Species Of Pathogenic Bacteria Research Articles

Biological activity of some phenolic compounds extracted from Agrimonia eupatoria against several pathogenic bacteria species

Abstract. Mohammed MA, Ali JF, Saeed YS, Yaseen IH, Ahmad BH. 2022. Biological activity of some phenolic compounds extracted from Agrimonia eupatoria against several pathogenic bacteria species. Biodiversitas 23: 4912-4917. Agrimonia eupatoria L. (Rosaceae) has been used for centuries in traditional medicine to overcome infectious diseases. This study was carried out to isolate, characterize, and determine the antibacterial activity of natural compounds obtained from A. eupatoria aerial parts. Three solvents were used in the extraction process. First, hexane was used for defatting plant samples. Then ethyl acetate and ethanol were used to obtain the fraction containing phenolic compounds and their antibacterial activity against several bacteria. The current study identifies several phenolic compounds isolated from A. eupatoria, including gallic acid, salicylic acid, cinnamic acids, and resorcinol, using thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). In addition, the disc diffusion method was used to determine the antimicrobial activity of several phenolic compounds against four bacterial isolates, i.e., Corynebacterium diphtheria, Bacillus cereus, Salmonella typhymurium, and Enterococcus faecalis. The results indicated that the plant compounds had an antibacterial activity proportional to the concentration. The B. cereus was the most sensitive to the compound isolated from A. eupatoria, followed by C. diphtheria, whereas S. typhimurium exhibited the most insensitive.

Bioactive secondary metabolites from two sponge-derived actinomycetes

Actinomycetes residing in marine habitat are an excellent treasure house of structurally novel and bioactive natural products with potent medicinal values. To exploit chemically diverse and bioactive natural products from actinomycetes living in underexplored ecological niche, we isolate a large number of marine actinomycetes from marine sponges, corals, algae, mollusks, sea grasses, and sediments collected from the South China Sea. In order to assess the values of these special marine actinomycetes in the green development of tropical agriculture, we screen the activity of marine actinomycetes against phytopathogenic fungi and bacteria. As a result, we identify two strains of sponge-derived actinobacteria <italic>Streptomyces</italic> sp. HMH1 and HML1 possessing antagonism effect against tested phytopathogenic microbes. The secondary metabolites produced by these two actinomycete strains and their anti-phytopathogenic fungi activity are investigated. The secondary metabolites from the fermentation extract of <italic>Streptomyces</italic> sp. HMH1 and HML1 are isolated and purified using various chromatography methods including silica gel column, reverse gel column and Sephadex LH-20 column chromatography. The structures of the isolated compounds are characterized by NMR, HR-ESI-MS spectroscopic data analyses and comparison with previously reported data. Three major compounds belonging to the family of actinomycin are purified from the solid fermentation extract of the sponge-derived actinobacterium <italic>Streptomyces</italic> sp. HMH1. They actinomycin D, actinomycin X₂, and actinomycin X_oβ. A compound identified as K-252d belonging to the family of indolocarbazole alkaloid is isolated from the solid fermentation extract of another sponge-derived actinobacterium <italic>Streptomyces</italic> sp. HML1. The anti-phytopathogenic fungi and bacteria activities of these compounds are evaluated against ten species of plant pathogenic fungi including <italic>Fusarium oxysporum</italic> FOC4, <italic>Lasiodiplodia theobromae, Phomopsis caricae-papayae</italic> Fetrak&amp;Cif., <italic>Corynespora cassiicola, Phytophthora capsica, Pythium aphanidermatum</italic> (Edson) Fitzp, <italic>Corynespora</italic> sp., <italic>Fusarium graminearum, Verticillium dahlia, Pestalotiopsis microspora</italic>, and two species of plant pathogenic bacteria including <italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic> and <italic>Ralstonia solanacearum</italic>. The bioactivity test results of the compound against agricultural pathogens show that actinomycin D possesses inhibitory activity against the growth of these tested phytopathogenic fungi and bacteria. among which, actinomycin D has the most potent inhibitory activity against the plant pathogenic fungi <italic>Lasiodiplodia theobromae, Phomopsis caricae-papayae</italic> Fetrak&amp;Cif., <italic>Fusarium graminearum</italic> and <italic>Phytophthora capsica</italic>, with inhibitory rate of (60.09 ± 0.66)%, (48.82 ± 0.66)%, (46.47 ± 1.14)% and (44.13 ± 0.66)%, respectively. In addition, actinomycin D displays strong antibacterial activity on the plant pathogenic bacteria <italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic> and <italic>Ralstonia solanacearum</italic> with bacteriostatic diameter at (36.00 ± 0.82) mm and (15.00 ± 0.47) mm, respectively. These results provide new compounds and bacteria resources for the development of high-efficiency biocontrol agents for agricultural disease control.

The Inhibitory Effect of Quercetin on Biofilm Formation of Listeria monocytogenes Mixed Culture and Repression of Virulence.

Listeria monocytogenes is the species of foodborne pathogenic bacteria that causes the infection listeriosis. The food production chain employs various methods to control biofilms, although none are completely successful. This study evaluates the effectiveness of quercetin as a food additive in reducing L. monocytogenes mixed cultures (ATCC19113, ATCC19117, and ATCC15313) biofilm formation on stainless steel (SS), silicon rubber (SR), and hand glove (HG) coupons, as well as tests its antimicrobial activities. With a minimum inhibitory concentration (MIC) of 250 µg/mL, the tested quercetin exhibited the lowest bactericidal action with no visible bacterial growth. In contrast, during various experiments in this work, the inhibitory efficacy of quercetin at sub-MICs levels (1/2, 1/4, and 1/8 MIC) against L. monocytogenes was examined. A control group was not added with quercetin. The current study also investigates the effect of quercetin on the expression of different genes engaged in motility (flaA, fbp), QS (agrA), and virulence (hlyA, prfA). Through increasing quercetin concentration, swarming and swimming motility, biofilm formation, and expression levels of target genes linked to flagella motility, virulence, and quorum-sensing were all dramatically reduced. Quercetin (0–125 μg/mL) was investigated on the SS, SR, and HG surfaces; the inhibitory effects were 0.39–2.07, 0.09–1.96 and 0.03–1.69 log CFU/cm2, respectively (p < 0.05). Field-emission scanning electron microscopy (FE-SEM) corroborated the findings because quercetin prevented the development of biofilms by severing cell-to-cell contacts and inducing cell lysis, which resulted in the loss of normal cell shape. Our findings suggest that plant-derived quercetin should be used as an antimicrobial agent in the food industry to control the development of L. monocytogenes biofilms. These outcomes suggest that bacterial targets are of interest for biofilm reduction, with alternative natural food agents in the food sector along the entire food production chain.

The effect of off-bottom versus on-bottom oyster culture on total and pathogenic Vibrio spp. abundances in oyster tissue, water and sediment samples

Varying culture methods are commonly used for eastern oyster, Crassostrea virginica, aquaculture in the Northeast United States. Vibrio vulnificus and V. parahaemolyticus, two human pathogenic bacteria species, accumulate in this edible, filter feeding shellfish. This study examined the use of two methods in an intertidal area (oysters cultured in trays and in bags on sediment) and two methods in a subtidal area (oysters cultured in trays and loose on the sediment) in Massachusetts over the growing season in 2015. Abundance of total V. vulnificus along with total and pathogenic (tdh+/trh+) V. parahaemolyticus were determined in oysters, sediment and water using real-time PCR. Temperature, salinity, turbidity and chlorophyll were continually measured every 15 min at each location.There were significantly higher abundances of total and pathogenic V. parahaemolyticus in on-bottom cultured oysters, while significantly higher abundances of V. vulnificus were identified in oysters from off-bottom culture in a subtidal location in Duxbury Bay, MA. In an intertidal location, Wellfleet Bay, MA, significantly higher abundances of total and tdh+V. parahaemolyticus were found in off-bottom oysters, but significantly higher abundances of V. vulnificus and trh+V. parahaemolyticus were found in on-bottom oysters.Spearman's correlation indicated that temperature is positively associated with concentrations of Vibrio spp. in oysters, water and sediment, but positive correlations between salinity and Vibrio spp. was also observed. Conversely, turbidity had a negative effect on Vibrio spp. concentrations in all sample types. There was no observed relationship inferred between chlorophyll and Vibrio spp. abundances in oysters, water or sediment.

Antibacterial Activity and Components of the Methanol-Phase Extract from Rhizomes of Pharmacophagous Plant Alpinia officinarum Hance.

The rhizomes of Alpinia officinarum Hance (known as the smaller galangal) have been used as a traditional medicine for over 1000 years. Nevertheless, little research is available on the bacteriostatic activity of the herb rhizomes. In this study, we employed, for the first time, a chloroform and methanol extraction method to investigate the antibacterial activity and components of the rhizomes of A. officinarum Hance. The results showed that the growth of five species of pathogenic bacteria was significantly inhibited by the galangal methanol-phase extract (GMPE) (p < 0.05). The GMPE treatment changed the bacterial cell surface hydrophobicity, membrane fluidity and/or permeability. Comparative transcriptomic analyses revealed approximately eleven and ten significantly altered metabolic pathways in representative Gram-positive Staphylococcus aureus and Gram-negative Enterobacter sakazakii pathogens, respectively (p < 0.05), demonstrating different antibacterial action modes. The GMPE was separated further using a preparative high-performance liquid chromatography (Prep-HPLC) technique, and approximately 46 and 45 different compounds in two major component fractions (Fractions 1 and 4, respectively) were identified using ultra-HPLC combined with mass spectrometry (UHPLC-MS) techniques. o-Methoxy cinnamaldehyde (40.12%) and p-octopamine (62.64%) were the most abundant compounds in Fractions 1 and 4, respectively. The results of this study provide data for developing natural products from galangal rhizomes against common pathogenic bacteria.

Pathogen agents from the family Enterobacteriaceae that cause acute diarrheal diseases

The research was conducted in 2017 - 2021, the clinical samples (fecal masses) were collected from patients from the Public Health Medical Institution of AMT Buiucani. A total of 3752 samples were investigated. Two species of pathogenic bacteria from the Enterobacteriaceae family were identified: Shigella spp and Salmonella spp. A total of 28 positive strains (0.75%) were isolated, of which 9 strains (0.24%) belong to the Shigella species and 19 strains (0.51%) - Salmonella. The share of Salmonella strains is 2 times higher compared to Shigella. In 2017, the higher number of strains were isolated - 12, with a share of 1.02%, of which the dominant strain was Salmonella with 0.68%. Of the total number of strains isolated in 2017, both Shigella and Salmonella strains had the largest share.

Changes and Trends of Drug Resistance of Pathogenic Bacteria in Blood Samples of a Tertiary-Level Teaching Hospital from 2016 to 2020

To investigate the distribution of pathogenic bacteria in blood samples and changes in their drug resistance in our hospital from 2016 to 2020, and to provide evidence for the diagnosis and treatment of clinical bloodstream infections. Bruker Corporation's matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for bacterial identification, VITEK 2 Compact was used for antimicrobial susceptibility test, some of which was done with the Kirby-Bauer method, and the data was statistically analyzed with WHONET 5.6 software. A total of 8931 bacterial strains, including 4502 (50.4%) Gram-positive bacteria and 4429 (49.6%) Gram-negative bacteria, were isolated from the blood samples between 2016 and 2020. Among the isolated bacteria of the order Enterobacterales, Escherichia coli (1773, 19.9%) ranked first, followed by Klebsiella pneumoniae (1067, 11.9%). The non-fermenting bacteria identified were predominantly Acinetobacter baumannii (293, 3.3%) and Pseudomonas aeruginosa (238, 2.7%). The top three Staphylococcus species were Staphylococcus epidermidis (970 strains, 10.9%), Staphylococcus hominis (713, 8.0%) and Staphylococcus aureus (541, 6.1%). Escherichia coli showed high in vitro susceptibility to cefoperazone/sulbactam, amikacin, polymyxin B, tigecycline, and carbapenems, and the sensitivity rate was consistently over 90%. The resistance rate to imipenem showed a trend of slow growth, and the resistance rate of meropenem was 2.2% to 3.4%. Klebsiella pneumoniae showed higher in vitro resistance rate to common antibiotics than that of Escherichia coli, with only the sensitivity rates to tigecycline and polymyxin B being higher than 90%, and the resistance rate to imipenem and meropenem increasing year by year. The resistance rate of Pseudomonas aeruginosa to imipenem decreased since 2017 (from 25.6% to18.6%), and the resistance rate of Acinetobacter baumanniito imipenem and meropenem were 73.7%-91.3% and 73.0%-91.3%. Staphylococcus resistant to vancomycin or linezolid was not found. Enterococci showed rather low resistance to vancomycin and linezolid. The distribution of common species of pathogenic bacteria in clinical blood samples in our hospital did not show significant changes, but the problem of multi-drug resistant bacteria is becoming increasingly more serious, especially so for carbapenem-resistant Klebsiella pneumoniae.

The Anti-tuberculosis Battle in Greece in the 1800s and 1900s

Tuberculosis is an infectious disease that mainly affects the lungs (known as pulmonary tuberculosis). Mycobacterium tuberculosis is a species of pathogenic bacteria in the family of Mycobacteriaceae and the causative agent of tuberculosis; it was discovered by Robert Koch in 1882. From about 1918 to 1939, tuberculosis in Greece was characterized as a social disease because it seemed to spread among the lower social classes, including displaced people living in refugee camps. The battle against tuberculosis involved private initiatives aimed at educating people on hygiene and establishing anti-tuberculosis institutions, such as sanatoria and preventoria.

Synthesis, characterization of ‎2-amino-pyran ‎and derivatives evaluation of the bacterial, ‎antioxidant and anticancer activity

Using ethanol as a solvent, heterocyclic hexagonal rings for 2-amino-pyran derivatives (I33-I40) were produced by reacting a mole of chalcones derivatives with a mole of malononitrile. Physical properties such as melting point, colour, and molecular weight and spectroscopic measurements such as the infrared spectrum, [1H-NMR], [13C-NMR] spectrum were used to confirm the accuracy of the prepared compounds' compositions. The biological activity of various produced compounds was investigated in two species of pathogenic bacteria, one of which is Gram-positive, Staphylococcus aureus, and the other, Gram-negative, Escherichia coli. Chemical solutions for the two substances (I25, I32) with concentrations (0,01, 0.001, 0.0001) mg /ml were created using a solvent DMSO and Multer Hinton Agar growth medium. The antibiotic Ciprofloxacin was utilized as a control sample for the diffusion sensitivity test of the bacterial isolates used in the investigation. Using DPPH root and varied concentrations, the impact of chemical (I32) on the elimination of free radicals was also investigated. Breast cancer cells were taken from Baghdad's Medical City and used to test the efficiency of several produced chemicals against them.

Metagenomic insights into the variation of bacterial communities and potential pathogenic bacteria in drinking water treatment and distribution systems

High-throughput sequencing of 16S rRNA gene amplicons was conducted to characterize the changing patterns of bacterial community and potential pathogens in full-scale drinking water treatment and distribution systems. Results showed that Actinobacteria was the predominant phylum in source water, while Proteobacteria dominated after chlorine disinfection and its relative abundance increased from 40.88%±9.45% to 67.86%±27.10%. The genera <italic>Pseudarthrobacter</italic>, <italic>Arenimonas</italic>, and <italic>Limnohabitans</italic> were effectively removed by chlorination, while <italic>Phreatobacter</italic>, <italic>Undibacterium</italic>, <italic>Pseudomonas</italic>, and <italic>Sphingomonas</italic> within the Proteobacteria phylum were greatly enriched after chlorination. Metagenomic analyses revealed the occurrence of 56 species of potential pathogenic bacteria within 17 genera in drinking water, mainly including <italic>Pseudomonas fluorescens</italic> and five mycobacteria species, which were also persistent in tap water samples. The bacteria were found to be involved in various pathways, among which considerable groups were related to human diseases, including infectious diseases and even cancers.

Assessment of cleaning stethoscopes using UV-C sanitation

Background: It is well established that stethoscopes harbor pathogenic bacteria species. Within hospital settings, these pathogens can be rapidly transmitted from room to room and can cause harm in vulnerable populations. The current literature demonstrates that disinfecting stethoscopes with isopropanol kills 99% of all bacteria. However, in practice this rarely occurs and disinfection is subject to user error. We assessed the efficacy of ultraviolet germicidal irradiation (UV-C) at decontaminating stethoscopes used at our rural healthcare system along with the cleaning habits of their users. Methods: Stethoscopes were randomly selected from the clinical staff of our hospital’s largest nursing unit. The stethoscopes were each swabbed for culture then exposed to UV-C for 20 seconds and sampled again. Users were asked to complete a survey during this process. Samples were then cultivated on tryptone soya broth (TSB) agar, and all growth was sent for identification via matrix-assisted laser desorption/ionization (MALDI-TOF). Later, the protocol was repeated to assess cleaning efficacy of the isopropanol wipes commonly used in our hospital. We collected pre- and postintervention samples after cleaning vigorously for 3 minutes according to the manufacturer’s guidelines. The samples were classified as follows: “cleaner” if the number of colonies decreased after sanitation, “sterilized” if the number of colonies decreased to zero, “no change” if the number of colonies stayed the same, and “no assessment” if there was no preintervention growth. Several samples “increased” in CFU count after the intervention, likely due to incomplete sampling, contamination, or incomplete penetration of UV-C. The Fisher exact test was used to analyze the effectiveness of the stethoscope sanitation techniques. Results: In total, 60 samples (33 used for analysis) were obtained from stethoscopes cleaned with UV-C (Fig. 1). Moreover, 34 samples (28 used for analysis) were obtained from stethoscopes cleaned with isopropanol (Fig. 2). Both UV-C (93.9% vs 6.1%; P &lt; .01) and isopropanol (100% vs 0%; P &lt; .01) resulted in a significant decrease in bacterial colonization on stethoscopes. UV-C was not more effective at sanitizing stethoscopes than isopropanol (93.9% vs 100%; P = .50). Conclusions: Both UV-C and isopropanol were effective at cleaning hospital stethoscopes. Given that UV-C is not subject to user error and that it takes less time to clean a stethoscope than isopropanol, it may be the superior option in a clinical setting.Funding: NoneDisclosures: None

Synthesis, spectroscopic, anti-bacterial activity, molecular docking, ADMET, toxicity and DNA binding studies of divalent metal complexes of pyrazole-3-one azo ligand

Treatment equivalent molar of pyrazole-3-one azo (HPyoz) ligand with divalent metal ions {Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)} afforded complexes of the chemical formula [MCl2(H2O)2(HPyoz)] {Co(II), Ni(II), and Cu(II)} or [MCl2(HPyoz)] {Zn(II), Cd(II) and Hg(II)}. The prepared complexes were characterized using IR, 1H, 13C NMR, Uv-visible spectra, xrd, SEM, conductance, and magnetic measurements. The results refer to that the HPyoz ligand behaves as bidentate via the nitrogen of azo group and oxygen of carbonyl group to afforded an octahedral complexes around transition metal ion {Co(II), Ni(II), and Cu(II)} or tetrahedral geometry around 12B group ions {Zn(II), Cd(II) and Hg(II)}. The results obtained from xrd and SEM images unequivocally declared the nano-sized of the prepared complexes. The lately studied compounds were examined for anti-bacterial activities towards four pathogenic species of bacteria. Molecular docking had been done based on screening against different targets, that show the good binding affinity of tested compounds with nucleoside diphosphate kinase (target site PDB ID: 3Q89), it's an important enzyme that generates nucleoside triphosphates (NTPs) or their deoxy derivatives by terminal phosphor-transfer from an NTP such as ATP or GTP to any nucleoside diphosphate or its deoxy derivative. As NTPs, particularly GTP, are important for cellular macromolecular synthesis and signaling mechanisms, Ndk plays an important role in bacterial growth, signal transduction and pathogenicity. In addition, The DNA binding properties of prepared complexes were evaluated. The intrinsic binding constant is calculated as 6.79 × 105, 4.72 × 105, 1.89 × 105 and 4.12 × 105M − 1 for the Ni-complex, Co-complex, Cu-complex and Zn-complex, and these results establish good binding characteristics of the prepared complexes with DNA

Molecular typing and prevalence of antibiotic resistance and virulence genes in Streptococcus agalactiae isolated from Chinese dairy cows with clinical mastitis.

Bovine mastitis is a common disease occurring in dairy farms and can be caused by more than 150 species of pathogenic bacteria. One of the most common causative organisms is Streptococcus agalactiae, which is also potentially harmful to humans and aquatic animals. At present, research on S. agalactiae in China is mostly concentrated in the northern region, with limited research in the southeastern and southwestern regions. In this study, a total of 313 clinical mastitis samples from large-scale dairy farms in five regions of Sichuan were collected for isolation of S. agalactiae. The epidemiological distribution of S. agalactiae was inferred by serotyping isolates with multiplex polymerase chain reaction. Susceptibility testing and drug resistance genes were detected to guide the clinical use of antibiotics. Virulence genes were also detected to deduce the pathogenicity of S. agalactiae in Sichuan Province. One hundred and five strains of S. agalactiae (33.6%) were isolated according to phenotypic features, biochemical characteristics, and 16S rRNA sequencing. Serotype multiplex polymerase chain reaction analysis showed that all isolates were of type Ia. The isolates were up to 100% sensitive to aminoglycosides (kanamycin, gentamicin, neomycin, and tobramycin), and the resistance rate to β-lactams (penicillin, amoxicillin, ceftazidime, and piperacillin) was up to 98.1%. The TEM gene (β-lactam-resistant) was detected in all isolates, which was in accordance with a drug-resistant phenotype. Analysis of virulence genes showed that all isolates harbored the cfb, cylE, fbsA, fbsB, hylB, and α-enolase genes and none harbored bac or lmb. These data could aid in the prevention and control of mastitis and improve our understanding of epidemiological trends in dairy cows infected with S. agalactiae in Sichuan Province.

Bacterial Indicators of Contamination in Highly Impacted Segment of Tropical Lagoon, Southwest Nigeria

Increasing deterioration of coastal waters is a major public health concern in many regions of the developing world. This study investigates the impact of water quality on the proliferation of bacterial pathogens in surface water, sediment and tissues of fish, Sarotherodon melanotheron from the Makoko axis of Lagos Lagoon. Analysis of physicochemical characteristics and microbial quality of samples followed standard methods and procedures. Measured water quality parameters (water temperature, turbidity, pH, salinity and dissolved oxygen) which showed no significant variation (p&gt;0.05) across study stations were within the Nigerian Federal Environmental Protection Agency set limit The highest total bacterial count (TBC) (214.09±43.95 x 105 CFU g-1), total coliform counts (TCC) (91.15±15.05 ×104 CFU g-1) and total faecal coliform (TFC) (36.22±12.98×10³ CFU g-1) were recorded in fish muscle tissue while the lowest TBC (52.39±39.72 x 105 CFU ml-1), TCC (33.45±33.94 ×104 CFU ml-1) and TFC (0.19±0.18×10³ CFU ml-1) were recorded in water sample. The bacterial species with the highest percentages of occurrence in water, sediment, fish gill and fish muscle tissue were Klebsiella pneumoniae (22.11 %), Enterobacter aerogenes (32.37 %), Escherichia coli (32.97 %) and E. coli (29.00 %) respectively. A very strong positive correlation (r = 1.00) was obtained between TBC in water and salinity as well as with dissolved oxygen levels. Likewise, the TBCs in fish parts (muscle tissue and gill) were positively correlated with the water temperature and turbidity. On the other hand, a negative correlation was obtained between pH and TBC in fish muscle tissue (r = -0.81) as well as with fish gut (r = -0.77). The relatively high counts of pathogenic bacteria species recorded during the study have serious public health implications.

Nanocomposites of Graphene Oxide-Silver Nanoparticles for Enhanced Antibacterial Activity: Mechanism of Action and Medical Textiles Coating.

The resistance of microorganisms to antibiotics is a crucial problem for which the application of nanomaterials is among a growing number of solutions. The aim of the study was to create a nanocomposite (composed of graphene oxide and silver nanoparticles) with a precise mode of antibacterial action: what enables textiles to be coated in order to exhibit antibacterial properties. A characterization of nanomaterials (silver nanoparticles and graphene oxide) by size distribution, zeta potential measurements, TEM visualization and FT-IR was performed. The biological studies of the nanocomposite and its components included the toxicity effect toward two pathogenic bacteria species, namely Pseudomonas aeruginosa and Staphylococcus aureus, interaction of nanomaterials with the outer layer of microorganisms, and the generation of reactive oxygen species and lipid peroxidation. Afterwards, antibacterial studies of the nanocomposite’s coated textiles (cotton, interlining fabric, polypropylene and silk) as well as studies of the general toxicity towards a chicken embryo chorioallantoic membrane model were conducted. The toxicity of the nanocomposite used was higher than its components applied separately (zones of growth inhibition for P. aeruginosa for the final selected concentrations were as follows: silver nanoparticles 21 ± 0.7 mm, graphene oxide 14 ± 1.9 mm and nanocomposite 23 ± 1.6 mm; and for S. aureus were: silver nanoparticles 27 ± 3.8 mm, graphene oxide 14 ± 2.1 mm, and nanocomposite 28 ± 0.4 mm. The viability of P. aeruginosa and S. aureus after treatment with selected GO-Ag decreased to 27% and 31%, respectively, compared to AgNPs, when the viability of both species was 31% and 34%, accordingly). The coated textiles showed encouraging antibacterial features without general toxicity towards the chicken embryo chorioallantoic membrane model. We demonstrated that graphene oxide might constitute a functional platform for silver nanoparticles, improving the antibacterial properties of bare silver. Due to the application of the nanocomposite, the textiles showed promising antibacterial features with a low general toxicity, thereby creating a wide possibility for them to be used in practice.

Application of Metal Nanoparticles for Production of Self-Sterilizing Coatings

Metal nanoparticles (NPs) are increasingly being used in many areas, e.g., industry, pharmacy, and biomedical engineering. NPs can be obtained through chemical and biological synthesis or using physical methods. AgNPs, AuNPs, CuNPs, FeNPs, MgNPs, SnO2NPs, TiO2NPs, and ZnONPs are the most commonly synthesized metal nanoparticles. Many of them have anti-microbial properties and documented activity supported by many tests against some species of pathogenic bacteria, viruses, and fungi. AgNPs, which are used for the production of commercial self-sterilizing packages, are one of the best-explored nanoparticles. Moreover, the EFSA has approved the use of small doses of silver nanoparticles (0.05 mg Ag·kg−1) to food products. Recent studies have shown that metal NPs can be used for the production of coatings to prevent the spread of the SARS-CoV-2 virus, which has caused the global pandemic. Some nanoparticles (e.g., ZnONPs and MgONPs) have the Generally Recognized As Safe (GRAS) status, i.e., they are considered safe for consumption and can be used for the production of edible coatings, protecting food against spoilage. Promising results have been obtained in research on the use of more than one type of nanometals, which prevents the development of pathogen resistance through various mechanisms of inactivation thereof.

Identification of bacteria by poly-aromatic hydrocarbon biosensors.

Human health is consistently threatened by different species of pathogenic bacteria. To fight the spread of diseases, it is important to develop rapid methods for bacterial identification. Over the years, different kinds of biosensors were developed for this cause. Another environmental risk is poly-aromatic hydrocarbons (PAHs) that may be emitted from industrial facilities and pollute environmental water and soil. One of the methods for their purification is conducted by the addition of bacteria that can degrade the PAHs, while the bacteria can be filtrated at the end of the process. Although many studies reported monitoring of the PAHs degradation by fluorescence, not much attention was dedicated to studying the influence of the PAHs on the intrinsic fluorescence of the degrading bacteria. In this work, we apply synchronous fluorescence (SF) measurements to study the ability of the 5 PAHs: 9-Antracene carboxylic acid (9ACA), Pyrene, Perylene, Pentacene, and Chrysene to interact with bacteria and change its fluorescence spectra. We show that upon incubation of each PAH with the bacterium E. coli, only the 2 PAHs 9ACA and Perylene cause an intensity decrease in the emission at λ = 300-375nm, which derives from the emission of tyrosine and tryptophan (TT). Also, we show that upon incubation of 9ACA and Perylene with 5 different pathogenic bacteria, the intensity increase or decrease in the TT emission is unique to each bacterial species. Based on this observation, we suggest that the PAHs 9ACA and Perylene can be utilized as biosensors for bacterial identification.

Evaluation of the Antimicrobial Effect of Graphene Oxide Fiber on Fish Bacteria for Application in Aquaculture Systems.

The growing importance of the domestic aquaculture industry has led not only to its continuous development and expansion but also to an increase in the production of wastewater containing pathogenic microorganisms and antibiotic-resistant bacteria. As the existing water purification facilities have a high initial cost of construction, operation, and maintenance, it is necessary to develop an economical solution. Graphene oxide (GO) is a carbon-based nanomaterial that is easy to manufacture, inexpensive and has excellent antimicrobial properties. In this study, the antimicrobial effect of GO polyester fibers on seven species of fish pathogenic bacteria was analyzed to evaluate their effectiveness in water treatment systems and related products. As a result of incubating GO polyester fibers with seven types of fish pathogenic bacteria for 1, 6, and 12 h, there was no antimicrobial effect in Vibrio harveyi, V. scopthalmi, and Edwardsiella tarda. In contrast, GO fibers showed antimicrobial effects of more than 99% against A. hydrophila, S. parauberis, S. iniae, and P. piscicola, suggesting the potential use of GO fibers in water treatment systems.

Identification of Antibacterial Components in the Methanol-Phase Extract from Edible Herbaceous Plant Rumex madaio Makino and Their Antibacterial Action Modes.

Outbreaks and prevalence of infectious diseases worldwide are some of the major contributors to morbidity and morbidity in humans. Pharmacophageous plants are the best source for searching antibacterial compounds with low toxicity to humans. In this study, we identified, for the first time, antibacterial components and action modes of methanol-phase extract from such one edible herbaceous plant Rumex madaio Makino. The bacteriostatic rate of the extract was 75% against 23 species of common pathogenic bacteria. The extract was further purified using the preparative high-performance liquid chromatography (Prep-HPLC) technique, and five separated componential complexes (CC) were obtained. Among these, the CC 1 significantly increased cell surface hydrophobicity and membrane permeability and decreased membrane fluidity, which damaged cell structure integrity of Gram-positive and -negative pathogens tested. A total of 58 different compounds in the extract were identified using ultra-HPLC and mass spectrometry (UHPLC-MS) techniques. Comparative transcriptomic analyses revealed a number of differentially expressed genes and various changed metabolic pathways mediated by the CC1 action, such as down-regulated carbohydrate transport and/or utilization and energy metabolism in four pathogenic strains tested. Overall, the results in this study demonstrated that the CC1 from R. madaio Makino are promising candidates for antibacterial medicine and human health care products.

Zinc(II) Complexes of Schiff Bases Derived from Bis-(2-hydrazino-1,3,4-thiadiazole-5- yl)Arene/Alkanes: Synthesis, Spectral Characterization and Biological Properties

A novel series of zinc(II) complexes of type [ZnL(H2O)2], has been synthesized by the reaction of zinc(II) acetate dihydrate with Schiff bases (H2L) derived from bis-(2-hydrazino-1,3,4-thiadiazole-5- yl)arene/alkanes and 2-hydroxynaphthaldehyde/3,5-dichlorosalicyldehyde in presence of a base. The structures of all the zinc complexes were proposed by elemental analysis and spectroscopic data (IR, 1H, 13C NMR). TGA investigations were carried out to confirm the presence of coordinated water molecules in the zinc complexes. The powder crystal structure of one particular zinc complex has been analyzed by XRD diffraction method and SEM studies have been carried out to investigate the surface morphology. The biological studies reveal that the synthesized zinc complexes possess good antimicrobial properties against different species of pathogenic fungi and bacteria.