Antimicrobial Efficiency of Chitosan and Its Methylated Derivative against Lentilactobacillus parabuchneri Biofilms

Abstract

Antimicrobial materials are considered potential alternatives to prevent the development of biofilm-associated contaminations. Concerns regarding synthetic preservatives necessitate the development of innovative and safe natural antimicrobials. In the present study, we discuss the in situ infrared attenuated total reflection spectroscopy (IR-ATR) investigations of the selective antimicrobial efficiency of chitosan in controlling the growth of Lentilactobacillus parabuchneri biofilms. The protonated charges of chitosan were additionally amplified by structural modification via methylation, yielding quaternized derivative TMC (i.e., N, N, N-trimethyl chitosan). To evaluate antimicrobial effectiveness against L. parab. biofilms, IR-ATR spectroscopy provided information on molecular mechanisms and insights into chemical changes during real-time biofilm inhibition studies. The integrated fiberoptic oxygen microsensors enabled monitoring oxygen (O2) concentration gradients within biofilms, thereby confirming the metabolic oxygen depletion dropping from 4.5 to 0.7 mg L−1. IR studies revealed strong electrostatic interactions between chitosan/its water-soluble derivative and bacteria, indicating that a few hours were sufficient to affect biofilm disruption. The significant decrease in the IR bands is related to the characteristic spectral information of amide I, II, III, nucleic acid, and extracellular polymeric matrix (EPS) produced by L. parabuchneri biofilms. Cell clusters of biofilms, microcolonies, and destabilization of the EPS matrix after the addition of biopolymers were visualized using optical microscopy. In addition, scanning electron microscopy (SEM) of biofilms grown on polystyrene and stainless-steel surfaces was used to examine morphological changes, indicating the disintegration of the biofilm matrix into individual cells. Quantification of the total biofilm formation correlated with the CV assay results, indicating cell death and lysis. The electrostatic interactions between chitosan and the bacterial cell wall typically occur between protonated amino groups and negatively charged phospholipids, which promote permeabilization. Biofilm growth inhibition was assessed by a viability assay for a period of 72 h and in the range of low MIC values (varying 0.01–2%). These results support the potential of chitosan and TMC for bacterial growth prevention of the foodborne contaminant L. parabuchneri in the dairy industry and for further implementation in food packaging.

Characterization of the Biofilms Formed by Histamine-Producing Lentilactobacillus parabuchneri Strains in the Dairy Environment

“…[ 13 , 65 , 66 ]. New materials that might prevent microbial growth are being explored [ 67 , 68 ], including the use of safe natural antimicrobial coating surfaces [ 69 ], but there remain many that are difficult to clean. The design requirements of equipment can also render effective cleaning and disinfection difficult [ 36 ].…”

Development of super nanoantimicrobials combining AgCl, tetracycline and benzalkonium chloride

“…The sterilized MRS medium was flushed into the system for 3 h with a delay of 5 min between measurements at a flow rate of 0.7 mL/min, which resulted in a residence time within the flow cell of ~ 150 s. After recording the conditioning film background, the MRS media were replaced with a bacterial solution (OD 600 = 0.7) for 2 h at a 0.7 mL/min flow rate with a 10 min delay between measurements. This period was optimized on the basis of the required time for initiating the attachment of L. parabuchneri biofilms at the ZnSe waveguide [ 37 , 38 ]. After 2 h of initial attachment of L. parabuchneri , sterile MRS medium was pumped again through the FTIR-ATR assembly cell for 24 h at a 0.5 mL/min flow rate.…”

Chitosan and Its Derivatives: Preparation and Antibacterial Properties

“…For example, one can obtain a quaternized version of chitosan, specifically its ammonium salt, by incorporating a quaternary ammonium group into the chitosan backbone. One notable study demonstrated that a quaternized chitosan variant, N , N , N -trimethylammonium chitosan chloride, had superior antibacterial capabilities, a wider spectrum of antimicrobial activity, and an accelerated rate of bacterial cell destruction than its unmodified counterpart [ 58 , 126 , 127 ].…”