Adaptive mechanism of the marine bacterium Pseudomonas sihuiensis-BFB-6S towards pCO2 variation: insights into synthesis of extracellular polymeric substances and physiochemical modulation

Highlights

• Optimal biofilm modulation can provide the adaptive response of bacteria.
• Potential characterization of EPS explored by microscopic and spectroscopic annotation.
• Modulation of EPS is a hallmark of the protection barrier.
• High concentration of pCO₂ can trigger protein-less EPS release.

Abstract

Marine bacteria can adapt to various extreme environments by the production of extracellular polymeric substances (EPS). Throughout this investigation, impact of variable pCO₂ levels on the metabolic activity and physiochemical modulation in EPS matrix of marine bacterium Pseudomonas sihuiensis – BFB-6S was evaluated using a fluorescence microscope, excitation-emission matrix (EEM), 2D-Fourier transform infrared correlation spectroscopy (2D-ATR-FTIR-COS), FT-NMR and TGA-DSC. From the results at higher pCO₂ levels, there was a substantial reduction in EPS production by 58–62.8 % (DW). In addition to the biochemical composition of EPS, reduction in carbohydrates (8.7–47.6 %), protein (7.1–91.5 %), and lipids (16.9–68.6 %) content were observed at higher pCO₂ levels. Functional discrepancies of fluorophores (tyrosine and tryptophan-like) in EPS, speckled differently in response to variable pCO₂. The 2D-ATR-FTIR-COS analysis revealed functional amides (CN, CC, CO bending, -NH bending in amines) of EPS were preferentially altered, which led to the domination of polysaccharides relevant functional groups at higher pCO₂. ¹H NMR analysis of EPS confirmed the absence of chemical signals from H-C-COOH of proteins, α, β anomeric protons, and acetyl group relevant region at higher pCO₂ levels. These findings can contribute new insights into the influence of pCO₂ on the adaptation of marine microbes in future ocean acidification scenarios.

Chakraborty S., Paidi M. K., Dhinakarasamy I., Sivakumar M., Clements C., Thirumurugan N. K. & Sivakumar L., 2024. Adaptive mechanism of the marine bacterium Pseudomonas sihuiensis-BFB-6S towards pCO2 variation: insights into synthesis of extracellular polymeric substances and physiochemical modulation. International Journal of Biological Macromolecules 261(2): 129860. doi: 10.1016/j.ijbiomac.2024.129860. Article (subscription required).

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