Resistance of Rhodococcus collection strains to the effects of ecotoxicant - ethoxylated nonylphenol

Ethoxylated nonylphenol (ENP), a widely used surfactant, is one of the most common xenoestrogens, hormone-like xenobiotics, the accumulation of which in the environment has a negative impact on the endocrine system of animals and humans, thereby increasing the level of environmental risk. Natural processes of ENP biodegradation are hindered due to its high toxicity to soil and aquatic microorganisms, which requires the selection of resistant strains-biodegraders of this ecopolutant. The screening of 50 strains of actinobacteria of the genus Rhodococcus from the Regional Specialised Collection of Alkanotrophic Microorganisms (acronym IEGM, http://www.iegmcol.ru) on resistance to ENP and the effect of xenobiotics on the dynamics of the formation of rhodococcal biofilms was studied. The strains R. ruber IEGM 615, 1263, and R. rhodochrous IEGM 655, isolated from oil-polluted ecosystems, resistant to high (MIC> 125 g/l) concentrations of ENP, were selected. It has been shown that long-term (up to 72 h) cultivation of R. ruber IEGM 71 biofilms in the presence of 15 g/l ENP contributed to an increase in the adhesive activity of cells and the synthesis of an exopolymer matrix, which plays a major role in protecting bacteria from the toxic effects of ENP. The obtained data reveal the potential of rhodococci for detoxification of xenoestrogens from the group of alkylated phenols, what can be used in the development of biotechnological methods of environmental purification from these ecotoxicants.