Detection of Herbicide Subclasses by an Optical Multibiosensor Based on an Array of Photosystem II Mutants

Abstract

Massive use of herbicides in agriculture over the last few decades has become a serious environmental problem. The residual concentration of these compounds frequently exceeds the maximum admissible concentration in drinking water for human consumption and is a real environmental risk for the aquatic ecosystem. Herbicides inhibiting photosynthesis via targeting photosystem II function still represent the basic means of weed control. A multibiosensor was constructed for detecting herbicides using as biosensing elements photosynthetic preparations coupled to an optical fluorescence transduction system (Giardi et al. EU patent EP1134585, 01830148.1-2204); this paper is about its application in the detection of herbicide subclasses in river water. Photosynthetic material was immobilized on a silicio septum inside a series of flow cells, close to diodes so as to activate photosystem II (PSII) fluorescence. The principle of the detection was based on the factthat herbicides selectively modify PSII fluorescence activity. The multibiosensor has the original feature of being able to distinguish the subclasses of the photosynthetic herbicides by using specific immobilized biomediators isolated from mutated organisms. This setup resulted in a reusable, portable multibiosensor for the detection of herbicide subclasses with a half-life of 54 h for spinach thylakoids and limit of detection of 3 x 10(-9) M for herbicides present in river water.

Biomaterial culture conditions impacting the performance of a PAM fluorometry based aquatic phytotoxicity assay

“…Merz et al, 1996;Beer and Bjork, 2000;Ralph, 2000;Juneau et al, 2002;Giardi et al, 2005). In 2001 the ToxY-PAM dual channel yield analyser was introduced as a new tool for the detection of phytotoxicants in the aquatic environment (Schreiber et al, 2002).…”

Photosynthetic Proteins Created by Computational and Biotechnological Approaches in Biosensing Applications

“…This trend has led to the emergence of a new technological science (Giardi and Pace 2005;Giardi and Piletska 2006) based on the use of protein components that function as core for numerous innovative devices. In fact, single change in the amino acid sequences of photosynthetic proteins can induce new properties, such as an increase in stability, in the specificity of the binding of analytes, and in the efficiency of photochemical processes.…”

Plant tissue-and photosynthesis-based biosensors

“…Numerous environmental factors are known to block the electron carriers between photosystem II and photosystem I, increasing the emitted fluorescence (Thomson, 1997). This method has often been employed to detect the photosynthetic activity of immobilised material (Naessens et al, 2000;Sanders et al, 2001;Giardi et al, 2005;Euzet et al, 2005).…”