Effect of oxytetracycline on Lactobacillus plantarum on surface enhanced Raman substrate based on Ag NRs

Abstract:

[Background] As a kind of tetracycline, oxytetracycline (OTC) is used widely in pharmacy making and animal breeding. Abuse and residues of antibiotics can easily lead to drug resistance of probiotics in the environment, and all kinds of probiotics can transfer drug-resistant genes to pathogenic bacteria after entering the body through food. The current screening methods for drug-resistant strains are time-consuming, and the results of the minimum inhibitory concentration determination may be biased, and the results do not directly show the antibacterial mechanism and drug resistance mechanism. [Objective] In this study, surface enhanced Raman spectroscopy (SERS) technology was used to explore the interaction between oxytetracycline and Lactobacillus plantarum, aiming to provide a theoretical basis for the rapid screening of microbial drug-resistant strains and provide ideas and methods for the study of antimicrobial mechanism and drug-resistant mechanism.[Methods] In this experiment, a kind of solid phase substrate with good and stable SERS enhanced effect was obtained after assembling silver nanorods and quartz. After adding oxytetracycline at different concentrations, Lactobacillus planatum was incubated for 30 min, 60 min and 90 min respectively. The assembled solid substrate was used to measure the SERS signal of the bacteria cells. The changes of the peak location and peak intensity of Raman spectrum could reflect the differences in the cell components of Lactobacillus planatum under different oxytetracycline concentrations and action time. The effect of oxytetracycline on the growth of Lactobacillus plantarum can be further inferred.[Results] The results showed that 0.5×MIC oxytetracycline mainly caused the decrease of SERS spectrum intensity. 1.0×MIC oxytetracycline at 90 min may lead to the destruction of the bacterial cell wall, the SERS spectra in, 1612 cm^-1and 1630 cm^-1 appear two peaks represent the tyrosine and amideⅠ. The cell wall was damaged by 2.0×MIC oxytetracycline at 60 min. [Conclusion] Raman spectroscopy detection can reflect the changes of bacterial cell state and intracellular and extracellular components, which is of great significance for the study of antimicrobial agents on bacteria and the mechanism of drug resistance, and also provides a good technical basis for the rapid screening of microbial drug-resistant strains.