreasing the populations of Alloprevotella and Allobaculum, both of which are producers of acetic and butyric acids, compounds known for their protective roles against Listeria. The reduction in these bacteria was linked to the production of LLS, suggesting that LLS functions as a bacteriocin targeting specific gut bacteria. The study also showed that the absence of LLS in mutant strains resulted in a lower ability to colonize the intestine and a reduced survival rate in the intestinal content, particularly within the first few hours after infection. These findings suggest that LLS’s bacteriocin activity is crucial for Listeria‘s ability to modify the gut microbiota to facilitate colonization and infection. Furthermore, the study demonstrated that LLS does not significantly alter the microbiota at the phylum level but induces changes at the genus level, emphasizing its specific role in targeting certain microbiota members.

What are the greatest implications of this study?

The findings have significant implications for understanding Listeria monocytogenes pathogenesis and its interaction with the gut microbiota. By identifying LLS as a bacteriocin that can modulate the microbiota, the study suggests that Listeria may actively shape the gut environment to enhance its own survival and facilitate infection. This opens new avenues for developing therapeutic strategies that target bacteriocins like LLS to prevent or mitigate Listeria infections, particularly in individuals with compromised immune systems or those undergoing treatments that disrupt the microbiota. The study also emphasizes the importance of considering the gut microbiota in the study of bacterial infections, as its modulation could play a critical role in disease outcomes.