The heterogeneity of the aquatic environment may create niches that enable the co-existence of bacteria with different defense traits. variation in the bottom-up and top-down control of the microbial communities 19, 20. Consequently, these communities experience highly variable conditions, creating fluctuations in their selection dynamics i.e. In addition to protozoan predation and viral lysis, aquatic bacterial communities are exposed to bottom-up forces such as limited nutrient availability 16, 17, 18. Several of these abilities are similar to those of PRB it is widely believed that many traits that render bacteria pathogenic in susceptible hosts were shaped by evolutionary forces outside the context of human-pathogen interactions, and should be seen as colonization factors that produce “accidental virulence” 15.īacteria in natural aquatic systems are exposed to diverse stressors that vary over time and over spatial scales. Pathogenic bacteria contain virulence factors that enable them to colonize a niche in their hosts, evade or suppress the host’s immune response, enter and exit host cells, or obtain nutrition from the host.
#The persistence trophy guide driver#
Interactions between bacteria and bacterivores have been suggested to serve as a driver or selective force for pathogen evolution 3, 10, 11, 12, 13, 14. elongation, aggregation, and filament or biofilm formation), increased growth rates, motility, toxicity and ability to replicate or avoid degradation in eukaryotic cells using specific outer membrane structures 4, 5, 6, 7, 8, 9. protozoa-resisting bacteria (PRB), frequently exhibit traits such as morphological adaptation (e.g. Bacteria that can survive protozoan predation, i.e. The long co-existence of bacteria and bacterivorous protozoa in aquatic and terrestrial ecosystems has led to the evolution of antipredator strategies in many bacterial groups 3. However, a better understanding of pathogens’ long-term fates in natural ecosystems is needed to accurately assess risks of exposure and design effective strategies for responding to emerging diseases 1, 2. Knowledge of pathogens’ environmental persistence is limited, largely because it is difficult to study these microbes in their natural environments. The potential for transmission of pathogenic bacteria from environmental reservoirs to susceptible hosts depends on the pathogens’ environmental distributions and the hosts’ behaviour. Our results show that PRB with different ecological strategies can be expected in water of high and intermediate nutrient levels and after major disturbances of an aquatic system. The predation-pressure (ratio between predator and bacterial biomass) had a positive effect on the abundance of the PRB genus Mycobacterium, while perturbation (enrichment and dilution) favored the PRB genus Pseudomonas that dominated the bacterial community in the disturbed systems. To estimate the effects of the microbial food web dynamics (microscopy of heterotrophic bacteria, phytoplankton, protozoa and rotifers) and physicochemical variables on the PRB abundance in the study system, a joint species distribution modelling approach was used. PRB was monitored by screening 16S rRNA amplicon sequence data for reads assigned to bacteria that previously has been shown to resist degradation by amoebae. To assess the role of nutrient availability and predation-pressure on selection for protozoa-resisting bacteria (PRB), an enrichment-dilution experiment was designed using laboratory microcosms containing natural lake water. However, the ecological mechanisms underpinning selection for protozoa-resistance in aquatic bacteria are poorly known.
#The persistence trophy guide drivers#
The long co-existence of bacteria and protozoa has led to the development of bacterial protozoa resistance strategies, which are suggested to serve as drivers for the evolution of pathogenic bacteria.
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