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Toward Quantitative Understanding of the Bioavailability of Dissolved Organic Matter in Freshwater Lake during Cyanobacteria Blooming
journal contribution
posted on 2017-05-03, 00:00 authored by Leilei Bai, Chicheng Cao, Changhui Wang, Huacheng Xu, Hui Zhang, Vera I. Slaveykova, Helong JiangOccurrence of cyanobacterial harmful
algal blooms (CyanoHAB) can
induce considerable patchiness in the concentration and bioavailability
of dissolved organic matter (DOM), which could influence biogeochemical
processes and fuel microbial metabolism. In the present study, a laboratory
4-stage plug-flow bioreactor was used to successfully separate the
CyanoHAB-derived DOM isolated from the eutrophic Lake Taihu (China)
into continuum classes of bioavailable compounds. A combination of
new state-of-the-art tools borrowed from analytical chemistry and
microbial ecology were used to characterize quantitatively the temporary
evolution of DOM and to get deeper insights into its bioavailability.
The results showed a total 79% dissolved organic carbon loss over
time accompanied by depletion of protein-like fluorescent components,
especially the relatively hydrophilic ones. However, hydrophilic humic-like
fluorescent components exhibited bioresistant behavior. Consistently,
ultrahigh resolution mass spectrometry (FTICR-MS) revealed that smaller,
less aromatic, more oxygenated, and nitrogen-rich molecules were preferentially
consumed by microorganisms with the production of lipid-like species,
whereas recalcitrant molecules were primarily composed of carboxylic-rich
alicyclic compounds. Moreover, the bioavailability of DOM was negatively
correlated with microbial community diversity in the bioreactor. Results
from this study provide deeper insights into the fate of DOM and relevant
biogeochemical processes in eutrophic lakes.