Ferricyanide mediated biochemical oxygen demand–development of a rapid biochemical oxygen demand assay

MICREDOX®—development of a ferricyanide-mediated rapid biochemical oxygen demand method using an immobilised Proteus vulgaris biocomponent

“…Theoretically the complete oxidation of the exogenous GGA substrate added would yield 1.62 C and, thus, these results demonstrate an average stoichiometric conversion efficiency of 58%. This is very similar to the 60.5% conversion expected for the standard BOD 5 test and to the 52% conversion of GGA by E. coli recorded by Morris et al (2001). The 78% conversion of GGA by E. coli observed by Pasco et al (2000) was somewhat higher and may be due to the different E. coli strains used in the two laboratories.…”

“…Second, unlike oxygen, the reduced form of the mediator has an initial background concentration of zero, thereby increasing the accuracy when quantifying the amount of oxidised mediator converted to its reduced form. In recent studies, we demonstrated that the ferricyanide-mediated microbial oxidation of organic substrates by Eschericha coli in a 1-h MICREDOX ® incubation was equivalent to that achieved in the traditional BOD 5 test (60.5%) (Pasco et al, 2000;Morris et al, 2001;Catterall et al, 2003). A second application, again demonstrated with E. coli, confirmed the utility of this method for rapidly quantifying the effect of toxic substances on microbial catabolism .…”

“…The rapid oxidation of substrates requires microbial strain(s) capable of degrading a diverse range of compounds and one approach is to use well-characterised microorganisms with broad substrate specificities. The feasibility of the MICREDOX ® method for rapid BOD monitoring has been confirmed using E. coli (Pasco et al, 2000;Morris et al, 2001) and showed the same trends expected of aerobic microbial oxidation in the presence of a mediator, but at greatly increased rates. However, E. coli was shown not to be a particularly good candidate for monitoring the BOD of wastewater due to its limited substrate range .…”

Development of a simple method for biotoxicity measurement using ultramicroelectrode array under non-deaerated condition

“…Chronoamperometry at microelectrode was used to measure quantity of the reduced mediator as it offers the advantages of simple and low cost operation, reproducibility and real time analysis [9][10][11]. Herein, the ultramicroelectrode array (UMEA) we adopted could effectively amplify the signal from the total limiting currents of multi individuals, so it could be used to distinguish little change of toxicity.…”

Mediated electrochemical measurement of the inhibitory effects of furfural and acetic acid on Saccharomyces cerevisiae and Candida shehatae

“…Diffusion limiting currents (quantitatively related to concentration) can be established within seconds and with virtually zero destruction of analyte (Morris et al 2001). Ferrocyanide accumulation arising from menadione-mediated reduction of ferricyanide indicates the intracellular redox activities of yeast cells.…”