Largest Inhibition Zone Research Articles

Ecological Aspect of Antibiotic Batumin Synthesis by Pseudomonas batumici

The species Pseudomonas batumici, isolated from the rhizosphere of eucalyptus in the humid subtropical zone, is a producer of the polyketide antibiotic batumin with highly selective activity against staphylococci. Batumin biosynthesis operon includes 28 genes or 74 151 bp. According to modern notions, the biosynthesis of energy-intensive metabolites, which probably includes batumin, is justified in the case of its multifunctionality for producers. The species P. batumici, as a representative of rhizosphere bacteria, must interact with plants and compete with the surrounding microbiota. Aim. To determine the role of batumin in the ecology of the rhizosphere producer strain P. batumici UCM B-321. Methods. The batumin producing strain P. batumici UCM B-321T was obtained from the Ukrainian Collection of Microorganisms. Antibiotic batumin was obtained by fermentation of P. batumici UCM B-321. Extraction was carried out from acidified P. batumici fermentation broth by chloroform (1:2). Chromatographic analysis of fermentation broth obtained after centrifugation was carried out by HPLC using liquid chromatograph Agilent 1200 with mass spectrometric detector Agilent G1956B. Batumin derivatives were obtained after the extraction of the fermentation broth of P. batumici using thin layer chromatography (TLC) on silica gel plates (Merck, USA) in the benzene-isopropanol system (5:1). Disc-diffusion method on phytopathogenic test-strains was used for bioautography. Biofilm formation by P. batumici strain was studied according to O’Toole by growing strain B-321 at 25 0C for 48 hours in 96-well plates on LB medium. Batumin effect upon bacterial mobility was studied using Volf and Berg method in Petri dishes with 0.5% semisolid bacterial agar. To research chemotaxis the soil strain Bacillus subtilis IMV B-7023 and the following concentrations of batumin were used: 20, 50, and 150 μg/mL. The studies were performed using Tso and Adler method. Results. Growth inhibition zones for phytopathogenic bacteria strains were the following (in mm): Pseudomonas syringae pv. syringae UCM B-1027T – 19±3, P. fluorescens IMV 8573 – 22±3, Pectobacterium carotovorum UCM B-1075T – 17±2. Activity against Xantomonas campestris pv. campestris UCM B-1049, Clavibacter michiganensis subsp. michiganensis IMV 102, Agrobacterium tumefaciens UCM B-1000 was not detected. Minimum inhibitory concentrations (MIC) in the range from 8 to 64 μg/mL for P. carotovorum UCM B-1075T, Erwinia aroidea IMV 1058, Proteus vulgaris UCM B-905 and P. fluorescens IMV 8573 are hardly comparable with the discovered against staphylococci. TLC analysis of its broth extract revealed five separate compounds with different values of retention factors: Rf1=0.42; Rf2=0.38; Rf3=0.31; Rf4=0.28; Rf5=0.25. The main component of extract was batumin, other four substances were present in minor quantities. All found substances had similar absorption maxima with the minimum differences between isomeric forms: descarbamoyl batumin-enol (Mr=505, λ=226 nm), descarbamoyl batumin-keto (Mr=505, λ=231 nm), batumin (Mr=548, λ=231 nm), batumin-enol (Mr=548, λ=228 nm) and 17-hydroxy-batumin (Mr=550, λ=229 nm). The largest inhibition zone (P. carotovorum UCM B-1075T) was on the third compound placement which represents of batumin, tiny inhibition zones were found around keto and enol form of descarbamoyl batumin. Observation of live bacterial cells in light microscope confirmed a serious disruption of motility in all these bacteria by batumin in the concentration far lower than the MIC for these organisms. Proteus actively moved in the control, but in presence of 10 μg/mL of batumin was almost no growth. The biofilm formation by P. batumici UCM B-321 was stimulated by supplementing batumin into the medium. The stimulation effect by batumin on the biofilm formation was equally strong when the compound was applied in the concentrations of 1 and 10 μg/mL. Batumin was not an attractant of the producer strain. However, in one of our experiments batumin has shown the properties of positive effector (attractant) for B. subtilis UCM B-7023 strain. Conclusion. The discovered features allow to consider the antibiotic batumin synthesized by P. batumici UCM B-321 as the essential tool for survival and competition of the producer strain in a natural habitat.

PHYTOCHEMICAL AND ANTIBACTERIAL ACTIVITIES OF A. CHEVALIERI HAMS (FABACEAE) STEM

Albizia chevalieri Hams (Mimosaceae/Fabaceae), mostly found in the Northern Sahel Savannah region of Nigeria as well as in Nigér and Senegal is a tree of the acacia type with a long list of folklore therapeutic claims that include its use as purgative, taenicidal, cough remedy, dysentery, cancer, diabetes mellitus, tuberculosis and snake bite remedy. However, many bacterial species have been reported to develop resistance to antibiotics commonly prescribed for dental infections. Therefore, the need to search for natural products for remedy to this problem cannot be overemphasized. The stem was collected, dried and powdered. The powder was thereafter extracted with distilled water and subsequently with methanol. Phytochemical screening was carried out using standard methods. Agar well diffusion, agar dilution and spread plate methods were employed to determine the zone of inhibition, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and rate of killing respectively. Phytochemical screening of methanol and aqueous extracts of Albizia chevalieri stem revealed the presence of phenol, alkaloid, saponins, tannins, steroids, triterpenes, flavonoids and carbohydrate as secondary metabolites. The two extracts showed broad spectrum of activity but the aqueous extract had larger zones of inhibition of 32 mm against S. mutans while methanol extract had higher zone of inhibition on S. aureus (24 mm). Low MIC and MBC values ranging from 6.25 mg/ml and 12.5 mg/ml respectively. The results obtained also provided scientific evidence for the use of A. chevalieri in folklore medicine in the treatment of tooth infections.

Uji Daya Hambat Ekstrak Daun Salam (Syzygium polyanthum wight) Terhadap Pertumbuhan Bakteri Porphyromonas Gingivalis Secara In Vitro

Chronic periodontitis is the most common type of periodontitis. The main cause of chronic periodontitis is bacterial colonization of plaque. Porphyromonas gingivalis is the main pathogen and has the highest prevalence of chronic periodontitis. Bay leaf extract (Syzygium polyanthum wight) is believed to have the pharmacological effect that can be used as antibacterial. The purpose of this research was to determine the inhibitory of bay leaf extract on the growth of Porphyromonas gingivalis in vitro. The method of this research was experimental laboratories with posttest only control group design. There were 30 samples divided into 6 groups, namely bay leaf extract concentration of 2.5%, 5%, 10%, 20%, 40% and Dimethyl Sulfoxide (DMSO) as a control. Inhibitory test using the Kirby-Bauer method with a paper disc on Mueller Hinton medium agar. Inhibition zone that created around paper disc was measured with the sliding caliper. The results were analyzed with One Way Anova and Post Hoc LSD test. The results of this research showed that the mean of bay leaf extract 40% had the largest inhibition zone that was 7,6 mm and the lowest formed by bay leaf extract 2,5% that was 1,94 mm. One Way Anova test showed that there was a significant difference among the group (p<0,05). The conclusion of this research there was significant difference inhibition among 2,5%, 5%, 10%, 20%, and 40% concentration of bay leaf extract on the growth of Porphyromonas gingivalis in vitro. The higher concentration of bay leaf extract resulting the greater inhibition zone.

Punica granatum L. extract contributes to phytopathogens control and enhances Eruca vesicaria (L.) Cav. germination in vitro and in vivo

The study aimed to investigate antimicrobial activity of the hydroalcoholic crude extract from the fruit peel of Punica granatum (Pp) and punicalagin compound (Pg) on phytopathogenic bacterial isolates and its potential use as a sustainable alternative in treatment of vegetable seeds. The antimicrobial activity in vitro was tested by agar well diffusion assay and through viability tests in liquid medium. In vivo treatment with Pp was tested on Eruca vesicaria seeds infected with Xanthomonas campestris pv. campestris. Pp induced the formation of large inhibition zones to the growth of the tested pathogens (35.33 mm – 6.66 mm), with dose-dependent effect. Viability tests confirmed the antimicrobial activity of the Pp on X. campestris pv. campestris and P. carotovorum subsp. carotovorum with minimum inhibitory concentration (MIC) of 125 μg/mL. Punicalagin compound presented MIC of the 31.25 μg/mL. The seed treatment with Pp indicated control of pathogen-induced symptoms in seedlings of the E. vesicaria and positive effect in seed germination, emergence and in stomatal functionality. The results indicate strong potential of the extract from the fruit peel of P. granatum and Punicalagin for formulating botanical pesticides for plant disease control.

ANTIBACTERIAL POTENTIAL OF ESSENTIAL OILS DERIVED FROM NATURAL, CALLUS AND IN-VITRO PROPAGATED SOURCES OF MELALEUCA ALTERNIFOLIA AGAINST COMMON BACTERIAL PATHOGENS

Objective: Melaleuca alternifolia (M. alternifolia) and its essential oil (EO) fractions have been used widely and traditionally in the treatment of various infectious diseases and hence its antibacterial potential is investigated in the present study.
 Methods: The antibacterial activity was studied through the agar disc diffusion method and broth dilution method, DNA fragmentation studies and confocal microscopy morphological studies were done. In-silico molecular interaction was studied against microbial target using docking software.
 Results: The inhibitory concentration of the EOs was recorded at 75% dilution with larger inhibition zones. The DNA fragmentation analyzed in the essential oil derived from in-vitro propagated leaves (EOIPL) of M. alternifolia treated bacterial cultures was compared with negative and positive controls. In Minimum Inhibitory Concentration (MIC) of EOIPL treated Staphylococcus aureus (S. aureus) showed time-dependent growth inhibition. The DNA content in the EOIPL treated bacterial cultures was comparatively less than in control cultures. The cell morphology changes of S. aureus cells were studied through confocal laser scanning microscopic analysis which showed a significant decrease in viable bacterial cells. The active component, terpinen-4-ol docked to autolysin receptor revealed stable interaction with the microbial target.
 Conclusion: Thus EOIPL was explored to possess bactericidal activity against common infectious bacteria and could in incorporated in therapeutic natural antibiotic formulations as with future studies.

WITHDRAWN: Anti-bacterial activity of gold nanoparticles against two type of antibiotic resistance pathogenic bacteria in Al-Hilla city

Gold nanoparticles (AuNPs) have attracted a lot of interest in recent decades due to their potential applications in a variety of fields. The antibacterial behavior of gold nanoparticles (AuNPs) against different pathogenic bacterial isolates is investigated in this study (Pseudomonas aeruginosa and Staphylococcus aureus). Disk diffusion assays were used to evaluate the antimicrobial efficacy of AuNPs at concentrations of 500, 250, 125, 62.5, and 31.25 g/ml. Our findings revealed that AuNPs of 25 nm in size had antibacterial activity against clinical MDR bacteria (P. aeurogenosa and Staph. aureus). In P. aerurogenosa, the largest inhibition zone was in average 19 mm with a concentration of 62.5 g/ml, and in Staph. aureus, the largest inhibition zone was in average 15.8 mm with a concentration of 62.5 g/ml.

Antimycotic potential of Kawayang tinik against pathogenic fungal species

The importance of discovering and obtaining new, natural and sustainable sources of potential drugs have been the focus of scientific communities due to the emergence of increasing cases of microbial resistance, one of the biggest health threats in our society today. This study aimed to determine the antimycotic potential of Bambusa blumeana (kawayang tinik) specifically its leaf, rhizome, root, inner culm and outer culm extracts using the agar well diffusion assay. Results of the study revealed that all kawayang tinik extracts produced statistically equal size zone of inhibition (ZOI) against Aspergillus niger at 1 mg/ ml concentration while the ethanolic root and leaf extracts showed larger ZOI against Penicillium chrysogenum compared to other kawayang tinik extracts. Furthermore, the results of the antifungal assay showed comparable activity of kawayang tinik extracts to Fluconazole, a pharmaceutically approved antifungal drug, at 1 mg/ml concentration. Phytochemical studies further revealed the presence of alkaloids, tannins, phenols, sterols, triterpenes and flavonoids in its different parts which may support its potential antimycotic properties.

In Vitro and FTIR Spectroscopy: Local Black Fruit Seed Extract as Antibacterial Aeromonas Hydrophila

Indonesia has many local plants with potential as herbal antibacterial properties, one of which is the local black fruit of Wandama. The objective of this study is to determine the antibacterial activity of the extract of black fruit seed against A. Hydrophila by in vitro and FTIR by Tilapia. The benefit of this research is to make black fruit seed extract as a natural remedy against tilapia attacked by Aeromonas Hydrophila. The antibacterial activity of black fruit seed extract against A. Hydrophila is investigated in vitro and using FTIR on tilapia in this research. The aim of this study is to establish black fruit seed extract as a natural treatment for tilapia infected with Aeromonas Hydrophila. The disc approach was used to conduct the in vitro research. Agar medium was poured into a sterile petri dish, and 2 drops of bacteria from the liquid medium were uniformly distributed and cooled. On the press, disc paper with black fruit seed extract was put and incubated for 18-24 hours at 35 C. An FTS 1000 version spectrophotometer system was used for the FTIR test. For the FT-IR study, a fraction of dried black fruit seeds was used. For clear preparation, 100 mg of dry extract is condensed in KBr pellets. A specimen of loaded black fruit seed samples was analyzed using FT-IR spectroscopy with a scanning range of 400-4000 cm-1 and a resolution of 4 cm-1. The results showed that the ethyl acetate fraction produced an inhibition zone (13.65 mm), the water fraction produced an inhibition zone (11.21 mm), and the n-hexane fraction produced the weakest inhibition zone (11.21 mm) (5.31mm). The concentration test results from 125 ppm, 250 ppm, 500 ppm and 1000 ppm obtained a large inhibition zone at a concentration of 1000 ppm with an inhibition zone area of 11.43 + 0.02. The absorbance value of black fruit seed extract in ethyl acetate solvent at 3430 cm-1 revealed the absorption band with the strongest vibration of the hydroxylate (-OH) functional group, according to FTIR research. Final thoughts with an average value of 13.65 + 0.06, black fruit seed extract using ethyl acetate can inhibit A. Hydrophila bacteria.

Utilization of waste glycerol for the production of biocontrol agents nigericin and niphimycin by Streptomyces hygroscopicus: bioprocess development

ABSTRACT Search for more environment-friendly methods for controlling plant diseases that would contribute to the goal of sustainability in agriculture is in focus. In the present study, the potential of Streptomyces hygroscopicus isolated from soil sample in the production of biocontrol agents, nigericin and niphimycin, effective against Alternaria alternata storage apple pathogen was examined. Also, modelling and optimization of medium composition for biocontrol agent biosynthesis was performed. The results showed that the optimum amount of C3H8O3, (NH4)2SO4 and K2HPO4 in the medium for Streptomyces hygroscopicus biosynthesis is 20, 0.25 and 1.46 g/L, respectively. Scale-up and validation of the obtained results performed in the 3 L laboratory-scale bioreactor showed that on the optimized medium at an aeration rate of 0.7 vvm and an agitation speed of 200 rpm, produced nigericin and niphimycin, showed high activity. Under the same conditions, cultivation of S. hygroscopicus was performed in a 7 L laboratory bioreactor in a medium with waste glycerol instead of pure glycerol. Results showed that the methanol extract of S. hygroscopicus cultivation liquid, containing nigericin and niphimycin, was high effective against two Alternaria isolates. This was confirmed in vitro by obtaining large inhibition zone diameters on A. alternata KA10 (47 mm) and T1Jg3 (44.33 mm) isolates. After successful in vitro analysis, in planta testing was performed. It was found that necrosis diameters that were measured on artificially inoculated apple fruits with A. alternata compared to necrosis diameter measured on untreated, control fruits, were 4.47 and 3.56 times smaller.

One-pot synthesis of zinc oxide nanoparticles via chemical precipitation for bromophenol blue adsorption and the antifungal activity against filamentous fungi

In this research, zinc oxide nanoparticles (ZnONPs) were prepared via a facile one-pot chemical precipitation approach and applied in the adsorption of bromophenol blue (BRB) and as antifungal agents against the filamentous fungi and plant pathogens; Alternaria alternata CGJM3078, Alternaria alternata CGJM3006 and Fusarium verticilliodes CGJM3823. The ZnONPs were characterized by the UV–Vis, FTIR, XRD, TGA, BET, SEM, TEM, and EDX techniques, which showed efficient synthesis. The characteristics ZnO UV–Vis absorption band was observed at 375 nm, while the XRD showed an average ZnONPs crystalline size of 47.2 nm. The SEM and TEM images showed an irregular shaped and aggregated porous structure of 65.3 nm average-sized ZnONPs. The TGA showed 22.9% weight loss at 800 °C indicating the high thermal stability of ZnONPs, while BET analysis revealed a surface area, pore volume and pore diameter of 9.259 m2/g, 0.03745 cm3/g and 9.87 nm respectively. The Freundlich, pseudo-second-order, and intra-particle diffusion models showed R2 > 0.9494 and SSE < 0.7412, thus, exhibited the best fit to the isotherm and kinetics models. Thermodynamics revealed feasible, endothermic, random, and spontaneous adsorption of BRB onto the synthesized ZnONPs. The antifungal assay conducted depicts strong antifungal activities against all three tested fungi. Noticeably, ZnONPs (0.002–5 mg/mL) showed maximum activities with the largest zone of inhibition against A. alternata CGJM 3006 from 25.09 to 36.28 mm. This was followed by the strain F. verticilliodes CGJM 3823 (range from 23.77 to 34.77 mm) > A. alternata CGJM3078 (range from 22.73 to 30.63 mm) in comparison to Bleach 5% (positive control). Additionally a model was proposed based on the possible underlying mechanisms for the antifungal effect. This research demonstrated the potent use of ZnONPs for the adsorption of BRB and as effective antifungal agents.

Resazomycins alter outer membrane protein expression in Francisella tularensis resulting in increased antibiotic susceptibility

A growing number of human pathogens are becoming resistant to most common antibiotics. Each year, antibiotic-resistant infections are responsible for 35,000 deaths in the United States and billions of dollars in health care costs. The development of new antibiotics is essential to combat this public health crisis. Our laboratory has identified a novel family of compounds based on the compound resazurin, known as resazomycins, that inhibit the growth of Neisseria gonorrhaeae and Francisella tularensis. The mechanism of action of these compounds remains unknown. We hypothesized that resazomycins disrupt the membrane integrity of N. gonorrhaeae and F. tularensis resulting in bacterial cell death. To test this hypothesis, we measured differences in inner and outer membrane protein expression of F. tularensis in the absence and presence of resazurin. Treatment with resazurin altered protein expression in the outer membrane of F. tularensis suggesting enhanced membrane permeability. Kirby Bauer assays were then performed to assess the susceptibility of F. tularensis to various detergents and antibiotics in the presence of sublethal concentrations of resazurin. Larger zones of inhibition were observed in the presence of resazurin suggesting increased antibiotic uptake due to perturbation of the outer membrane. Further investigation is needed to determine the exact target of resazomycins.

Evaluation of the Antimicrobial Activity of Some Components of the Essential Oils of Plants Used in the Traditional Medicine of the Tehuacán-Cuicatlán Valley, Puebla, México.

In Tehuacán-Cuicatlán valley (Mexico), studies have been carried out on the essential oils of medicinal plants with antimicrobial activity and it was found that they present compounds in common such as: α-pinene, β-pinene, carvacrol, eugenol, limonene, myrcene, ocimene, cineole, methyl salicylate, farnesene, and thymol. The goal of this study was to assess the antimicrobial activity of essential oils’ compounds. The qualitative evaluation was carried out by the Kirby Baüer agar diffusion technique in Gram-positive bacteria (11 strains), Gram-negative bacteria (18 strains), and yeasts (8 strains). For the determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), the agar dilution method was used. All the evaluated compounds presented antimicrobial activity. The compounds eugenol and carvacrol showed the largest inhibition zones. Regarding yeasts, the compounds ocimene, cineole, and farnesene did not show any activity. The compounds eugenol, carvacrol, and thymol presented the lowest MIC; bactericidal effect was observed at MIC level for S. aureus 75MR, E. coli 128 MR, and C albicans CUSI, for different compounds, eugenol, carvacrol, and thymol. Finally, this study shows that the essential oils of plants used by the population of Tehuacán-Cuicatlán valley share compounds and some of them have antibacterial and fungicidal activity.

Biological synthesis of silver nanoparticles using animal blood, their preventive efficiency of bacterial species, and ecotoxicity in common carp fish.

Possible high biodeterioration of the microorganisms due to their metabolic pathway and activities on stone materials causes solemn problems in cultural heritage. Different kinds of laboratory-scale methods have been used for the reduction of microbial growth, that is, chemical, mechanical, and physical, which are cost-effective and not ecofriendly. In the current study, an ecofriendly approach utilizing silver nanoparticles were synthesized using sheep blood serum. Transmission electron microscopy results have confirmed the spherical and well dispersed silver nanoparticles with an average size of 32.49 nm, while energy dispersive X-ray has shown the abundance of silver nanoparticles. The efficiency against bacterial species was verified through laboratory-scale testing. The strong antibacterial activity was confirmed when B-AgNPs was tested against different bacterial species isolated from the Beishiku Cave Temple. The largest zone of inhibition was measured 26.48 ± 0.14 mm against Sphingomonas sp. while the smallest zone of inhibition measured was 9.70 ± 0.27 mm against Massilia sp. Moreover, these ecofriendly B-AgNPs were tested for daily based dose in different concentrations (0.03, 0.06, and 0.09 mg/L) against common carp fish for a long exposure (20 days) and 6.5% fatality was found. The highest lethal concentration (LC50 ) for fish (0.61 ± 0.09 mg/L). No doubt, the laboratory scale applications have revealed the best results with minute toxicity in fish. Therefore, sheep serum should be continued to synthesize silver nanoparticles on a large scale. A strict monitoring system should be developed for the synthesis and application of AgNPs.

Differential proteomic response of Agaricus bisporus and Trichoderma aggressivum f. europaeum to Bacillus velezensis supernatant

Trichoderma aggressivum, a mycopathogen causing green mould disease, is a major problem in Agaricus bisporus cultivation due to crop loss, and resistance to chemical fungicides. There is an urgent need for novel biological ways to control mycopathogens without affecting the growth of A. bisporus. Bacteria from the mushroom-casing environment were identified and tested for antagonistic effect on T. aggressivum. Bacillus velezensis produced a large zone of inhibition and its supernatant inhibited the growth of T. aggressivum [−37%], and slightly stimulated A. bisporus growth [+2%]. Label free quantitative-proteomic (LFQ) analysis of changes in the abundance of T. aggressivum proteins following exposure to B. velezensis supernatant indicated increased abundance of proteins associated with catabolic processing of amino acids (40-fold), amino oxidase proteins (14-fold), oxidoreductase proteins (13-fold, 4-fold) and hydrolases (3-fold). Proteins that decreased in relative abundance were antioxidants (29-fold), NTF2 domain containing protein (17-fold), 60S ribosomal protein L-13 (14-fold), glucoamylase proteins (13-fold), proteasome subunit proteins (11-fold) and other ribosomal proteins (9-fold). LFQ analysis revealed that exposing A. bisporus to B. velezensis supernatant led to a decrease in: prohibitin (13-fold, 6-fold), proteasomal proteins (11-fold), cytosolic adaptor domain containing protein (5-fold), aldehyde dehydrogenase (4-fold), ribosomal proteins (4-fold), DLH domain-containing protein (4-fold) and PKS_ER domain containing protein (3-fold). The results indicate that A. bisporus was not under stress upon contact with B. velezensis. Whereas a detrimental effect of B. velezensis on T. aggressivum is shown by inhibition of growth and damage-preventing proteins and increased abundance of proteins associated with stress.

FABRICATION OF ANTIBACTERIAL MATERIAL USING DIFFERENT ACETATE SALTS

Ammonium, Cadmium, Cobalt, Sodium and Magnesium acetates were diluted inside both distilled water and Isopropanol alcohol separately and then tested as antibacterial material against (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella sp. and Candida albicans). Among diluted salts in water only Cadmium and Cobalt acetate had inhibition zones. The particles sizes inside distilled water were 5.6 and 25.5 nm for diluted Cadmium and Cobalt acetate respectively as measured by particle size distribution test. The addition of all used acetate salts on Isopropanol alcohol increased its ability for killing tested bacteria. All diluted acetates in Isopropanol alcohol had inhibition zones, both Cadmium and Cobalt acetates had equal or larger inhibition zones than those diluted in water. Minimum bactericidal concentration (MBC), minimal inhibitory concentration (MIC) and biofilm inhibition% were measured for Cadmium acetate and cobalt acetate.

Physiochemical synthesis of Silver/Kaolinite nanocomposites and study their antibacterial properties

Silver nanocomposites (Ag NCs) were prepared by two methods, chemical and physical synthesis using sodium borohydride and gamma irradiation as a reducing tool. A one-step silver/kaolinite nanocomposite (Ag/Kln NCs) synthesis method has been developed successfully by irradiation technique at room temperature and under ambient pressure. The Ag/Kln NCs produced by the ?-irradiation technique is pure without chemical residues, has a good distribution with enhanced antibacterial properties, and environmentally friendly. The effects of various experimental parameters on the formation of NCs, such as the concentration of Ag+ and the irradiation dose, have been investigated. A study on antimicrobial susceptibility was undertaken to determine the antibacterial properties of Ag NCs in the presence of gram-positive and gram-negative bacteria. The susceptibility of the microorganisms to varying concentrations of Ag NCs synthesized via physical synthesis using gamma irradiation was compared to those synthesized chemically. Concentrations of Ag NCs used were 0.5, 1.0, 2.0, 5.0, and 10 % for chemical synthesis and irradiation doses used for physical synthesis were 7, 13, 20, 30, 40, 50, 65 and 80 kGy. Observation on well diffusion variant showed a significantly large zone of inhibition for physically synthesized NCs, (63 to 107% relative to control) which indicates high antimicrobial activity. Chemically synthesized NCs using the same experimental set up however showed a significantly smaller zone of inhibition. The Ag/Kln NCs in 20kGy showed higher antibacterial activity against Enterococcus faecalis and Escherichia coli as gram-positive and gram-negative bacteria. These suggest that Ag/Kln NCs can be employed as an effective bacteria inhibitor and can be applied in the medical field.

Growth and adhesion inhibition of pathogenic bacteria by live and heat-killed food-origin Lactobacillus strains or their supernatants.

The study aimed to evaluate qualitatively and quantitatively the antimicrobial capacity of 10 potential probiotic Lactobacillus strains against model enteropathogens and spoilage microorganisms. The probiotic strains (live and heat-killed forms) were also assessed for their ability to inhibit adhesion of selected pathogens to Caco-2 cells. The largest inhibition zones (the diffusion method) were connected with the usage of whole bacteria cultures (WBC), also high and moderate with cell-free supernatant (CFS) and the lowest with cell-free neutralized supernatant (CNS). The highest antagonistic activity of Lactobacillus strains was observed against L. monocytogenes strains, moderate activity against Salmonella, Shigella, Escherichia coli, Pseudomonas and, the lowest against S.aureus, Bacillus and Enterococcus. The inhibition of adhesion to Caco-2 cells was very high in the case of E. coli, Salmonella and L. monocytogenes, and moderate in the case of S.aureus. On average, the inhibition effect was higher when pathogenic bacteria were treated by WBC, than heat-killed Lactobacillus. Although, in most samples, the effect was not significantly different (P> 0.05). The strains Lb. brevis O24 and Lb. rhamnosus K3 showed the biggest overall antimicrobial properties, and were most effective in adherence inhibition of investigated indicator strains. These bacteria or their metabolites can be used for the production of various foods or pharmaceutical products.

Solvent Dependency of Sorghum Bran Phytochemicals Acting as Potential Antioxidants and Antibacterial Agents.

SUMMARYResearch backgroundSorghum bran, although considered as an agricultural waste, is an abundant source of various bioactive compounds. These bioactive compounds require specific extraction with particular solvents and therefore ionic liquid and three different conventional solvents, viz. anhydrous methanol, acidified methanol and water were used in this work.Experimental approachTo evaluate the phytochemicals in the different sorghum bran extracts, total phenol content, flavonoids, condensed tannins and anthocyanins were determined as per standard protocols. Liquid chromatography with tandem mass spectrometryanalysis of extracts was also performed for their phenolic profiling. The antioxidant activity of the extracts was estimated via three assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation decolourization assay and Cu2+ reducing antioxidant capacity (CUPRAC) method. The antibacterial activity against two most opportunistic foodborne pathogens: Escherichia coli and Staphylococcus aureus was measured by agar well diffusion assay and minimum inhibitory concentration (MIC) was determined by serial dilution method.Results and conclusionsIonic liquid extract of sorghum bran gave the highest yield ((14.9±0.7) %), which indicated that various possible interactions like Van der Waals forces, H-bonding, hydrophobic and cation-π bonding can occur when ionic liquid is used as an extractant compared to other conventional solvents, although total phenol mass fraction expressed as gallic acid equivalents on dry mass basis was only (7.4±0.7) mg/g. The hydrophobicity of the ionic liquid also helped in efficient extraction of condensed tannins ((63.2±2.1) mg/g expressed on dry mass basis), which resulted in significant antioxidant activity of the ionic liquid extract ((85.2±1.2) µmol/g in DPPH assay, (100.8±0.9) µmol/g in ABTS assay and (63.2±1.9) µmol/g in CUPRAC). An interesting revelation reported in this work is the inability of DPPH assay to evaluate the antioxidant activity in acidic environment. The anhydrous methanolic extract of sorghum bran displayed pH sensitivity, making the extract beneficial for certain applications. Qualitative analysis of extracts revealed greater number of phenolic compounds to be present in methanol and distilled water extracts. Moreover, various derivatives of apigenin and luteolin were also observed in all four extracts. In addition, the acidified methanol extract of the sorghum bran exhibited antimicrobial property at a concentration of 12 mg/mL. A larger inhibition zone was observed against Escherichia coli than Staphylococcus aureus, while the MIC against these two bacteria was 2.2 and 1.1 mg/mL, respectively.Novelty and scientific contributionThis paper presents the first information on the application of ionic liquids as extracting phase for sorghum bran polyphenols and the quantification of such extracts. As evident from the study, each solvent has its own role in the extraction of bioactive compounds. This work also proves that sorghum bran imparts antibacterial activity against foodborne pathogens.

Synthesis and characterization of Ag@AgCl-reinforced cellulose composites with enhanced antibacterial and photocatalytic degradation properties

In the present work, Ag@AgCl-reinforced cellulose composites with enhanced antibacterial and photocatalytic degradation properties were successfully synthesized via oil bath heating method. During the process, zinc chloride (ZnCl2) solution was used as both Cl− resource to form AgCl and the solvent to dissolve cellulose. The samples were synthesized with different temperatures, times, and concentrations of ZnCl2 solution. The morphology, microstructure and phase of the as-prepared samples were analyzed with X-ray powder diffraction (XRD), fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), photocatalytic activity studies and inhibition zone experiments. Results showed that dye solution could be completely degraded by the materials in 1 h, and higher concentrations of ZnCl2 solution favored for larger inhibition zones (higher to 10.8 mm). This synthetic strategy displayed here offers more possibilities to high value-added applications of cellulose.

Antibacterial (Staphylococcus aureus and Escherichia coli) and Antifungal (Saccharomyces cerevisiae) Activity Assay on Nanoemulsion Formulation of Ethanol Extract of Mangosteen Leaves (Garcinia mangostana L.) as Fruit Preservative

Fruits after harvesting will decay faster if not handled properly. Fruits can be demaged by bacterial and fungal. Mangosteen leaves contain xanthons which are antibacterial and antifungal. 50% ethanol extract of mangosteen leaves is formulated in Nanoemulsion preparations using the SNEDDS (Self-Nanoemulsifying Drug Delivery System) method. The mangosteen leaves 50% ethanol extract nanoemulsion formulation consisted of VCO (Virgin Coconut Oil) as oil, tween 80 as surfactant, and PEG 400 as cosurfactant. There are 3 formulations with variations in the concentration of mangosteen leaves ethanol extract, there are concentrations of 1%, 2%, and 3%. All formulations have a T% of more than 90%. The results of the particles measurement of nanoemulsion using PSA were in formulation 1 amounting to 16.1 nm; formula 2 is 16.7 nm; and formula 3 is 16.6 nm. The zeta potential characterization shows that formula 1 has a zeta value of -40.9 mV. The three formulations had a pH of 5. The largest inhibitory zone in the mangosteen leaf ethanol extract against S.aureus and E. coli bacteria were 11.08 mm and 5.87 mm respectively. Whereas in the S. cerevisiae antifungal test there was no inhibition zone at all concentrations. In the antibacterial and antifungal tests nanoemulsion preparations did not produce inhibitory zones in each concentration. Nanoemulsion preparations can retain the quality of strawberries when compared to the non-nanoemulsion preservative group, both in room storage and refrigerator temperature. The best preservative result is when the fruit is coated with nanoemulsion preservative and stored in refrigerator temperature.