Effect of Sodium Lauryl Sulfate on Sorption of Cells of the Electrogenic Bacterium Strain Micrococcus luteus on Carbon Cloth.

Results of a study into the effect of anionic surfactant sodium lauryl sulfate on the sorption of cells of the electrogenic bacteria strain Micrococcus luteus 1-I on the surface of carbon cloth used as electrodes in microbial fuel cell (MFC) technology are presented. Investigations using spectrophotometry, microscopy and microbiology revealed an increase in the degree of sorption of microbial cells on carbon cloth under the action of sodium lauryl sulfate at concentrations of 10 and 100 mg/l. The sorption of cells did not significantly differ from the control at a surfactant content of 200, 400 and 800 mg/l. It had no negative effect on bacterial growth in the concentration range from 10 to 800 mg/l. Due to the fairly high resistance of the electrogenic strain M. luteus 1-I to sodium lauryl sulfate, a widespread component of wastewater, it may be considered as a prospective bioagent for the treatment of domestic wastewater using MFC technology.

Electrochemical Characteristics of the Oxidation of Sulfur- and Iron-Containing Compounds by Acidophilic Microorganisms.

The electrochemical features of the interactions of sulfur- and iron-containing compounds (ferrous sulfate, elemental sulfur, pyrite tailings, cysteine, sodium thiosulfate) with a model acidophilic consortium, including the genera Leptospirillum, Sulfobacillus, Acidithiobacillus, Ferroplasma, and Acidiplasma, were studied. The method of cyclic voltammetry recorded redox processes at the electrode/solution interface in the presence of the studied sulfur- and iron-containing compounds. In general, the modeling consortium led to the intensification of these processes. The characteristics of the diffuse layer near the electrode/solution interface were studied using electrochemical impedance spectroscopy. The introduction of microorganisms and/or substrates into the supporting electrolyte led to a decrease in the slope and can be interpreted as evidence of their effect on the diffusion part of the double layer. Its contribution decreases in favor of ion transport. All this, in general, does not contradict the assumption of cell adsorption on the electrode surface. Confocal laser scanning microscopy confirmed this assumption and showed cell adhesion to the surface. The data obtained confirm the importance of bioelectrochemical processes of the studied group of microorganisms in biotechnological processes associated with the leaching of metals from sulfide ores.

Antioxidant activity of humic substances via bioluminescent monitoring in vitro.

This work considers antioxidant properties of natural detoxifying agents-humic substances (HS) in solutions of model inorganic and organic compounds of oxidative nature-complex salt K3[Fe(СN)6] and 1,4-benzoquinone. Bioluminescent system of coupled enzymatic reactions catalyzed by NAD(P)H: FMN-oxidoreductase and bacterial luciferase was used as a bioassay in vitro to monitor toxicity of the oxidizer solutions. Toxicities of general and oxidative types were evaluated using bioluminescent kinetic parameters-bioluminescence intensity and induction period, respectively. Antioxidant activity of HS was attributed to their ability to decrease both general and oxidative toxicities; the HS antioxidant efficiency was characterized with detoxification coefficients D GT and D OxT, respectively. Dependencies of D GT and D OxT on HS concentration and time of preliminary incubation of the oxidizers with HS were demonstrated. The optimal conditions for detoxification of the oxidizers were >20-min incubation time and 0.5 × 10(-4) to 2 × 10(-4) M of HS concentration. The present study promotes application of the enzymatic luminescent bioassay to monitor toxicity of pollutants of oxidative nature in environmental and waste waters in remediation procedures.

Bioluminescence as a tool for studying detoxification processes in metal salt solutions involving humic substances.

The paper considers effects of humic substances (HS), as natural attenuators of toxicity, on solutions of model inorganic pollutants, metal salts - Pb(NO(3))(2), СоСl(2), CuSO(4), Eu(NO(3))(3), СrСl(3), and K(3)[Fe(СN)(6)]. Luminous bacteria Photobacterium phosphoreum and bioluminescent system of coupled enzymatic reactions were used as bioassays to monitor toxicity of salt solutions. The ability of HS to decrease or increase toxicity was demonstrated. Detoxifying concentrations of HS were determined; detoxification coefficients were calculated at different times of exposure of salt solutions to HS. To study the combined effects of HS and salts on bioluminescent assay systems, the rates of biochemical reactions and bacterial ultrastructure were analyzed. The detoxifying effects were explained by: (1) decrease of free metal content in water solutions under metal-HS binding; (2) increase of biochemical reaction rates in a bioluminescent assay system under HS effect; (3) enhancement of mucous layers on cell surface as a response to unfavorable impact of toxicants. Detoxifying mechanisms (2) and (3) reveal the active role of bioassay systems in detoxification processes.

Bioluminescent method in studying the complex effect of sewage components.

The inhibition of bacterial luminescence has been used in testing industrial enterprises sewage. The toxicity of the sewage is less than the total toxicity of separate components due to neutralization of quinone products of polyphenol oxidation in the reactions with the other phenol components of sewage. Toxicity increase is due to their influence on the cell membrane. Studies of cell ultrastructure confirm this fact. The studied mechanism of the complex effect allowed a more accurate forecast of the ecological situation during the discharge of phenol compounds and metals. It also showed the necessity of taking into account the complex effect of sewage components on contaminant discharge into water reservoirs.

[Bioluminescent method of assessing the toxicity of colored substances in waste waters from celluose sulfate manufacture]. / Bioliuminestsentnyi metod otsenki toksichnosti okrashennykh veshchestv stochnykh vod sul'fattselliuloznogo proizvodstva.

The aim of this work was to study the applicability of a bioluminescent technique for assaying the toxicity of solutions containing lignin sulfate and coloured compounds isolated from the sewage of the sulfate-cellulose industry after biological purification. Solutions of the studied compounds (pH 7.0) quenched the bioluminescence of the luminescent bacterium Beneckea harveyi in proportion to their colour index and their content of phenol hydroxyls. This biotest based on quenching the luminescence of bacteria under the action of a toxic agent is rapid and highly reproducible. Therefore, it can be used for assaying the toxicity of sulfate-cellulose industry sewage containing hardly oxidizible coloured compounds. The toxic action of sewage can be predicted basing in the found dependence between the colour index of solutions containing coloured compounds and the intensity of bacterial bioluminescence.

[Elimination of quinones from aqueous environments by phenols and the effect of their mixtures on the luminescence of Beneckea harveyi bacteria]. / Eliminirovanie khinonov iz vodnykh sred fenolami i vliianie ikh smesei na svechenie bakterii Beneckea harveyi.

In the mixture of hydroquinone with other phenols the content of quinones has been measured by potentiometrical and polarographical methods. The decrease of quinone content in the mixture in comparison with the pure solution has been noted. The toxicity of solution estimated according to extinction of luminescence of bacteria at adding other phenols decreases.

[Quenching of the luminescence of phosphorescent bacteria as a test for assessing the toxicity of the phenol components of sewage]. / Gashenie liuminestsentsii svetiashchikhsia bakterii kak test dlia otsenki toksichnosti fenol'nykh komponentov stokov.

The object of this work was to estimate whether the luminescence of luminescent bacteria could be used as a biological test for assessment of the toxicity of phenol compounds in sewage. The toxicity of phenol compounds for luminescent bacteria was compared in terms of three indices: the quenching of luminescence, the inhibition of dehydrogenase activity and the ability to grow. Among the three indices, the quenching of luminescence was characterized by the highest sensitivity and the most rapid response.

[Polarographic study of quinones formed during oxidation of caffeic and chlorogenic acids]. / Poliarograficheskoe izuchenie khinonov, obrazuiushchikhsia pri okislenii kofeinoi i khlorogenovoi kislot

Polarographic behaviour of a number of substituted ortho-benzenquinones was studied in weakly acidic, neutral and weakly caustic solutions (up to pH --9.0). Half-wave potential depends on the solution pH, indicating protonization of the carbonyl groups of the quinones. Protonization is probably stipulated by the hydroxonium ions. Protonization may take place not only under the action of water, but also under the effect of other acidic components, as indicated by the dependence of E1/2 on the undissociated acetic acid centrifugation. The condensation and polymerization reactions are characteristic for the ortho-quinones. A shift of the quinone potential indicates dimerization of the electrode products.