Isolation and characterization of outer membrane vesicles of pectobacterium brasiliense 1692

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Authors

Maphosa, Silindile
Moleleki, Lucy N.

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MDPI

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.

Description

SUPPLEMENTARY MATERIAL : FIGURE S1: Size distribution and concentration of nanoparticles in cell-free supernatants of exponential and stationary phase Pbr1692 cultures; TABLE S1: Pectobacterium brasiliense 1692 Outer Membrane Vesicle associated proteins.

Keywords

Outer membrane vesicles (OMVs), Virulence, Competition, Pectobacterium brasiliense (Pbr), Gram-negative bacteria’s (GNB), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM)

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Citation

Maphosa, S.; Moleleki, L.N. Isolation and Characterization of Outer Membrane Vesicles of Pectobacterium brasiliense 1692. Microorganisms 2021, 9, 1918. https://DOI.org/ 10.3390/microorganisms9091918.