May 13, 2006

Sensitive and meaningful measures of bacterial metabolic activity using NADH fluorescence

Water Research
Melissa Wos, Peter Pollard


Successful biological wastewater treatment depends on bacterial metabolic activity. Commercial fluorimeters are designed to monitor this activity using the native fluorescence of Nicotinamide Adenine Dinucleotide [NADH]. However, fluorescence measurements in wastewater treatment plants remain scarce due to difficulties with interpreting fluorescence data. This paper shows that fluorescence probe measurements taken from wastewater do not represent bacterial cell metabolic activity because intracellular NADH is likely swamped by the stable extracellular NADH fraction. Thus, a simple filtration/extraction/centrifugation method was developed to collect the bacterial cells, extract the intracellular NADH using heat treatment in Tris buffer and collect the purified intracellular NADH fraction. NADH standards were used to quantify NADH from the unknown wastewater samples where limits of detection were between 1 nmol mL(-1) and 0.35 micromol mL(-1). Fluorescence of [NADH] greater than 0.35 micromol mL(-1) was self-quenched. At high pH's NADH was stable outside the cell. NADH was stable at neutral and basic pH ranges of pH 7 to 11, but declined proportionally below a pH of 7. Since commercially available fluorescence probes used for mea...Continue Reading

Mentioned in this Paper

Metabolic Process, Cellular
Neuro-Oncological Ventral Antigen 2
Bacterial cell
Alkalescens-Dispar Group
Ethanol Measurement
Environmental Sludge

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