BIOTECHNOLOGICAL POTENTIAL OF NEW STRAINS OF HYDROCARBON-OXIDIZING BACTERIA

Abstract

The ingress of oil has a depressing effect on the soil biocenosis, which is enhanced in the presence of other pollutants (heavy metals, chlorides, herbicides), which ultimately leads to the withdrawal of significant land areas (including agricultural ones) from the target turnover. For the bioremediation of such areas, oil-degrading microorganisms are needed that are resistant to additional pollutants, as well as a set of useful properties that increase the efficiency of cleaning and restoring disturbed soils. In this work, three isolates were isolated that actively grew in a liquid medium containing oil. As a result of sequencing the nucleotide sequence of the 16S rRNA gene, it was reliably established that all strains belong to the species Acinetobacter calcoaceticus . The bacteria showed a high oil-oxidizing ability (89.7-97.0%), which was assessed by the degree of destruction of the aliphatic fraction, including in the presence of herbicides based on 2,4-dichlorophenoxyacetic acid (Octapon extra), imazethapyr (Tapir) and tribenuron-methyl ( Special forces) (degree of biodestruction 40.4-54.1%). Microorganisms used aromatic hydrocarbons (including polycyclic ones) as a carbon source. They demonstrated high cell surface hydrophobicity (78-85%) with respect to hexadecane and exhibited emulsifying activity of more than 50%. The bacteria were tolerant to the herbicides Tapir and Spetsnaz in amounts up to 1% volume (mass). The herbicide Octapon extra was more toxic to bacteria - the growth of all strains occurred at its concentration in the medium not higher than 0.5% volume. Microorganisms showed resistance to sodium chloride in an amount of 3.0-5.0% and lead ions (1.00-1.25 g/l). They produced the enzyme lipase and were capable of fixing atmospheric nitrogen and dissolving inorganic phosphate (including in the presence of oil or herbicides). The studied Acinetobacter spp. stimulated the growth of barley (aboveground and underground parts), especially the A. calcoaceticus strain P32 (elongation of shoots and roots by 15.3 and 49.5%, respectively). The data obtained indicate that all three strains have certain prospects for use in the purification of complexly contaminated soils.