Affiliation:
1. Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901
Abstract
ABSTRACT
Membrane vesicles are released from the surfaces of many gram-negative bacteria during growth. Vesicles consist of proteins, lipopolysaccharide, phospholipids, RNA, and DNA. Results of the present study demonstrate that membrane vesicles isolated from the food-borne pathogen
Escherichia coli
O157:H7 facilitate the transfer of genes, which are then expressed by recipient
Salmonella enterica
serovar Enteritidis or
E. coli
JM109. Electron micrographs of purified DNA from
E. coli
O157:H7 vesicles showed large rosette-like structures, linear DNA fragments, and small open-circle plasmids. PCR analysis of vesicle DNA demonstrated the presence of specific genes from host and recombinant plasmids (
hly
, L7095,
mobA
, and
gfp
), chromosomal DNA (
uidA
and
eaeA
), and phage DNA (
stx1
and
stx2
). The results of PCR and the Vero cell assay demonstrate that genetic material, including virulence genes, is transferred to recipient bacteria and subsequently expressed. The cytotoxicity of the transformed enteric bacteria was sixfold higher than that of the parent isolate (
E. coli
JM109). Utilization of the nonhost plasmid (pGFP) permitted the evaluation of transformation efficiency (ca. 10
3
transformants μg of DNA
−1
) and demonstrated that vesicles can deliver antibiotic resistance. Transformed
E. coli
JM109 cells were resistant to ampicillin and fluoresced a brilliant green. The role vesicles play in genetic exchange between different species in the environment or host has yet to be defined.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
290 articles.
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