About this Research Topic
Dissolved Organic Matter (DOM) is the major pool of organic carbon in marine and freshwaters, and the link between detrimental organic matter and microorganisms represents one of the largest fluxes in aquatic carbon cycling. In order to comprehend aquatic carbon cycling it is central to understand which factors regulate microbial utilization and transformation of DOM in those environments. Evidence suggests that microbial utilization of DOM is influenced by the bacterial community structure but also by the source and composition of DOM (e.g. size, complexity, aromaticity, aliphaticity). Yet, despite a wide interest in assessing the regulating factors of DOM bioavailability, it is still to a large extent unknown what mechanisms control the ability of microorganisms to utilize DOM and how this changes in different aquatic environments.
The DOM pool in aquatic environments consists of several thousands of compounds and each individual compound is found at very low concentrations. Thus, for a long time it has been hard to characterize DOM. During the last years, methods for characterizing DOM based on both optical properties (absorbance and fluorescence) and high-resolution mass spectrometry, have developed. In addition, advances in next generation sequencing technologies make it possible to reveal both compositional and functional information about microbial communities. Finally, the growing body of literature on the various facets of microbial communities functioning and DOM cycling has led to a critical mass of published data available for cross-system syntheses. Together, these developments open up possibilities to link microbial communities with the transformation of specific carbon compounds. Although several recent studies have already shown that specific taxa are associated with particular groups of carbon compounds, few studies have included functional measurements showing the link to ecosystem process rates.
This Research Topic focuses on studies (including e.g. original research, perspectives, mini-reviews, and opinion papers) that investigate and discuss:
- Variability of DOM composition and transformations in time and space, in the same or among different aquatic environments.
- Specific transformation of DOM in relation to composition of microbial community.
- Specific transformation of DOM in relation to composition of the DOM pool.
- Factors controlling DOM processing and its link to ecosystem processes.
Keywords: dissolved organic matter, carbon cycling, bacterial communities, ecosystem processes, aquatic environments
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