Transporters and Efflux Pumps Are the Main Mechanisms Involved in Staphylococcus epidermidis Adaptation and Tolerance to Didecyldimethylammonium Chloride

Transcriptomic signature of bacteria exposed to benzalkonium chloride

The COVID-19 pandemic has highlighted our reliance on biocides, the increasing prevalence of resistance to biocides is a risk to public health. Bacterial exposure to the biocide, benzalkonium chloride (BAC), resulted in a unique transcriptomic profile, characterised by both a short and long-term response. Differential gene expression was observed in four main areas: motility, membrane composition, proteostasis, and the stress response. A metabolism shift to protect the proteome and the stress response were prioritised suggesting these are main resistance mechanisms. Whereas "well-established" mechanisms, such as biofilm formation, were not found to be differentially expressed after exposure to BAC.

Antibacterial and Antioxidant Study of New Pharmaceutical Formulation of Didecyldimethylammonium Bromide Via Pharmaceutical Deep Eutectic Solvents (PDESs) Principle

Combination therapies have been studied by many researchers using different techniques and methods to solve some solid drug problems and improve more effective treatments for humans and animals. One of the more significant findings to emerge from this study is that the combination of pharmaceutical agents by using pharmaceutical deep eutectic solvents (PDESs) in order to produce dual action drugs and reduce the drug resistance. The major objective of this study was to investigate the dual functionality of drugs (antioxidant and antibacterial activity) via the principle of PDESs. The produced PDESs were characterized via different techniques, namely differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and UV-Vis spectrophotometry. We herein tested a panel of novel liquid formulations of didecyldimethylammonium bromide (DDMAB) against a selection of pathogenic bacteria, classifying their spectrum of activity against Gram-positive and Gram-negative bacteria. The current study found that the PDESs can be used to produce drugs with dual functionalities. The produced PDES from (ascorbic acid: DDMAB) exhibits stronger antibacterial activity against Gram-positive Staphyloccocus aureus and Staphyloccocus epidermidis than gram negatives. One of the most interesting PDESs studied in this research was that of DDMAB and ascorbic acid. This forms a eutectic which is far from the solid drugs issues and shows dual functionality like antibacterial and antioxidant activity. This study has found that there is a correlation between the molecular docking study and the biological activities of the combined drugs.

Investigating Differential Expressed Genes of Limosilactobacillus reuteri LR08 Regulated by Soybean Protein and Peptides

Soybean protein and peptides have the potential to promote the growth of Lactobacillus, but the mechanisms involved are not well understood. The purpose of this study is to investigate differentially expressed genes (DEGs) of Limosilactobacillus reuteri (L. reuteri) LR08 responding to soybean protein and peptides using transcriptome. The results showed that both digested protein (dpro) and digested peptides (dpep) could enhance a purine biosynthesis pathway which could provide more nucleic acid and ATP for bacteria growth. Moreover, dpep could be used instead of dpro to promote the ABC transporters, especially the genes involved in the transportation of various amino acids. Interestingly, dpro and dpep played opposite roles in modulating DEGs from the acc and fab gene families which participate in fatty acid biosynthesis. These not only provide a new direction for developing nitrogen-sourced prebiotics in the food industry but could also help us to understand the fundamental mechanism of the effects of dpro and dpep on their growth and metabolisms and provides relevant evidence for further investigation.

Kinetics of Bacterial Adaptation, Growth, and Death at Didecyldimethylammonium Chloride sub-MIC Concentrations

Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are standard indexes for determining disinfection effectiveness. Nevertheless, they are static values disregarding the kinetics at sub-MIC concentrations where adaptation, growth, stationary, and death phases can be observed. The understanding of these dynamic mechanisms is crucial to designing effective disinfection strategies. In this study, we studied the 48 h kinetics of Bacillus cereus and Escherichia coli cells exposed to sub-MIC concentrations of didecyldimethylammonium chloride (DDAC). Two mathematical models were employed to reproduce the experiments: the only-growth classical logistic model and a mechanistic model including growth and death dynamics. Although both models reproduce the lag, exponential and stationary phases, only the mechanistic model is able to reproduce the death phase and reveals the concentration dependence of the bactericidal/bacteriostatic activity of DDAC. This model could potentially be extended to study other antimicrobials and reproduce changes in optical density (OD) and colony-forming units (CFUs) with the same parameters and mechanisms of action.

Elucidating the Role of Virulence Traits in the Survival of Pathogenic E. coli PI-7 Following Disinfection

Reuse and discharge of treated wastewater can result in dissemination of microorganisms into the environment. Deployment of disinfection strategies is typically proposed as a last stage remediation effort to further inactivate viable microorganisms. In this study, we hypothesize that virulence traits, including biofilm formation, motility, siderophore, and curli production along with the capability to internalize into mammalian cells play a role in survival against disinfectants. Pathogenic E. coli PI-7 strain was used as a model bacterium that was exposed to diverse disinfection strategies such as chlorination, UV and solar irradiation. To this end, we used a random transposon mutagenesis library screening approach to generate 14 mutants that exhibited varying levels of virulence traits. In these 14 isolated mutants, we observed that an increase in virulence traits such as biofilm formation, motility, curli production, and internalization capability, increased the inactivation half-lives of mutants compared to wild-type E. coli PI-7. In addition, oxidative stress response and EPS production contributed to lengthening the lag phase duration (defined as the time required for exposure to disinfectant prior to decay). However, traits related to siderophore production did not help with survival against the tested disinfection strategies. Taken together, the findings suggested that selected virulence traits facilitate survival of pathogenic E. coli PI-7, which in turn could account for the selective enrichment of pathogens over the non-pathogenic ones after wastewater treatment. Further, the study also reflected on the effectiveness of UV as a more viable disinfection strategy for inactivation of pathogens.