Abstract
This study investigated the ability of rhodococci to biodegrade diclofenac (DCF), one of the polycyclic non-steroidal anti-inflammatory drugs (NSAIDs) most frequently detected in the environment. Rhodococcus ruber strain IEGM 346 capable of complete DCF biodegradation (50 µg/L) over 6 days was selected. It is distinguished by the ability to degrade DCF at high (50 mg/L) concentrations unlike other known biodegraders. The DCF decomposition process was accelerated by adding glucose and due to short-term cell adaptation to 5 µg/L DCF. The most typical responses to DCF exposure observed were the changed ζ-potential of bacterial cells; increased cell hydrophobicity and total cell lipid content; multi-cellular conglomerates formed; and the changed surface-to-volume ratio. The obtained findings are considered as mechanisms of rhodococcal adaptation and hence their increased resistance to toxic effects of this pharmaceutical pollutant. The proposed pathways of bacterial DCF metabolisation were described. The data confirming the C-N bond cleavage and aromatic ring opening in the DCF structure were obtained.
Highlights
In recent years, there is a growing interest to study the bioavilability and toxic effects of pharmaceutical pollutants on environmental microorganisms, which act as primary response systems and trigger the adaptive reactions
104 rhodococcal strains from the Regional Specialised Collection of Alkanotrophic Microorganisms (IEGM, WDCM 768, http://www.iegmcol.ru) were used. They belonged to 10 Rhodococcus species: R. cercidiphylli (1 strain), R. corynebacterioides (2 strains), R. erythropolis (41 strains), R. jostii (3 strains), R. koreensis (1 strain), R. pyridinivorans (2 strains), R. qingshengii (4 strains), R. rhodochrous (8 strains), R. ruber (41 strains), and R. wratislaviensis (1 strain)
Screening of 104 Rhodococcus strains from the IEGM collection resulted in selection of R. ruber IEGM 346 highly tolerant (MIC 200 mg/L) to DCF
Summary
There is a growing interest to study the bioavilability and toxic effects of pharmaceutical pollutants on environmental microorganisms, which act as primary response systems and trigger the adaptive reactions. The present study relies on the assumption that members of the genus Rhodococcus could play important ecological roles in biological detoxification and decontamination of soils and water They are stable inhabitants of polluted soils, water bodies, activated sludge, and wastewater; they have high oxidoreductase activities, abundant adaptation abilities for various toxic compounds, and high bioremediation potential for contaminated environments[1,2,3,4]. An “exploratory” analysis of their possible role as key biooxidizers of pharmaceuticals from the group of non-steroidal anti-inflammatory drugs (NSAIDs) ubiquitously detected in the environment was in focus[14,15] One of such anthropogenic micropollutants is diclofenac (DCF), a phenylacetic acid derived NSAID widely available and used in the world human medicine and veterinary. Safety and economic criteria, the biotechnological ways of converting these environmental stressors are recognized as priority approaches
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
