Bacteriostatic Activity Research Articles

Ligand-Free Silver Nanoparticles: An Innovative Strategy against Viruses and Bacteria.

The spread of antibiotic-resistant bacteria and the rise of emerging and re-emerging viruses in recent years constitute significant public health problems. Therefore, it is necessary to develop new antimicrobial strategies to overcome these challenges. Herein, we describe an innovative method to synthesize ligand-free silver nanoparticles by Pulsed Laser Ablation in Liquid (PLAL-AgNPs). Thus produced, nanoparticles were characterized by total X-ray fluorescence, zeta potential analysis, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate the nanoparticles' cytotoxicity. Their potential was evaluated against the enveloped herpes simplex virus type 1 (HSV-1) and the naked poliovirus type 1 (PV-1) by plaque reduction assays and confirmed by real-time PCR and fluorescence microscopy, showing that nanoparticles interfered with the early stage of infection. Their action was also examined against different bacteria. We observed that the PLAL-AgNPs exerted a strong effect against both methicillin-resistant Staphylococcus aureus (S. aureus MRSA) and Escherichia coli (E. coli) producing extended-spectrum β-lactamase (ESBL). In detail, the PLAL-AgNPs exhibited a bacteriostatic action against S. aureus and a bactericidal activity against E. coli. Finally, we proved that the PLAL-AgNPs were able to inhibit/degrade the biofilm of S. aureus and E. coli.

Screening Studies of the Antimicrobial Activity of the Pyrimidine Compound 2,2-[6-Bromo-2,4-Dioxoquinazoline-1,3(2H)diyl]bis(N-Carbamimidoylacetamide)

The aim of this study was to screen the antimicrobial activity of a pyrimidine compound under the laboratory code VMA-21-01. Antimicrobial activity was studied in relation to: Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumonia, and Proteus mirabilis. The antimicrobial activity of 2,2-[6-Bromo-2,4-dioxoquinazoline- 1,3(2H)diyl]bis(N-carbamimidoylacetamide) was carried out in vitro by serial dilution and determination of its minimum inhibitory concentration. The sensitivity of microorganisms to the test substance was determined in a meat-peptone broth (visual assessment), followed by reinoculation on meat-peptone agar and colony count. DMSO tubes were used as a control. A 4% gentamicin solution was used as a comparison drug. In an in vitro experiment, it was found that the pyrimidine compound 2,2-[6-Bromo-2,4-dioxyquinazoline-1,3(2H)diyl]bis(N-carbamimidoylacetamide) under the laboratory cipher VMA21-01 has bactericidal activity against K. pneumonia comparable to the comparison drug gentamicin, as well as bacteriostatic activity against S. aureus, S. pneumoniae, E. coli, and P. mirabilis.

Evaluation of bacteriostatic and antioxidant activities of various extracts from aerial part of Piper nigrum grown in Gulf countries traditionally used for the treatment of various infectious diseases

AbstractPiper nigrum (P. nigrum) is a tropical medicinal plant widely available in Southeast Asian countries including Oman. In Asian It has a long history of usage in places such as Oman for treating of rheumatism, colds, and various infections. Based on the medicinal uses, the purpose of this research is to create diverse fractions using increasing solvent polarity from the aerial part of the collected plant species and evaluate their antibacterial and antioxidant activities by using established bioassays. The aerial part was collected from the Southern part of Oman and processed using the standard method. The processed materials were recovered using the maceration method using methanol, and the methanol raw extracts was further fractionated with water extraction, butanol, ethyl acetate (ETA), hexane, and dichloromethane are produced using different liquid polarities. Each of the six plant extracts was tested for antioxidant and antibacterial potential at different concentrations against DPPH (1, 1-diphenyl-2-picrylhydrazyl) and agar diffusion methods. All of the fractions at varied concentrations shown promising antioxidant activity with DPPH against the gallic acid. The maximum activity was observed in hexane extract, while the smallest potential was noticed in butanol extract, in the following order: hexane > chloroform > water > methanol > ethyl acetate > butanol extract. The antibacterial efficacy of six different polarities extracts gives moderate activity against two Gram-positive bacteria strains namely S. saprophyticus and S. aureus and three Gram-negative namely P. vulgaris, K. senegalensis and E. coli. Among the six extracts, hexane extract had the most antibacterial activity, whereas butanol extract had the smallest activity. The remaining four extracts, chloroform, ethyl acetate, methanol, and water, all had comparable activity. In conclusion, the extracts with the greatest activity from the chosen plant types might be employed as natural antioxidants to treat infectious disorders.

Activity of Paullinia pinnata leaf fractions on bacterial isolates associated with treatment-failure wounds

The current surge of multidrug resistant infections has led to many cases of treatment failure in clinical practices. This has necessitated the search for new drugs from natural sources which could be used to curb this menace. Paullinia pinnata (Linn.) leaves are deployed traditionally for the treatment of various ailments such as malaria and the treatment of wounds. The essence of this study is to assess the antibacterial potential of P. pinnata leaf fractions on four antibiotic-resistant bacteria isolated from treatment failed wounds. The n-hexane and ethyl acetate fractions were obtained from the methanol extract of the leaves of P. pinnata by the one-solvent system fractionation. The antibacterial capacity of the fractions was determined by the agar well diffusion method and gentamicin (30 µg/mL) was the control. Clinical isolates of two Gram-positive (Staphylococcus aureus and Bacillus cereus) and two Gram-negative (Klebsiella pneumoniae and Proteus vulgaris) bacteria were used. The fractions showed no activity to moderate activity at lower concentrations. The ethyl acetate fraction showed bacteriostatic activity in a dose-dependent manner and was better than that of n-hexane, and could therefore be a good drug target for antimicrobial therapies, especially for wound treatment.

Characterization and Assessment of Native Lactic Acid Bacteria from Broiler Intestines for Potential Probiotic Properties.

Probiotics are the most promising alternative to antibiotics for improving animal production and controlling pathogenic infections, while strains derived from natural hosts are considered highly desirable due to their good adaptation to the gastrointestinal tract. The aim of this study was to screen Lactobacillus with broad-spectrum antibacterial activity from broilers fed an antibiotic-free diet and evaluate their potential as poultry probiotics. A total of 44 lactic acid bacteria (LAB) strains were isolated from the intestines of healthy broilers, among which 3 strains exhibited outstanding antimicrobial activity and were subsequently identified through 16S rRNA sequencing as Enterococcus faecium L8, Lactiplantibacillus plantarum L10, and Limosilactobacillus reuteri H11. These three isolates demonstrated potent bacteriostatic activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella cholerae, with inhibition zones ranging from 15.67 ± 1.53 to 21.33 ± 0.58 mm. The selected LAB strains exhibited high tolerance to acid and bile salts, with L. reuteri H11 displaying the highest survival rate (ranging from 34.68% to 110.28%) after exposure to 0.3% (w/v) bile salts for 6 h or a low pH environment (pH 2, 2.5, and 3) for 3 h. Notably, L. reuteri H11 outperformed other strains in terms of hydrophobicity (84.31%), auto-aggregation (53.12%), and co-aggregation with E. coli ATCC 25922 (36.81%) and S. aureus ATCC 6538 (40.20%). In addition, the three LAB isolates were either fully or moderately susceptible to the tested antibiotics, except for strain L8, which resisted gentamycin and vancomycin. Consequently, these three LAB strains, especially L. reuteri H11, isolated from the intestines of broiler chickens, represent promising probiotic candidates that can be employed as feed additives to enhance production performance and control poultry pathogens.

Antibacterial Activities of the Algal Bromophenol Methylrhodomelol Against Pseudomonas aeruginosa.

Methylrhodomelol (1: ) is a bromophenol from the red alga Vertebrata lanosa that has been associated with antimicrobial properties. The aim of the current study was, therefore, to assess the antimicrobial potential of this compound in more detail against the gram-negative pathogen Pseudomonas aeruginosa. 1: exerted weak bacteriostatic activity against different strains when grown in minimal medium, whereas other phenolics were inactive. In addition, 1: (35 and 10 µg/mL) markedly enhanced the susceptibility of multidrug-resistant P. aeruginosa toward the aminoglycoside gentamicin, while it did not affect the viability of Vero kidney cells up to 100 µM. Finally, pyoverdine release was reduced in bacteria treated at sub-inhibitory concentration, but no effect on other virulence factors was observed. Transcriptome analysis of treated versus untreated P. aeruginosa indicated an interference of 1: with bacterial carbon and energy metabolism, which was corroborated by RT-qPCR and decreased ATP-levels in treated bacteria. In summary, the current study characterized the antibacterial properties of methylrhodomelol, revealed its potential as an adjuvant to standard antibiotics, and generated a hypothesis on its mode of action.

Dapsone – Reinventing the Wheel or Rekindling Possibilities?

Dapsone, once a fabric dye, is a versatile pharmaceutical for treating diseases like leprosy, malaria, and HIV-AIDS-related pneumonia. Discovered in 1908 but not utilized for its antimicrobial properties until the 1930s, dapsone faced initial setbacks due to toxicity, prompting the development of a safer derivative, Promin. Chemically, dapsone's lipid-soluble nature allows for extensive distribution throughout the body and involves complex metabolism, with a variable elimination half-life. Its clinical efficacy is due to its bacteriostatic action, inhibiting dihydrofolic acid synthesis, and its anti-inflammatory effects on neutrophils. Dapsone's dosing is tailored to the individual's condition and is approved for various dermatological conditions. However, its use is limited by contraindications in certain anemic conditions and potential side effects such as hemolytic anemia and methemoglobinemia, necessitating careful monitoring and management strategies to mitigate risks. Despite these challenges, dapsone's broad therapeutic utility and ongoing research into its mechanisms maintain its status as a significant medical therapy.

Biosynthesis of Cissus rotundifolia Stem-Mediated Titanium Dioxide Nanoparticles and Their Anticariogenic Activity against Streptococcus mutans and Lactobacillus sp.

ABSTRACT Introduction: The green synthesis of metal oxide nanoparticles using plant extracts has emerged as an eco-friendly method. Titanium dioxide nanoparticles (TiO2NPs) were synthesized using Cissus rotundifolia in this study. Titanium dioxide nanoparticles were utilized in restorative medicine for enhanced medicinal properties and in dental composites for their antimicrobial activities. Cissus rotundifolia is recognized as a medicinal plant due to its diverse properties, including mild laxatives, anti-inflammatory, and hyperglycemic activities. Materials and Methods: The antimicrobial activity of the prepared nanoparticles against Lactobacillus Sp. and Streptococcus mutans was evaluated using agar well diffusion method. The bactericidal and bacteriostatic activity of the prepared TiO2NPs was examined using time-kill kinetic analysis. Results: The prepared nanoparticles exhibited potential antimicrobial activity against Lactobacillus sp. (12 mm) at the highest concentration of 100 µg/mL. The prepared nanoparticles also exhibited excellent bactericidal activity against Lactobacillus Sp. and mild bacteriostatic activity against Staphylococcus mutans at the highest concentration of 100 µg/mL. Conclusion: The synthesized TiO2NPs showed significant antimicrobial activity against dental pathogens. The observed anticariogenic activity shows the potential of nanoparticles for dental applications. Hence, the prepared nanoparticles can be used in the field of dentistry as an antimicrobial agent instead of synthetic drugs causing more side effects.

Critical view on antimicrobial, antibiofilm and cytotoxic activities of quinazolin-4(3H)-one derived schiff bases and their Cu(II) complexes

A series of nine 2,3-disubstituted-quinazolin-4(3H)-one derived Schiff bases and their three Cu(II) complexes was prepared and tested for their antimicrobial activities against reference strains Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and resistant clinical isolates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis (VRE). All the substances were tested in vitro against Mycobacterium tuberculosis H37Ra ATCC 25177, M. kansasii DSM 44162 and M. smegmatis ATCC 700084. While anti-enterococcal and antimycobacterial activities were insignificant, 3-[(E)-(2-hydroxy-5-nitrobenzylidene)amino]-2-(2-hydroxy-5-nitrophenyl)-2,3-dihydroquinazolin-4(1H)-one (SB3) and its Cu(II) complex (SB3–Cu) demonstrated bacteriostatic antistaphylococcal activity. In addition, both compounds, as well as the other two prepared complexes, showed antibiofilm activity, which resulted in a reduction of biofilm formation and eradication of mature S. aureus biofilm by 80% even at concentrations lower than the values of their minimum inhibitory concentrations. In addition, the compounds were tested for their cytotoxic effect on the human monocytic leukemia cell line THP-1. The antileukemic efficiency was improved by the preparation of Cu(II) complexes from the corresponding non-chelated Schiff base ligands.

Estimation of MBC: MIC Ratio of Herbal Extracts against Common Endodontic Pathogens

ABSTRACT Herbal extracts have evoked interest owing to the small number of terpenoids and phenolic compounds, which impart antimicrobial, antioxidant, and anti-inflammatory properties. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) of four herbal extracts (lemon grass oil, basil oil, peppermint oil, and Obicure tea extract) against endodontic pathogens along with the MIC: MBC/MFC ratio were evaluated. The antimicrobial activity by detecting the MIC of three essential oils and tea extract was evaluated against eight common endodontic pathogens by the broth dilution method, while MBC was detected by subculturing onto blood agar from the first –three to five tubes from the MIC dilution tubes (showing no turbidity), which were plated on blood agar. All herbal extracts proved to be effective antimicrobials against tested endodontic pathogens. Basil oil had a bacteriostatic effect on all the organisms (P < 0.05). Mint oil showed bacteriostatic activity on Enterococcus (E.) faecalis and Peptostreptococcus (P > 0.05). Tea extract had a bacteriostatic effect (P > 0.05) against all tested microbes except Actinomyces, Lactobacilli, Staphylococcus (S.) aureus, and Fusobacterium (F.) nucleatum. Lemon grass oil had a bactericidal effect against all the organisms and a bacteriostatic effect against Peptostreptococcus (P > 0.05). It can be concluded that basil oil showed a strong bactericidal effect on the test organisms. The MIC for the organisms ranged from 0.2 to 50 μg/ml.

Deinococcus wulumuqiensis R12 synthesized silver nanoparticles with peroxidase-like activity for synergistic antibacterial application.

The use of a combination of several antibacterial agents for therapy holds great promise in reducing the dosage and side effects of these agents, improving their efficiency, and inducing potential synergistic therapeutic effects. Herein, this study provides an innovative antibacterial treatment strategy by synergistically combining R12-AgNPs with H2O2 therapy. R12-AgNPs were simply produced with the supernatant of an ionizing radiation-tolerant bacterium Deinococcus wulumuqiensis R12 by one-step under room temperature. In comparison with chemically synthesized AgNPs, the biosynthesized AgNPs presented fascinating antibacterial activity and peroxidase-like properties, which endowed it with the capability to catalyze the decomposition of H2O2 to generate hydroxyl radical. After the combination of R12-AgNPs and H2O2, an excellent synergistic bacteriostatic activity was observed for both Escherichia coli and Staphylococcus aureus, especially at low concentrations. In addition, in vitro cytotoxicity tests showed R12-AgNPs had good biocompatibility. Thus, this work presents a novel antibacterial agent that exhibits favorable synergistic antibacterial activity and low toxicity, without the use of antibiotics or a complicated synthesis process.

Phytochemical screening and investigation on the antibacterial activity of fermented noni (Morinda citrifolia) fruit juice extracts on selected microorganisms in Makurdi Metropolis

Plant products are generally useful for medicinal purposes, one of which is the noni plant. Noni or pace (Morinda citrifolia L.) fruit juice was extracted using aqueous and methanol solvents, then fermented and screened for the presence or absence of bioactive constituents (phytochemicals) using the modified standard procedures. The major phytochemical constituents revealed were alkaloids, anthraquinones, cardiac glycosides, and flavonoids, phenolic compounds, saponins, tannins, reducing sugar, saponnins, carbohydrate and terpenoids. Bacterial cell viability and MIC values were also determined by turbidity test. The lowest concentration of the extract with clear suspension was considered the MIC values. The lowest concentration of the extract in the post-incubation suspensions which did not harbour any bacterial growth upon spotting on MHA after overnight incubation at 37° C was considered the MBC values. The test was performed in triplicates alongside antibiotics ciprofloxacin (5μg) as a positive control at a concentration of 0.1mg/ml. Antibacterial activity was perfumed against three bacteria (Salmonella typhi, Escherichia coli, and Staphylococcus aureus) by agar-well diffusion method. Activity was observed for both methanolic and aqueous extracts of Morinda citrifolia L. fruit juice against the organisms tested. The extracts had both bacteriostatic and bactericidal activity against the test microorganisms. The Minimum Inhibitory Concentration (MIC) test revealed that the bacterial isolates were inhibited between concentrations of 50mg/ml and 25mg/ml for the methanolic extract, and between 100mg/ml and 50mg/ml for the aqueous extract of the fermented fruit juice. The extract was bactericidal from the range of 100mg/ml to 200mg/ml for both extracts, though with the exception of S. aureus which was bactericidal at 50mg/ml for methanolic extract.

Biodegradable packing food films based on PBAT containing ZnO and MoO3

AbstractMolybdenum trioxide (MoO3) and zinc oxide (ZnO) were incorporated into the poly(butylene adipate‐co‐terephthalate) (PBAT) matrix using casting method to obtain packing films for food transportation with outstanding properties and no formation of microplastics. Consequently, these films were evaluated using Fourier transform infrared spectroscopy, time domain and carbon‐13 nuclear magnetic resonance, x‐ray diffraction, contact angle measurement, and thermogravimetric analysis. The light barrier properties of the films were analyzed using transmittance mode in UV–VIS–NIR regions and the contact angle of composite films exhibited greater hydrophilicity compared to the pure polymer films. Regardless of the concentration, the fillers did not significantly modify the degradation onset temperature and the temperature of maximum degradation rate. However, ZnO caused a new thermal degradation event (around 330°C) that was not observed in the other films, possibly due to the second crystallization process. Composite films filled with 0.3% ZnO, 0.3% and 0.5% MoO3 showed greater molecular homogeneity than the pure polymer matrix, with the PBAT/MoO3 films demonstrating even greater homogeneity than PBAT/ZnO films; this response presumably comes from the satisfactory intermolecular interaction or adequate dispersion and distribution of the particles. The addition of 0.5% MoO3 in the matrix influenced the PBAT film, resulting in amorphous materials with the highest molecular mobility and opacity. Besides, in view of antimicrobial tests, all nanocomposites showed potential bacteriostatic activity. So, it can be conveniently used for food transportation and may avoid microplastic formation, after been discarded.

Toxicity evaluation of a strain isolated from pollack digestive tract using Paramecium caudatum

A strain was isolated from the digestive organs of Walleye pollack residing in the East Sea of the DPR Korea, which not only produces cryophilic protease, organic acid but also has intestinal adhesion property and bacteriostatic activity against pathogens. The strain was classified and identified as Pseudomonas fragi by genetic system classification methods and registered as KCCC 10110 at the Korean Centre for Culture Collection (KCCC) of the State Academy of Sciences, DPR KOREA. In vivo and in vitro toxicity of Pseudomonas fragi KCCC 10110 was evaluated using Paramecium caudatum. In the treatments with P. fragi KCCC 10110, Bacillus subtilis KCCC 11214 and Lactobacillus lactis KCCC 13208, all of these being well known as non-toxic and probiotic for animals and fishes, higher microbial counts and normal movement of P.caudatum were observed while significant lower cell numbers and abnormal movement of P.caudatum were shown in the treatments with pathogenic strains Clostridium tetani 473, Salmonella typhosa 901 and Aeromonas punctata 823. These results suggest that probiotic and pathogenic bacteria have different influence on Paramecium caudatum and that the strain isolated from Walleye pollack digestive tract is non-toxic.

Determination of the chemical composition and evaluation of the antimicrobial and antioxidant potential of the essential oil from Cryptocarya ovalifolia van der Werff leaves (Lauraceae)

The present work aims to evaluate the chemical composition, the antimicrobial and antioxidant properties of the essential oil from Cryptocarya ovalifolia van der Werff (COEO) leaves collected in Mandraka forest. COEO was extracted by steam distillation from fresh leaves, with a yield of 0.7%. COEO appeared as a clear liquid, yellow, with a pleasant odour and relative density of 0.8943 at 20 °C, a refractive index of 1.4746, an optical rotation of – 31°13, an acid index of 0.638 and an ester index of 6.375. A total of 31 constituents accounting for 99.98% of the total essential oil content were identified by gas chromatography/mass spectrometry. The main component was sabinene (30.65%) and the major components (>5%) were limonene (17.33%), methyleugenol (14%) and α-pinene (8.33%). The antibacterial activity was tested on nine pathogenic microorganisms including four Gram positive bacteria, four Gram negative bacteria and one yeast using the disk diffusion and the microdilution assays. COEO was active on 4 strains with inhibition zone diameter (IZD) ranging from 8.7 mm (Bacillus cereus) to 12.7 mm (Clostridium perfringens). Minimum Inhibitory Concentration (MIC) varied from 1.12 to 2.23 mg/ml and Minimum Bactericidal Concentration (MBC) was 8.93 mg/ml for all strains. COEO had bacteriostatic action on Streptococcus pneumoniae, Clostridium perfringens, Bacillus cereus and Candida albicans (MBC/MIC>4) and bactericidal action on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi and Vibrio fischeri (MBC/MIC≤4). COEO exhibited radical scavenging activity against DPPH with an IC50 of 123.29 mg/ml. By oral route, its LD50 was 1.9/Kg body weight.

Surface Charge-Switchable Antifouling Block Copolymer with Bacteriostatic Properties.

Zwitterionic polymers are an emerging family of effective, low-fouling materials that can withstand unintended interactions with biological systems while exhibiting enhanced activity in bacterial matrix deterioration and biofilm eradication. Herein, we modularly synthesized an amphiphilic block copolymer, ZABCP, featuring potential bacteriostatic properties composed of a charge-switchable polyzwitterionic segment and a redox-sensitive pendant disulfide-labeled polymethacrylate block. The leucine-appended polyzwitterionic segment with alternatively positioned cationic amine and anionic carboxylate functionalities undergoes charge alterations (+ve → 0 → -ve) on pH variation. By introducing appropriate amphiphilicity, ZABCP forms distinct vesicles with redox-sensitive bilayer membranes and zwitterionic shielding coronas, enabling switching of surface charge. ZABCP vesicles exhibit 180 ± 20 nm hydrodynamic diameter, and its charge switching behavior in response to pH was confirmed by the change of zeta potential value from -23 to +36 mV. The binding interaction between ZABCP vesicles with lysozyme and pepsin proteins strengthens when the surface charge shifts from neutral (pH 7.4) to either anionic or cationic. This surface-charge-switchable phenomenon paves the way for implementing cationic ZABCP vesicles for bacterial cell growth inhibition, which is shown by the pronounced transition of cellular morphology, including clustering, aggregation, or elongation as well as membrane disruption for both Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative). Such enhanced bacteriostatic activity could be ascribed to a strong electrostatic interaction between cationic vesicles and negatively charged bacterial membranes, leading to cell membrane disruption. Overall, this study provides a tailor-made approach to adopt low-fouling properties and potential bacteriostatic activity using zwitterionic polymers through precise control of pH.

Resistance of a mixed bacterial culture isolated from bee dysbiosis to disinfectant in laboratory conditions

Disinfection is one of the components of preventive actions to prevent disease in animals by infectious agents. Through the elimination of agents of infectious diseases in the environment, it is able to interrupt the mechanisms of the epizootic process. For the development of beekeeping and obtaining quality and products, it is necessary to carry out activities in apiaries, which include disinfection. The introduction of new disinfectants in the field is possible after preliminary laboratory tests. The aim of our research objective to investigate the resistance of a mixed bacterial culture isolated from bees with the symptoms of dysbiosis to disinfectant under laboratory conditions. Bacteriological investigations carried out in Petri dishes using meat-peptone agar and Mueller-Hinton agar. The disinfectant diluted with distilled water at concentrations of 0.25 %, 0.5 %, 1,25 % and 2,5 %. On the Mueller Hinton agar, the bacterial elimination zones recorded at 1.25 % (11,6 ± 0,45 mm) and 2.5 % (12,4 ± 0,27 mm) concentration of disinfectant at 1 day of investigation, and 7,4 ± 0,27 mm (1,25 %), 11,2 ± 0,42 mm (2.5 %) at 72 hours of the experiment, respectively. In addition, the bacterial growth inhibition effect increased with experimental time and ranged from 24.0 ± 0.35 mm (0.5 %) to 28.2 ± 0.22 mm (2.5 %) on day 3 of the study. Bacteriostatic and bactericidal effects appeared to be less pronounced on meat-peptone agar. The highest diameters of inhibition of the processes of reproduction and development of microorganisms from mixed microbial association on this medium were recorded at 1.25 % and 2.5 % concentrations of the disinfectant at the 3rd day of the investigation with diameters of the zones of inhibition of growth 15.6 ± 0.45 mm and 26.4 ± 0.27 mm, respectively. The specificity of diffusion of the investigated active substance from the discs into the agar medium thickness was also noted. This effect has a varying effect on infectious agents in in vitro experiments. Thus bacteriological laboratory experiments should be performed on several culture media in purpose of obtaining accurate results. The analysis of the obtained results indicates the demonstration of antimicrobial effect of the investigated disinfectant against mixed bacterial culture in the form of bactericidal and bacteriostatic actions. Therefore, a promising direction of research for veterinary doctors and apiary business owners is the search for effective and efficient disinfectants. Laboratory investigation of the activity of a remedy are the first step before it is approbation.

Anti-Listerial Activity of Bacteriocin-like Inhibitory Substance Produced by Enterococcus lactis LBM BT2 Using Alternative Medium with Sugarcane Molasses.

Listeria monocytogenes is a foodborne pathogen that contaminates food-processing environments and persists within biofilms on equipment, thus reaching final products by cross-contamination. With the growing demand for clean-label products, the search for natural antimicrobials as biopreservants, such as bacteriocins, has shown promising potential. In this context, this study aimed to evaluate the anti-listerial action of bacteriocins produced by Enterococcus lactis LBM BT2 in an alternative medium containing sugarcane molasses (SCM). Molecular analyses were carried out to characterize the strain, including the presence of bacteriocin-related genes. In the kinetic study on SCM medium E. lactis, LBM BT2 showed biomass and bacteriocin productions similar to those observed on a sucrose-based medium (control), highlighting the potential of the sugarcane molasses as a low-cost substrate. Stability tests revealed that the molecule remained active in wide ranges of pH (4-10) and temperature (60-100 °C). Furthermore, the proteolytic treatment reduced the biomolecule's antimicrobial activity, highlighting its proteinaceous nature. After primary purification by salting out and tangential flow filtration, the bacteriocin-like inhibitory substance (BLIS) showed bacteriostatic activity on suspended L. monocytogenes cells and against biofilm formation at a concentration of 0.625 mg/mL. These results demonstrate the potential of the produced BLIS as a biopreservative in the food industry.

Synthesis, antibacterial activity, and 3D-QASR studies of matrine-indole derivatives as potential antibiotics

Matrine and indole have antibacterial, anticancer, and other biological activities, in order to develop new antibiotics to solve the problem of multi-drug resistant bacteria. In this paper, we synthesized a series of 29 novel matrine derivatives as potential drug candidates by combining indole analogs and matrine. The antibacterial activity of these compounds was evaluated through minimum inhibitory concentration (MIC) assays against five bacterial strains (S. aureus, C. albicans, P. acnes, P. aeruginosa, and E. coli). The obtained results demonstrated promising antibacterial efficacy, particularly for compounds A20 and A18, which exhibited MICs.au values of 0.021 and 0.031 mg/ml, respectively, against S. aureus. Moreover, compounds A20 and A27 displayed remarkable MICc.al values of 2.806 and 4.519 mg/ml, respectively, against C. albicans, surpassing the performance of the clinical antibiotic penicillin G sodium (0.0368 mg/ml) and fluconazole (4.849 mg/ml). These findings underscore the significant bacteriostatic activity of the matrine derivatives. Furthermore, to gain a deeper understanding 3D-QSAR modeling was employed, revealing the critical influence of steric structure, charge distribution, hydrophobic interactions, and hydrogen bonding within the molecular structure on the bacteriostatic activity of the compounds. Additionally, molecular docking simulations shed light on the interaction between compound A20 and bacterial proteins, highlighting the involvement of hydrogen bonding, hydrophobic interactions, and π-π conjugation in the formation of stable complexes that inhibit the normal functioning of the proteins. This comprehensive analysis provided valuable insights into the antibacterial mechanism of the novel matrine derivatives, offering theoretical support for their potential application as antibiotics.

Phenylpropane biosynthesis and alkaloid metabolism pathways involved in resistance of Amorphophallus spp. against soft rot disease.

Soft rot of konjac (Amorphophallus spp.) is a devastating disease caused by the bacterium Pectobacterium carotovorum subsp. carotovorum (Pcc) with serious adverse effects on plantation development, corm quality and crop yield due to the current lack of effective control measures. The main objective of the present study was to elucidate the mechanisms underlying plant resistance to soft rot disease. A combination of transcriptomic and metabolomic analyses demonstrated significant enrichment of differentially expressed genes (DEG) and differentially accumulated metabolites (DAM) associated with plant hormones, phenylpropanoid biosynthesis and, in particular, alkaloid metabolism, in Amorphophallus muelleri following Pcc infection compared with A. konjac, these data implicate alkaloid metabolism as the dominant mechanism underlying disease resistance of A. muelleri. Quantitative real-time polymerase chain reaction analysis further revealed involvement of PAL, CYP73A16, CCOAOMT1, RBOHD and CDPK20 genes in the response of konjac to Pcc. Analysis of the bacteriostatic activities of total alkaloid from A. muelleri validated the assumption that alkaloid metabolism positively regulates disease resistance of konjac. Our collective results provide a foundation for further research on the resistance mechanisms of konjac against soft rot disease.