Abstract
BackgroundBacteria adapted to live within animals can protect their hosts against harmful infections. Beyond antagonism with pathogens, a ‘defensive’ bacterial symbiont could engage in additional interactions with other colonizing micro-organisms. A single bacterium might thus have cascading ecological impacts on the whole microbiome that are rarely investigated. Here, we assess the role of a defensive symbiont as a driver of host-associated microbiota composition by using a bacterial species (Enterococcus faecalis) that was previously experimentally adapted to a nematode host model (Caenorhabditis elegans).ResultsAn analysis of 16S rRNA data from C. elegans exposed to E. faecalis and subsequently reared in soil, reveal that symbiont adaptation to host environment or its protective potential had minimal impact on microbiota diversity. Whilst the abundance of Pseudomonas was higher in the microbiota of hosts with protective E.faecalis (and another protective species tested), a few other genera – including Serratia and Salinispora – were less abundant in hosts colonized by all E. faecalis strains. In addition, the protective effect of E. faecalis against virulent Staphylococcus aureus pathogens was maintained despite multi-species interactions within the microbiota.ConclusionsOur results reveal the degree to which a new, evolving symbiont can colonise and maintain pathogen-resistance with minimal disruption to host microbiota diversity.
Highlights
Bacteria adapted to live within animals can protect their hosts against harmful infections
The evolved E. faecalis population conferring enhanced protection (E. faecalis P), evolved E. faecalis not conferring enhanced protection (E. faecalis NP), and the ancestral E. faecalis (E. faecalis Ancestral E.faecalis (Anc)) correspond to a randomly-selected replicate population from CCE E. faecalis, SE E. faecalis, and ancestral E. faecalis populations, respectively, in King et al (2016) [10]. These populations have different genetic compositions, and E. faecalis P contains non-synonymous SNPs in genes putatively associated with superoxide production, a mechanism for pathogen suppression [10]
We measured how the Protection by E. faecalis maintained amidst microbiota We examined whether within-host adaptation by E. faecalis P resulted in increased within-host density and protection persistence in the nematode-microbiome system
Summary
Bacteria adapted to live within animals can protect their hosts against harmful infections. Animals can harbor a diversity of microbes. Many of these micro-organisms can be beneficial and protect their hosts against pathogen infection [1, 2]. These defensive microbial symbionts can be important in determining infection outcomes across natural host populations [3, 4], and for hosts in agricultural or biomedical contexts [5,6,7,8]. Hosts are protected when these defensive symbionts, for example, block the growth or establishment of pathogens These symbionts can suppress invading parasites and
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
