Transfer of the pSLT Plasmid and its Impact on Intestinal Cell Apoptosis

doi:10.19586/j.2095-2341.2025.0090

Current Biotechnology ›› 2026, Vol. 16 ›› Issue (2): 388-394.DOI: 10.19586/j.2095-2341.2025.0090

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Transfer of the pSLT Plasmid and its Impact on Intestinal Cell Apoptosis

Tian HONG¹(), Lulu ZHAO¹, Yifan DU², Jingwen LI¹, Erning CHEN¹, Meihong DU¹()

^1.Institute of Analysis and Testing，Beijing Academy of Science and Technology （Beijing Center for Physical & Chemical Analysis），Bejing 100094，China
^2.School of Biomedicine，Beijing City University，Beijing 100094，China

Received:2025-07-29 Accepted:2025-12-25 Online:2026-03-25 Published:2026-04-27
Contact: Meihong DU

Abstract

Abstract:

The pSLT plasmid is a specific virulence plasmid primarily found in Salmonella enterica serovar Typhimurium strains. This study aimed to explore the feasibility of horizontal gene transfer （HGT） of the Salmonella pSLT virulence plasmid and investigate its effects on cell necrosis and apoptosis. The Kanamycin resistance gene derived from plasmid pKD46 was integrated into the Salmonella pSLT plasmid using λRed homologous recombination technology. Salmonella enterica serovar Typhimurium （ATCC 14028） served as the donor strain， and Escherichia coli （ATCC 25922） as the recipient strain. Conjugation was performed using the M9 minimal medium plate mating method. The obtained transconjugants were cultured in Kanamycin-supplemented MacConkey broth to verify acid and gas production. Single colonies were isolated， followed by confirmatory PCR and sequencing for the inserted Kana gene. Human colon carcinoma cells （HCT116）， representing intestinal cells， were infected with transconjugants at a multiplicity of infection （MOI） of 100. Cell necrosis and apoptosis were assessed using flow cytometry （Annexin V/PI staining）. The results showed that single colonies grew on nutrient agar plates containing Kanamycin， confirming successful recombination and insertion of the Kana gene fragment into pSLT （creating pSLT^Kana）. Transconjugants exhibited acid and gas production in Kanamycin-supplemented MacConkey broth， demonstrating the successful conjugative transfer of the pSLT^Kana plasmid to Escherichia coli. Compared to the control group， the ATCC 25922 （wild-type E. coli） treatment group did not cause a significant change （P>0.05） in the proportion of Annexin V/PI double-positive cells （indicating late apoptosis/necrosis）. In contrast， both the ATCC 25922 pSLT^Kana （E. coli harboring pSLT） and ATCC 14028 （Salmonella with native pSLT） treatment groups showed a significant reduction （P<0.01） in the proportion of Annexin V/PI double-positive cells. By constructing the ATCC 14028 pSLT^Kana recombinant strain， this study confirmed the feasibility of HGT of the pSLT virulence plasmid from Salmonella to E. coli. The ATCC 25922 pSLT^Kana strain exhibited a potential inhibitory effect on necrosis and apoptosis in intestinal cells. These findings provide crucial scientific data and insights for clinical treatment strategies and public health safety oversight.

Key words: Salmonella, pSLT, Escherichia coli, conjugation transfer

CLC Number:

Q935

Tian HONG, Lulu ZHAO, Yifan DU, Jingwen LI, Erning CHEN, Meihong DU. Transfer of the pSLT Plasmid and its Impact on Intestinal Cell Apoptosis[J]. Current Biotechnology, 2026, 16(2): 388-394.

Figures/Tables 6

Fig. 1 EcoRⅠ restriction site in the pKD46 plasmid

Fig. 2 EcoRⅠ digestion of pKD46 plasmid

Fig. 3 Agarose gel electrophoresis of PCR products

Fig. 4 Identification of the pSLTkana plasmid by Sanger sequencing

Fig. 5 Cultivation of Zygomycetes on MacConkey agar

Fig. 6 Apoptosis detection in human colorectal cancer cells

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Transfer of the pSLT Plasmid and its Impact on Intestinal Cell Apoptosis

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