Characteristics of Bacteriophage Isolates and Expression of Shiga Toxin Genes Transferred to Non Shiga Toxin-Producing E. coli by Transduction

• Published in: Journal of microbiology and biotechnology Vol. 31; no. 5; pp. 710 - 716
• Main Authors: Park, Da-Som, Park, Jong-Hyun
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society for Microbiology and Biotechnology 28.05.2021; 한국미생물·생명공학회
• Subjects: Coliphages - classification; Coliphages - genetics; Coliphages - isolation & purification; Coliphages - physiology; Escherichia coli - genetics; Escherichia coli - growth & development; Escherichia coli - metabolism; Escherichia coli - virology; Gene Expression; Lysogeny; Myoviridae - classification; Myoviridae - genetics; Myoviridae - isolation & purification; Research article; Shiga Toxin - genetics; Shiga Toxin - metabolism; Transduction, Genetic; Virulence Factors - genetics; Virulence Factors - metabolism; 생물학; non-pathogenic E. coli; Shiga toxin; Bacteriophage; convertant; transduction
• ISSN: 1017-7825; 1738-8872
• DOI: 10.4014/jmb.2102.02040

A risk analysis of Shiga toxin (Stx)-encoding bacteriophage was carried out by confirming the transduction phage to non-Stx-producing (STEC) and subsequent expression of the Shiga toxin genes. The virulence factor was identified in five phages, and both and were found in four phages from a total of 19 phage isolates with seven non-O157 STEC strains. The four phages, designated as φNOEC41, φNOEC46, φNOEC47, and φNOEC49, belonged morphologically to the Myoviridae family. The stabilities of these phages to temperature, pH, ethanol, and NaClO were high with some variabilities among the phages. The infection of five non-STEC strains by nine Stx-encoding phages occurred at a rate of approximately 40%. Non-STEC strains were transduced by Stx-encoding phage to become lysogenic strains, and seven convertant strains had and/or genes. Only the gene was transferred to the receptor strains without any deletion. Gene expression of a convertant having both and genes was confirmed to be up to 32 times higher for Stx1 in 6% NaCl osmotic media and twice for Stx2 in 4% NaCl media, compared with expression in low-salt environments. Therefore, a new risk might arise from the transfer of pathogenic genes from Stx-encoding phages to otherwise harmless hosts. Without adequate sterilization of food exposed to various environments, there is a possibility that the toxicity of the phages might increase.