Analysis of Antibiofilm Activities of Bioactive Compounds from Honeyweed (Leonurus sibiricus) Against P. aeruginosa: an In Vitro and In Silico Approach

Mass Spectrometric Identification of Metabolites after Magnetic-Pulse Treatment of Infected Pyrus communis L. Microplants

The major goal of this study is to create a venue for further work on the effect of pulsed magnetic fields on plant metabolism. It deals with metabolite synthesis in the aforementioned conditions in microplants of Pyrus communis L. So far, there have been glimpses into the governing factors of plant biochemistry in vivo, and low-frequency pulsed magnestatic fields have been shown to induce additional electric currents in plant tissues, thus perturbing the value of cell membrane potential and causing the biosynthesis of new metabolites. In this study, sixty-seven metabolites synthesized in microplants within 3-72 h after treatment were identified and annotated. In total, thirty-one metabolites were produced. Magnetic-pulse treatment caused an 8.75-fold increase in the concentration of chlorogenic acid (RT = 8.33 ± 0.0197 min) in tissues and the perturbation of phenolic composition. Aucubin, which has antiviral and antistress biological activity, was identified as well. This study sheds light on the effect of magnetic fields on the biochemistry of low-molecular-weight metabolites of pear plants in vitro, thus providing in-depth metabolite analysis under optimized synthetic conditions. This study utilized high-resolution gas chromatography-mass spectrometry, metabolomics methods, stochastic dynamics mass spectrometry, quantum chemistry, and chemometrics, respectively. Stochastic dynamics uses the relationships between measurands and molecular structures of silylated carbohydrates, showing virtually identical mass spectra and comparable chemometrics parameters.

Gene Expression, Structural Characterization, and Functional Properties of Exopolysaccharide Produced from Potential Probiotic Enterococcus faecalis NOC219 Strain

This study aimed to reveal the structural characterization and functional properties of microbial EPS-NOC219 material produced by the Enterococcus faecalis NOC219 strain with high EPS yield isolated from yogurt, with simultaneously, demonstrating the potential of this EPS for future industrial applications. According to the results of the analyses made for this aim, it was determined that the NOC219 strain contains the epsB, p-gtf-epsEFG, and p-gtf-P1 genes. In addition, it was also revealed that the EPS-NOC219 structure is expressed by the epsB, p-gtf-epsEFG, and p-gtf-P1 genes and has a heteropolymeric feature consisting of glucose, galactose, and fructose units. According to the results of the analyses made for this aim, it was determined that the EPS-NOC219 structure, which was produced from the NOC219 strain containing the epsB, p-gtf-epsEFG, and p-gtf-P1 genes, had a heteropolymeric structure consisting of glucose, galactose, and fructose units. On the other hand, it was shown that this structure had a thickener property, high heat stability exhibited a pseudoplastic flow behavior, and had a high melting point. This showed that the EPS-NOC219 had high heat stability and could be used as a thickener in heat treatment processes. In addition, it was revealed that it is suitable for plasticized biofilm production. On the other hand, the bioavailability of this structure was demonstrated with its high antioxidant activity (55.84%) against DPPH radicals and high antibiofilm activity against Escherichia coli (77.83%) and Listeria monocytogenes (72.14%) pathogens. These results suggest that the EPS-NOC219 structure may be an alternative natural resource for many industries as it has strong physicochemical properties and a healthy food-grade adjunct.

Cell-Free Supernatants (CFSs) from the Culture of Bacillus subtilis Inhibit Pseudomonas sp. Biofilm Formation

Biofilm inhibition has been identified as a novel drug target for the development of broad-spectrum antibiotics to combat infections caused by drug-resistant bacteria. Although several plant-based compounds have been reported to have anti-biofilm properties, research on the anti-biofilm properties of bacterial bioactive compounds has been sparse. In this study, the efficacy of compounds from a cell-free supernatant of Bacillus subtilis against a biofilm formation of Pseudomonas sp. was studied through in vitro, in vivo and in silico studies. Here, in well diffusion method, Bacillus subtilis demonstrated antibacterial activity, and more than 50% biofilm inhibition activity against Pseudomonas sp. was exhibited through in vitro studies. Moreover, molecular docking and molecular dynamics (MD) simulation gave insights into the possible mode of action of the bacterial volatile compounds identified through GC-MS to inhibit the biofilm-formation protein (PDB ID: 7M1M) of Pseudomonas sp. The binding energy revealed from docking studies ranged from -2.3 to -7.0 kcal mol-1. Moreover, 1-(9H-Fluoren-2-yl)-2-(1-phenyl-1H-ttetrazole5-ylsulfanyl)-ethanone was found to be the best-docked compound through ADMET and pharmacokinetic properties. Furthermore, MD simulations further supported the in vitro studies and formed a stable complex with the tested protein. Thus, this study gives an insight into the development of new antibiotics to combat multi-drug-resistant bacteria.

Potential Bioactive Compounds from Marine Streptomyces sp. and Their In Vitro Antibiofilm and Antibacterial Activities Against Antimicrobial-Resistant Clinical Pathogens

Antimicrobial resistance issues have risen dramatically in recent years, posing a severe concern to humans worldwide. The urgent need to find novel compounds for pharmaceutical applications prompts the research of under-explored environments such as marine ecosystems. The present study was designed to discover novel secondary metabolites, and we have isolated about 30 actinomycetes from the marine soil samples collected in Thondi (Ramanathapuram, Tamil Nadu, India), where most isolates are associated with the genus Streptomyces. Out of 30, one potentially active strain (Streptomyces sp. SRMA3) was identified using primary and secondary screening methods against the drug-resistant clinical pathogens. The active metabolites extracted from the selected active isolate were subjected to partial purification and characterization using Fourier transform infrared spectrophotometer (FTIR) and gas chromatography-mass spectroscopy (GC-MS) analysis. The minimum inhibitory concentration (MIC) value was determined for the active metabolite. Further, the partially purified active fraction was revealed for its antibacterial and antibiofilm activity against drug-resistant clinical pathogens. Light and fluorescence microscopy detected the viability and adhesion of the biofilm-forming drug-resistant pathogens. Growth curve analysis showed that the active metabolite has the potential to inhibit drug-resistant pathogens. The synergistic effect of active metabolite with commercial antibiotics also revealed that it could enhance the activity of antibiotics in antimicrobial resistance pathogens. This study shows that the isolated Streptomyces sp. SRMA3 is a potentially active strain, and the metabolite derived from this strain has a good antibacterial and antibiofilm activity against antimicrobially resistant clinical pathogens and could be used for various biotechnological applications.

Considerable Production of Ulvan from Ulva lactuca with Special Emphasis on Its Antimicrobial and Anti-fouling Properties

In the current study, a significant amount of ulvan was extracted from Ulva lactuca collected from Alexandria coastline, Egypt, using a simple extraction method. According to the chemical analysis, the obtained polysaccharide content is estimated to be 36.50 g/100 g with a high sulfate content of 19.72%. Physio-chemically, the FTIR analysis confirmed the presence of sulfated groups attached to the carbohydrate backbone. The GC–MS results revealed the presence of various monosaccharides with relative abundances in the order: fucopyranose (22.09%) > L-rhamnose (18.17%) > L-fucose (17.46%) > rhamnopyranose (14.29%) > mannopyranose (8.59%) > α-D-glactopyranose (7.64%) > galactopyranose (6.14%) > β-arabinopyranose (5.62%). In addition, the SEM–EDX depicted an amorphous architecture with a majority wt% for the elements of C, O, and S. The partially purified ulvan demonstrated potent antimicrobial activity against some fish and human pathogenic microbes. The inhibition zone diameter ranged from 11 to 18 mm. On the other hand, the prepared ulvan-chitosan hydrogel significantly improved the antimicrobial activity as the inhibition zone diameter ranged from 12 to 20. Moreover, when compared to the controls, the extracted ulvan demonstrated anti-fouling properties and successfully disrupted the biofilm formed on a glass slide submerged in seawater.