Session AES-P-408 - AES08 Sunday Biotransformations: Bioremediation, Biodegradation, Biofouling and Biocorrosion 

Molecular Characterization and Discrimination of Heavy Metal Acclimated (Acutely and Gradually) Environmental Species by FTIR Spectroscopy Coupled with Chemometrics

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 June 22, 2025, 10:00 AM - 4:00 PM Exhibit Hall
Authors
E. S. Kepenek1, A. Gozen2, M. Severcaan2, F. Severcan3;
1Istanbul Kent University, Istanbul, Turkey, 2Middle East Technical University, Ankara, Turkey, 3Altinbas University, Istanbul, Turkey
Disclosures
E.S.Kepenek: None. A.Gozen: n/a. M.Severcaan: n/a. F.Severcan: n/a.
Abstract
Cadmium and lead are two heavy metals that cause severe toxicity at very low concentrations and whose environmental concentrations need to be under control urgently. Resistant bacteria have increasingly been utilized in bioremediation. Furthermore, metal-acclimated bacteria are preferred for bioremediation as they produce more resistant strains, which is important since we need to select the most resistant bacteria for bioremediation [1,2]. In this study, we acclimated the environmental species (Brevundimonas sp., Gordonia sp., Microbacterium oxydans) acutely (A) and gradually (G) to the same final metal (Cd, Pb) concentrations that were 5-6 times higher than the MIC values to determine whether the nature of the acclimation and concentrations ​​of metal caused differences in the degree and profile of resistance [3]. To achieve this goal, we applied ATR-FTIR spectroscopy coupled with chemometrics (PCA, HCA, SIMCA). FTIR analysis revealed sharp differences between the acclimation groups (A, G) and the control (C) in the lipid, protein, and carbohydrate regions. These groups significantly differed from each other in membrane dynamics, including changes in the structure and composition. Furthermore, while a significant decrease in total protein concentrations was observed in all acclimation groups, notable differences were detected in their protein profile. Also, a remarkable increase in exopolymer production occurred in acclimated groups. Interestingly, bacteria under acute cadmium exposure produced a significantly higher amount of exopolymer than they did under gradual exposure. On the contrary, gradually acclimated strains produced significantly higher amounts of exopolymer than acutely acclimated ones under lead exposure [4]. A clear discrimination of bacterial groups, not seen in the other studies in the literature, was observed in all spectral regions in chemometrics (PCA, HCA, SIMCA), most probably caused by extended periods of acclimation and differences in the nature of acclimation (A, G), which created bacteria with a resistance degree/profile and molecular background [5]. Here, we have shown for the first time that there were significant differences in the molecular profiles of acutely and gradually heavy metal-acclimated bacteria using ATR-FTIR spectroscopy, a handy, reliable, and rapid technique, and chemometrics. The outputs of this study could be used to devise different genetic manipulation approaches needed to generate more resistant bacterial strains.