Transcriptomic Analysis of the Molecular Mechanisms Underlying the Antibacterial Activity of IONPs@pDA-Nisin Composites toward Alicyclobacillus acidoterrestris

Abstract

A simple and no-drug resistance antibacterial method was developed by the synthesis of heat-stable and pH-tolerant nisin-loaded iron oxide nanoparticles polydopamine (IONPs@pDA) composites. The composites had a crystal structure and diameters of 25 ± 3 nm, with a saturation magnetization (M s) of 43.7995 emu g–1. Nisin was successfully conjugated onto the IONPs@pDA nanoparticles, as evinced by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. The novel synthesized material showed good performance in reducing Alicyclobacillus acidoterrestris, a common food spoilage bacterium that represents a significant problem for the food industry. Treatment of A. acidoterrestris cells with composites resulted in membrane damage, as observed by live/dead staining and scanning electron microscopy and transmission electron microscopy analyses. Further, the composites exhibited highly efficient antibacterial activity against cells in only 5 min. Transcriptomic sequencing of culture RNA pools after exposure to composites resulted in a total of 334 differentially expressed genes that were primarily associated with transcriptional regulation, energy metabolism, membrane transporters, membrane and cell wall syntheses, and cell motility. Thus, these results suggested that changes in transcriptional regulation caused by aggregated composites on target cells led to major changes in homeostasis that manifested by decreased energy metabolism, pore formation in the membrane, and repressed cell wall synthesis. Concomitantly, cell motility and sporulation activities were both repressed, and finally, intracellular substances flowed out of leaky cells. The proposed biocontrol method represents a novel means to control microorganisms without inducing drug resistance. Further, these results provide novel insights into the molecular mechanisms underlying the antibacterial activity of composites against microorganisms.

The photocatalytic antibacterial molecular mechanisms towards Pseudomonas syringae pv. tabaci by g‐C3N4 nanosheets: insights from the cytomembrane, biofilm and motility disruption

“…tabaci cope with numerous unseasonable stresses. Similar gene expression regulation has also been observed in Alicyclobacillus acidoterrestris induced by IONPs@pDA‐Nisin composites 23 . To grow under these stress conditions, bacteria must overcome growth‐limiting effects, usually reducing their efficiency in replication, transcription, and translation to decrease membrane fluidity, alter redox status, and change the stability of some secondary structures 40…”

“…Experiments performed with a LIVE/DEAD BacLight bacterial viability kit are used for detecting cell membrane integrity 23 . Dead or dying cells with a compromised membrane will stain red, whereas the cells with intact membrane will stain green.…”

“…tabaci , adsorption observations were also performed. The cell morphology of the bacteria was further investigated by TEM (JEM‐2100, JEOL) and SEM (S‐3400N, Hitachi) 22,23 . Briefly, the fresh bacterial suspensions were cultivated and resuspended in sterilized water until the cell density reached the logarithmic phase.…”

Inactivation Effect of Thymoquinone on Alicyclobacillus acidoterrestris Vegetative Cells, Spores, and Biofilms

“…CLSM observation was carried out according to the method described by Song et al (2019) , with minor modifications. A. acidoterrestris DSM 3922 suspensions treated with TQ (0, 1 × MIC, and 2 × MIC) were incubated at 45°C for 60 min.…”

“…CLSM observation was carried out according to the method described by Song et al (2019), with minor modifications.…”