Oil-Destructor Bacteria With Resistance to the Presence of Additional Pollutants

Abstract

Throughout the world, significant areas of agricultural land are polluted with hydrocarbons. Their microbiological purification is hampered by the presence of residual amounts of pesticides (herbicides, in particular), which inhibit the vital activity of oil-destructing bacteria. In addition, along with crude oil, heavy metals and salts (mainly chlorides) can enter arable soils, which, in turn, have a negative effect on microorganisms. Therefore, for the bioremediation of such territories, hydrocarbon-oxidizing bacteria resistant to the presence of additional pollutants should be used. In the present work, three isolates were identified that are capable of active growth in a liquid medium with oil. Using time-of-flight matrix-activated laser desorption-ionization (MALDI-TOF) mass spectrometry of the cellular protein fraction, sequencing of the nucleotide sequence of the 16S rRNA gene and phylogenetic analysis, the species of microorganisms belonging to the genus Acinetobacter was determined. The bacteria had a significant ability to biodegrade oil (71.8-74.1%), which was estimated from the degree of destruction of the aliphatic oil fraction by the gas chromatographic method after preliminary extraction with hexane. The resistance of microorganisms to the presence of herbicides, heavy metals, and sodium chloride was determined by their growth on meat-peptone agar with different concentrations of preparations, salts of these metals, or NaCl. The strains showed resistance to the presence in the medium of herbicides based on 2,4-D and imazethapyr at a concentration of 10.0 ml/l, sodium chloride in an amount of 5.0-6.0%, and lead ions (1.00-1.25 g/l). In addition, they produced lipase and were capable of fixing atmospheric nitrogen and dissolving inorganic phosphate. The last two properties are important for stimulating the growth and development of remedial plants. The obtained results indicate that all three strains have certain prospects of application for cleaning oil-contaminated agricultural soils and require further study of their biotechnological potential.