The secretome of the environmental bacterium Pseudomonas protegens PBL3 has broad-spectrum antimicrobial activity against plant and human pathogenic bacteria

Sep 29, 2026

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Antimicrobials are widely used to manage bacterial diseases in humans, pets, livestock, and aquatic animals, but this extensive use has driven antimicrobial resistance (AMR), a growing global health threat. Antimicrobials to control plant bacterial diseases remain far more limited, endangering food security and highlighting a need for new antimicrobial compounds with novel modes of action. Pseudomonas protegens PBL3 secretome inhibits multiple plant and human pathogens, with growth inhibition spanning 25%–95% depending on the pathogen, supporting its potential for agriculture and clinical use.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages10

Reading Time25 min

AccessFree to download

Abstract

Importance

Keywords

Introduction and background

Antimicrobial resistance and limitations in agriculture

Natural microbial sources of antimicrobials

Prior evidence for P. protegens PBL3 secretome

| Open Peer Review | Bacteriology | Research Article The secretome of the environmental bacterium Pseudomonas protegens PBL3 has broad-spectrum antimicrobial activity against plant and human pathogenic bacteria Biwesh Ojha,1,2 Kiyara Grosz,3 Clemencia M. Rojas1,4 AUTHOR AFFILIATIONS See affiliation list on p. 8. ABSTRACT Antimicrobials are widely used to manage bacterial diseases in humans, pets, and livestock. Unfortunately, their extensive use has contributed to the emergence of antimicrobial resistance (AMR), a threat to global health. In contrast to the widespread antimicrobial use in medicine and veterinary, the use of antimicrobials to control bacterial diseases in plants is limited, posing a threat to global food security. These two threats highlight the urgent need to discover novel antimicrobial compounds with new modes of action. Previously, we demonstrated that the environmental bacterium Pseudomonas protegens PBL3 inhibits the growth of the plant pathogenic bacterium Burkholderia glumae, indicating that this strain produces and secretes potent antimicrobial compounds. In this study, we showed that the P. protegens PBL3 secretome also shows a broad spectrum of activity against plant pathogenic Burkholderia sp., as well asthe human pathogens Acinetobacter baumannii, Escherichia coli O157:H7, Listeria innocua, Enterococcus faecium, and Staphylococcus aureus, with levels of growth inhibition ranging from 25% to 95% depending on the specific pathogen. These results highlight the P. protegens PBL3 secretome as a promising source of natural antimicrobial compounds with potential applications in both agriculture and clinical settings. IMPORTANCE This work shows that the environmental bacterium called Pseudomonas protegens PBL3 produces and secretes molecules that have a broad spectrum of activity against pathogenic bacteria causing important diseases in plants and humans. The use of the collection of molecules that P. protegens PBL3 produces and secretes (secretome) instead of single molecules is likely to be more effective, as this collection of molecules is expected to be of diverse chemical structure and mode of action, which makes it less likely that pathogenic bacteria develop resistance to them. These findings highlight the potential of beneficial microbes as a sustainable source of broad and effective antimicrobials for both agriculture and medicine. KEYWORDS antimicrobials, plant pathogens, human pathogens, bacteria A ntimicrobials to control bacterial diseases have long been used to manage bacterial infections in humans, pets, livestock, and aquatic animals as therapeutic or prophylactic agents (1–4) . However, this widespread use of antimicrobials has significantly contributed to the emergence of antimicrobial resistance (AMR) (4) . The AMR threat is becoming a matter of global concern that has not been mitigated, as most of the recently approved antimicrobials are derivatives of previously known classes (5, 6), and bacteria quickly evolve mechanisms to render them ineffective. In contrast to the widespread use of antimicrobials in the medical and veterinary fields, the use of antimicrobials to combat bacterial diseases in crops has been limited, as effective antimicrobials for those pathogens have not been identified, have proven ineffective, or Editor Lindsey Price Burbank, USDA-ARS San Joaquin Valley Agricultural Sciences Center, Parlier, California, USA Peer Reviewer Liezel del Castillo Atole, Partido State University, Goa, Camarines Sur, Philippines Address correspondence to Clemencia M. Rojas, [crojas2@unl.edu](crojas2@unl.edu). authors declare conflict of interest have only been approved for agricultural use for a limited number of bacterial pathogens (7, 8) . Thus, both the threat of antimicrobial resistance in the medical and veterinary fields and the absence of effective antimicrobials in agriculture necessitate the discovery of new molecules with unique chemistries and modes of

FAQs

What is the main focus of the study?

The study investigates whether the secretome (molecules produced and secreted) of Pseudomonas protegens PBL3 has broad-spectrum antimicrobial activity against plant and human pathogens.

Why is antimicrobial resistance a key concern mentioned in the document?

The document states that widespread antimicrobial use has contributed to the emergence of antimicrobial resistance (AMR), and newly approved antimicrobials are often derivatives of existing classes, allowing bacteria to evolve quickly.

What pathogens were reported to be inhibited by the P. protegens PBL3 secretome?

The document reports activity against plant pathogenic Burkholderia species and several human pathogens including Acinetobacter baumannii, Escherichia coli O157:H7, Listeria innocua, Enterococcus faecium, and Staphylococcus aureus.

Sep 29, 2026

Upload by Mimi