Microbiological landscape of oil-contaminated soil and its bioremediation by microorganisms

Abstract

The composition of microbial contaminants of soil samples contaminated with oil and oil products from oil depots of ports in southern Ukraine was investigated, and the possibility of their bioremediation by microorganisms present in the soil was determined. The microbiological landscape of the soil contaminated with oil and oil products was established, the quantitative and qualitative characteristics, group and dendrological composition of microorganisms were determined, and their potential ability to biodegrade petroleum hydrocarbons was determined. The degree of sanitary and ecological contamination of the samples was characterized by the number of the main groups of microorganisms - mesophilic aerobic and facultative anaerobic microorganisms (MAFAnM), molds, yeasts, as well as the dominance of MAFAnM by 3-5 orders among the studied groups of microorganisms. According to MAFANM, the number of thermophilic bacteria, titers of nitrifying bacteria, E. coli, Clostridium perfringens, bacteria of the genus Proteus, and the degree of oil contamination, the soil samples studied are characterized as contaminated and heavily contaminated. According to the study of morphological, tintorial, cultural, biochemical properties, 130 species were identified and 9 morphogroups of bacteria in oil-contaminated soil samples were determined. A dendrogram was constructed based on the set of studied properties of the isolated microorganisms. According to the results of the screening, the microorganisms isolated from contaminated soil samples are capable of biodegradation of long-chain alkanes of petroleum hydrocarbons. The identified groups of microorganisms can be arranged in the following sequence in order of increasing this indicator: Bacillus subtilis and Paenibacillus macerans ˂ Paenibacillus polymyxa ˂ Bacillus licheniformis ˂ Bacillus thuringiensis ˂ Bacillus megaterium ˂ Bacillus pumilis ˂ Bacillus cereus ˂ Paenibacillus circulans. Paenibacillus circulans and Bacillus cereus were identified as the most promising strains, biotransforming up to 48 percent of the total amount of hydrocarbons.