MICROBIAL SENSORS FOR NAPHTHALENE USING SPHINGOMONAS SP B1 OR PSEUDOMONAS-FLUORESCENS WW4

Amperometric biosensors for naphthalene were developed using either im mobilized Sphingomonas sp. B1 or Pseudomonas fluorescens WW4 cells. Th e microorganisms were immobilized within a polyurethane-based hydrogel , which was used for a microbial biosensor for the first time, Both st rains were shown to be equally suited for the quantification of naphth alene in aqueous solutions. The biosensors were tested in a now-throug h system and a stirred cell (batch method). In both systems a linear r esponse down to the detection limit was obtained. Measurements in the flow-through system gave sensitivities of up to 1.2 nA mg(-1) l(-1) an d a linear range from 0.03 mg/l to 2.0 mg/l. The response lime (t(95)) was 2 min and the sample throughput six per hour; the repeatability w as within +/- 5%. With the batch method, sensitivities of between 3 nA mg(-1) l(-1) and 5 nA mg(-1) l(-1) and a linear range of 0.01-3.0 mg/ l were obtained; the response time was between 3 min and 5 min. The se nsors reached an operational lifetime of up to 20 days. The sensitivit y of both sensors for naphthalene was, in most cases, more than four t imes higher than for various other substrates.