Catabolism of organophosphonates: biochemistry, physiology and interactions of degrading bacteria in the environment

The major contribution of microorganisms in metabolism of natural and synthetic phosphonates, the biochemical bases of these processes and possible interactions between degrading bacteria in natural and anthropogenic ecosystems are presented in the light of the recent data on significant role of reduced phosphorus compounds in the biosphere. Special emphasis is placed on C-P lyase and phosphonatase which are pivotal enzyme systems for catabolism of both natural and synthetic phosphonates. Modern data on structure, diversity, regulation and physiological role of both enzymes are reviewed and discussed.

Self-defending (self-degasing) materials for protection against organophosphorus compounds

The paper presents an analysis of theoretical and experimental studies of national and foreign scientists developing “self-cleaning” (self-degassing) materials for personal protection, providing increased survival of people under the influence of warfare organophosphorus compounds. The use of enzymes as components of modern protective materials obtained using nano- and chemical-biological biocatalytic technologies is summarized.

Enzymatic detection of organophosphorus compounds

Organophosphorus compounds (OPC) are capable of affecting a wide variety of biological targets, including enzymes. At the same time, there is a large group of enzymes that modify these OPC, mainly by hydrolysis. In total, both those and other enzymes can be involved in determining the content of various OPC. This chapter presents the latest scientific developments in the field of enzyme biosensors for the analysis of OPC in a wide variety of environmental objects. For these purposes, soluble and immobilized forms of enzymes, their various combinations, as well as crude enzymes as a components of microorganisms’ cells can be used. Modern methods make it possible to reach the detection limits of OPC of 10–12 g/L with optical or electrochemical registration of the signal, which opens up enormous prospects for the use of such biosensors in practice. Special examples of commercially available enzyme biosensors for OPC determining are provided.

Research on cholinesterases in the Soviet Union and Russia

This work presents the historical aspect of the study of cholinesterases and the effects of their inhibition by organophosphorus compounds, which were carried out in the USSR and Russia, from the 1930s–1940s to the present.

Enzyme-based nanocomplexes and their construction for detoxification of organophosphorus compounds

Organophosphorus compounds (OPC) pose a serious threat, as they can have a neurotoxic effect on the human body, even death. In this regard, the main challenge of our times is the search for effective ways of degradation of OPC. In this case, preference is given to biological methods of OPC detoxification, which do not require the use of harsh chemical methods of degradation and are suitable for in vivo use. One of such methods is the use of biocatalysts — enzymes capable of hydrolyzing OPC. To stabilize the activity of enzymes, as well as leveling a possible immune response from the body when used in vivo, various modification methods are used, such as nanocapsulation, the formation of enzymepolyelectrolyte complexes, immobilization of the enzyme on various functionalized carriers, etc. The chapter contains the information on examples of such biocatalysts, discussion of their advantages and disadvantages.

Immobilized enzymatic biocatalysts and their application for destruction of organophosphorus compounds in water, soil and air systems

Undecomposed residues of organophosphorus compounds (OPC) after treatment with pesticides of plants or animals often fall into natural objects (water, soil and air). Modern approaches to the immobilization of enzymes allowing obtaining of stable biological products are described, as well as the possible using of immobilized enzymes for the decomposition of different OPC: paraoxone, methyl and ethyl paraoxone, coumaphos, parathion, methyl and ethyl parathion, chlorpyrifos, soman, VX, methylphosphonic acid and its isobutyl and diisobutyl ethers, diisopropyl fluorophosphate.

Microbial biocatalysts in the biocatalytic processes of the degradation of organophosphorus compounds

A number of single microorganisms and microbial consortia, carrying out the destruction of organophosphorus compounds (OPC) by using their own enzymatic systems, were identified and investigated. They can use OPC as a source of nutrients such as carbon and/or phosphorus. The rate of OPC decomposition varies and depends mainly on environmental conditions (pH, temperature, availability of oxigen, etc.) and composition of native microbial community. The development of genetically modified organisms capable of degrading OPC, the immobilization of cells and the creation of artificial consortia are approaches that increase the efficiency of biodegradation of OPC.

Main steps of developing chemical organophosphorus agents abroad

Organophosphorus compounds (OPC) occupy a special place among chemical warfare agents (CWA). High level of toxicity, a wide range of physicochemical properties, polyapplication of action already in the 1930s attracted the close attention of foreign military experts. In 1936, the German chemist Gerhard Schrader for the first time synthesized O-ethyl-dimethylamidocyanophosphate, known today as a herd. By the beginning of the Second World War, the staff of his laboratory synthesized over two thousand new OPC. Some of these compounds were selected for further study as CW agents and subsequently were adopted as weapons by the German army. In 1938 the same Gerhard Schrader have synthesized the organophosphorus compound, closed to tabun, but more toxic: O-isopropyl methyl fluorophosphate, called sarin. In 1944 the German chemist, the 1938 Nobel laureate in chemistry Richard Kuhn synthesized soman and revealed the damaging effect of organophosphorus CWA’s. In 1941 the British chemist Bernard Saunders synthesized diisopropyl fluorophosphate. During World War II the industrial production of organophosphorus CWA’s was organized in Germany, Great Britain and in the USA. Germany produced tabun, sarin and soman, the western allies: diisopropyl fluorophosphate. Till the end of World War II the leadership in the sphere of the development of nerve agents belonged to Nazi Germany. After the end of the war the German scientists, many of whom were devoted Nazis, continued their work under the auspices of military departments of the USA and Great Britain. Subsequently phosphorylated thiocholine esters: V-series substances (VG, VM, VR, VX, EA 3148, EA3317 agents etc.) were synthesized with their participation. The wide range of organophosphorus compounds was tested on volunteers in Porton Down (Great Britain) and in the Edgewood arsenal (USA). But after the synthesis of V-series agents the work on organophosphorus CWA’s did not stop. In recent years there appeared the tendency of the transformation of real threats connected with the chemical weapons use, to propaganda sphere. In recent years, there has been a tendency toward the transformation of real threats associated with the use of chemical weapons into provocation and an advocacy field, but this does not mean that the search for new CWA in Western countries has been stopped.

Immunochemical methods for detection of organophosphorus compounds

Organophosphorus compounds (OP) are found in environmental objects and food products. Due to their high toxicity and inhibition of cholinesterase activity, it is necessary to control residual amounts of OP. The most common methods for determining OP are gas and liquid chromatography with various detection methods. However, chromatographic analysis is lengthy, requires complex sample preparation and expensive equipment, which limits its use for screening a large number of samples and continuous monitoring of the content of OP. To detect the OP, it is necessary to use High Throughput Screening methods, using simple, fast and inexpensive analysis methods. Currently, immunochemical methods are increasingly used to determine OP. These methods are based on the recognition of the analyte (antigen) by specific receptors (antibodies) with the formation of the antigen-antibody complex and the measurement of the analytical signal generated by the immunochemical test system in response to complex formation, which leads to high sensitivity and specificity of the analysis.

Bioanalytical systems based on cholinesterases for detection of organophosphates

Various types of electrochemical sensors based on the inhibition of butyrylcholinesterase (BChE) have been presented for the analysis of organophosphates (OPC). A special design of thick film sensors and electrochemical detector for cholinesterases assay and their inhibitors in aqueous samples has been developed. For this assay, thiol sensitive sensors based on screen printed graphite electrode modified with nanoparticles of manganese dioxide were used. High sensitivity of manganese dioxide modified thick film sensors towards thiocholine and therefore low detection limit of BChE (1 pM) enabled their use for subnanomolar detection of an organophosphate pesticide diazinon, and other irreversible inhibitors of BChE. This work also presents modern innovative approach for the analysis of BChE by Raman spectroscopy. New SERS-substrates based on silver paste for sensitive quantification of BChE activity were obtained, characterized and applied to thiocholine detection, with LOD (TCh) being 260 nM. Real samples of human plasma were analyzed; a good correlation between spectrophotometric detection and Raman detection was shown. The developed technique is inexpensive and easy-to-use and has promising potential for analysis of OPC.