[Formation of a methylotrophic denitrifying biocenosis in a system of sewage treatment for nitrates]

A methylotrophic denitrifying bioenosis composed of hyphomicrobes and paracocci was isolated from the active ooze in a system of sewage purification from nitrates. The morphological and physiological characteristics of the isolated Hyphomicrobium sp. Z-115 and Paracoccus denitrificans Z-100 and Z-121 strains differed from those of the type strains, which made it difficult to identify them and to isolate them as a pure culture. This should be taken into account while determining the agents operating in such purification systems. The rate of growth, the rate of nitrate reduction and the activity of enzymes involved in methanol assimilation are higher in the anabolic syntrophic bicenosis than in its components in pure culture. A combined culture composed of the collection Hyphomicrobium and Paracoccus strains was neither effective nor stable under the conditions of anaerobic growth with nitrate and methanol. Therefore, the natural biocenosis af the purification system cannot be substituted by an artificial one composed of the collection cultures.