IMPROVEMENT OF THE MODEL OF TRANSFORMATION OF NITROGEN-CONTAINING SUBSTANCES IN A WATER BODY FOR THE SOLUTION OF NATURE MANAGEMENT PROBLEM

In the article is considered the one of aspects of nature management regulation – an account of successive transformation of pollutants in a water body, that come with waste waters of industrial, municipal and agricultural enterprises. It is necessary at the determination of permissible pollutants emission with waste waters that doesn’t allow the excess of the permissible level of substances content in the control point of a water body. This problem is considered on the example of successive transformation of nitrogen-containing substances in the following transformation order: organic nitrogen – ammonium nitrogen - nitrite nitrogen – nitrate nitrogen. The topicality of the modeling of nitrogen-containing substances is conditioned by their role in water ecosystems functioning. At that existent mathematical models of natural water quality formation that take into account substances transformation contain the large number of unknown parameters. So, the use of such models in problems of nature management regulation is problematic, because identification of model parameters is a separate very complicated scientific problem. And existent models with relatively small number of parameters don’t take into account the natural pollution of water bodies, caused by the life activity of organisms; substance losses in the transformational chain are also possible. The improved matrix mathematical model of nitrogen-containing substances transformation without the indicated shortcomings is offered.

Chloromethylmuconolactones as Critical Metabolites in the Degradation of Chloromethylcatechols: Recalcitrance of 2-Chlorotoluene

ABSTRACT To elucidate possible reasons for the recalcitrance of 2-chlorotoluene, the metabolism of chloromethylcatechols, formed after dioxygenation and dehydrogenation by Ralstonia sp. strain PS12 tetrachlorobenzene dioxygenase and chlorobenzene dihydrodiol dehydrogenase, was monitored using chlorocatechol dioxygenases and chloromuconate cycloisomerases partly purified from Ralstonia sp. strain PS12 and Wautersia eutropha JMP134. Two chloromethylcatechols, 3-chloro-4-methylcatechol and 4-chloro-3-methylcatechol, were formed from 2-chlorotoluene. 3-Chloro-4-methylcatechol was transformed into 5-chloro-4-methylmuconolactone and 2-chloro-3-methylmuconolactone. For mechanistic reasons neither of these cycloisomerization products can be dehalogenated by chloromuconate cycloisomerases, with the result that 3-chloro-4-methylcatechol cannot be mineralized by reaction sequences related to catechol ortho-cleavage pathways known thus far. 4-Chloro-3-methylcatechol is only poorly dehalogenated during enzymatic processing due to the kinetic properties of the chloromuconate cycloisomerases. Thus, degradation of 2-chlorotoluene via a dioxygenolytic pathway is evidently problematic. In contrast, 5-chloro-3-methylcatechol, the major dioxygenation product formed from 3-chlorotoluene, is subject to quantitative dehalogenation after successive transformation by chlorocatechol 1,2-dioxygenase and chloromuconate cycloisomerase, resulting in the formation of 2-methyldienelactone. 3-Chloro-5-methylcatechol is transformed to 2-chloro-4-methylmuconolactone.

Biotransformation of 2,4,6-Trinitrotoluene withPhanerochaete chrysosporium in Agitated Cultures at pH 4.5

ABSTRACT The biotransformation of 2,4,6-trinitrotoluene (TNT) (175 μM) byPhanerochaete chrysosporium with molasses and citric acid at pH 4.5 was studied. In less than 2 weeks, TNT disappeared completely, but mineralization (liberated14CO2) did not exceed 1%. A time study revealed the presence of several intermediates, marked by the initial formation of two monohydroxylaminodinitrotoluenes (2- and 4-HADNT) followed by their successive transformation to several other products, including monoaminodinitrotoluenes (ADNT). A group of nine acylated intermediates were also detected. They included 2-N-acetylamido-4,6-dinitrotoluene and its pisomer, 2-formylamido-4,6-dinitrotoluene and its p isomer (as acylated ADNT), 4-N-acetylamino-2-amino-6-nitrotoluene and 4-N-formylamido-2-amino-6-nitrotoluene (as acetylated DANT), 4-N-acetylhydroxy-2,6-dinitrotoluene and 4-N-acetoxy-2,6-dinitrotoluene (as acetylated HADNT), and finally 4-N-acetylamido-2-hydroxylamino-6-nitrotoluene. Furthermore, a fraction of HADNTs were found to rearrange to their corresponding phenolamines (Bamberger rearrangement), while another group dimerized to azoxytoluenes which in turn transformed to azo compounds and eventually to the corresponding hydrazo derivatives. After 30 days, all of these metabolites, except traces of 4-ADNT and the hydrazo derivatives, disappeared, but mineralization did not exceed 10% even after the incubation period was increased to 120 days. The biotransformation of TNT was accompanied by the appearance of manganese peroxidase (MnP) and lignin-dependent peroxidase (LiP) activities. MnP activity was observed almost immediately after TNT disappearance, which was the period marked by the appearance of the initial metabolites (HADNT and ADNT), whereas the LiP activity was observed after 8 days of incubation, corresponding to the appearance of the acyl derivatives. Both MnP and LiP activities reached their maximum levels (100 and 10 U/liter, respectively) within 10 to 15 days after inoculation.