Schisandrin A Has an Antibacterial Effect on Escherichia coli by Affecting Ribosome Function

Abstract

Background: Escherichia coli pollution is a significant microbial pollutant that affects human and animal health and is an important factor that restricts the development of the poultry industry. This study aimed to investigate the antibacterial effect of Schisandrin A on Escherichia coli. Methods: Escherichia coli was divided into a control group and a Schisandrin A treatment group. The minimal inhibitory concentration (MIC) of Schisandrin A on Escherichia coli was determined. The growth curve was drawn by measuring absorbance values at 600 nm at 0 h, 2 h, 4 h, 6 h, 8 h, 10 h, and 12 h, and the antibacterial effect of Schisandrin A on Escherichia coli was observed. The integrity of the cell membrane and cell wall of Escherichia coli was detected using an electron microscope. The permeability of the Escherichia coli wall was measured using Alkaline phosphatase (AKP) activity and Propidium Iodide (PI) staining. Transcriptome sequencing was carried out to explore the antibacterial mechanism of Schisandrin A on Escherichia coli. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to detect the expression of virulence genes in Escherichia coli. Results: The study found that Schisandrin A has a minimum inhibitory concentration (MIC) of 3.13 mg/mL against Escherichia coli. When added at a concentration of ½ MIC, Schisandrin A can slow down the growth rate of Escherichia coli, damage the cell structure, and significantly downregulate the virulence genes ferric aerobactin receptor IutA (iutA), yersiniabactin non-ribosomal peptide synthetase HMWP2 (irp2) and type 1 fimbriae periplasmic chaperone (fimC) (p < 0.05). Transcriptome results showed that Schisandrin A could downregulate the expression of 50S ribosomal subunit protein L24 (rplX), 30S ribosomal subunit protein S12 (rpsL), 50S ribosomal subunit protein L13 (rplM), 50S ribosomal subunit protein L5 (rplE) and 30S ribosomal subunit protein S5 (rpsE) in ribosomes and upregulate 50S ribosomal subunit protein L31B (ykgM) expression. Conclusions: Schisandrin A has an inhibitory effect on Escherichia coli. It can destroy the bacterial structure and affect bacterial colonization and metabolism. Its bacteriostatic mechanism is related to the damage to ribosome function.