Response of Rhodococcus cerastii IEGM 1278 to toxic effects of ibuprofen

Abstract

The article expands our knowledge on the variety of biodegraders of ibuprofen, one of the most frequently detected non-steroidal anti-inflammatory drugs in the environment. We studied the dynamics of ibuprofen decomposition and its relationship with the physiological status of bacteria and with additional carbon and energy sources. The involvement of cytoplasmic enzymes in ibuprofen biodegradation was confirmed. Within the tested actinobacteria, Rhodococcus cerastii IEGM 1278 was capable of complete oxidation of 100 μg/L and 100 mg/L of ibuprofen in 30 h and 144 h, respectively, in the presence of an alternative carbon source (n-hexadecane). Besides, the presence of ibuprofen induced a transition of rhodococci from single- to multicellular lifeforms, a shift to more negative zeta potential values, and a decrease in the membrane permeability. The initial steps of ibuprofen biotransformation by R. cerastii IEGM 1278 involved the formation of hydroxylated and decarboxylated derivatives with higher phytotoxicity than the parent compound (ibuprofen). The data obtained indicate potential threats of this pharmaceutical pollutant and its metabolites to biota and natural ecosystems.

Cellular Modifications of Rhodococci Exposed to Separate and Combined Effects of Pharmaceutical Pollutants

“…On the seventh day of the experiment, a complete removal was observed only for meloxicam. Previously, we have shown the ability of rhodococci to completely biodegrade acetylsalicylic acid as the sole carbon and energy source and to co-metabolize diclofenac (with glucose), ketoprofen and ibuprofen (with n-hexadecane) [25][26][27][28]. Here, we confirmed for the first time the biodegradability of naproxen and meloxicam using Rhodococcus spp.…”

“…Interestingly, in the presence of meloxicam, no lag phase was observed for R. ruber IEGM 439 cells, while in the presence of naproxen and ibuprofen, the lag phases for all Rhodococcus strains tested were two and three days, respectively. A gradual decrease in CO 2 release in the presence of naproxen (on the third day) and ibuprofen (on the fifth day) may suggest the formation and accumulation of toxic metabolites during biodegradation [28]. In addition, the maximum CO 2 production was registered for meloxicam, exhibiting the highest biodegradability according to our data.…”

“…Respirometry analysis is one of the indicators of bacterial activity during biodegradation of complex organic substrates [26,28,34]. Our respirometry test data showed that the catalytic activity of rhodococci increased significantly (p < 0.05) in the presence of NSAIDs: the average values of CO 2 accumulation by cells exposed to pharmaceuticals were 1.4-1.9 times higher than those in the controls (Figure 1).…”

“…As effective biodegraders of ibuprofen, meloxicam, and naproxen, we used previously selected Rhodococcus strains with highly active oxygenases, namely R. cerastii IEGM 1278 [28,29], R. ruber IEGM 439, and R. rhodochrous IEGM 63 from the Regional Specialised Collection of Alkanotrophic Microorganisms (acronym IEGM, the large-scale research facilities (USU) # 73559, the core facilities (CKP) # 480868, the World Federation for Culture Collections (WFCC) # 285; http://www.iegmcol.ru/strains, accessed on 27 April 2022). The strains were selected considering their geography and source of isolation as well as for the well-known catalytic activities of rhodococci against complex organic compounds [30].…”

“…Earlier, we have first shown the ability of individual members of the genus Rhodococcus for complete biodegradation of analgesic and spasmolytic agents, including paracetamol [22], drotaverine [23,24], and acetylsalicylic acid [25], as well as highly toxic nonsteroidal antiinflammatory drugs (NSAIDs) diclofenac [26], ketoprofen [27], and ibuprofen [28].…”