How do metals interact with periphytic biofilms?
Maxime Leclerc1, Maxime Wauthy2, Dolors Planas3
1GRIL, Département de Sciences Biologiques, Université de Montréal, 1375 Thérèse-Lavoie-Roux Ave., Montréal, QC H2V 0B3, Canada; GRIL, GEOTOP, Département de Sciences Biologiques, Université du Québec à Montréal, 141 Président-Kennedy Ave., Montréal, QC H2X 1Y4, Canada.
The Science of the Total Environment
|March 16, 2023
Summary
The periphyton extracellular matrix regulates metal transfer in biofilms. Specific components in loosely bound fractions scavenge metals, while tightly bound fractions enhance essential metal bioavailability for microorganisms.
Area of Science:
- Environmental Science
- Aquatic Ecology
- Biogeochemistry
Background:
- The extracellular matrix of periphyton plays a crucial role in regulating metal transfer within biofilms.
- This process has significant implications for metal bioavailability and transfer into aquatic food webs.
Purpose of the Study:
- To investigate the retention of metal species in loosely (LB) and tightly bound (TB) fractions of periphyton matrix.
- To analyze the composition of fluorescent dissolved organic matter (FDOM) and its co-occurrence with metals in periphyton.
- To understand the contrasting roles of different matrix fractions in metal mobility.
Main Methods:
- Analysis of periphyton matrix from three pristine lakes at different growth stages.
- Measurement of FDOM composition using parallel factor analysis (PARAFAC).
- Quantification of essential and non-essential metals and their relationship with FDOM components in LB and TB fractions.
Main Results:
- Periphyton LB and TB fractions exhibited distinct FDOM compositions compared to the water column.
- PARAFAC identified five FDOM components, with C2 (humic-like) and C4 (tryptophan-like) originating from periphyton.
- LB fractions showed positive metal-FDOM relationships, suggesting a metal scavenging role, while TB fraction's C2 component correlated with essential metal bioavailability.
Conclusions:
- The periphyton extracellular matrix has contrasting roles in metal mobility, acting as a metal scavenger in LB fractions and promoting bioavailability in TB fractions.
- These findings challenge traditional views of the matrix solely as a protective barrier.
- The study proposes an experimental model to further investigate metal regulation by periphytic extracellular polymeric substances.
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