Microbial associations from 10 oxidizing lakes, situated in the region of the oil refinery Plama Ltd, were investigated. The general number of microorganisms for each taxonomic group was determined. The isolated oil-assimilating strains of bacteria, fungi and actinomycetes belonged mostly to the genera
Pseudomonas
,
Bacillus
,
Penicillium
, sections
Aureus
and
Cynereus
. The inhibiting effect of the oil products and the ability of the isolated microorganisms to assimilate oil were studied.