Does co-extracted dissolved organic carbon cause artefacts in cell-based bioassays?

Area of Science:

• Environmental Science
• Analytical Chemistry
• Toxicology

Background:

• Bioanalytical tools are vital for water quality monitoring, especially for complex samples like wastewater rich in dissolved organic carbon (DOC).
• The impact of co-extracted DOC on cell-based bioassays, unlike chemical analyses or isolated enzyme assays, remains poorly understood.
• Wastewater-derived DOC can interfere with analytical methods, necessitating an evaluation of its effects on biological assays.

Purpose of the Study:

• To investigate the influence of different molecular weight fractions of wastewater-derived DOC on cell-based bioassays.
• To assess potential adverse effects of DOC on specific bioassays: Vibrio fischeri bioluminescence inhibition, Pseudokirchneriella subcapitata algae growth, and AREc32 oxidative stress response.
• To determine if DOC co-extracted from wastewater interferes with the reliability of these bioanalytical tools.

Main Methods:

• Utilized mixture experiments as diagnostic tools to evaluate DOC effects.
• Tested various molecular weight fractions of wastewater-derived DOC.
• Assessed three distinct cell-based bioassays: a bacterial luminescence test (Vibrio fischeri), an algal growth assay (Pseudokirchneriella subcapitata), and a human cell line assay for oxidative stress (AREc32).

Main Results:

• Dissolved organic carbon (DOC) did not exhibit suppressive effects when tested in mixtures with reference compounds.
• Binary mixture experiments indicated that co-extracted DOC generally does not interfere with the performance of cell-based bioassays.
• Minor deviations in toxicity predictions for low molecular weight DOC fractions were observed, potentially due to natural components influencing Vibrio fischeri, alongside organic micropollutants.

Conclusions:

• Wastewater-derived dissolved organic carbon (DOC) does not appear to adversely affect the tested cell-based bioassays for water quality monitoring.
• The findings suggest that common bioanalytical tools, including bacterial, algal, and human cell assays, are robust in the presence of wastewater DOC.
• Further research may be needed to fully elucidate the minor deviations observed, considering the interplay of natural organic matter and micropollutants.