Measuring aerobic respiration in stream ecosystems using the resazurin‐resorufin system

Abstract

The use of smart tracers to study hydrologic systems is becoming more widespread. Smart tracers are compounds that irreversibly react in the presence of a process or condition under investigation. Resazurin (Raz) is a smart tracer that undergoes an irreversible reduction to resorufin (Rru) in the presence of cellular metabolic activity. We quantified the relationship between the transformation of Raz and aerobic bacterial respiration in pure culture experiments using two obligate aerobes and two facultative anaerobes, and in colonized surface and shallow (<10 cm) hyporheic sediments using reach‐scale experiments. We found that the transformation of Raz to Rru was nearly perfectly (minr2 = 0.986), positively correlated with aerobic microbial respiration in all experiments. These results suggest that Raz can be used as a surrogate to measure respiration in situ and in vivoat different spatial scales, thus providing an alternative to investigate mechanistic controls of solute transport and stream metabolism on nutrient processing. Lastly, a comparison of respiration and mass‐transfer rates in streams suggests that field‐scale respiration is controlled by the slower of respiration and mass transfer, highlighting the need to understand both biogeochemistry and physics in stream ecosystems.

New outlook in BOD measurement and bioprocess management: the Enverdi® kit

“…1). This strong equivalence also confirms concomitant works showing that the fluorescence intensity resulting from the reduction by bacteria of a resazurin-based reagent is clearly correlated to the bacterial oxygen uptake for BOM mineralisation [32][33][34].…”

“…When the indicator is reduced by bacteria, the original molecule is converted into a highly fluorescent product. Given that the indicator reduction is proportional to the bacterial oxygen uptake, the bacterial respiration activity can be quantify through fluorescence intensity measurement [32][33][34]. This analytical approache can be used to assess the positive or negative effect of a particular substance or an unknown mixture on the bacterial respiration.…”

Ecosystem respiration increases with biofilm growth and bed forms: Flume measurements with resazurin

“…Resazurin (Raz) is a metabolically active compound that reacts irreversibly to resorufin (Rru) [Haggerty et al, 2008[Haggerty et al, , 2009Argerich et al, 2011]. The rate of the Raz-to-Rru reaction provides a measure of net aerobic respiration [González-Pinzón et al, 2012]. Since Raz does not exist in streams, and is not subject to reaeration, changes in ER due to processes such as turbulence can be measured more accurately.…”

Transport of Conservative and “Smart” Tracers in a First-Order Creek: Role of Transient Storage Type

“…Haggerty et al [12] developed a metabolically-active transient storage (MATS) model to demonstrate that these tracers may be used to quantify the metabolic activity associated with TS and to assess interactions within small streams. Specifically, the Raz-Rru system allows the measuring of aerobic respiration and the quantification of spatial differences in metabolism in headwater streams [13,14]. TS has not been separated into STS and HTS in the above works, and the whole TS was assumed to be metabolically active.…”