New Methods, New Concepts: What Can Be Applied to Freshwater Periphyton?

Abstract

Microbial interactions play an essential role in aquatic ecosystems and are of the great interest for both marine and freshwater ecologists. Recent development of new technologies and methods allowed to reveal many functional mechanisms and create new concepts. Yet, many fundamental aspects of microbial interactions have been almost exclusively studied for marine pelagic and benthic ecosystems. These studies resulted in a formulation of the Black Queen Hypothesis, a development of the phycosphere concept for pelagic communities, and a realization of microbial communication as a key mechanism for microbial interactions. In freshwater ecosystems, especially for periphyton communities, studies focus mainly on physiology, biodiversity, biological indication, and assessment, but the many aspects of microbial interactions are neglected to a large extent. Since periphyton plays a great role for aquatic nutrient cycling, provides the basis for water purification, and can be regarded as a hotspot of microbial biodiversity, we highlight that more in-depth studies on microbial interactions in periphyton are needed to improve our understanding on functioning of freshwater ecosystems. In this paper we first present an overview on recent concepts (e.g., the "Black Queen Hypothesis") derived from state-of-the-art OMICS methods including metagenomics, metatranscriptomics, and metabolomics. We then point to the avenues how these methods can be applied for future studies on biodiversity and the ecological role of freshwater periphyton, a yet largely neglected component of many freshwater ecosystems.

Wastewater microorganisms impact microbial diversity and important ecological functions of stream periphyton

“…This aspect was poorly described so far, as most studies looked either at the overall effluent toxicity (Liao et al, 2019;Nega et al, 2019;Peng et al, 2018;Romero et al, 2019), or at other wastewater constituents, such as nutrients (Lebkuecher et al, 2018) and micropollutants (Carles et al, 2021;Chonova et al, 2019;Tamminen et al, 2022;Tardy et al, 2021;Tlili et al, 2020). Our study also points towards the importance of species interactions within periphyton communities, as well as between prokaryotes and eukaryotes, which occur among co-existing species in periphyton (Gubelit and Grossart, 2020). For instance, studies on diatom-bacterial interactions revealed a high species-specific interdependence of the algal host and bacteria, as each diatom species developed a bacterial community that differed in its composition (Grossart et al, 2005;Koedooder et al, 2019;Stock et al, 2019).…”

Legionella pneumophila and Free-Living Nematodes: Environmental Co-Occurrence and Trophic Link

“…Unlike in cooling towers, biofilms in lakes are hotspots for biodiversity, with a wide variety of microorganisms and their grazers in numerous ecological niches [ 69 , 70 ]. However, no L. pneumophila could be detected in the investigated swimming lakes, although the water temperature (mean: 25.1 °C, Table S1 ) during the sampling period was suitable for its growth [ 71 , 72 ].…”

Metabolomics insight into the influence of environmental factors in responses of freshwater biofilms to the model herbicide diuron

“…Black empty ellipses highlight how exposure times are discriminated although further investigations are still needed to provide quantitative evidence of this causal relationship. In addition, this fatty acid, as others, has been described as antibacterial or as growth inhibitor of some algae species (i.e., involved in allelopathic interactions) (Allen et al 2015, Gubelit andGrossart 2020). Hence, their downregulation might trigger shifts in community composition and so its functioning and associated ecosystem functions supported by these microbial communities.…”