Pseudomonas putida as a receptor element of microbial sensor for naphthalene detection

Sensitive Simultaneous Determinations of 1,2-Dihydroxynaphthalene and Catechol by an Amperometric Biosensor

An amperometric biosensor for 1,2-dihydroxynaphthalene (DHN) and catechol (Cat) has been developed in order to monitor the biodegradaton of polycyclic aromatic hydrocarbons (PAHs). DHN is a common intermediary metabolite in naphthalene and phenanthrene degradation, while Cat is produced by further degradation. These compounds were detected by a biosensor modified with pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). The biosensor was based on signal amplification by enzyme-catalyzed redox cycling and was able to detect DHN and Cat at very low concentrations down to 10^-9 M. Since the anodic waves of DHN and Cat were well separated, simultaneous determinations of these compounds were possible. Although the current signal for DHN was reduced in repeated measurements due to the oxidative polymerization of DHN, it can be avoided when the concentration of DHN was sufficiently low (<1 μM).

Applications of microbial cell sensors

Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of microbial cell sensors have been developed as analytical tools. The microbial cell sensor utilizes microbes as a sensing element and a transducer. The characteristics of microbial cell sensors as sensing devices are a complete contrast to those of enzyme sensors or immunosensors, which are highly specific for the substrates of interest, although the specificity of the microbial cell sensor has been improved by genetic modification of the microbe used as the sensing element. Microbial cell sensors have the advantages of tolerance to measuring conditions, a long lifetime, and good cost performance, and have the disadvantage of a long response time. In this review, applications of microbial cell sensors are summarized.

Development of microbial sensors and their application

Many types of microbial sensors have been developed as analytical tools since the first microbial sensor was studied by Karube et al. in 1977. The microbial sensor consists of a transducer and microbe as a sensing element. The characteristics of the microbial sensors are a complete contrast to those of enzyme sensors or immunosensors, which are highly specific for the substrates of interest, although the specificity of the microbial sensor has been improved by genetic modification of the microbe used as the sensing element. Microbial sensors have the advantages of tolerance to measuring conditions, a long lifetime, and cost performance, and also have the disadvantage of a long response time. In this review, the long history of microbial sensor development is summarized.

Biosensor development in Russia

The review summarizes the current Russian research in the field of biological sensors for detection of carbohydrates, alcohols, medicines, enzyme inhibitors, toxicants, heavy metal ions, as well as viruses and microbial cells. Some of the presented works describe the analytical parameters of biosensors; other publications provide a basis for their development. The review covers mainly publications that have appeared over the past 10 years. As a whole, the collected material gives an idea of the main tendencies of biosensor development in Russia. The review is not meant to be comprehensive but highlights the major trends in this field in the last decade.

Bacteria-degraders as the base of an amperometric biosensor for detection of anionic surfactants

Several strains belonging to genera Pseudomonas and Achromobacter and characterized by the ability to degrade anionic surfactants were tested as potential bases of microbial biosensors for surfactant detection. For each strain the substrate specificity and stability of sensor signals were studied. The total amount of the substrates tested (including carbohydrates, alcohols, aromatics, organic acids, etc.) was equal to 60; the maximal signals were observed towards the anionic surfactants. The lower limit of detection for sodium dodecyl sulfate used as a model surfactant was in the field of 1 microM for all the strains. The created microbial biosensor model can extend the practical possibilities for rapid evaluation of surfactants in water media.