Highest Inhibition Zone Diameter Research Articles

Optimized submerged batch fermentation for metabolic switching in Streptomyces yanglinensis 3-10 providing platform for reveromycin A and B biosynthesis, engineering, and production.

The cultivation system requires that the approach providing biomass for all types of metabolic analysis is of excellent quality and reliability. This study was conducted to enhance the efficiency and yield of antifungal substance (AFS) production in Streptomyces yanglinensis 3-10 by optimizing operation conditions of aeration, agitation, carbon source, and incubation time in a fermenter. Dissolved oxygen (DO) and pH were found to play significant roles in AFS production. The optimum pH for the production of AFS in S. yanglinensis 3-10 was found to be 6.5. As the AFS synthesis is generally thought to be an aerobic process, DO plays a significant role. The synthesis of bioactive compounds can vary depending on how DO affects growth rate. This study validates that the high growth rate and antifungal activity required a minimum DO concentration of approximately 20% saturation. The DO supply in a fermenter can be raised once agitation and aeration have been adjusted. Consequently, DO can stimulate the development of bacteria and enzyme production. A large shearing effect could result from the extreme agitation, harming the cell and deactivating its products. The highest inhibition zone diameter (IZD) was obtained with 3% starch, making starch a more efficient carbon source than glucose. Temperature is another important factor affecting AFS production. The needed fermentation time would increase and AFS production would be reduced by the too-low operating temperature. Furthermore, large-scale fermenters are challenging to manage at temperatures that are far below from room temperature. According to this research, 28°C is the ideal temperature for the fermentation of S. yanglinensis 3-10. The current study deals with the optimization of submerged batch fermentation involving the modification of operation conditions to effectively enhance the efficiency and yield of AFS production in S. yanglinensis 3-10.

Novel bioactive petrodispersing agents based on cationic polymeric surfactant: Design, synthesis, and surface indices

Novel bioactive cationic polymeric surfactants based on fatty acid derived from natural wastes were developed with different hydrophilic head groups, which were employed for collecting the thin petroleum film from water surface and dispersing it. The preparation procedures pass through three steps, in first step lauryl methacrylate (LMA) was copolymerized with methacrylic acid (MAA) with different feed from the two monomers to obtain five copolymers of poly(LMA-co-MAA) (P1-5) of different molar ratio. In second step, carboxylic groups in copolymers (P1-5) were esterified with N,N‘-dimethyl-ethanol amine and finally the modified copolymers (PE1-5) were quaternized with Butyl-2-chloroacetate and Hexyl-2-chloroacetate to afford the bioactive PSB1-5 and PSH1-5, respectively. The structure of synthetic compounds was confirmed by FT-IR and 1H NMR. Upon examination, the surface-active characteristics of the bioactive petrodispersing agents that were synthesized exhibited significant defoaming capacity, good wettability, and foaming qualities. The synthesized PSB1-5 and PSH1-5 were applied for petro-collecting and dispersing in solid state and diluted form on three water sources. In sea water and diluted form, the results showed that PSB1-5 showed better effects than PSH1-5. Also, the antimicrobial efficiency of the synthesized PSB(1-5) and PSH(1-5) were tested. The data obtained from FT-IR and 1H NMR spectra proved the esterification of carboxylic group in copolymers due to the appearing of peak at 1738 cm−1 for carbonyl group of formed esters and the disappearing for proton of carboxylic group in 1H NMR. Also, data obtained from antimicrobial studies showed that the highest inhibition zone diameter against C. albicans, L. monocytogenes, S. aureus, Salmonella sp. and E. coli were observed for PSH(1-5). Which PSH-2 gives the highest value of inhibition zone diameter of 3.2 mm against L. monocytogenes. The results exhibited that PSH(1-5) showed the stronger antimicrobial functions than PSB(1-5).

Comparation of n-Heksan and Etanol in Bawang Dayak (Elutherine palmifolia L. Merr) Extraction for Inhibiting Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the bacteria that causes nosocomial infections. The incidence of nosocomial infections caused by Pseudomonas aeruginosa is around 10-15%. Nosocomial infections caused by these bacteria are increasingly difficult to treat. This happens because more and more strains are resistant to several antibiotics (Multidrug Resistance), so the selection of antibiotics against Pseudomonas aeruginosa is very difficult. This study aims to determine and analyze the effect of using polar and nonpolar solvents on Dayak onion bulb extract on the inhibitory ability of Pseudomonas aeruginosa. The method used in this study was Kirby-Bauer disk diffusion using 8 sample and 5 replication with assay solvent 96% ethanol and n-hexane extract of Dayak onion bulbs (Eleutherine palmifolia L. Merr) with concentration variations of 75%, 80%, and 85%. Positive control used ciprofloxacin 5 µg and positive control DMSO 10%. The results showed that on phytochemical screening of solvent ethanol 96% contained flavonoids and n-hexane contained triterpenoids. Ethanol 96% solvent obtained a higher presentase yield than n-heksan solvents and the highest inhibition zone diameter was 85% concentration in 96% ethanol solvent. The results of statistical analysis with Mann Whitney test showed a significant difference between the treatment groups (p<0.05).

Extraction and purification of biosurfactant by locally isolated Enterococcus faecium bacteria and study of its antimicrobial activity

In this research, the biosurfactant production by Enterococcus faecium isolated from Raw cow's milk was studied when growing in the MRS medium containing Lactose as a carbon source without Tween-80. E.faecium supernatant exhibited emulsion action of 60% towards kerosene oil as oil in water, while the surface activity was 34 mm. Biosurfactants with surface tension activity properties were extracted and partially purified from E. faecium by cold acetone 3:1, The chemistry structure of the biosurfactant was analyzed, which indicated that it is a glycol-lipo-peptide. Biosurfactant that purified from E. faecium showed antibacterial activity by reducing growth of several pathogenic G-ve and G+ve bacteria, including aureus, Staphylococcus epidermidis, Streptococcus sp., Staphylococcus Escherichia coli, Klebsiella sp., Pseudomonas aeroginosa, Acinetobacter sp. and Serratia sp. The inhibitory activity of biosurfactant against pathogenic bacteria was studied by using agar diffusion method, where the biosurfactant had higher inhibitor activity against E. coli, where highest diameter of inhibition zone was (23mm). At all concentrations examined, a biosurfactant derived from E. faecium considerably decreased bacterial adhesion, albeit to a lower amount. Keyword: Enterococcus faecium, LAB, Biosurfactant, Antibacterial and Antiadhesive activity.

Investigation of New Potential Uses of Pistacia terebinthus for Various Industries

Investigation of New Potential Uses of Pistacia terebinthus for Various Industries
 ABSTRACT: Pistacia terebinthus has been used extensively in alternative medicine. Inhibitory activity of ethanol fruit extract from P. terebinthus fruit on food-borne and clinical test microorganisms was obtained to determine the potential use of the extract for food and pharmaceutical industries as a natural antimicrobial source. Antibacterial activity of the ethanol extract on fish originated pathogen bacteria was also determined for its potential use in the feed industry. In addition, the effect of the extract on the probiotic bacteria originated from breast milk were tested to obtain the potential use of the extract together with probiotic bacteria for pharmaceutical and food industries. Antimicrobial activity was obtained by performing micro-dilution and macro-dilution assays as well as disc diffusion. Among the food-borne and clinical test microorganisms, the highest inhibition zone diameter (22.39±1.92 mm) was detected on Listeria monocytogenes. The highest antibacterial activity on the fish pathogens was recorded as 17.67±0 mm against Vibrio anguillarum A4. It was determined that P. terebinthus fruit extract had higher antimicrobial activity against some test microorganisms than Amikacin and Gentamicin antibiotics. Antifungal activity on Candida glabrata was also investigated by counting viable cell. At a concentration of 20 mg/mL, no viable cells were determined after 24 hours. The extract inhibited all the tested LAB, however, with low MIC and MBC values. The sun protection factor (SPF) of the extract and the extract+cream mixture at 10 mL concentration was recorded as 9.36 and 7.51. The results of the study indicated that P. terebinthus fruit ethanol extract can be an alternative as a natural additive in various industries such as feed, food, pharmaceutical and cosmetic industries.
 Keywords: Menengiç, Antimicrobial activity, Extract, Lactic acid bacteria, Solar protection

Phytochemical and Antibacterial Screening of Chromolaena odorata Leaf Extract

The discovery of antibacterial drugs from natural sources as a substitute for preventing bacterial resistance has become necessary due to the increase in bacterial drug resistance. Chromolaena odorata has been reported to have antibacterial effects. Therefore, this study investigated the phytochemical components and antibacterial properties of C. odorata leaves. C. odorata leaves were collected, prepared, and extracted using a standard procedure with 95% methanol and 95% ethanol, respectively. Both extracts were subjected to phytochemical screening and Gas Chromatography-Mass Spectrometry to detect phytochemical compounds. Chromolaena odorata methanolic extract at a concentration of 50 mg/mL, 100 mg/mL, 150 mg/mL and 200 mg/mL was carried out for antibacterial screening using the agar well diffusion tested on Staphylococcus aureus (ATCC 43330), Bacillus subtilis (B29), Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 15442). The methanolic extract was present with tannin, terpenoid, alkaloid, and saponin while ethanolic extract was present with tannin and alkaloid. The GC-MS chromatogram identified as many as 27 and 19 compounds for ethanolic and methanolic extract, respectively. The C. odorata ethanolic extract consists mainly of Phenol (0.51%), Sesquiterpenoid (20.69%) and Fatty acid (39.2%). Meanwhile, C. odorata methanolic extract consists of Sesquiterpenoid (62.26%) and Fatty acid (17.11%). Antibacterial activity of S. aureus was the highest inhibition zone diameter with 7.67 mm to 10.33 mm from 50 mg/ml to 200 mg/mL concentration of C. odorata extract. Escherichia coli and B. subtilis inhibition zones diameter was 200 mg/mL concentration of C. odorata extract. No antibacterial activities were obtained for P. aeruginosa. This study suggests that C. odorata consists of a variety of phytochemicals and contains antibacterial properties. Thus, C. odorata represents a promising natural source for antibacterial resistance drugs.

Development and characterization of edible films based on flaxseed gum incorporated with Piper betle extract

There has been a shift from use of petroleum-based plastics, causing serious environmental pollution, towards innovative and biodegradable edible packaging. The present study documents the development of composite edible films based on the flaxseed gum (FSG) modified by the incorporation of betel leaf extract (BLE). The films were assessed for physicochemical, mechanical, morphological, thermal, antimicrobial and structural characteristics. Scanning electron microscopy images indicated that the roughness decreased with an increase in BLE concentration. The water vapor permeability of the FSG-BLE films ranged from 4.68 to 1.59 × 10−9 g s− 1 m− 2 Pa− 1, lower than that of the control sample (6.77 × 10−9 g s− 1 m− 2 Pa− 1). The BLE4 (containing 10 % BLE) films had the highest tensile strength of 32.46 MPa compared to the control sample (21.23 MPa). Similarly, EAB and seal strength of the films incorporated with BLE were ameliorated. X-ray diffraction pattern and FTIR illustrated the shift of amorphous to crystalline behavior and a significant interaction among the BLE and FSG functional groups. Furthermore, the thermal stability of the treated films was not affected significantly however, they showed improved antimicrobial activity with the highest diameter of inhibition zone in the BLE4 sample. This study concluded that the FSG-BLE composite films (BLE4 in particular) can be considered as novel packaging material for food conservation coupled with a potential to enhance the shelf life of perishable food products.

Nano-Chitosan/Eucalyptus Oil/Cellulose Acetate Nanofibers: Manufacturing, Antibacterial and Wound Healing Activities

Accelerated wound healing in infected skin is still one of the areas where current therapeutic tactics fall short, which highlights the critical necessity for the exploration of new therapeutic approaches. The present study aimed to encapsulate Eucalyptus oil in a nano-drug carrier to enhance its antimicrobial activity. Furthermore, in vitro, and in vivo wound healing studies of the novel nano-chitosan/Eucalyptus oil/cellulose acetate electrospun nanofibers were investigated. Eucalyptus oil showed a potent antimicrobial activity against the tested pathogens and the highest inhibition zone diameter, MIC, and MBC (15.3 mm, 16.0 μg/mL, and 256 μg/mL, respectively) were recorded against Staphylococcus aureus. Data indicated a three-fold increase in the antimicrobial activity of Eucalyptus oil encapsulated chitosan nanoparticle (43 mm inhibition zone diameter against S. aureus). The biosynthesized nanoparticles had a 48.26 nm particle size, 19.0 mV zeta potential, and 0.45 PDI. Electrospinning of nano-chitosan/Eucalyptus oil/cellulose acetate nanofibers was conducted, and the physico-chemical and biological properties revealed that the synthesized nanofibers were homogenous, with a thin diameter (98.0 nm) and a significantly high antimicrobial activity. The in vitro cytotoxic effect in a human normal melanocyte cell line (HFB4) proved an 80% cell viability using 1.5 mg/mL of nano-chitosan/Eucalyptus oil/cellulose acetate nanofibers. In vitro and in vivo wound healing studies revealed that nano-chitosan/Eucalyptus oil/cellulose acetate nanofibers were safe and efficiently enhanced the wound-healing process through enhancing TGF-β, type I and type III collagen production. As a conclusion, the manufactured nano-chitosan/Eucalyptus oil/cellulose acetate nanofiber showed effective potentiality for its use as a wound healing dressing.

Bjerkandera adusta Collected from Niğde: Analysis of Total Phenolic Compound, Antioxidant, vnd Antimicrobial Properties

Macrofungi have long been used as food and medicinal purposes by humankind. This study aimed to identify a macrofungus sample collected from Niğde, Türkiye in 2019 via molecular techniques and determine the content of total phenolic compounds, antioxidant and antimicrobial activities. According to data obtained from the sequence analysis of ITS fragment of rDNA the macrofungus sample was identified as Bjerkandera adusta (Willd.) P. Karst (1880). The sample was extracted with ethanol and methanol. Total phenolic compound content, antioxidant activity via DPPH scavenging method and antimicrobial activity via disc diffusion method of B. adusta was determined by using these extracts. The amount of total phenolic compounds was found as 772.28 µg GAE/mL for a methanolic extract of B. adusta. The ethanol extract of B. adusta showed 79.66% scavenging activity of 0.1 mM DPPH solution. The highest inhibition zone diameter was measured as 28±1 mm against P. aeruginosa by ethanolic extract, while the lowest antimicrobial activity was found in 15 µL methanol extract against S. typhimurium with an inhibition zone diameter of 8.7±1.2 mm.

Green Synthesis of Silver Nanoparticles Using Aloe vera L. and Screening Its Activity Against Gram Negative Bacteria

The current research was done to produce silver nanoparticles by green synthesis from Aloe vera leaf extract to evaluate the antibacterial properties against gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis and Acinetobacter baumannii). Atomic Force Microscopy (AFM) was used to determine the average size and form of the nanoparticles which was 55 nm. Scanning electron microscopy (SEM) shows the Ag NPs have a spherical and smooth surface region. UV–visible spectroscopy (UV-Vis) was used to measure the wavelength range, which showed a sharp peak at 450 nm. X-ray Diffraction (XRD) which show the Ag NPs have three strongest peaks, the measured particle sizes were 15.4 and 18.3 and 22.1 nm. Different functional groups of biomolecules are responsible for the reduction and capping processes, as shown by Fourier Transform Infrared Spectroscopy (FTIR). Different concentrations of Ag NPs (12.5, 25, 50 and100) mg/ml were examined against multiple drug resistance (MDR) isolates, and the results showed the highest diameter of inhibition zone against P. mirabilis, K. pneumoniae, E.coli, A. baumannii were (23, 22, 21 and 20)mm respectively at concentration(100) mg/ml and the lowest zone at concentration (12.5)mg/ml at the same isolates were (13, 12, 10 and10) mm.

LC-MS/MS profiling, antibiofilm, antimicrobial and bacterial growth kinetic studies of Pluchea dioscoridis extracts

Abstract The therapeutical applications of ornamental plants have been categorized to be of a great effectiveness in multiple industries from ancient times until present days. Pluchea dioscoridis is widely known Egyptian wooden plant that has been extensively applied for different medicinal purposes. In this study, LC-ESI-MS/MS analysis of the potent antimicrobial ethyl acetate and n-butanol extracts of P. dioscoridis leaves led to identification of 28 and 21 compounds, respectively. The identified compounds were categorized as phenolic acids, phenolic acids derivatives, organic acids, flavonoids (aglycones and glycosides), secoiridoids, coumarin derivatives, and gallotannins derivatives. Among them, caffeic acid 3-sulfate was the most predominate in the investigated extracts followed by ferulic acid and dicaffeoyl-quinic acid. Also, the antimicrobial potentiality of different extracts was evaluated against different pathogenic microbes including Enterobacter cloacae, Micrococcus leutus, Aeromonas hydrophila, Bacillus subtilis, Bacillus cereus, Bacillus lichneformis and Clostridium species. Furthermore, different concentrations of the most potent extract were assayed for antibacterial efficacy on growth curve kinetics against the susceptible bacteria along 4days incubation period. Our gathered data confirmed that, the antimicrobial activity against tested bacteria was different according to the solvent used in the extraction process. Mostly, all the extracts showed a wide spectrum antibacterial activity except the plant water extract which shows a mild activity against Clostridium sp. only. Based on the highest inhibition zone diameter, the ethyl acetate extract followed by butanol extract exhibited the highest inhibition zone with Micrococcus luteus and B. subtilis (20.0 and 18.5 mm) respectively. Determining the effect of ethyl acetate extract at different concentration (0, 0.66, 1.66, 3.33, 6.67, 13.34 and 20.01 mg mL−1) on M. luteus growth kinetics, the data assured that the antibacterial activity shows concentration dependent manner with the highest antibacterial activity at 20.01 mg mL−1 culture. The data also confirmed that, none of the selected concentration showed bactericidal activity in the prepared cultures, and with the prolonged incubation period the bacteria acquire resistance against the extract beginning from second or third day of incubation.

Inhibitory Effect of Nepeta Crispa L. and Nepeta Cataria Extracts on Candida Albicans Growth: An In-vitro Study

Background and Objectives Considering the existence of many medicinal plants in Iran and the high prevalence of oral candidiasis, the present study aims to evaluate the inhibitory effects of Nepeta crispa L. and Nepeta cataria extracts on Candida albicans growth. Subjects and Methods After preparing the extracts of two plants, their minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) for C albicans were measured by broth microdilution method. The inhibitory effect of the extracts was evaluated by the disk diffusion method and measuring the diameter of inhibition zone. Data were analyzed in SPSS software, version 22. The significant level was set at 0.05. Results The MIC of N. crispa L. and N. cataria extracts was 1.1 and 2.4 μg/mL, respectively. Their MLC was 4 and 6 μg/mL, respectively. The highest inhibition zone diameter was for nystatin (21.31 mm), while the lowest diameter was for N. cataria extract (11.60 mm). No. significant difference was observed in the inhibition zone diameter between nystatin and N. crispa L. extract (P>0.05). Conclusion The inhibitory effect of N. crispa L. extract on the candida albicans growth is not significantly different from the effect of nystatin. Although N. cataria extract has inhibitory effect, its effect is significantly lower than the effect of nystatin.

<i>In vitro</i> Analysis of the Antimicrobial Properties of Propolis Collected from Jimma, Ethiopia

The effectiveness of antimicrobial drugs becomes uncertain due to the emergence of multidrug resistant microorganisms, which highlights the need for alternative antibacterial agents. Natural products are of great importance in the search for biologically active compounds. The present study aimed at investigating the antibacterial properties of propolis, one of the natural bee products, against <em>S. aureus</em>, <em>P. aeruginosa</em> and <em>E. coli.</em> Propolis was extracted using 30 %, 50 %, 70 %, and 99.9 % ethanol. The <em>in vitro</em> antibacterial activities of propolis extracts were evaluated by the disc diffusion method with concentrations between 500 and 4000 ?g/ml. Among the extracts, the 50 % and 70 % propolis extracts showed strong antibacterial activity against all tested strains with inhibition zones ranging from 6.64 ± 0.15 to 11.99 ± 0.04 mm.<em> P. aeruginosa</em> was sensitive strain to the ethanolic extracts of propolis with the highest inhibition zone diameter of 11.99 ± 0.04 mm. Statistically significant differences in growth inhibition were observed among the types of extracts (30 %, 50 %, 70 % and 99.9 %) against <em>P. aeruginosa</em> (p < 0.05) and <em>E. coli</em> (p < 0.05), but the effect was not significant on <em>S. aureus</em> (p > 0.05). All propolis extracts showed no effect on <em>S. aureus</em> at concentrations below 2000 ?g/ml. Propolis extracts showed a lower zone of inhibition compared to the effect demonstrated by the positive control. Overall, the results indicate that ethanolic extracts of Ethiopian propolis has a promising antibacterial activity which could be of an antibiotic development benefit.

In vitro antimicrobial properties of apis mellifera L. and Meliponulla beccarii L. honeys from Kellem and West Wollega Zones, Western Ethiopia

ABSTRACT Honey is a sweet natural product synthesized from nectars of flowers by different types of honey bees. It has been used as medicine in different cultures. The aim of this study was to investigate the antimicrobial activities of honey samples from different sources against selected clinical and standard microorganisms. Antimicrobial activities of the honey samples against selected standard and clinical microorganisms were done using agar disc and agar well diffusion methods. The highest diameter of inhibition zone against clinical and standard strains was recorded for Meliponula beccarii honey (MBH) (16 ± 3 mm) followed by Apis mellifera fresh honey (AMFH) (15 ± 2 mm) and Apis mellifera market honey (AMMH) (11 ± 3 mm) by well diffusion method. The mean inhibition zone recorded by the disc diffusion method were generally lower than that of the well diffusion method. However, none of the honey samples inhibited Candida albicans. The mean Minimum Inhibitory Concentration (%) and Minimum Bactericidal Concentration (%) against all the tested bacteria were 9.9 and 53.6 by MBH, 11.0 and 56.2 by AMFH, and 15.4 and 64.3 by AMMH, respectively. The fresh honey samples directly collected from the hives and honey samples from stingless bees showed higher antimicrobial effects against the tested pathogenic bacteria. This implies that honey could be used as an alternative therapy against diseases caused by the bacterial pathogens.

SUPLEMENTATION OF VIRGIN COCONUT OIL (VCO) PRODUCTS WITH INTARAN (Azadirachta indica) LEAF EXTRACT IN INHIBITING THE GROWTH OF ACNE BACTERIA Propianibacterium acnes

<p>The dangers of resistance to Propionibacterium acnes and the high cost of treatment prompted the discovery of medicinal sources from natural substances that could act as antibacterials. One of them is using post-harvest coconut products in the form of virgin coconut oil (VCO) with extract of intaran leaves (Azadirachta indica). The purpose of this study was to determine the phytochemical characteristics, inhibition zone and their categorization and to study the difference or effect of VCO supplemented with extracts of intaran leaves (Azadirachta indica) with various concentrations on the growth of Propionibacterium acnes. This study used a posttestonly control group design. The VCO mixed with extracts of intaran leaves with various concentrations of 5%, 10%, 15%, 20% and 25%. The antibacterial test was carried out using the Kirby-Bauer disc diffusion method. Data analysis used the Kruskall Wallis and Mann Whitney test. The VCO mixture supplemented with extracts of intaran leaves showed the presence of tannins, flavonoids, terpenoids, saponins, and alkaloids. The mean diameter of the inhibition zone of virgin coconut oil (VCO) supplemented with leaf extract at a concentration of 5%, 10%, 15%, 20% and 25% of the growth of P. acnes is 9.4 mm; 18.3 mm; 9.9 mm; 12.6 mm; and 9.9 mm. Data analysis showed that there were differences and the effect of adding extracts to the resulting inhibition zone diameter. The concentrations of leaf extract of 5%, 15%, and 25% were classified as moderate, while the concentrations of 10% and 20% of leaf extract were classified as strong. The 10% concentration had the highest inhibition zone diameter in inhibiting the growth of P. acnes. This combination has the potential to treat acne and needs to be carried out in vivo research.</p>

Disruption of metabolic function and redox homeostasis as antibacterial mechanism of Lindera glauca fruit essential oil against Shigella flexneri

Current trend in food safety and public health is focusing on the use of natural antimicrobials. The Lindera glauca fruit with rich resource and essential oil has emerged as potential application in China. This work aimed to detect chemical compounds of L. glauca fruit essential oil (LGFEO) and to evaluate antimicrobial activity and mechanism of LGFEO for develop natural antimicrobials. A total of 70 volatile compounds were identified, and the major groups were monoterpene (56.62%) and sesquiterpene (39.71%). The analysis of antimicrobial activity indicated that LGFEO could effectively inhibit the growth of all tested 13 food-borne pathogens, of which Shigella flexneri had the highest inhibition zone diameter (DIZ, 25.45 nm), and the lowest minimum inhibitory concentration (MIC, 0.156 μg/mL) and bactericidal concentration (MBC, 0.312 μg/mL). To unravel antibacterial mechanism of LGFEO on S. flexneri , the dynamic changes for bacterial growth curve, material release, and the levels of intracellular mallondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), and ROS-detoxifying enzymes were analyzed in S. flexneri cells exposed to LGFEO at different concentrations (1/2 × MIC, 1 × MIC and 2 × MIC) and times (0–24 h), revealing that LGFEO could cause cell material leakage, antioxidant enzyme inactivation, H 2 O 2 and MDA accumulation, and bacterial growth inhibition. Also, antibacterial action of LGFEO was conducted on key enzymes of respiratory metabolic (glycolysis, oxidative pentose phosphate pathway, tricarboxylic acid cycle, and respiratory chain), and the levels of intracellular ATP, ADP, nicotinamide adenine dinucleotide (NAD + and NADH), nicotinamide adenine dinucleotide phosphate (NADP + and NADPH), and oxidized and reduced glutathione (GSSG and GSH) in LGFEO-treated S. flexneri cells, indicating a role of LGFEO in repressing respiratory pathway and electron transport with low redox potential. All these revealed that LGFEO could effectively induce H 2 O 2 accumulation and lipid peroxidation, resulting in cell membrane damage and metabolic function disruption, giving rise to a disturbance of redox homeostasis, which may be the main cause of growth inhibition or cell death for S. flexneri . • Essential oil contains 70 volatile compounds with good antimicrobial activity. • The first time for antibacterial mechanism from energy and respiratory metabolism. • Antibacterial action of essential oil involves in H2O2-mediated oxidative stress. •Essential oil-induced disruption of redox homeostasis as main antibacterial action.

Tripleurospermum disciforme (C.A.Mey.) Sch.Bip., Tanacetum parthenium (L.) Sch.Bip, and Achillea biebersteinii Afan.: efficiency, chemical profile, and biological properties of essential oil

BackgroundTripleurospermum disciforme (C.A.Mey.) Sch.Bip., Tanacetum parthenium (L.) Sch.Bip., and Achillea biebersteinii Afan. are the most important species of the Asteraceae family that are used in traditional medicine as antiseptics, analgesics, and anti-ulcers. This study aimed to evaluate and compare the yield, chemical profile, and antibacterial and antifungal properties of the essential oils of these three species for the first time. For this purpose, plant materials were collected in June 2019 from Javinan region (Kashan, Iran).ResultsBased on the ANOVA results the species had a significant effect on yield, chemical composition, and diameter of the inhibition zone of some microorganisms (P ≤ 0.01). The highest yield belonged to T. disciforme essential oil (~ 1.433%). Analysis of essential oil compounds showed that in T. disciforme, anisole, p-1-cyclohexen-1-yl- (55.95%), modephene (10.00%), and cis-β-farnesene (11.94%), in T. parthenium, camphor (43.43%), camphene (9.40%), and bornyl acetate (6.76%), and in A. biebersteinii linalool (34.49%), p-cymene (15.31%), and α-terpineol (7.43%) were the main and predominant compounds. The highest inhibition zone diameter by the essential oil of T. parthenium and A. biebersteinii against Aspergillus brasiliensis (~ 13 mm) was observed. The strongest inhibitory and lethal activity was related to T. disciforme essential oil against Klebsiella pneumoniae, Shigella dysenteriae, Escherichia coli (~ 8.50 mm), and Candida albicans (MIC and MBC = 62.5 μg/mL), which were equivalent to rifampin and twice as potent as nystatin, respectively.ConclusionsTherefore, the essential oil of the studied species of Asteraceae may be a promising and potential strategy for controlling some microorganisms and a possible natural alternative to some antibiotics.Graphic

Functional group characterization of lactic bacterial biosurfactants and evaluation of antagonistic actions against clinical isolates of methicillin-resistant Staphylococcus aureus.

The present study investigated the antimicrobial and antibiofilm potential of biosurfactants derived from Lactobacillus fermentum Lf1, L. fermentum LbS4 and Lactobacillus plantarum A5 against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). The cell wall-bound and intracellular biosurfactants were extracted by solvent extraction method. Fourier-transform infrared spectroscopy-based characterization of biosurfactants revealed the heterogeneous chemical composition involving proteins, fatty acids and carbohydrate moieties in LbS4 and A5, while only the sugar and lipid fractions in Lf1. Fatty acid profiling using Gas chromatography-mass spectrometry indicated hexadecanoic acid and stearic acid as the predominant fatty acids in the biosurfactants of all these strains. Biosurfactants demonstrated dose-dependent antibacterial action against MRSA isolates with the highest inhibition zone diameter (30·0±0·0 to 35·0±0·0mm) recorded at 400mgml-1 . Biosurfactants showed an excellent staphylococcal antibiofilm activity by preventing the biofilm formation and disrupting the preformed biofilms. Visual inspection through scanning electron microscopy witnessed the biosurfactants-induced alteration in the cell membrane integrity and subsequent membrane pore formation on staphylococcal cells. Taken together, our findings emphasize the prospects of biomedical applications of biosurfactants as bactericidal and biofilm controlling agents to confront staphylococcal nosocomial infections.

In Vitro antibacterial activity of Yemeni medicinal plants (Ocimum basilicum and Peganum harmala) against some human pathogenic bacteria

This study aims to evaluate the antimicrobial potential of ethanolic and water extracts of Ocimum basilicum and Peganum harmala cultivated in Yemen against some pathogenic bacteria (Escherichia coli, Kebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus). The antimicrobial activities and minimum inhibitory concentrations (MIC) of the plant extracts have been determined using Agar well diffusion method. The activity was expressed as inhibition zone diameter (IZD). A significant difference was noticed in the antibacterial activities and in the values of MIC at a significant level of α = 0.05. The aqueous extract of O. basilicum caused the highest IZD (2.2± 0.28 cm) against E. coli at 20%, whereas for alcoholic extract, the highest IZD (2.90 ± 1.27 cm) was achieved against K. pneumoniae at the same concentration. The increasing of aqueous and alcoholic extract concentration reduces the ability of the solvent to extract the active compounds from plants and weakens their inhibitory effect. The MIC values were varied depending on the source of extract, the type of bacteria and the type of solvent. In conclusion, the plant extracts used in this work could be of great value as natural antimicrobials. Further studies are needed to develop new alternative pharmacological possibilities for applications.

Toxicity assessment of green synthesized Cu nanoparticles by cell-free extract of Pseudomonas silesiensis as antitumor cancer and antimicrobial

Spherical homogeneous 32 nm, protein coated Pseudomonas silesiensis strain A3 CuNPs was investigated for their cytotoxicity effect as well as antimicrobial and antitumor activity. CuNPs cytotoxicity was estimated using human normal lung cell lines (Wi38) against CuNPs with concentrations ranging from 25 to 150 μg/mL using neutral red uptake assay. The cytotoxicity study revealed that the bacterial CuNPs had an impact on Wi38 cell viability at concentrations of 25, 50, 100 and 150 μg/mL CuNPs were 95.8, 91.1, 89.2 and 82.3%, respectively, with a strong correlation coefficient (r = 0.94) and a CuNPs IC50 value of 1057.0 μg/mL. CuNPs exhibit a broad-spectrum antimicrobial activity against various microorganism species, including fungi and Gram positive and negative bacteria using the agar-well diffusion method. The findings revealed that the most sensitive pathogens were Staphylococcus aureus ATCC5638 and Aspergillus flavus ATCC 9643 which tended to have a high inhibition zone diameter (50 and 47 mm, respectively). The minimum inhibitory concentration (MIC) of CuNPs was 50 μg/mL. The minimum lethal concentration (MLC) values were 50 and 75 μg/mL for S. aureus ATCC 5638 and A. flavus ATCC 9643, respectively. MLC/MIC ratio was ≤2, suggesting the CuNPs had a bactericidal or fungicidal effect on both pathogenic strains. Results also indicated that bacterial CuNPs at varying concentrations of 25, 50, 100 and 150 μg/mL were such a good antitumor agent against A549 lung carcinoma cell lines with an IC50 value of 137.5 μg/mL and a cell viability of 89.3, 79.6, 64.9 and 44.1%, respectively. The results also suggested that the biosynthesized-CuNPs were an antimicrobial and anticancer agent that could be used in future in food preservation, biomedicine and pharmaceutical fields.