Discussion – Environmental Microbiology

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Biodegradation of imidazolium ionic liquids by activated sludge microorganisms

Abstract

Biological properties of ionic liquids (ILs) have been usually tested with the help of standard biodegradation or ecotoxicity tests. So far, several articles on the identification of intermediate metabolites of microbiological decay of ILs have been published. Simultaneously, the number of novel ILs with unrecognized characteristics regarding biodegradability and effect on organisms and environment is still increasing. In this work, seven imidazolium ionic liquids of different chemical structure were studied. Three of them are 1-alkyl-3-methyl-imidazolium bromides, while the other four are tetra- or completely substituted imidazolium iodides. This study focused on the identification of intermediate metabolites of the aforementioned ionic liquids subjected to biodegradation in a laboratory activated sludge system. Both fully substituted ionic liquids and 1-ethyl-3-methyl-imidazolium bromide were barely biodegradable. In the case of two of them, no biotransformation products were detected. The elongation of the alkyl side chain made the IL more susceptible for microbiological decomposition. 1-Decyl-3-methyl-imidazolium bromide was biotransformed most easily. Its primary biodegradation up to 100 % could be achieved. Nevertheless, the cleavage of the imidazolium ring has not been observed.

I thought that this paper would be fun to examine since the methods of wastewater treatment is such an important topic to society.

Liwarska-Bizukojc E, Maton C, Stevens CV. Biodegradation of imidazolium ionic liquids by activated sludge microorganisms. Biodegradation. 2015;26(6):453-463. doi:10.1007/s10532-015-9747-0.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4725721/

JaÅ‚owiecki, Åukasz et al. “Microbial Community Profiles in Wastewaters from Onsite Wastewater Treatment Systems Technology.’ Ed. Andrew C Singer. PLoS ONE 11.1 (2016): e0147725. PMC. Web. 15 Feb. 2018.

Summary

The aim of the study was to determine the potential of community-level physiological profiles (CLPPs) methodology as an assay for characterization of the metabolic diversity of wastewater samples and to link the metabolic diversity patterns to efficiency of select onsite biological wastewater facilities. Metabolic fingerprints obtained from the selected samples were used to understand functional diversity implied by the carbon substrate shifts. Three different biological facilities of onsite wastewater treatment were evaluated: fixed bed reactor (technology A), trickling filter/biofilter system (technology B), and aerated filter system (the fluidized bed reactor, technology C). High similarities of the microbial community functional structures were found among the samples from the three onsite wastewater treatment plants (WWTPs), as shown by the diversity indices. Principal components analysis (PCA) showed that the diversity and CLPPs of microbial communities depended on the working efficiency of the wastewater treatment technologies. This study provided an overall picture of microbial community functional structures of investigated samples in WWTPs and discerned the linkages between microbial communities and technologies of onsite WWTPs used. The results obtained confirmed that metabolic profiles could be used to monitor treatment processes as valuable biological indicators of onsite wastewater treatment technologies efficiency. This is the first step toward understanding relations of technology types with microbial community patterns in raw and treated wastewaters.

I chose this paper because it gives a good insight on the diversity of microbes that are examined during wastewater treatment and it also elaborates on how exactly they were able to determine what microorganisms were found during the shifts in the substrate.

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