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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Extreme Microbiology
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1493843
This article is part of the Research Topic Industrial Application of Extreme Microbes: Harnessing the Power of Nature's Extremophiles View all articles

Deciphering supramolecular arrangements, micellization patterns and antimicrobial potential of bacterial rhamnolipids under extreme treatments of temperature and electrolyte

Provisionally accepted
Samia Sikandar Samia Sikandar 1Asif Jamal Asif Jamal 1*Afsheen Mansoor Afsheen Mansoor 1Dr. Muhammad I. Ali Dr. Muhammad I. Ali 1Michael Urynowicz Michael Urynowicz 2Zaixing Huang Zaixing Huang 3*
  • 1 Quaid-i-Azam University, Islamabad, Pakistan
  • 2 Department of Civil and Architectural Engineering, University of Wyoming, Laramie, Wyoming, United States
  • 3 China University of Mining and Technology, Xuzhou, Jiangsu Province, China

The final, formatted version of the article will be published soon.

    The micellization properties of rhamnolipids (RLs) in extreme electrolyte concentrations and temperatures have gained considerable attention due to their broad industrial applications. In this study, the aggregation behavior, specifically the micellization pattern (CMC) of RLs produced from a newly isolated thermophilic strain of Pseudomonas aeruginosa from a harsh environment of an oil field, was investigated by a spectrophotometric method at various temperatures (293 K-393 K) and electrolyte concentrations (NaCl: 2%-20%). The result indicated that the CMC values (0.267-0.140 mMdm -3 ) were both electrolyte-and temperature-dependent exhibiting a U-shaped trend as temperature and NaCl concentration increased. Variations in NaCl concentration and temperature also affected the standard Gibbs free energy (ΔG o mic), enthalpy (ΔH o mic), and entropy (ΔS o mic) of micellization. The molecule also showed stability at a broad range of temperatures, pH, and NaCl concentrations. Thin-layer chromatography (TLC) and Fourier-transform infrared (FTIR) analysis confirmed the similarity in composition between the crude extract and the commercial RL with Rf values of 0.72 for mono-rhamnolipids and 0.28 for di-rhamnolipids. FTIR analysis confirmed the chemical nature particularly key aliphatic functional groups present in the fatty acid tail of RLs and the -COC-bond in the structure of the rhamnose moiety. Additionally, LC-ESI-QTOF analysis confirmed corresponding ionic fragments of mono-and di-rhamnolipids congeners. Furthermore, the antimicrobial potential was determined against different human pathogens in the absence and presence of NaCl by measuring zones of inhibition. The result revealed enhanced inhibitory effects against Gram-positive pathogens (S. aureus, S. epidermidis and L. monocytogene), with zones of inhibition of 26, 30, and 20 mm in the presence of NaCl.These findings underline the role of NaCl in the micellization of RL molecules and highlight their importance in environmental applications, pharmaceuticals, and various life science sectors.

    Keywords: Critical micelle concentration, biosurfactant, Rhamnolipid, thermodynamic parameters, Micellization, Electrolytes

    Received: 09 Sep 2024; Accepted: 08 Oct 2024.

    Copyright: © 2024 Sikandar, Jamal, Mansoor, Ali, Urynowicz and Huang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Asif Jamal, Quaid-i-Azam University, Islamabad, Pakistan
    Zaixing Huang, China University of Mining and Technology, Xuzhou, 221116, Jiangsu Province, China

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