Toxicity assessment
Toxicity to the bioluminescent organism Vibrio
fischeri was assayed using the Merck ToxAlert†
100 (Merck Eurolab, UK) according to BS EN
ISO 11348:1998. All samples were serially diluted
in 2% w/v NaCl, and each assay was performed in
duplicate at pH 7.0, 15 8C. Sodium chloride (2%
w/v) was used as the negative control. The sample
concentration that inhibited 50% of the light
output after a 5 min exposure period (EC50) was
automatically determined using the WINTOX software
supplied with ToxAlert† 100. Where appropriate
the EC50 value refers to the concentration
(mg l1) of the sample under test. However, for
bioreactor samples where the toxic component was
unidentified, the units are expressed as percent
dilution of original sample. Colour correction was
according to the manufacturer’s instruction