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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Extreme Microbiology
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1367490
This article is part of the Research Topic Exploring the Diversity, Ecological Significance, and Systematics of Uncultivated Prokaryotic Taxa View all 4 articles

MAGs-centric crack: How long have spore-positive Frankia and most Protofrankia microsymbionts remained recalcitrant to axenic growth?

Provisionally accepted
Maher Gtari Maher Gtari 1,2*Radhi Maaoui Radhi Maaoui 2Faten Ghodhbane-Gtari Faten Ghodhbane-Gtari 3Karim Ben Slama Karim Ben Slama 4Imed Sbissi Imed Sbissi 5
  • 1 Carthage University, Tunis, Tunisia
  • 2 National Institute of Applied Science and Technology, Tunis, Tunisia
  • 3 Higher Institute of Biotechnology of Sidi Thabet, University of Manouba, Sidi Thabet, Ariana, Tunisia
  • 4 Tunis El Manar University, Tunis, Tunisia
  • 5 Institut des Régions Arides, Medenine, Tunisia

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

    Nearly fifty years after the ground-breaking isolation of the primary Comptonia peregrina microsymbiont under axenic conditions, efforts to isolate a substantial number of Protofrankia and Frankia strains continue with enduring challenges and complexities. This study aimed to streamline genomic insights through comparative and predictive tools to extract traits crucial for isolating specific frankia in axenic conditions. Pangenome analysis unveiled significant genetic diversity, suggesting untapped potential for cultivation strategies. Shared metabolic strategies in cellular components, central metabolic pathways, and resource acquisition traits offered promising avenues for cultivation. Ecological trait extraction indicated that most uncultured strains exhibit no apparent barriers to axenic growth. Despite ongoing challenges, potential caveats, and errors that could bias predictive analyses, this study provides a nuanced perspective. It highlights potential breakthroughs and guides refined cultivation strategies for these yet-uncultured strains. We advocate for tailored media formulations enriched with simple carbon sources in aerobic environments, with atmospheric nitrogen optionally sufficient to minimize contamination risks. Temperature adjustments should align with strain preferences-28-29°C for Frankia and 32-35°C for Protofrankia-while maintaining an alkaline pH. Given potential extended incubation periods (predicted doubling times ranging from 3.26 to 9.60 days, possibly up to 21.98 days), patience and rigorous contamination monitoring are crucial for optimizing cultivation conditions.

    Keywords: Frankia, Protofrankia, obligate/facultative microsymbionts, Metagenome-assembled genomes, Ecological traits, axenic conditions

    Received: 08 Jan 2024; Accepted: 04 Jul 2024.

    Copyright: © 2024 Gtari, Maaoui, Ghodhbane-Gtari, Ben Slama and Sbissi. 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: Maher Gtari, Carthage University, Tunis, Tunisia

    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.