Spatial metabolic fingerprinting using FT-IR spectroscopy: investigating abiotic stresses on Micrasterias hardyi

Abstract

The release of active pharmaceutical ingredients (APIs) into the environment is an ecologically important topic for study because, whilst APIs have been designed to have a wide range of biological properties for the target of interest (usually in man), little information on potential ecological risks is currently available regarding their effects on the organisms that inhabit the environment. In this study, the algae Micrasterias hardyi was exposed to propranolol, metoprolol (beta-adrenergic receptor agonist drugs) and mefenamic acid (a non steroidal anti-inflammatory drug), at concentrations ranging between 0.002-0.2 mM. Initial studies showed that Fourier transform infrared (FT-IR) spectroscopy on algal homogenates illustrated that all three APIs had a quantitative effect on the metabolism of the organisms and it was possible to estimate the level of API exposure from the FT-IR metabolic fingerprints using partial least squares (PLS) regression. From the inspection of the PLS loadings matrices it was possible to elucidate that all drugs caused effects on protein and lipid levels. Most strikingly propranolol had significant effects on the lipid components of the cell. These were dramatically reduced possibly as a consequence of loss of membrane integrity. In order to investigate this further, FT-IR microspectroscopy was used to generate detailed metabolic fingerprinting maps. These chemical maps revealed that all the drugs had a dramatic effect on the distribution of various chemical species throughout the algae, and that all drugs had an affect on protein and lipid levels. In particular, as noted in the PLS analyses for propranolol treated cells, the lipid complement found in the lipid storage areas in the processes of M. hardyi was greatly reduced. This illustrates the power of spatial metabolic fingerprinting for investigating abiotic stresses on complex biological species.

Combining Raman and FT-IR Spectroscopy with Quantitative Isotopic Labeling for Differentiation of E. coli Cells at Community and Single Cell Levels

“…N-H bending of peptides and proteins45 . Details of the affected FT-IR bands and their corresponding assignments are provided inTable S2.…”

Phenotypic Characterization of Shewanella oneidensis MR-1 under Aerobic and Anaerobic Growth Conditions by Using Fourier Transform Infrared Spectroscopy and High-Performance Liquid Chromatography Analyses

“…For instance, FT-IR spectroscopy has proved sensitive enough for analysis of the chemical composition of a single strain of Escherichia coli after exposure to ionic liquids (6), for functional genomics screening (22), for measuring abiotic perturbations in algae (39), and for characterization of microbial degradation pathways (16). We believe that this technique offers considerable potential for rapid differentiation of metabolic changes of bacteria responding to contrasting growth regimes in natural and engineered environments, although this remains to be demonstrated.…”

Monitoring the Effects of Chiral Pharmaceuticals on Aquatic Microorganisms by Metabolic Fingerprinting

“…Previous studies have suggested that ␤-blockers do not affect microbes due to the absence of the API receptors in these organisms (10,23). However, in another study conducted by our group we reported that (Ϯ)-propranolol significantly reduced the amount of lipid storage components of the alga Micrasterias hardyi 649/15 and caused a marked reduction in the cellular protein content (34). In addition, the findings obtained by metabolic fingerprinting suggested that the phenotype was altered during exposure to this API (34).…”

“…However, in another study conducted by our group we reported that (Ϯ)-propranolol significantly reduced the amount of lipid storage components of the alga Micrasterias hardyi 649/15 and caused a marked reduction in the cellular protein content (34). In addition, the findings obtained by metabolic fingerprinting suggested that the phenotype was altered during exposure to this API (34). To our knowledge, no further studies on the metabolic effects of propranolol in aquatic microorganisms have been carried out.…”