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Updated: Jan 23, 2026

Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays
Published on: October 1, 2013
Screening sediment samples used as anolytes in microbial fuel cells for microbial electron transfer activity using
Kartik S Aiyer1, B S Vijayakumar2
1Department of Biosciences, Sri Sathya Sai Institute of Higher Learning, Prasanthi Nilayam, Puttaparthi, Andhra Pradesh, 515134, India. aiyerkartiksatyanarayan@sssihl.edu.in.
Objective:
The dye reduction-based electron-transfer activity monitoring (DREAM) assay was employed to screen sediment and wastewater samples functioning as anolytes in a microbial fuel cell (MFC) for their microbial electron transfer activity.
Results:
Electron transfer to redox dyes from microbial activity reduced the dyes and the resulting extent of reduction was measured as DREAM assay coefficient. Methylene blue was decolourised, while resazurin underwent florigenic change from blue to pink to colourless upon formation of resorufin and dihydroxyresorufin. DREAM assay coefficient conformed to power density obtained in the MFC. A correlation was observed between chemical oxygen demand of the sample and the DREAM coefficient (+ 0.934) and also between DREAM coefficient and power density generated (+ 0.976). Highest DREAM coefficient and power density was observed for activated sludge.
Conclusions:
The DREAM assay is a rapid, sensitive and low-cost method to assess microbial electron transfer activity for inocula used as anolytes in a MFC.
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