Skip to main content

ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Extreme Microbiology
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1468929
This article is part of the Research Topic Microbial Ecology and Biotechnological Potential of Alkaline Environments View all 3 articles

Quantitative proteomics reveals oxygen-induced adaptations in Caldalkalibacillus thermarum TA2.A1 microaerobic chemostat cultures

Provisionally accepted
Samuel De Jong Samuel De Jong Martijn Wissink Martijn Wissink Kadir Yildirim Kadir Yildirim Martin Pabst Martin Pabst Mark van Loosdrecht Mark van Loosdrecht Duncan G. McMillan Duncan G. McMillan *
  • Delft University of Technology, Delft, Netherlands

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

    The thermoalkaliphile Caldalkalibacillus thermarum possesses a highly branched respiratory chain.These primarily facilitate growth at a wide range of dissolved oxygen levels. The aim of this study was to investigate the regulation of C. thermarum respiratory chain. C. thermarum was cultivated in chemostat bioreactors with a range of oxygen levels (0.25% O2 -4.2% O2). Proteomic analysis unexpectedly showed both the type I and the type II NADH dehydrogenase present is constitutive.The two terminal oxidases detected were the cytochrome c:oxygen aa3 oxidase, whose abundance was highest at 4.2% O2. The cytochrome c:oxygen ba3 oxidase was more abundant at most other O2 levels, but its abundance started to decline below 0.42% O2. We expected this would result in emergence of the cytochrome c:oxygen bb3 complex or the menaquinol:oxygen bd complex, the other two terminal oxidases of C. thermarum; but neither was detected. Furthermore, the sodium-proton antiporter complex Mrp was downregulated under the lower oxygen levels. Normally, in alkaliphiles, this enzyme is considered crucial for sodium homeostasis. We propose that the existence of a sodium:acetate exporter decreases the requirement for Mrp under strong oxygen limitation.

    Keywords: chemostat, regulation, adaptation, alkaliphile, Microaerobic, Respiration

    Received: 22 Jul 2024; Accepted: 09 Sep 2024.

    Copyright: © 2024 De Jong, Wissink, Yildirim, Pabst, van Loosdrecht and McMillan. 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: Duncan G. McMillan, Delft University of Technology, Delft, Netherlands

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.