Mj. Silva et Jl. Wong, ELECTROCHEMICAL BIOASSAY SYSTEM - REDOX RESPONSES OF ESCHERICHIA-COLICULTURES TO ENVIRONMENTAL STRESSES, Bioelectrochemistry and bioenergetics, 37(2), 1995, pp. 141-148
Redox responses of Escherichia coli based on the anaerobic metabolism
of glucose to hydrogen are characteristic of the culture. Four unique
E. coli strains and one resistant strain were monitored in a multichan
nel electrochemical analyzer. The redox measurements and absorbance as
well as their kinetics, observed during culture growth, were compared
to differentiate strains and to correlate with phenotypes. Mixed cult
ures of two strains to simulate the emergence of a resistant populatio
n yielded two peak potentials. On increasing or decreasing the initial
cell concentration of one strain or the other, the respective potenti
al peak was moved forward or backward in the time-scale, thereby allow
ing peak identification. The electrochemical bioassay system, calibrat
ed by known cultures, was used to evaluate various environmental stres
s factors: culture media without nutrients or substrates, extended cul
turing under impoverished conditions, freezing, cooling, or heating cu
ltures to lethal temperatures for different periods of time, and expos
ing cultures to increasing doses of a phenolic toxicant. This system a
ppears to be responsive to the stress factors in a quantitative and re
producible manner, and hence may find use in environmental risk assess
ments.