In this work sediment samples collected from a coastal lagoon (Italy), were tested with a new Microtox® assay designed for solid samples, the Basic Solid Phase Test (Basic SPT). According to this method, bacteria are exposed to sediment suspension dilutions and light production is directly measured on suspended sediments without any further manipulation. The purpose of the experiments here described was to evaluate the performance of the Microtox® Basic SPT taking into account the colour and turbidity of the sample during the whole measurement. Firstly, bacteria are dispensed into the sediment sample dilutions, and the maximum signal received immediately after dispensing (I0) is compared to the signal after 5, 15 and 30 minute contact times (I5, I15, and I30 respectively). Secondly, absorbance of sediment samples was spectrophotometrically measured in triplicates at 490 nm, and EC50 values were corrected according to the manufacturer. EC50 data obtained with the two correction procedures compared to those of the standard MicrotoxÒ Basic SPT test suggest that sample colour affects the results at high EC50 values; however this effect is generally negligible at low EC50 values.
Sediment intrisic turbidity influence on Microtox Basic Solid-Phase test.
BRUZZI, LUIGI;GUERRA, ROBERTA;ABBONDANZI, FEDERICA;CAMPISI, TIZIANA;IACONDINI, ANTONELLA
2004
Abstract
In this work sediment samples collected from a coastal lagoon (Italy), were tested with a new Microtox® assay designed for solid samples, the Basic Solid Phase Test (Basic SPT). According to this method, bacteria are exposed to sediment suspension dilutions and light production is directly measured on suspended sediments without any further manipulation. The purpose of the experiments here described was to evaluate the performance of the Microtox® Basic SPT taking into account the colour and turbidity of the sample during the whole measurement. Firstly, bacteria are dispensed into the sediment sample dilutions, and the maximum signal received immediately after dispensing (I0) is compared to the signal after 5, 15 and 30 minute contact times (I5, I15, and I30 respectively). Secondly, absorbance of sediment samples was spectrophotometrically measured in triplicates at 490 nm, and EC50 values were corrected according to the manufacturer. EC50 data obtained with the two correction procedures compared to those of the standard MicrotoxÒ Basic SPT test suggest that sample colour affects the results at high EC50 values; however this effect is generally negligible at low EC50 values.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
