Table 1 Outer membrane vesicles, bacterial producers, and their activity

A mutant Escherichia coli strain

Sucrose gradient ultracentrifuge

Delivering small interfering RNA (siRNA) targeting kinesin spindle protein (KSP)

OMVs can be used as cell-specific drug-delivery vehicles toward several cancers

[199]

Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bacteroides uniformis, E. coli, Barnesiella intestinihominis, Faecalibacterium prausnitzii, Bifidobacterium longum Parabacteroides distasonis,, Eubacterium rectale, Roseburia inulinivorans, Lactobacillus reuteri

Membrane filtration and multiple cycles of ultracentrifugation

Proteins

OMVs provide great information in the communication between the microbiota and the host for preventing cancer and disease development

[200]

E. coli ΔmsbB OMVs

Filtration and ultracentrifugation

OMV encoding lipid A acyltransferase (msbB, had been inactivated (E. coli msbB−/−, ΔmsbB))

OMVs as therapeutic factors to treat various cancer through immunotherapy

[189]

Pseudomonas. aeruginosa

Filtration and ultracentrifugation

sRNA52320

sRNA52320 was plentiful in OMVs that diminished the LPS- and OMV-stimulated IL-8 generation. Besides, sRNA52320 attenuated OMV-stimulated keratinocytes-derived chemokine (KC) production and neutrophil infiltration

[54]

Helicobacter pylori

Filtration and centrifugation

sncRNAs (sR-2509025 and sR-989262)

Diminished LPS or OMV- stimulated IL-8 generation by cultured AGS cells (a human gastric adenocarcinoma cell line). Overall, these results are in accord with the notion that sncRNAs in OMVs derived from H. pylori have a new action in the pathogen-host interactions

[201]

B. fragilis and B. thetaiotaomicron

Tris ethylenediaminetetraacetic acid (EDTA)-sodium deoxycholate buffers/filtration, and multiple centrifugations

Different protein profiles and a safe endotoxin content

OMVs can be used in vivo studies as new therapeutic candidates

[194]

Meningococcal strain

Fractionated centrifugation

MenBvac, and MeNZB

Administration of the single and the combination of MenBvac and MeNZB vaccines considerably influence the outcomes of serogroup B meningococcal disease

[202]

ClearColi™, an endotoxin-free strain of E. coli

Ammonium sulfate, ultrafiltration, ultracentrifugation, and precipitation-based exosome isolation kit

Proteins

OMVs from the pre-stationary phase using ammonium sulfate (70%) + ultracentrifugation with enhanced yield could be used in vaccine studies

[203]

Neisseria gonorrhoeae

Filtration and ultracentrifugation

Naturally released OMVs (nOMVs) (rmp-deficient GC nOMVs)

These methods shedlight on future in vivo experiments on the anti-N's protective efficacy. gonorrhoeae stimulated by these nOMVs

[204]