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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Microbiotechnology
Volume 15 - 2024 | doi: 10.3389/fmicb.2024.1514950

An environmental isolate of Pseudomonas, 20EI1, reduces Aspergillus flavus growth in an iron-dependent manner and alters secondary metabolism

Provisionally accepted
Elizabeth M Wyman Elizabeth M Wyman 1William Scott Grayburn William Scott Grayburn 2Matthew K Gilbert Matthew K Gilbert 1Matthew Lebar Matthew Lebar 1Jessica M Lohmar Jessica M Lohmar 1Jeffrey W Cary Jeffrey W Cary 1Thomas J C Sauters Thomas J C Sauters 3Antonis Rokas Antonis Rokas 3Ana M. Calvo Ana M. Calvo 2*
  • 1 United State Department of Agriculture (USDA), New Orleans, Louisiana, United States
  • 2 Northern Illinois University, DeKalb, United States
  • 3 Vanderbilt University, Nashville, Tennessee, United States

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

    Aspergillus flavus is an opportunistic pathogenic fungus that infects oilseed crops worldwide. When colonizing plants, it produces mycotoxins, including carcinogenic compounds such as aflatoxins. Mycotoxin contamination results in an important economic and health impact. The design of new strategies to control A. flavus colonization and mycotoxin contamination is paramount. In this study, we identified a promising new isolate of Pseudomonas spp., 20EI1, and observed that it is able to reduce the growth of A. flavus. Furthermore, we determined that this growth inhibition is irondependent. To further elucidate the nature of this bacterial-fungus interaction, we performed chemical and transcriptomics analyses. In the present study, Pseudomonas 20EI1 reduced or blocked the production of aflatoxin, as well as cyclopiazonic acid and kojic acid. Expression of iron-related genes was altered in the presence of the bacteria and genes involved in the production of aflatoxin were down-regulated. Iron supplementation partially reestablished their expression. Expression of other secondary metabolite (SM) genes was also reduced by the bacteria, including genes of clusters involved in cyclopiazonic acid, kojic acid and imizoquin biosynthesis, while genes of the cluster corresponding to aspergillicin, a siderophore, were upregulated. Interestingly, the global SM regulatory gene mtfA was significantly upregulated by 20EI1, which could have contributed to the observed alterations in SM. Our results suggest that Pseudomonas 20EI1 is a promising biocontrol against A. flavus, and provide further insight into this bacterial-fungal interaction affecting the expression of numerous genes, among them those involved in SM.

    Keywords: Aspergillus flavus, Pseudomonas, biocontrol, Transcriptome, secondary metabolism, aflatoxin, Iron, MtFA

    Received: 21 Oct 2024; Accepted: 26 Dec 2024.

    Copyright: © 2024 Wyman, Grayburn, Gilbert, Lebar, Lohmar, Cary, Sauters, Rokas and Calvo. 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: Ana M. Calvo, Northern Illinois University, DeKalb, United States

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