Isolation,Identification,Growth Characteristics and Genetic Evolution of 25 Non-virulent and Non-antibiotic Resistant Escherichia coli Strains Isolated From Pig Intestines
The aim of this study was to isolate Escherichia coli strains without virulence genes and drug resistance from pig intestines,and to analyze their growth performance and genetic evolution relationships.PCR was used to detect 13 virulence genes commonly found in porcine pathogenic E.coli,and susceptibility tests were conducted for 7 classes(14 types)of antibiotics.The growth curves of the non-virulent and non-resistant strains were determined,and a phylogenetic tree was constructed based on the 16S rRNA gene sequences.The results showed that 206 E.coli strains were isolated and identified in this study.Among them,107 E.coli strains did not contain 13 tested virulence genes,of which 25 strains were sensitive to 7 classes of antibiotics(14 kinds),and these 25 strains(non-virulent and non-resistant)showed similar growth performance to 3 typical E.coli strains.16S rRNA phylogenetic tree analysis showed that 4 E.coli strains were close to typical probiotic strains.Based on the results of growth curves and 16S rRNA phylogenetic tree,the four strains may be high-quality native Escherichia coli strains in pig gut and have research potential.
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