Detoxication of Solutions of Organic Oxidants by Humic Substances: Bioluminescence Monitoring

Abstract

The search for the methods of detoxication is a key direction in modern ecology and biotechnology. One of the possible ways of detoxication of pollutants may be the use of humic substances-the products of natural transformation of various organic substances. Today, more and more data on the ability of humic substances to decrease the detrimental influence of toxicants appear [1,2]. Earlier, the effect of detoxication was studied using classic test systems, such as fish, algae, crustaceans, and plants [2][3][4][5][6].However, despite the long-term experience of studying the properties of humic substances, the question on the mechanism of the detoxicating effect of humic substances remains open. It was assumed that the detoxicating properties of humic substances are determined by their ability to reduce oxidants. The presence in humic substances of phenolic groups and fragments carrying unpaired electrons allows to assume the possibility of transition (in particular, bivalent mercury) into reduced and, respectively, less toxic forms upon interaction with humic substances [7,8]. It was also assumed that toxicants are bond by humic substances, which prevents penetration of such large aggregates into cells [9].To study the mechanisms of detoxication of toxicants by humic substances in detail, simple test systems (such as luminous bacteria) are especially promising. They have great advantages over the biotests that were used earlier due to high rate of analysis, sensitivity, simplicity, and possibility of instrumental recording of toxicity.This study is devoted to investigation of the mechanism of detoxication of solutions of organic oxidants using humic substances. Quinones-the products of oxidation of the very widely spread organic pollutants, phenols, were chosen as model organic substances. MATERIALS AND METHODSIn this study, we used a series of quinones with different redox characteristics: 1,4-benzoquinone, tetrafluoro-1,4-benzoquinone, methyl-1,4-benzoquinone, tetramethyl-1,4-benzoquinone, and 1,4-naphtoquinone.The toxicity of quinones was assessed using the bioluminescence biotest Microbiosensor 677F [10], which is based on lyophilized luminous bacteria Photobacterium phosphoreum and produced at the Institute of Biophysics, Siberian Division, Russian Academy of Sciences (Krasnoyarsk).The preparation Gumat-80 (OOO Gumat, Irkutsk) was used as a source of humic substances. The concentrations of humic substances inhibiting bioluminescence most by 20% were selected.Measurements were performed with a BLM-8802 bioluminometer (design office Nauka, Krasnoyarks) [11]. The bioluminescence intensity in the control ( I 0 ) was compared with the bioluminescence intensity recorded in the presence of quinones ( I q ) at a concentration C q . The toxicity of quinone solutions was expressed as I q / I 0 . We used the concentrations of quinone at which I q / I 0 = 0.3-0.5.The degree of detoxication of quinone solutions with humic substances was characterized using the detoxication coefficient K = I qh / I q , where I qh is the ma...

Pollutant toxicity and detoxification by humic substances: mechanisms and quantitative assessment via luminescent biomonitoring

“…Bioluminescent assays were applied for the first time in 2005 to monitor changes in the toxicity of pollutant solutions exposed to HS (Fedorova et al , 2005. The HS concentration ranges applicable for the bioluminescent assays, bacteria-based and enzyme-based, were determined there.…”

“…Detoxifying ability of HS in solutions of quinones of different redox potentials was studied in Fedorova et al (2007Fedorova et al ( , 2005. The bioluminescent assays (luminous bacterial strain Photobacterium phosphoreum and NADH:FMN-oxidoreductase-luciferase enzyme system isolated from these bacteria) were applied there for the first time to monitor changes in the toxicity of quinones exposed to HS.…”

Fluorescence and bioluminescence analysis of sequential UV‐biological degradation of p‐cresol in water

“…Future work will focus on identifying the photoand metabolism products formed and evaluating their toxicity and biodegradability. (2,4,5,6,7,9,11,13) and presence (3,8,10,12,14) of humic acids, without pre-irradiation (2,3,7,8) and under irradiation (4, 9, 10, mercury lamp; 5, 11, 12 , 308 nm; 6, 13, 14, 222 nm), and after fungal degradation (7)(8)(9)(10)(11)(12)(13)(14); the subsequent bio-UV degradation of p-cresol (15).…”

“…Bioluminescence measurements were performed using an Angstrem chemiluminometer (Design Office Real, Novosibirsk, Russia), using the bioluminescence assay, which is based on lyophilized luminous bacteria (Photobacterium phosphoreum) that are produced at the Institute of Biophysics (Krasnoyarsk, Russia) (14,15). The bioluminescence intensity in the control (I 0 ) was compared with the bioluminescence intensity recorded in the presence of p-cresol (I).…”