Development of respirometry methods to assess the microbial activity of thermophilic bioleaching archaea

Three adapted methods to quantify biomass and activity of microbial leaching cultures

“…When energy conservation occurs by aerobic respiration, as it is the case for At. ferrooxidans, several techniques of respirometric analysis can be applied (du Plessis et al, 2001;Harahuc et al, 2000;Sampson and Blake, 1999). Obligate chemolithoautotrophs oxidise four atoms of ferrous iron at the expense of one molecule oxygen (reaction 1).…”

“…The Clark electrode which is most frequently used for this purpose has certain disadvantages, especially during long-term measurements. The membrane is sensitive towards iron precipitates (du Plessis et al, 2001) which may affect its response time. In addition, the measuring principle causes a weak but permanent oxygen consumption (Atkinson and Smith, 1973) which might get relevant in small-scale assays.…”

“…However, one should keep in mind that due to its mechanism the electrode consumes oxygen (Atkinson and Smith, 1973) and thereby influences long-term measurements. In addition, mineral precipitates may coat the electrode and impair its response (du Plessis et al, 2001).…”

The use of oxygen uptake rate to monitor discovery of microbial and enzymatic biocatalysts

“…Several variations of the respirometer (which is also often described as a device for measuring biological oxygen demand, BOD) have been patented or published (Gilson, 1969;Merrell et al, 1974;Mikesell, 1973;Nakouzi et al, 1996;Pippen and Kramer, 1973;Yoon, 1998). Respirometric techniques have been used in a range of applications including evaluation of the physiology of various microorganisms such as thermophilic bioleaching archaea (Du Plessis et al, 2001), the response of Saccharomyces cerevisiae to metabolite pulses (Wu et al, 2003), the bio-oxidation of sulfide minerals (Boon et al, 1998), the effect of over-expression of HAP4 on metabolic fluxes in S. cerevisiae (Van Maris et al, 2001) and the kinetics of iron oxidation by Thiobacillus ferrooxidans (Boon et al, 1999). Diez-Caballero Arnau and Rodriguez Albalat (2000) patented a micro-biosensor which uses respirometric principles to evaluate the levels of chemicals in water.…”

Bioremediation of petroleum‐impacted soils from investigation‐derived wastes

“…It is estimated that less than 1 percent of the total population of microorganisms in soil typically is recovered by this method (Burlage et al, 1998;Critter et al, 2001). Microbial metabolic activity can be estimated by measuring either CO 2 production or O 2 consumption (respirometry), which reflects biological and biochemical activity (Cortassa et al;2001, Critter et al;, du Plessis et al, 2001Kim et al, 2001; Bioremediation can be accomplished either in situ (e.g., air sparging or soil vapor extraction) or ex situ (e.g., land treatment or bioreactors). Tzoris et al, 2002).…”