Microbial bioconversion of pollutants.

Microorganisms totally detoxicate xenobiotics of various chemical structures, which are serious and, in some cases, very hazardous pollutants. At present, the efforts of a number of researchers promoted the establishment in this country of a collection of microorganisms able to degrade volatile toxic pollutants--toluene, isomeric xylenes, styrene, alpha-methylstyrene, crotonaldehyde; widely distributed xenobiotics chlorobenzoic acids; isomeric aryldicarboxylic acids; and ecologically hazardous pollutants such as aromatic nitrocompounds. The active strains-destructors are mainly representatives of the genera Pseudomonas and Rhodococcus. Research into their physiological characteristics, key enzymes, pathways of xenobiotics degradation, genetic mechanisms determining the degradation of these foreign compounds, and behaviour of the strains in a real environment made it possible to develop the theoretical principles of using these microbial cultures to purify real industrial wastes and remediate polluted areas of soil and water. Improvement of the methods of immobilizing the active xenobiotics-degrading strains on cheap and efficient carriers made it possible to significantly intensify the cleanup process of industrial wastes and eliminate a number of problems during the development of the biotechnologies for industrial waste cleanup. Successfully operated at present are the biotechnologies of the local cleanup of waste waters of terephthalate production, microbial purification of industrial waste waters in nylon-66 production from hexamethylenediamine, purification of coke production wastes from phenols, waste waters of polyisocyanate production from aromatic amines, local purification of waste waters in synthetic rubber production from alpha-methylstyrene, acetaldehyde production wastes from crotonaldehyde and mercury. Microbial strains constructed by gene engineering methods for the cleanup of contaminated soils from dicofol and 3-chlorobenzoate were successfully applied (Golovleva et al. 1988).