Infection by a eukaryotic gut parasite in wild Daphnia sp. associates with a distinct bacterial community

Abstract

Host-associated bacterial communities can play an important role in host fitness and resistance to diseases. Yet, few studies have investigated tripartite interaction between a host, parasite and host-associated bacterial communities in natural settings. Here, we use 16S amplicon sequencing to compare gut- and body- bacterial communities of wild water fleas belonging to the Daphnia longispina complex, between uninfected hosts and those infected with the common and virulent eukaryotic gut parasite Caullerya mesnili (Family: Ichthyosporea). We report community-level changes in host-associated bacteria with the presence of the parasite infection; namely decreased alpha diversity and increased beta diversity at the site of infection, i.e. host gut (but not host body). We also report decreased abundance of bacterial taxa proposed elsewhere to be beneficial for the host, and an appearance of taxa specifically associated with infected hosts. Our study highlights the host-microbiota-infection link in a natural system and raises questions about the role of host-associated microbiota in natural disease epidemics as well as the functional roles of bacteria specifically associated with infected hosts.

The effect of hypoxia onDaphnia magnaperformance and its associated microbial and bacterioplankton community: a scope for Genotype x Microbial community interactions upon environmental stress ?

“…The environment and host genotype, which influence the microbial community composition and functionality to achieve a balanced state, can cause these interactions to be temporary and susceptible to selection (Macke et al, 2020, Akbar et al, 2022. It has been shown that depriving Daphnia of its microbiota is detrimental to its fitness and the association between microbial imbalance and disease states is becoming clear, also in Daphnia (Rajarajan et al, 2022, Bulteel et al, 2021. Daphnia gut microbial community responses have been detected upon exposure to environmental stress (Houwenhuyse et al, 2021), for example upon exposure to antibiotics (Callens et al, 2018, Akbar et al, 2020 and parasites (Bulteel et al, 2021, Rajarajan et al, 2022.…”

“…It has been shown that depriving Daphnia of its microbiota is detrimental to its fitness and the association between microbial imbalance and disease states is becoming clear, also in Daphnia (Rajarajan et al, 2022, Bulteel et al, 2021. Daphnia gut microbial community responses have been detected upon exposure to environmental stress (Houwenhuyse et al, 2021), for example upon exposure to antibiotics (Callens et al, 2018, Akbar et al, 2020 and parasites (Bulteel et al, 2021, Rajarajan et al, 2022. Another specific example of the effects of a microbiome-related reaction to environmental conditions in D. magna was described for toxic cyanobacteria.…”