AUTHOR=Scheuring István , Rasmussen Jacob A. , Bozzi Davide , Limborg Morten T. 

TITLE=A strategic model of a host–microbe–microbe system reveals the importance of a joint host–microbe immune response to combat stress-induced gut dysbiosis

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.912806

DOI=10.3389/fmicb.2022.912806

ISSN=1664-302X

ABSTRACT=<p>Microbiomes provide key ecological functions to their host; however, most host-associated microbiomes are too complicated to allow a model of essential host–microbe–microbe interactions. The intestinal microbiota of salmonids may offer a solution since few dominating species often characterize it. Healthy fish coexist with a mutualistic <italic>Mycoplasma</italic> sp. species, while stress allows the spread of pathogenic strains, such as <italic>Aliivibrio</italic> sp. Even after a skin infection, the <italic>Mycoplasma</italic> does not recover; <italic>Aliivibrio</italic> sp. often remains the dominant species, or <italic>Mycoplasma</italic>–<italic>Aliivibrio</italic> coexistence was occasionally observed. We devised a model involving interactions among the host immune system, <italic>Mycoplasma</italic> sp. plus a toxin-producing pathogen. Our model embraces a complete microbiota community and is in harmony with experimental results that host–<italic>Mycoplasma</italic> mutualism prevents the spread of pathogens. Contrary, stress suppresses the host immune system allowing dominance of pathogens, and <italic>Mycoplasma</italic> does not recover after stress disappears.</p>