The role of phages as top-down and bottom-up regulators of freshwater ecosystems
Biotic interactions between members of different trophic levels such as predator-prey and host-parasite relationships are among the most studied interspecies phenomena in ecology. In microbial ecology such biotic interactions have received only little attention. One of the main biotic factors influencing bacterial communities are phages (i.e., bacteriophages, viruses that infect bacteria). Phages play an intrinsic role in aquatic ecosystems. On one hand, phages are top-down regulators for microbial communities as they modulate microbial population size and diversity through the selective lysis of specific bacterial groups. On the other hand, phages have bottom-up effect, as they supply readily available organic matter released from the lysed infected cells (i.e., the ’viral shunt’). Despite the obvious importance of phages in aquatic ecosystems, studies that aim to assess the effect of the viral shunt or those that analyse the correlations between viral and bacterial diversity are rare. The project aims to address the following main research questions:
- What are the effects of phages as bottom-up regulators on the carbon flux of freshwater ecosystems?
- Is there a difference in the effect of phages as top-down regulators of bacterial communities depending on the attributes of the impacted bacteria or on properties of the phages?
- What is the role of ssDNA phages in shaping freshwater bacterial communities and ecosystems?
Inland water virus scope (IWVS)
The primary goal of the Inland Water Virus Scope project is to establish a broad and unbiased repository of inland water metaviromes. The project will not only expand the number of inland water viral metagenomes available but together with extensive metadata including microbial community genetic profiling will provide an unprecedented framework for host-contextualized viral ecology studies. This aim will be achieved through the study of three sample sets originating from diverse inland aquatic ecosystems (Swedish water samples from streams to lakes, high discharge Floridian freshwater springs, high frequency time-series of Hungarian soda pans) that will provide a broad scope of inland water viral diversity through space, time and environmental conditions.
The consequences of the interaction between viral and bacterial communities during community coalescence in aquatic ecosystems
Community coalescence is a special form of dispersal, where entire communities are mixed together with their environment. My previous studies show that the composition of coalescing bacterial communities is typically not predictable by conservative mixing models. These deviations from neutral models are suggested to be the result of the special factors that influence the outcome of community coalescence. One of them is the interchange of the predators and parasites (i.e., phages for bacteria) of both communities. In the project, this special factor of community coalescence is dissected through microcosm experiments. The results of the project will help understand what effect the mixing of phages of the coalescing communities has on the community assembly of the bacterial communities.
Deciphering the microbial community dynamics of Central-European soda lakes