Isolation and Characterization of Outer Membrane Vesicles of Pectobacterium brasiliense 1692.

Silindile Maphosa,Lucy Novungayo Moleleki

doi:10.3390/microorganisms9091918

Silindile Maphosa, Lucy Novungayo Moleleki

Open Access

https://doi.org/10.3390/microorganisms9091918

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Journal: Microorganisms	Publication Date: Sep 9, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: University of Pretoria

Abstract

Pectobacterium brasiliense (Pbr) 1692 is an aggressive phytopathogen affecting a broad host range of crops and ornamental plants, including potatoes. Previous research on animal pathogens, and a few plant pathogens, revealed that Outer Membrane Vesicles (OMVs) are part of Gram-negative bacteria’s (GNB) adaptive toolkit. For this reason, OMV production and subsequent release from bacteria is a conserved process. Therefore, we hypothesized that OMVs might transport proteins that play a critical role in causing soft rot disease and in the survival and fitness of Pbr1692. Here, we show that the potato pathogen, Pbr1692, releases OMVs of various morphologies in Luria Bertani media at 31 °C. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) confirmed the production of OMVs by Pbr1692 cells. Transmission Electron Microscopy showed that these exist as chain-, single-, and double-membrane morphologies. Mass spectrometry followed by Gene Ontology, Clusters of Orthologous Groups, Virulence Factor, CAZymes, Antibiotic Resistance Ontology, and Bastion6 T6SE annotations identified 129 OMV-associated proteins with diverse annotated roles, including antibiotic stress response, virulence, and competition. Pbr1692 OMVs contributed to virulence in potato tubers and elicited a hypersensitive response in Nicotiana benthamiana leaves. Furthermore, Pbr1692 OMVs demonstrated antibacterial activity against Dickeya dadantii.

Highlights

Soft Rot Pectobacteriaceae (SRP) are Gram-negative bacteria (GNB) responsible for annual crop losses amounting to millions of dollars worldwide [1]
We found that Pbr1692 produces Outer Membrane Vesicles (OMVs) and outer-inner membrane vesicles (OIMVs)
We demonstrated that Pbr1692 formed double- and single-membrane OMVs and defined their roles in infection and survival

Summary

Introduction

Soft Rot Pectobacteriaceae (SRP) are Gram-negative bacteria (GNB) responsible for annual crop losses amounting to millions of dollars worldwide [1]. Like other soft rot bacteria, exhibits many determinants that ensure their persistence in the environment and expansion into new territory and hosts. The role of secretion systems in the coordinated interaction of bacteria with their environment, target hosts, and other bacteria is pivotal [12]. These systems release many proteinaceous and chemical substances for virulence and persistence from the cell cytosol to the extracellular milieu, neighboring cells, 4.0/)

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