Opportunistic pathogenic bacteria cause microbiota dysbiosis through enzyme secretion
In both plants and animals, the innate immune system serves a crucial role in maintaining microbiota homeostasis and health. An investigation conducted by the Vorholt lab identified causal relationships among microbiota members responsible for microbiome perturbation in immunocompromised plants.
The microbiota can provide health benefits, but some bacterial species can also harm the host, a condition often associated with microbiome dysbiosis. Researchers in the Vorholt lab had previously identified opportunistic pathogenic Xanthomonas bacteria that cause dysbiosis in immunocompromised plants. In their latest work, they addressed the question of whether the disturbed microbiota is the cause or consequence of disease. They conducted bacterial genetic screens, assembled synthetic bacterial communities and tested properties of the opportunistic pathogens. The authors showed that these bacteria secrete a cocktail of plant cell wall degrading enzymes via the so-called type-2 secretion system. Xanthomonas uses those enzymes to degrade plant tissue, thereby causing damage and releasing nutrients that also promotes a number of commensal bacteria, leading to a profound disruption of the microbiota.
Understanding the properties of individual species in the microbiota and their interplay with the host is important when microbial consortia will be applied to enhance agricultural plant productivity. Lastly, the findings of the plant opportunistic pathogens and their impact on host health and microbiota homeostasis revealed striking similarities to other organisms, such as dysbiosis in the human gut.
Link to the paper in external page "Nature Microbiology".