Reference Microorganisms Research Articles

Bioactive Content and in vitro Antioxidant and Enzyme-Inhibitory Potential of Leaf and Fruits of Parsnip (Pastinaca sativa L. subsp. Urens)

Parsnip (Pastinaca sativa L. subsp. urens) is one of the species of Pastinaca genus. This plant has been traditionally used worldwide for the treatment of various diseases and cultivated for its nutritional values. The aim of this study was to determine the antimicrobial and enzyme-inhibitory potentials of the fruits and leaves of parsnips as well as their bioactive properties such as their antioxidant activities, total phenolic and flavonoid contents in their hexane and ethanol extracts. The total phenolic and flavonoid contents were determined using Folin-Ciocalteu and aluminum chloride colorimetric methods, respectively. The antioxidant activities of extracts were determined by three methods of DPPH and ABTS radical scavenging activities and iron-chelating ability. In the leaves, the highest total phenolic content (60.94 mg GAE/g extract) was found in ethanol extracts while the highest total flavonoid content (21.47 mg RuE/g extract) was determined in hexane extracts. Ethanol extracts of leaves showed the highest radical scavenging activities in both assays of DPPH and ABTS with the IC50 values of 1039±1.35 and 150.7±0.81 µg/mL, respectively. Growth inhibition zone diameters (mm) of PSFE, PSLE, PSFH, PSLH (2 mg/mL) against reference microorganisms were -/-/15/15, -/-/15/14, 10/10/22/15, -/-/15/14 and MIC values -20>/20>/20>/20>, 20>/20>/20>/2.5, 0.625/10/-/-, 20>/20>/20>/20> mg/mL for Staphylococcus aureus ATCC6538, Micrococcus luteus ATCC9341, Bacillus subtilis ATCC6633, Candida albicans ATCC14053, respectively. Antimicrobial activity was not determined against other reference microorganisms.

In Vitro Antimicrobial Activity of Volatile Compounds from the Lichen Pseudevernia furfuracea (L.) Zopf. Against Multidrug-Resistant Bacteria and Fish Pathogens.

Lichens are symbiotic organisms with unique secondary metabolism. Various metabolites from lichens have shown antimicrobial activity. Nevertheless, very few studies have investigated the antimicrobial potential of the volatile compounds they produce. This study investigates the chemical composition and antimicrobial properties of volatile compounds from Pseudevernia furfuracea collected in two regions of Morocco. Hydrodistillation was used to obtain volatile compounds from samples collected in the High Atlas and Middle Atlas. Gas chromatography-mass spectrometry (GC-MS) analysis identified phenolic cyclic compounds as the primary constituents, with atraric acid and chloroatranol being the most abundant. Additionally, eight compounds were detected in lichens for the first time. The antimicrobial activity of these compounds was assessed using disc diffusion and broth microdilution methods. Both samples demonstrated significant antimicrobial effects against multidrug-resistant human bacteria, reference microorganisms, fish pathogens, and Candida albicans, with minimum inhibitory concentrations (MICs) ranging from 1000 µg/mL to 31.25 µg/mL. This study provides the first report on the volatile compounds from Pseudevernia furfuracea and their antimicrobial effects, particularly against fish pathogens, suggesting their potential as novel antimicrobial agents for human and veterinary use. Further research is warranted to explore these findings in more detail.

Inhibition of Microbial Growth and Biofilm Formation in Pure and Mixed Bacterial Samples.

Hydraulic fracturing, or fracking, requires large amounts of water to extract fossil fuel from rock formations. As a result of hydraulic fracturing, the briny wastewater, often termed back-produced fracturing or fracking water (FW), is pumped into holding ponds. One of the biggest challenges with produced water management is controlling microbial activity that could reduce the pond water's reusable layer and pose a significant environmental hazard. This study focuses on the characterization of back-produced water that has been hydraulically fractured using chemical and biological analysis and the development of a high-throughput screening method to evaluate and predict the antimicrobial effect of four naturally and commercially available acidic inhibitors (edetic acid, boric acid, tannic acid, and lactic acid) on the growth of the FW microbiome. Liquid cultures and biofilms of two laboratory model strains, the vegetative Escherichia coli MG1655, and the spore-forming Bacillus atrophaeus (also known as Bacillus globigii, BG) bacteria, were used as reference microorganisms. Planktonic bacteria in FW were more sensitive to antimicrobials than sessile bacteria in biofilms. Spore-forming BG bacteria exhibited more sensitivity to acidic inhibitors than the vegetative E. coli cells. Organic acids were the most effective bacterial growth inhibitors in liquid culture and biofilm.

Enhanced antimicrobial efficacy of chlorhexidine-encapsulated halloysite nanotubes incorporated in presurgical orthopedic appliances: an in vitro, controlled study.

Presurgical infant's orthopedic appliances (PSIOs) play an increasingly crucial role in the interdisciplinary management of neonatal CLP, aiming to improve and maintain adequate nasolabial aesthetics, followed by primary lip/nasal surgery in both unilateral and bilateral CLP cases. The use of PSIOs in cleft lip and palate patients can lead to contamination with oral microflora, acting as a potential reservoir for infectious microorganisms. Acrylic surfaces might provide retention niches for microorganisms to adhere, and inhabit, which is difficult to control in immunocompromised patients, thus predisposing them to increased infection risks. The objective of this multi-assay in vitro study was to investigate the effects of incorporating chlorhexidine-loaded halloysite nanotubes (CHX-HNTs) fillers on the morphological, cytotoxic, release, and antimicrobial characteristics of self-cured acrylic polymethyl methacrylate (PMMA) material used in pre-surgical orthopedic appliances. Disk-shaped PMMA specimens were prepared with varying proportions of CHX-HNTs. A control group without any addition served as a reference, and four experimental samples contained a range of different concentrations of CHX-HNTs (1.0, 1.5, 3, and 4.5 wt%). The antimicrobial efficacy was assessed using an agar diffusion test against common reference microorganisms: Candida albicans, Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus agalactiae. Cytotoxicity was examined using the L929 cell line (mouse fibroblasts) through a (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide, MTT) cell viability assay. The release kinetics of CHX were monitored using UV-spectral measurements. The statistical analysis used a one-way ANOVA followed by Tukey's post hoc test. The integration of CHX-HNTs in PMMA exhibited a substantial dose-dependent antifungal and antibacterial effect against microorganisms at tested mass fractions (1.0 to 4.5 wt%). CHX release was sustained for up to 60 days, supporting prolonged antimicrobial activity. Furthermore, no significant cytotoxicity was determined in the L929 fibroblast cell line (control), indicating the biocompatibility of the CHX-HNTs-enhanced PMMA. Incorporating CHX-HNTs in PMMA successfully enhanced its antimicrobial properties, providing sustained CHX release and superior antimicrobial efficacy. These findings demonstrate the potential of antimicrobial nanoparticles in dental therapies to improve therapeutic outcomes. However, rigorous further clinical trials and observational studies are warranted to validate the practical application, safety, and efficacy. This study has the potential to make a major impact on the health of infants born with cleft lip and palate by helping to reduce the prevalence of infectious illnesses. The incorporation of CHX-HNTs into PMMA-based appliances is a novel promising preventive approach to reduce microbial infections.

P-037 Zinc oxide/collagen (ZnOC) biocomposites for the development of novel meshes

Abstract When we talk about abdominal wall hernias, we are talking about a complex surgical approach. In recent years there is a special interest in the use and development of meshes with antimicrobial properties. Doctors are making efforts to continue progress in this area. We propose the development of meshes covered with Zinc Oxide in a collagen matrix. They have biomedical applications and antimicrobial properties. The objectives of the study are to highlight the major contributions that Zinc Oxide in collagen matrices could make, in the development of new antimicrobial properties. The research will test both the synthesis method of Zinc Oxide in collagen matrix, as well as its ability to inhibit the bacterial activity of different species of bacteria. We demonstrate the significant contributions that could be made by using composites based on Zinc Oxide in collagen matrices for the development of new biocompatible medical devices with antimicrobial properties. This will lead to important advances in the development of new networks based on Zinc Oxide in collagen matrix (ZnOC). Physicochemical characterization of ZnOC composites was performed, using appropriate techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM and EDS) and transmission electron microscopy (TEM), infrared spectroscopy (FTIR). The antimicrobial properties of ZnOC biocomposites was investigated using clinical and reference microorganisms belonging to Gram positive, Gram negative and fungal families.

Secondary Metabolites From the Grasshopper-Derived Entomopathogenic Fungus Aspergillus Tamarii NL3 and Their Biological Activities

Chromatographic purification of the ethyl acetate extract of the entomopathogenic fungus Aspergillus tamarii NL3 culture broth led to the isolation of griseofulvin (1), isogriseofulvin (2), cytochalasin J (3), solamargine (4), and solasonine (5). The chemical structures of these compounds were identified by HRESIMS and NMR spectra, as well as by comparison with literature data. This is the first report on the isolation of 1-4 from the Aspergillus genus and compound 5 from A tamarii. Compounds 1 and 2 exhibited antifungal activity against the reference fungi with MICs of 16 to 128 µg/mL. Compound 3 displayed weak antimicrobial activity against most of the tested microorganisms with MICs ≥ 128 µg/mL, except for Bacillus subtilis and Aspergillus niger with MICs of 64 µg/mL. Compounds 4 and 5 showed activity against a wide spectrum of the reference microorganisms with MICs of 16 to 128 µg/mL but showed stronger antifungal than antibacterial activity. Furthermore, all isolates exhibited weak ABTS and DPPH scavenging activities with scavenging rates of 18.92% to 32.64% and 24.62% to 31.06%, respectively, at the concentration of 100 µg/mL.

Evaluation of the Antimicrobial Efficacy of Different Intracanal Medications on Enterococcus Faecalis Biofilm: A Comparative In-Vitro Study

The total elimination of microorganisms during endodontic therapy, although it is desired, is difficult to achieve. Even after canal filling, microorganisms can be in the dentin mass and periapical region. This study aims to evaluate in vitro the antibacterial efficacy of different intracanal medications on an Enterococcus faecalis biofilm. It was used reference microorganisms, Enterococcus faecalis NEWP0012, where the bacterial suspension was seeded uniformly on Mueller Hinton (MH) agar. The plates were incubated under aerobic conditions, at a constant temperature in the range of 35°C-37°C, for 24 hours. The intracanal medications tested were: G1 Calcium hydroxide associated with 2% Chlorhexidine, G2 Calcium hydroxide associated with ozone stratum, G3 Calcium hydroxide associated with paramonochlorophenol, G4 Calcium hydroxide associated with Otosporin®, G5 Calcium hydroxide, G6 2% Chlorhexidine, G7 Ozone extract, G8 Paramonochlorophenol, G9 Otosporin®, G10 Saline solution, G11 Calcium hydroxide associated with iodoform, G12 Iodoform, G13 Calcium hydroxide associated with NDP, G14 NDP. After handling the materials, they were impregnated on 5 mm diameter absorbent paper discs and distributed equidistantly on the plates seeded with the microorganism. The experimental data were obtained by measuring the zone of inhibition within 24 h, 72 h, and 7 days. In this way, the microorganism was classified as resistant or sensitive to the different products. The test was reproduced 3times. After analysis, it was observed that within 24 hours, 7 hours, and 7 days, only the groups G1 Calcium hydroxide associated with 2% chlorhexidine (18mm of halo of inhibition), G5 Calcium hydroxide (13mm of halo of inhibition), G6 2% chlorhexidine (16mm of halo of inhibition) and G9 Otosporin® (9 mm of halo of inhibition) showed a halo of inhibition in the time intervals. However, the groups did not show halo of inhibition, being ineffective against E. faecalis. According to the obtained data, chlorhexidine gel 2% showed larger halos of inhibition, however, calcium hydroxide was associated with chlorhexidine gel 2%, calcium hydroxide and Otosporin®. Therefore, new research with different methods should be used to verify the efficacy of the medications used, since they presented divergence compared to another research already carried out.

Evaluation of the Microbiological Effectiveness of Three Accessible Mask Decontamination Methods and Their Impact on Filtration, Air Permeability and Physicochemical Properties.

The need to secure public health and mitigate the environmental impact associated with the massified use of respiratory protective devices (RPD) has been raising awareness for the safe reuse of decontaminated masks by individuals and organizations. Among the decontamination treatments proposed, in this work, three methods with the potential to be adopted by households and organizations of different sizes were analysed: contact with nebulized hydrogen peroxide (H2O2); immersion in commercial bleach (NaClO) (sodium hypochlorite, 0.1% p/v); and contact with steam in microwave steam-sanitizing bags (steam bag). Their decontamination effectiveness was assessed using reference microorganisms following international standards (issued by ISO and FDA). Furthermore, the impact on filtration efficiency, air permeability and several physicochemical and structural characteristics of the masks, were evaluated for untreated masks and after 1, 5 and 10 cycles of treatment. Three types of RPD were analysed: surgical, KN95, and cloth masks. Results demonstrated that the H2O2 protocol sterilized KN95 and surgical masks (reduction of >6 log10 CFUs) and disinfected cloth masks (reduction of >3 log10 CFUs). The NaClO protocol sterilized surgical masks, and disinfected KN95 and cloth masks. Steam bags sterilized KN95 and disinfected surgical and cloth masks. No relevant impact was observed on filtration efficiency.

Phytochemical Profile and Biological Activity of the Ethanolic Extract from the Aerial Part of Crocus alatavicus Regel & Semen Growing Wildly in Southern Kazakhstan.

The composition of the ethanolic extract from the aerial parts of Crocus alatavicus Regel & Semen from southern Kazakhstan spontaneous flora was analyzed together with the determination of its antibacterial, antifungal, antiviral and anticancer activity. The phytochemical profile analysis by high-performance liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry (HPLC/ESI-QTOF-MS) revealed the presence of multiple kaempferol derivatives. High-performance reverse-phase liquid chromatography combined with a photodiode-array detection (RP-HPLC/PDA) found that kaempferol 3-O-dihexoside and kaempferol 3-O-acyltetrahexoside accounted for 70.5% of the kaempferol derivatives. The minimum inhibitory concentration (MIC) values of the extract for all the tested reference microorganisms were high, reaching 10 mg/mL for yeasts and 20 mg/mL for bacteria. In contrast, antiviral activity was observed at 2 mg/mL, resulting in the inhibition of the HSV-1-induced cytopathic effect and the reduction in virus infectious titer by 1.96 log, as well as the viral load by 0.85 log. Among the tested prostate cancer cell lines, significant cytotoxic activity of the extract was noted only on the LNCaP cell line, with an IC50 value of 1.95 mg/mL. The LNCaP cell line treated with 2 mg/mL of the extract showed a noticeably reduced number of spindle-shaped cells with longer cellular projections, a significant increase in the peak corresponding to the population of apoptotic cells in the sub-G1 phase and a decreased intracellular glutathione (GSH) level, suggesting the prooxidative properties of the extract. The obtained data provide novel information about the flavonoids present in the aerial part of C. alatavicus and suggest its potential application as a source of the compounds active against HSV-1 and metastatic, androgen-sensitive prostate cancer.

Microbial Contamination and Survival Rate on Different Types of Banknotes.

In the COVID-19 pandemic context, numerous concerns have been raised regarding the hygienic status of certain objects we interact with on a daily basis, and especially cash money and their potential to harbor and transmit pathogenic bacteria. Therefore, in the present study, we analyzed different currency bills represented by British pounds (5 £, 10 £ and 20 £), Romanian lei (1 leu, 5 lei and 10 lei), U.S. dollars (1 $, 5 $ and 10 $) and Euros (5 €, 10 € and 20 €) in order to evaluate the bacterial survival rate and bacterial adherence. We used five reference microorganisms by American Type Culture Collection (ATCC, Manassas, VA, USA): Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Enterococcus sp. ATCC 19952, Salmonella enterica subsp. enterica serovar Typhi ATCC 6539, and Listeria monocytogenes ATCC 7644. Microorganisms were selected in accordance with the criteria of prevalence, pathogenicity, opportunism, and incidence. However, Maldi-TOF analysis from samples taken from the banknotes revealed only a few of the common pathogens that are traditionally thought to be found on banknotes. Some of the most important factors for the survival of pathogenic agents on surfaces are the presence of organic matter, temperature and humidity. Our data showed that Salmonella enterica survived 72 h on every banknote tested, while L. monocytogenes tended to improve persistence in humid conditions. Survival rate is also influenced by the substrate composition, being lower for polymer-based banknotes especially for Salmonella enterica, Listeria monocytogenes and Enterococcus sp. The adherence of bacterial strains was lower for polymer-based banknotes British pounds and Romanian Leu, in contrast to the cotton-based U.S dollars and Euro banknotes. The risk of bacterial contamination from the banknote bills is high as indicated by both a strong survival capacity and low adherence of tested bacteria with differences between the two types of materials used for the tested banknotes.

Basic physiology of Pseudomonas aeruginosa contacted with carbon nanocomposites

Experiments describing properties of nanomaterials on bacteria are frequently limited to the disk diffusion method or other end-point methods indicating viability or survival rate in plate count assay. Such experimental design does not show the dynamic changes in bacterial physiology, mainly when performed on reference microorganisms (Escherichia coli and Staphylococcus aureus). Testing other microorganisms, such as Pseudomonas aeruginosa, could provide novel insights into the microbial response to nanomaterials. Therefore, we aimed to test selected carbon nanomaterials and their components in a series of experiments describing the basic physiology of P. aeruginosa. Concentrations ranging from 15.625 to 1000 µg/mL were tested. The optical density of cultures, pigment production, respiration, growth curve analysis, and biofilming were tested. The results confirmed variability in the response of P. aeruginosa to tested nanostructures, depending on their concentration. The co-incubation with the nanostructures (in concentration 125 µg/mL) could inhibit the population growth (in most cases) or promote it in the case of graphene oxide. Furthermore, a specific concentration of a given nanomaterial could cause contradictory effects leading to stimulation or inhibition of pigmentation, an optical density of the cultures, or biofilm formation. We have found that particularly nanomaterials containing TiO2 could induce pigmentation in P. aeruginosa, which indicates the possibility of increased virulence. On the other hand, nanocomposites containing cobalt nanoparticles had the highest anti-bacterial potential when cobalt was displayed on the surface. Our approach revealed changes in respiration and growth dynamics that can be used to search for nanomaterials’ application in biotechnology.

Design of InnoPrimers-Duplex Real-Time PCR for Detection and Treatment Response Prediction of EBV-Associated Nasopharyngeal Carcinoma Circulating Genetic Biomarker.

Nasopharyngeal carcinoma (NPC) is an epithelial tumor with high prevalence in southern China and Southeast Asia. NPC is well associated with the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) 30 bp deletion by having its vital role in increased tumorigenicity and decreased immune recognition of EBV-related tumors. This study developed an InnoPrimers-duplex qPCR for detection of NPC blood circulating LMP1 30 bp deletion genetic biomarker for early diagnosis and treatment response prediction of NPC patients. The analytical and diagnostic evaluation and treatment response prediction were conducted using NPC patients’ whole blood (WB) and tissue samples and non-NPC cancer patients and healthy individuals’ WB samples. The assay was able to detect as low as 20 ag DNA per reaction (equivalent to 173 copies) with high specificity against broad reference microorganisms and archive NPC biopsy tissue and FNA samples. The diagnostic sensitivity and specificity were 83.3% and 100%, respectively. The 30 bp deletion genetic biomarker was found to be a good prognostic biomarker associated with overall clinical outcome of NPC WHO type III patients. This sensitive and specific assay can help clinicians in early diagnosis and treatment response prediction of NPC patients, which will enhance treatment outcome and lead to better life-saving.

Evaluation of antibacterial and antifungal properties of selected mouthwashes: in vitro studies

Abstract Introduction. Mouthwashes should include antimicrobial compounds to inhibit microorganism multiplication, thus the formation and development of dental plaque. Aim. The aim of the study was to evaluate the antibacterial and antifungal effectiveness of mouthwashes depending on their active ingredients. Material and methods. In the study, the effect of antibacterial and antifungal properties of mouthwashes on reference bacterial and yeast-like fungi strains was examined. The first type of the assessed mouthwashes contained only sodium fluoride or sodium fluoride and amine fluoride as active ingredients, while the second type contained sodium fluoride and cetylpyridinium chloride. In the study, a well diffusion method was used to test microorganisms constituting natural or pathogenic microflora of oral mucosa. The used reference microorganisms came from the ATCC: L. acidophilus ATCC 4356, Lactobacillus rhamnosus ATCC 53103, S. mutans ATCC 25175, and Candida yeasts: C. albicans ATCC 2091, C. albicans ATCC 10231, Candida parapsilosis ATCC 22019, Candida glabrata ATCC 90030, Candida krusei ATCC 14243. Results. The mouthwashes containing sodium fluoride and cetylpyridinium chloride showed an inhibitory effect against a greater number of reference strains used in the study than did mouthwashes that contained only sodium fluoride (or sodium fluoride and amine fluoride) as active ingredients. Against the four reference strains of Candida genus, the mouthwashes with an inorganic and organic fluoride compound showed no or minimum inhibitory effect or were much less effective than the mouthwashes that also contained cetylpyridinium chloride. Conclusion. Mouthwashes containing multiple ingredients with different antimicrobial mechanisms show synergistic action against the bacterial and fungal microflora responsible for the accumulation of dental plague.

Diversity and Antimicrobial Activity of Vietnamese Sponge-Associated Bacteria.

This study aimed to assess the diversity and antimicrobial activity of cultivable bacteria associated with Vietnamese sponges. In total, 460 bacterial isolates were obtained from 18 marine sponges. Of these, 58.3% belonged to Proteobacteria, 16.5% to Actinobacteria, 18.0% to Firmicutes, and 7.2% to Bacteroidetes. At the genus level, isolated strains belonged to 55 genera, of which several genera, such as Bacillus, Pseudovibrio, Ruegeria, Vibrio, and Streptomyces, were the most predominant. Culture media influenced the cultivable bacterial composition, whereas, from different sponge species, similar cultivable bacteria were recovered. Interestingly, there was little overlap of bacterial composition associated with sponges when the taxa isolated were compared to cultivation-independent data. Subsequent antimicrobial assays showed that 90 isolated strains exhibited antimicrobial activity against at least one of seven indicator microorganisms. From the culture broth of the isolated strain with the strongest activity (Bacillus sp. M1_CRV_171), four secondary metabolites were isolated and identified, including cyclo(L-Pro-L-Tyr) (1), macrolactin A (2), macrolactin H (3), and 15,17-epoxy-16-hydroxy macrolactin A (4). Of these, compounds 2-4 exhibited antimicrobial activity against a broad spectrum of reference microorganisms.

Association of Gut Microbiota during Early Pregnancy with Risk of Incident Gestational Diabetes Mellitus.

We aimed to assess the association between gut bacterial biomarkers during early pregnancy and subsequent risk of gestational diabetes mellitus (GDM) in Chinese pregnant women. Within the Tongji-Shuangliu Birth Cohort study, we conducted a nested case-control study among 201 incident GDM cases and 201 matched controls. Fecal samples were collected during early pregnancy (at 6-15 weeks), and GDM was diagnosed at 24 to 28 weeks of pregnancy. Community DNA isolated from fecal samples and V3-V4 region of 16S rRNA gene amplicon libraries were sequenced. In GDM cases versus controls, Rothia, Actinomyces, Bifidobacterium, Adlercreutzia, and Coriobacteriaceae and Lachnospiraceae spp. were significantly reduced, while Enterobacteriaceae, Ruminococcaceae spp., and Veillonellaceae were overrepresented. In addition, the abundance of Staphylococcus relative to Clostridium, Roseburia, and Coriobacteriaceae as reference microorganisms were positively correlated with fasting blood glucose, 1-hour and 2-hour postprandial glucose levels. Adding microbial taxa to the base GDM prediction model with conventional risk factors increased the C-statistic significantly (P < 0.001) from 0.69 to 0.75. Gut microbiota during early pregnancy was associated with subsequent risk of GDM. Several beneficial and commensal gut microorganisms showed inverse relations with incident GDM, while opportunistic pathogenic members were related to higher risk of incident GDM and positively correlated with glucose levels on OGTT.

Biosynthesis of Silver Nanoparticles by Aspergillus terreus: Characterization, Optimization, and Biological Activities.

In this study, mycelial filtrate of Aspergillus terreus BA6 was used to reduce AgNO3 to form silver nanoparticles (AgNPs). The effect of seven independent variables on the diameter of AgNPs was studied by applying design of experiments (DOE). At optimal conditions, the diameter of AgNPs was reduced by approximately 26.7% compared to the basal culture condition and AgNO3 concentration was found to be the most significant factor affecting the diameter of AgNPs. A. terreus nano-Ag was characterized using UV-visible spectroscopy, transmission electron microscopy, energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zeta potential. The maximum UV absorption was obtained at 420 nm and the microscopic results showed particles with narrow size distribution ranging from 7 to 23 nm. XRD pattern of AgNPs revealed four diffraction peaks of metallic silver and the EDX spectrum showed a strong signal attributed to Ag nano-crystals. AgNPs mycofabricated by A. terreus showed potent minimum inhibitory concentration (MIC) and broad minimum bactericidal/fungicidal concentration (MBC/MFC) against 12 reference microorganisms. The MIC and MBC/MFC values of AgNPs were 0.312 to 1.25 μg/ml and 0.625 to 10 μg/ml, respectively. Nevertheless, AgNPs did not demonstrate any antagonistic activity against Coxsackie B virus. The in vitro cytotoxicity of the mycosynthesized AgNPs showed significant antitumor activity against adenocarcinoma epithelial cells from human breast cancer (Mcf-7) cell line with an inhibitory concentration (IC50) of 87.5 μg/ml.

Antimicrobial activity of bioactive components of essential oils from Citrus sinensis against important pathogens

Alternative strategies to treat multidrug resistant pathogens are indispensable due to the scarcity of new therapeutically effective antibiotics. The present work was conducted to investigate the antimicrobial effects of essential oils extracted from Citrus sinensis, locally known as “Mousami”, against various important pathogens as well as their phytochemical characterisation. Essential oils were extracted from Cit. sinensis peels by the steam distillation method, and a 0.23% yield was obtained. Chemical composition of the extracted essential oil was analysed through gas chromatography/mass spectrometry (GC/MS). The analysis revealed that the Cit. sinensis essential oil was composed of a variety of chemical compounds; mostly are monoterpene hydrocarbon and 0.62% of limonene (dipentene), as well as oxygenated monoterpenes and 0.50% limonene oxide, also known as eucalyptol. Standard reference microorganisms, i.e., E. coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Salmonella Typhi (ATCC 24682), Bacillus subtilis (ATCC 6633), Aspergillus flavus (ATCC 204304), and Candida albicans (ATCC 10231) were used, and the in vitro antimicrobial effect of Cit. sinensis essential oils was observed against these strains by disc diffusion method. Statistical analysis of the resulting data was done by using Least Significant Difference (LSD) method and Analysis of Variance (ANOVA) to assess the significant association between biological activities of essential oils at p &lt; 0.05. Using microbroth dilution assay, maximum sensitivity was exhibited by E. coli and Can. albicans among the tested microbial strains. The zones of inhibition were significantly different, having diameters of 34.0 ± 1.5 and 55.0 ± 0.5 mm for the said bacterial and fungal strains, respectively; and their MIC values were 0.0007 ± 0.0001 and 0.0007 ± 0.0006 mg/ml, respectively. Thin layer chromatography-bioautography (TLC-bioautography) showed dipentene as biologically most active antimicrobial component. Hence, it was established that broad spectrum antimicrobial effect against important microorganisms was elucidated by essential oil extracts from Cit. sinensis that may be used as a natural antimicrobial to treat various infections caused by pathogens of public health interest.

ИЗУЧЕНИЕ АНТИМИКРОБНОЙ АКТИВНОСТИ НОВЫХ ДЕЗИНФИЦИРУЮЩИХ СРЕДСТВ ИЗ ГРУППЫ ЧЕТВЕРТИЧНЫХ АММОНИЕВЫХ СОЕДИНЕНИЙ

The purpose of this article was to study the antimicrobial activity of new disinfectants from the group of Quaternary ammonium compounds. In the course of experimental studies of new disin-fectants synthesized at the Arbuzov Institute of veterinary medicine, it was found that all of them have a certain antimicrobial activity against reference strains of gram-negative (Escherichia coli, En-terobacter cloacae, Pseudomonas aeruginosa, Klebsiella pneumonia, Salmonella typhimurium) and gram-positive (Staphylococcus aureus, Enterococcus fecalis, Bacillus Cereus) of bacteria. The anti-microbial activity of the studied disinfectants ranges from 7.8 to 500 micrograms/ml of the medium. Of the six studied compounds, the most pronounced antimicrobial activity is the drug F-5, the min-imum suppressive concentration of which was 7.8 mcg/ml of the medium, and the minimum bacteri-cidal concentration against 6 strains of reference microorganisms: Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, Enterococcus fecalis, Enterobacter cloacae, Salmonella typhimurium was at the level of 15.6 mcg/ml of the medium.

Interactions between microorganisms and composite material with marble & granite filler

It is promising to develop new composite materials which have antimicrobial activity for many applications; this is our goal in this study. All experiments were done to achieve this an important objective by studying the interaction between the new composites and some pathogenic reference microorganisms. The produced composite was manufactured from industrial wastes. Recently, many research groups in all fields have focusing work on removing the wastes and recycling it as useful materials. In this study, the preparing new composite from marble and granite wastes with thermoplastic matrix PMMA was investigated. This composite is considered as new type of micro-nano composite because it has fillers in the nano and micro sizes. Pathogenic microorganisms, used in this study, obtained from the American type culture collection (ATCC; Rockville, MD, USA), yeast and one pathogenic fungus were applied. The evaluation of analysis was done by spectrophotometer SEM and EDX techniques. The suitable applications of new composite material were mentioned based upon the interaction recorded in the study. The study ends with recommendation for future modifications in the new composite materials to improve its resistances to microorganism.

Effectiveness of Bacteriocin-Producing Lactic Acid Bacteria and Bifidobacterium Isolated from Honeycombs against Spoilage Microorganisms and Pathogens Isolated from Fruits and Vegetables

Screening natural products for bacteriocin-producing bacteria may be the equilibrium point between the consumer demand for mild processing and the industry’s need for hazard control. Raw unprocessed honeycombs filled with oregano honey from the alpine mountainous territory of Epirus, Greece were screened for bacteriocinogenic lactic acid bacteria and Bifidobacterium spp., with inhibitory action towards some pathogens and spoilage microorganisms isolated from fresh fruits and vegetables (number and type of strains: three E. coli, two L. monocytogenes, two Salmonella spp., two B.cereus, two Erwinia spp., one Xanthomonas spp., L. innocua (ATCC 33090TM) and E. coli 0157:H7 (ATCC 69373)). Among the 101 collected isolates (73 Lactobacillus, 8 Lactococcus, 8 Leuconostoc and 12 Bifidobacterium species) from the oregano honeycombs (an original finding since there are no other reports on the microbial biodiversity of the flora of the oregano honey), 49 strains of lactic acid bacteria (LAB) and Bifidobacterium spp. were selected and tested for their bacteriocin-producing capacity (34 Lactobacillus, 6 Lactococcus, 5 Leuconostoc and 4 Bifidobacterium). The antibacterial activity exerted by the tested LAB and Bifidobacterium strains was not of the same potency. Our results suggest that the main molecules involved in the antimicrobial activity are probably bacteriocin-like substances (a conclusion based on reduced antibacterial activity after the proteolytic treatment of the cell-free supernatant of the cultures) and this antimicrobial activity is specific for the producing strains as well as for the target strains. The spoilage bacteria as well as the reference microorganisms showed increased resistance to the bacteriocin-like substances in comparison to the wild-type pathogens.