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Background Agar has been commonly used as one of the materials to fabricate magnetic resonance imaging phantoms in the past few decades. In this study, eleven agar gel phantoms with different iron (III) oxide (Fe2O3) masses were prepared. This study was aimed to evaluate the signal-to-noise ratio (SNR) uniformity and stability of agar gel phantoms with and without the addition of Fe2O3 at two different time points (TPs). Fe2O3 powder was used as a relaxation modifier to manipulate and produce various SNR, T1 and T2 values. These phantoms were scanned using turbo spin echo pulse sequence to produce T1- and T2-measurement images. The SNR was then computed by plotting 1, 3 and 25 regions of interest on the images using ImageJ software. The T1 and T2 relaxation equations were then fitted to the experimental results of SNR versus TR and SNR versus TE curves for the determination of saturation (SNRo), T1 and T2 values. Results The results demonstrated that the agar gel phantoms were able to maintain SNR uniformity but not SNR stability after 4 weeks of phantom preparation. The change in the water content and microstructure of the phantoms have no significant effect on T2 relaxation but on T1 relaxation. The T1 and T2 of the agar gel phantoms were minimally affected although there was a systemic increase in the content of the Fe2O3 powder. Conclusions It can be concluded that the agar gel phantoms exhibited the characteristics of SNR uniformity, but they showed instability of SNR at TP2. The Fe2O3 in powder form is not an effective relaxation modifier to reduce the T1 and T2 when it is introduced into the agar gel phantoms. Dissolved nanosized particles should be the focus of future studies.

The presence of sulfate groups in agar compromises the agar quality by affecting the crosslinking during gelling process. Some arylsulfatases can catalyze the hydrolysis of sulfate bonds in agar to improve the agar quality. Immobilized arylsulfatases prove beneficial advantages for their industrial applications. Here, a previously characterized mutant arylsulfatase K253H/H260L was immobilized on the synthesized magnetic Fe3O4 nanoparticles after functionalization by tannic acid (MNPs@TA). The surface properties and molecular structures of the immobilized arylsulfatase (MNPs@TA@ARS) were examined by scanning electron microscopy and Fourier transform infrared spectroscopy. Enzymatic characterization showed that MNPs@TA@ARS exhibited shifted optimal temperature and pH with deviated apparent Km and Vmax compared to its free counterpart. The immobilized arylsulfatase demonstrated improved thermal and pH stability and enhanced storage stability with modest reusability. In addition, MNPs@TA@ARS displayed enhanced tolerance to various inhibitors and detergents. The utilization of the immobilized arylsulfatase for agar desulfation brought the treated agar with improved quality.

Background Spread of carbapenem-resistant Enterobacterales (CRE) is a significant concern in intensive care unit (ICU) settings. Approaches to routine screening for CRE colonization in all ICU patients vary depending on institutional epidemiology and resources. The present study was aimed to evaluate the performance of HiCrome Klebsiella pneumoniae carbapenemase (KPC) agar for the detection of CRE colonization in ICU settings taking the Centers for Disease Control and Prevention (CDC) recommended method as reference. Methods Two-hundred and eighty rectal swabs (duplicate) from 140 patients were subjected to CRE detection in HiCrome KPC agar and MacConkey agar (CDC criteria). Results Using CDC method, total 41 CRE isolates were recovered comprising of 29 Escherichia coli, 11 Klebsiella, and 1 Enterobacter spp. On the other hand, 49 isolates of CRE recovered from 140 rectal swabs using HiCrome KPC agar, out of which 33 were E. coli, 15 Klebsiella, and 1 Enterobacter sp. Statistical Analysis Sensitivity, specificity, negative, and positive predictive values of CRE screening by HiCrome KPC agar were found to be 100% (91.4–100), 91.9% (84.8–95.8), 83.6% (70.9–91.4), and 100% (95.9–100), respectively, taking the CDC recommended method as reference. Conclusion HiCrome KPC agar has high sensitivity in screening CRE colonization. Further studies are needed to establish its applicability for detecting the predominant circulating carbapenemases in the Indian setting.

Background and Objectives: Urinary tract infections (UTI) are one of the most frequent infections encountered in hospital settings as well as in community, making urine the most cultured specimens in laboratories across the world. Urine samples occupy most of the time and manpower in the form of resources in the microbiology laboratories. The microbiological performance of HiCrome UTI agar was compared with cysteine lactose electrolyte deficient (CLED) agar for isolation and presumptive identification of bacteria from urine culture with ease of reporting with less human resource and reduction in the cost. Materials and Methods: The study was conducted in a total of 208 collected midstream catch urine samples from patients attending the Department of Microbiology, Khartoum Teaching Hospital Central Laboratories. Urine samples received in the bacteriology laboratory were inoculated on CLED agar and for HiCrome UTI agar simultaneously and incubated overnight. Isolates were identified by the colony's color for HiCrome UTI agar and by standard microbiological techniques for CLED agar. Results: Out of 208 urine samples tested, significant growth was obtained in 94 (45.2%) plates of CLED agar and 84 (40.4%) of HiCrome UTI; moreover, 15 (7.2%) and 28 (13.5%) plates showed mixed with no growth observed in 99 (47.6%) and 96 (46.1%) on CLED agar and HiCrome UTI agar, respectively. The rate of presumptive identification was found significantly higher on HiCrome UTI agar (94%) than CLED agar (84%) (P < 0.05) as the primary urine culture medium. out of 43 (100%) polymicrobial growths 28 (65.1%) were demonstrated distinctly on HiCrome UTI agar and only 15 (34.9%)were obtained fromCLED agar. Conclusions: HiCrome UTI agar was found to be more useful as a primary urine culture medium in both higher rate of isolation and presumptive identification of uropathogens in comparison to conventional media. Its inherent characteristics in demonstrating polymicrobial growth and ease of rapid identification by distinct colony color are unique.

The aim of the study has been to develop a biodegradable film from marine polysaccharides. The optimization of polysaccharides quantity for the composite film was sought by empirical response surface methodology. The Box–Behnken Model Design was applied to optimize the concentration of chitosan (1.0-2.0% (w/v), agar (1.0-2.0% (w/v) and glycerol (0.1-0.5% (w/v) as independent variables to achieve the goal. The overall desirability function fits with the quadratic model (0.862043) at a significant level (p < 0.05) for the optimum concentration of chitosan (1.5% (w/v), agar (2.0% (w/v) and glycerol (0.41% (w/v) to obtain the minimum water vapor permeability (7.25 10-10g m m-2 Pa-1 s-1) and maximum tensile strength (12.21 Ma P), elongation at break (7.32%) and puncture resistance (16.18 N) in the optimized composite film. The absolute residual errors of experimental and predicted responses were between 1.24 and 3.56% acceptable levels. Attenuated total reflection–Fourier transform infrared spectroscopy confirmed the intermolecular non-covalent hydrogen bond between the hydroxyl groups of agar and glycerol with the amino group of chitosan. 3D atomic force microscopy images revealed that the chitosan, agar and glycerol film has layer-by-layer smooth surface properties due to homogenous interaction among the polysaccharides; this provides the film with good mechanical properties and with functional application. Chitosan was found to be responsible for the lower level of water vapor permeability and higher puncture resistance of the film. Tensile strength and elongation at break were influenced by agar and glycerol. The whiteness of the film was negatively affected with the concentration of chitosan.

Water pollution emerges from different sources such as industry, domestic uses, use of pesticides and fertilisers and other daily uses of organic materials. Wastewater treatment has received great ...

Fungal sporulation is affected by many environmental factors, for example, we previously observed that embedding of a hydrophobic polymer net in an agar plate medium significantly accelerates spore formation of some fungi. Here, it was found that the fungal spore formation depended on the surface hydrophobicity of cultivation vessels used for the plate cultivation. In a polypropylene (PP) vessel, six fungal strains produced spores of 1.5 to 514.8 times of those growing in a glass vessel. The contact of vegetative hyphae on the surface of the vessels might trigger the fungal spore formation. Moreover, the spore formation was synergistically accelerated by the reduction of nitrogen source content in an agar plate medium and by the contact to hydrophobic polymers. The synergistic effect depended on the surface area of the hydrophobic polymer. Thus, the combination of the reduction of nitrogen source and the embedding of hydrophobic polymer is expected as a novel and effective procedure for production of fungal spores which are useful for the inoculum in fermentation industry and biocontrol agent in agriculture.

The effectiveness of Agar gels for copper stain removal from marble surfaces was systematically studied. Gels with different agar concentrations (1, 3, 5%) and different chelating agents used as additives (ethylenediaminetetraacetic acid, EDTA, and ammonium citrate tribasic, TAC) were tested on laboratory marble specimens for different contact times (30 and 60 min). For better characterization, hydrogels were lyophilised and cryogels were obtained. Systematic comparison of different formulations was feasible on cryogels and performed in terms of: (i) the morphological properties, by field-emission scanning electron microscopy (FE-SEM); (ii) the type of Cu(II)-complexes formed and their quantitative comparison by electron paramagnetic resonance (EPR) spectroscopy; (iii) the total amount of copper removed from marble surfaces, by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). AgarArt 1% with TAC exhibited the highest effectiveness for copper stain removal after 60 min contact (431 μg/cm2). Such a good cleaning effectiveness can be ascribed to the co-presence of the following properties: efficient metal coordination, which is related to the additive presence, and favourable gel morphology, related both to the gel concentration and to the additive type. In fact, it was observed that both the low gel concentration and the presence of TAC are related to a narrow pore size distribution in gels, besides the possibility of copper coordination. The presence of EDTA results in a broader pore size distribution and in a lower gel strength, with respect to gels with TAC. Thus, a new procedure for studying gels was proposed, which allows to optimize the conditions for metal stain removal from built heritage.

Starch-based films plasticised with sorbitol and citric acids as cross-linking agents were synthesised by the solvent casting method with varying concentrations of agar. The films were characterise...

The present study intended to develop improved biopolymer film from seaweed polysaccharides. The quantity optimization of polysaccharides for the composite film was sought by empirical response surface methodology. To achieve the goal, Box–Behnken model was applied to the concentration of three independent variables, viz. agar (1.0–2.0% w/v), alginate (1.0–2.0% w/v) and carrageenan (1.0–2.0% (w/v). The glycerol was used as a plasticizer and kept constant (25% w/w) for total solid mass. The overall desirability function fits with the quadratic model at 99.78% level of significance for the optimization of agar (1.99% w/v), alginate (1.45 w/v) and carrageenan (2.0% w/v) to reach minimum water vapor permeability and maximum tensile strength, elongation at break and puncture resistance. The absolute residual error (1.04–3.37%) of experimental and predicted response was also validated. Attenuated total reflection-Fourier transform infrared spectroscopy confirmed the interactions such as stretching at 2900 cm−1 region corresponded to C–H stretching vibration and an intensity peak observed at 1200 cm−1 of AAC film corresponded to sulfate ester groups. The shift in crystalline nature of composite film was confirmed by XRD. The 3D image of atomic force microscopy showed layer-by-layer assembly of intermolecules at 310-nm resolution, and the characterized smooth surface has more functional application. The carrageenan and agar are found to be more responsible for the film properties such as moisture content, thickness, whiteness index, transparency, swelling and erosion than alginate.

In this study, it was aimed to investigate the synthesis, characterization and drug release behaviors of organohydrogels containing pH-sensitive Agar (A), Glycerol (G), Sweet Almond oil (SAO). Organohydrogels, which contained Agar, Glycerol and different amounts of Sweet Almond oil, were synthesized via the free-radical polymerization reaction with emulsion technique using glutaraldehyde or methylene bis acrylamide crosslinkers. Then, the degree of swelling, bond structures, blood compatibility and antioxidant properties of the synthesized organohydrogels were examined. In addition, Organohydrogels which loaded with Ceftriaxone (antibiotic) and Oxaliplatin (an anti-cancer agent), were synthesized with the same polymerization reaction and release kinetics were investigated. In vitro release studies were performed at media similar pH to gastric fluid (pH 2), skin surface (pH 5.5), blood fluid (pH 7.4) and intestinal fluid (pH 8), at 37° C. The effects on release of crosslinker type and sweet almond oil amount were investigated. Kinetic parameters were determined using release results and these results were applied to zero and first-order equations and Korsmeyer-Peppas and Higuchi equations. Diffusion exponential was calculated for drug diffusion of organohydrogels and values consistent with release results were found.

In this study, the effect of cellulose nanofibers (CNF) prepared from carrot slag on the properties of agar biocomposite films is investigated. The composite film was characterized by ultraviolet–visible spectroscopy (UV-Vis), tensile test, fourier transforms infrared (FT-IR) spectroscopy and Transmission electron microscopy (TEM). The transmittance, mechanical properties and chemical structure of the composite film containing different CNF content (0.1, 0.3 and 0.5 phr based on agar) were studied. The UV-Vis showed that the transmittance of the film was decreased with increasing content of CNF. The FT-IR spectrum showed that the generation of hydrogen bonds leads to good interface bonding between Agar and CNF. Moreover, the performance of the bionanocomposite was improved by the addition of CNF. The composite containing 0.3 phr CNF results in a maximum tensile strength of 25.97 MPa. However, the tensile strength of the 0.5 phr CNF containing one is reduced to 24.42 MPa due to the agglomeration of CNF. The TEM shows that the diameter of CNF is 2.5 nm and the length is 18.20 nm. The usage of CNF obtained from carrot slag can not only recycle the waste from food industry, but also can be used as a reinforcing agent for preparing biodegradable composite film. It has potential uses in the development of biodegradable food packaging materials and biomedical applications.

Chitinolytic mold, such as Mucor circinelloidesis can be utilized to produce chitinase enzyme for shrimp shell’s chitin hydrolysis into N-acetylglucosamine (NAG). For that purpose, entrapment of chitinase on agar as a carrier could be an alternative way to improve NAG production. This study aimed to investigate the stability of immobilized semi-purified chitinase on agar for multiple cycles fermentation to produce NAG. In this study, 0.6 mL of semi-purified chitinase enzyme was immobilized into 3% of agar matrices and tested for four fermentation cycles to obtain highest NAG concentration and good enzyme activity. The results indicate that the immobilized chitinase could be used for 6 hours fermentation or three fermentation cycles. The NAG concentration produced after three cycle were 1042.22 ± 16.20 ppm. Besides, the immobilized enzyme was considerably stable up to the third cycles with activity value of about 4.74 U/mL.Keywords: agar; immobilized;NAG; repeated fermentation

International audience; The commercial value of agar in the phycocolloid market depends mostly on the agar yield and quality. The present study investigates the agar content and characterization of two Gelidiales Gelidium corneum and Gelidium microdon from the Moroccan Atlantic coast. Spectroscopic and rheological characterization of extracted agar without and with alkali pretreatments were evaluated. The highest agar yield was detected for mild alkaline pretreatment (N2CO3). The native agar content in G. corneum was 16.21%, while those pretreated with NaOH and N2CO3 ranged from 6.2 to 20.50 %. The agar yields of G. microdon showed values of 12.23%, 14.87%, and 17.73%, corresponding respectively to native agar, NaOH, and Na2CO3 pretreatments. Agar with alkali pretreatments depicted the better gelling property with higher gel strength and elevated gelling and melting temperatures. 13C NMR spectroscopy showed that G. Corneum has a typical unsubstituted and weakly methylated agar pattern. However, G. microdon revealed the presence of methyl and sulfate groups at the C4 of 4-O-L-galactose residues, responsible for the low gelling ability of the native agar. The decline of sulfate groups after alkali pretreatments were proved by FTIR spectroscopy. This study demonstrates that G. microdon produces a quality of agar similar to that of G. corneum. Thus G. microdon could be regarded as a potential additional source of agar industry in Morocco.

Bio-plastics are biodegradable materials which can be obtained from the renewable sources such as corn starch, straw, vegetable fats and oils, wood-chips, recycled food waste, saw dust etc. They can be used as an alternative to the commercial plastics in the market which contaminate our environment. Now-a-days bio-plastics are worldwide popular due to its concern towards the environment, limited fossil fuel resources and the climatic change. The purpose of this study is to assess the properties of the starch based bio-plastics prepared from Amorphophallus paeonifolius and Manihot esculenta using glycerol and agar-agar as the plasticizers. The synthesized bio-plastic was characterized with the help of UV-Visible spectrophotometer, FT-IR spectroscopy and SEM Analysis.

Thermophilic spore-forming bacteria are found ubiquitously in natural environments and, therefore, are present in a number of agricultural food products. Spores produced by these bacteria can survive harsh environmental conditions encountered during food processing and have been implicated in food spoilage. During research efforts to develop a standardized method for enumerating spores in dairy powders, the dairy powder-associated thermophilic sporeformer Anoxybacillus flavithermus was discovered growing in uninoculated control plates of tryptic soy agar (TSA) supplemented with 1% (w/v) starch, after incubation at thermophilic (55°C) growth temperatures. This article reports the investigation into the source of this thermophilic sporeformer in TSA medium components and characterization of the bacterial isolates collected. Aqueous solutions of tryptic soy broth powder from four suppliers and four agar-agar powders (two manufacturing lots from one supplier [agar A_1 and agar A_2] and two from separate suppliers [agar B and agar C]) were subjected to two different autoclave cycle times (121°C for 15 min or 121°C for 30 min) and then prepared as TSA. After incubation at 55°C for 48 h, bacterial growth was observed only in media prepared from both lots of agar A agar-agar powder, and only when they were subjected to a 15-min autoclave cycle, implicating these powders as a source of the sporeformer contamination. Genetic characterization of 49 isolates obtained indicated the presence of five unique rpoB allelic types of the thermophilic sporeformer Geobacillus spp. in agar-agar powder from agar A. These results not only highlight the importance of microbiological controls but also alert researchers to the potential for survival of thermophilic sporeformers such as Anoxybacillus and Geobacillus in microbiological media used for detection and enumeration of these same thermophilic sporeformers in products such as dairy powders. HIGHLIGHTS

Blood Agar Plates (BAP) are composed of blood as one of the compositions. Sheep’s blood is usually used, but since it is difficult to be obtained, human AB blood type was used as an alternative. In preparing BAP, blood is defibrinated to lyse the blood clotting factors. Blood clots can also be prevented by adding anticoagulants, such as ethylenediaminetetraacetic acid (EDTA). This study aims to investigate the potential use of EDTA as a substitute for defibrination in preparing BAP with human AB blood type. This study employed a completely randomized design with true experimental method using Staphylococcus aureus as the sample. The parameters were the number of colonies, types of hemolysis, and hemolysis zone. The results showed that the S. aureus grown on BAP with EDTA-human AB blood type was 64 colonies (mean), produced β-hemolytic pattern, and 6 mm hemolytic zone. In contrast, the S. aureus grown on BAP with defibrinated human AB blood type showed 82 colonies (mean), β-hemolytic pattern, and 5 mm hemolytic zone. There were significant differences in the number of colonies (0.000 < α) and hemolytic zones (0.02 < α). However, there was no difference in the hemolysis type (both treatments produced β-hemolysis). EDTA was possible to be used as a substitute for defibrination in preparing BAP to assess the hemolysis type of S. aureus, but it might not be able to be used as a benchmark for counting the number of colonies and determining the hemolysis zone of S. aureus.

From the perspective of sustainable economic development, the advanced fluorescent anti-counterfeiting technology concept is trying to encrypt information onto polymer materials with toughness, self-healing, and stimulus-responsive properties. Herein, a low cost and biocompatible fluorescent double network (DN) hydrogel based an anti-counterfeiting platform is demonstrated. The fluorescent hydrogels (agar/pAM–PCD DN gels) were composed of agar with a thermally reversible sol–gel transition property as the first physical network and polymerizable carbon dots (PCD) crosslinked polyacrylamide (pAM) as the second chemical network. Due to the thermally reversible sol–gel transition property, the interpenetrated physical/chemical crosslinked double network structure and the unique fluorescent characteristics of PCD, the as-prepared agar/pAM–PCD DN gels simultaneously presented excellent mechanical properties (tensile stress of 1.56 MPa, tensile strain of 1400%, and tearing energy of 3420 J m−2), rapid recoverability (30 min with 56.7%/63.3% stiffness/toughness recovery at 95 °C), good self-healing property (self-healing toughness/strain of 0.54 MPa/580% after 12 h resting at 95 °C), as well as photo- and Fe3+-sensing luminescence. The as-prepared agar/pAM–PCD DN hydrogels were further used for the fabrication of luminescent patterns with robustness, stretch resistance, and a self-healing ability for smart anti-counterfeiting. We anticipate that the agar/pAM–PCD DN hydrogels hold enormous potential in developing new-generation anti-counterfeiting materials and technology for data information encryption and protection.

Agar has numerous applications in biomedical and biopharmaceutical fields in gel form. However the hard and tough nature of agar films and their vulnerability to microbial attacks prevent their usage in wound dressing applications. In this work, agar - locust bean gum (LBG) and agar - salep films were prepared for the first time to improve its physical, antimicrobial and cell viability properties. LBG and salep incorporated films resulted in higher antimicrobial and cell viability properties than agar films, which are very important in wound dressing applications. Agar - LBG films had higher water vapor permeabilities and were insoluble in water and in phosphate buffer solutions. Salep incorporation resulted in lower water vapor permeability and films were soluble in both media. All films were transparent, allowing good observability. With LBG and salep addition, lower tensile strength films were obtained and thicknesses of all films were appropriate for wound dressing applications. Due to their solubility, agar - salep films can be preferred especially for the cases where removal from the wound without damaging the tissue structure is a priority.

The prevalence of hypercholesterolemia in Indonesia reaches 11.2%. Hypercholesterolemia can occur due to lack of exercise, consume too much food containing fat and cholesterol, and lack of fiber intake. Rice bran and red yeast rice contain fiber and phytochemical compounds that can reduce cholesterol, including alkaloids, saponins, tannins, flavonoids, and phenolics. The purpose of this study is to use rice bran and red yeast rice as an alternative snack that can potentially bind cholesterol. Rice bran and red yeast rice are added to agar to obtain gelatin snacks with high fiber content and phytochemical compounds. Agar is made into three formulas. Hedonic rating tests have been carried out, so that obtain the formula that is most preferred by consumers. The test results show that the formula with the addition of sodium citrate of 0.3% is most preferred, with the addition of bran and red yeast rice each of 30 and 0.8 grams and the use of agar for 7 grams. Gelatin products contain 14.80% food fiber and total flavonoids by 0.02%. The total phenolic was not detected in agar products. The results of the cholesterol-binding test in vitro showed that gelatin products can bind cholesterol by 60.11%.

Herein we report the synthesis of graphene oxide-based agar composites using a solution casting method. Graphene oxide was synthesized by modified Hummer’s method and was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The graphene oxide-based agar composites were characterized using X-ray diffraction (XRD) and UV-visible spectroscopy. Optical band gap obtained from the Tauc plot showed that the composites could be used in the photodegradation of dyes. The synthesized composite material was checked for its practical applicability in the degradation of methylene blue dye under solar irradiation; with an increase in the concentration of graphene oxide, catalyst, and H2O2, the rate constant increases. The rate constant was found to be inversely proportional to the concentration of methylene blue dye. Dosage of graphene oxide was found to be the most prominent factor in increasing the rate of photodegradation. It is clear from the data for the reaction system that the degradation reaction follows pseudo-first-order kinetics. Keywords: Composites; Ultra-sonication; Photodegradation; Methylene Blue; XRD; Graphene Oxide; Kinetics; Biocompatibility

In this work, the modification of agar is presented with the synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinked agar. The effect of crosslinking agar with succinic acid on tensile strength and water absorption were studied. Crosslinking was confirmed with Fourier infrared spectroscopy. The tensile strength of agar was increased by 70% by succinic acid crosslinking (from55 ± 9.97 MPa to 93.40 ± 9.97 MPa) and the crosslinked agar absorbed only 18.66% water compared to uncrosslinked agar. The tensile strength of agar was increased by 56% by bacterial cellulose reinforcement (55 ± 9.97 MPa to 86.30 ± 14.70 MPa). The strength of agar was improved by 101% by the synergistic effect of bacterial cellulose reinforcement and succinic acid crosslinking (55 ± 9.97 MPa to 111 ± 12.30 MPa). Cytocompatibility studies of the developed films suggested that the crosslinked samples can also have potential applications in biomedical engineering apart from packaging applications.

The radical proliferation of pathogenic bacteria and their infections causes significant issues for human health and the environment. Today, biopolymers are used to produce different nanoparticles. In the present investigation, the fabricated chitosan/agar-silver nanoparticles (Cht/Ar-AgNPs)-coated papers were tested for antibacterial applications. Agar was used as a reducing agent for the synthesis of AgNPs. Synthesized Ar-AgNPs were examined through optical, phase crystallinity and topological analysis. Cht and Ar-AgNPs solution was mixed with various ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 by weight. In addition to that, the conformity of Cht/Ar-AgNPs-coated papers was characterized by structural, spectral, and morphological analysis. However, Cht/Ar-AgNPs-coated papers were subjected to antibacterial properties. The ratio of (6:4) Cht/Ar-AgNPs-coated paper showed excellent antibacterial agent, and it can be used as extending the food product shelf life.

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8–15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of Pseudomonas aeruginosa and Staphylococcus aureus in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram‐negative P. aeruginosa. Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.

The oligosaccharides from agar hydrolysis have special biological activities, and exhibit application prospects in cosmetic, food and pharmaceutical industry. In this study, two novel β-agarases (AgaA and AgaB) were screened and characterized. It was found that the AgaA was an endo-type agarase which could efficiently hydrolyzed agar or agarose to form neoagarobiose (NA2), neoagarotetraose (NA4) and neoagarohexaose (NA6), while the AgaB was an exo-type and bifunctional enzyme that showed activities towards both agarose and porphyran. Based on the properties of the two enzymes, we developed modular strategy for enzymatic production of neoagarobiose through a two-stage hydrolysis reaction. The cheap substrate agar was first liquefied by AgaA at high temperature to form neoagaroligosaccharides, which together with the sulfated polysaccharides were homogenized by AgaB to form neoagarobiose as the final product. High concentration of agar (10 g/L) was almost completely converted into neoagarobiose with high purity.

The problem of recycling polymer waste is one of the most actual problems. One way to solve this problem is to create biodegradable food packaging. By mixing solutions of starch and agar at different mass ratios of polymers in the presence of glycerol, biodegradable films are obtained. Their structural and mechanical characteristics are determined. It is shown that the values of strength, modulus of elasticity and puncture resistance of films are maximal at the mass ratio of agar/starch 7-9. A comparison of the roughness of the films obtained from starch, agar and their mixture showed that the greatest roughness is possessed by films based on starch. The introduction of agar into the films of starch leads to a significant reduction in their roughness. To regulate the structural and mechanical properties of films, it is proposed to use Cа and Mg salts. The influence of Ca2+and Mg2+ions on the strength and deformation characteristics of biofilms was studied. It is shown that Ca2+ions monotonically increase the strength characteristics of starch-agar films, while the curves of changes in these parameters in the presence of Mg2+ions have maxima at a concentration of 0.5%. The difference in the effect of Ca2+and Mg2+ions on the structural and mechanical properties of films is explained by the hydration degree of these ions. The biodegradability of starch-agar films was controlled by changing their IR spectra. The most significant changes are observed in the intensity and localization of peaks corresponding to O-H, C-H and C-C bonds, which can be evidence of changes in the structure of films due to the destruction of the grid of hydrogen bonds and hydrophobic interactions, as well as the break of hydrocarbon chains and the destruction of the skeleton of carbohydrate molecules.

In the production of natural fruit juices, the uniform distribution of fruit pulp particles in the volume is of great importance, which determines the aggregate stability of the system. To maintain the aggregate stability of fruit juices, stabilizers are used, which are polymers or surfactants. In this regard, the influence of natural polymer agar on the stability of melon juice containing particles of melon pulp has been studied. The initial melon juice had a pH of 5.78 and a titrated acidity of 970.29mg of citric acid/L, the content of soluble solids in it corresponded to 10.08 TSS Brix. Samples of melon juice with concentrations of 50, 70 and 90% were used for research. The study of the stability of melon juice in the presence of agar was carried out for 6 days on the Turbiscan device (France). It is shown that at concentrations of agar introduced into melon juice of 0.005% and 0.01%, the system retains its aggregate stability, but when switching to a concentration of 0.02%, the stability of the system decreases. The size of melon pulp particles changes accordingly. If the addition of agar concentration of 0.05% and 0.01% to the melon pulp reduces the particle size of the melon pulp, then an increase in the agar concentration to 0.02% causes a certain increase in the particle size of the fruit pulp. This effect of agar concentration on the aggregate stability of melon juice is explained by the fact that at low concentrations, polymer macromolecules, covering the surface of melon pulp particles, protect them from sticking. When the polymer concentration increases, melon pulp particles begin to stick together due to the coupling of loops and tails of agar macromolecules adsorbed on their surface

The aim of the study was to carry out clinical and microbiological testing of selective growth medium Acinetobacter phenylalanine agar to isolate and identify bacterial species belonging to the Acinetobacter calcoaceticus - Acinetobacter baumannii complex (ACB complex). For this, 400 samples of clinical material (wound discharge, blood, urine, bronchoalveolar lavage) were examined in 2018 in the Clinical and Bacteriological Laboratory of the Military Medical Academy by using routine assays (seeding on blood agar growth medium, pure culture isolation and identification by using biochemical assays as well as VITEK 2 microbial identification system, bioMerieux) and plating together with growth medium Acinetobacter phenylalanine agar selective to Acinetobacter spp. owing to L-phenylalanine as a sole nitrogen and carbon source additional selected with trimethoprim. ACB complex Acinetobacters were identified 18-24 hours later after incubation at 37 °C by emergence of typical colonies on selective medium. Control tests for cytochrome oxidase as well as oxidative / fermentation (OF)-glucose test by using peroxide-hydrogen microvolume method (for 1 h) allowed to rapidly distinguish ACB complex Acinetobacters from other bacteria as well as from Acinetobacter spp. unable to glucose oxidation. Next, species identity for all isolated Acinetobacter strains was established by using matrix-activated laser desorption / ionization with time-of-flight mass spectrometry (MALDI - TOF MS). It was found that by using novel vs. routine assay Acinetobacter spps. were isolated in 26 (18 samples – in monoculture, 8 – in association with Pseudomonas aeruginosa or Klebsiella pneumoniae subsp. pneumoniae with tiny associate colonies) vs. 20 (7 – in monoculture, 13 – in association with Pseudomonas aeruginosa , Klebsiella, Escherichia, Citrobacter, Providencia, Staphylococcus, Enterococcus, Candida albicans ). Using MALDI-TOF MS method revealed that 25 out of 26 Acinetobacter strains isolated on selective growth medium belonged to the ACB complex ( A. baumannii - 23, A. pittii - 2), whereas one strain ( A. baylyi ) did not belong to ACB complex. Hence, the diagnostic specificity of the Acinetobacter phenylalanine agar synthetic growth medium for isolation and identification of the A. calcoaceticus - A. baumannii complex species comprised 96.2%, with diagnostic sensitivity exceeding that one for routine assay by 25%. Use of selective growth medium accelerates research by allowing to isolate and identify ACB complex Acinetobacter spp. 18-24 h later after plating clinical material. Selectivity of growth medium was potentially stable, as its major trophic selection factor did not depend on acquired bacterial antibiotic resistance, which is also suitable as a synthetic growth medium for standardized studies.

Background Colistin has become a last-resort antibiotic for the management of multidrug-resistant gram-negative bacteria. The disk diffusion test is cheap and easy to perform but may be unreliable for colistin susceptibility testing due to poor diffusion of the large colistin molecule. An improved agar diffusion test would increase the reliability of colistin susceptibility testing. This study aimed to modify Muller-Hinton agar (MHA) to improve colistin diffusion in agar. Methods MHA was modified by reducing the agar concentration from 100% to 30% and supplementing with protamine. We tested 60 gram-negative clinical isolates of Pseudomonas aeruginosa (N=27) and Acinetobacter calcoaceticus-baumannii complex (N=33). Disk diffusion test results were interpreted based on minimum inhibitory concentrations determined by broth microdilution. Results The modified MHA yielded the best performance metrics, including 94.7% sensitivity, 100% specificity, and an area under the curve of 0.995 (95% confidence interval, 0.982–1.000), P

Background and Aim: Direct observation, scanning electron microscopy (SEM) is a common method used for the observations of biofilms. N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide) (EDC) fixation method has proven to be a valuable fixation method in the observation of these biofilms. Still, it entails a method of biofilm fixation that can damage slim structures, leading to the impossible observation of biofilm development. In contrast, alcian blue and lysine (ABL) fixation technique appears more glycocalyx of biofilm, fully preserved samples, which may provide much insight into the development of B. subtilis biofilms. Materials and Methods: Here, the evaluation of the fixation of ABL technique for the study of B. subtilis biofilms was carried out in situ, on Congo red agar. In doing so, the comparison to commonly use conventional EDC technique for sample fixation, and observation was carried out. Observations were based on SEM over 30 samples. Results: Overall, ABL technique provided excellent observation of biofilms formed in situ, on Congo red agar, and revealed slime structures, which have not been observed, much in standard EDC fixation or earlier in other studies of these biofilms in B. subtilis. Conclusion: This study reported the appropriate use of ABL in the fixation technique for the preservation of biofilm of B. subtilis.

This study reports the development of a novel and simple formulation for probiotic delivery using chitosan-coated agar-gelatin gel particles. This methodology involves the production of agar-gelatin particles by thermally treating a mixture of agar and gelatin solutions at high temperatures (121 °C) and subsequently coating with chitosan. The particles were able to protect the probiotic strain Lactobacillus plantarum NCIMB 8826 during incubation for 2 h in simulated gastric fluid (pH 2), as no statistically significant loss (P > 0.05) in cell concentration was observed, and also resist dissolution in simulated intestinal fluid (pH 7.2). Interestingly, this protection is related to the fact that the intense thermal treatment affected the physicochemical properties of agars and resulted in the formation of a strong and tight polymer network, as indicated by the X-ray diffraction (XRD) analysis. Using an in vitro faecal batch fermentation model simulating the conditions of the distal part of the large intestine (pH 6.7–6.9), it was demonstrated by quantitative real-time PCR that the majority of L. plantarum cells were released from the agar-gelatin particles within 30 to 48 h. Overall, this work led to the development of a novel methodology for the production of probiotic-containing particles, which is simpler compared with current encapsulation technologies and has a lot of potential to be used for the controlled release of probiotics and potentially other solid bioactives in the large intestine.Key Points• Chitosan gel particles is a simple and scalable method of probiotic encapsulation.• Autoclaving agar-gelatin particles increases their stability at low pH.• Chitosan gel particles protected L. plantarum during gastrointestinal conditions.• Probiotics could be controlled release in the colon using chitosan gel particles.

Background: Candida species are responsible for various clinical infections ranging from mucocutaneous infection to life threatening invasive diseases. Recently there is a serious concern with increased resistance of antifungal drugs and its consequences. Thus, identification of Candida and its antifungal susceptibility testing has a paramount significance in the management of Candidal infections. The aim of the study was to determine antifungal susceptibility pattern of Candida by Mueller-Hinton agar media supplemented with glucose and methylene blue for disk diffusion testing of fluconazole, miconazole, clotrimazole, amphotericin B and nystatin. Methods: A total of 35 Candida species was isolated from 2000 clinical specimens over 6 month’s period from July 2016 to December 2016. Growths on Blood agar and chromogenic agar were evaluated for colony appearance and microscopic examination. Antifungal susceptibility testing was performed by disk diffusion using Mueller-Hinton agar supplemented with glucose and methylene blue. Results: Candida species were more sensitive to clotrimazole (88.58%) and amphotericin B (88.58%) followed by nystatin ((77.14%), miconazole (74.29%) whereas fluconazole showed the highest level of resistance (60%). Conclusions: The increase in resistance to fluconazole is of serious concern as it is the most commonly used azole for candidiasis. The sensitivity profile of Candida isolates will be helpful to choose appropriate antifungal agents, thus decreasing patient’s morbidity and mortality. J Dhaka Medical College, Vol. 28, No.1, April, 2019, Page 28-33

Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens that cause symptoms of severe gastrointestinal disease, including haemolytic uraemic syndrome (HUS), in humans. Currently in England, STEC serotypes other than O157:H7 are not cultured at the local hospital laboratories. The aim of this study was to evaluate the utility of CHROMagar STEC for the direct detection of STEC from faecal specimens in a diagnostic setting, compared to the current reference laboratory method using PCR targeting the Shiga-toxin gene (stx) to test multiple colonies cultured on MacConkey agar. Of the 292 consecutive faecal specimens submitted to the Gastrointestinal Bacterial Reference Unit that tested positive for stx by PCR, STEC could not be cultured on MacConkey agar or CHROMagar STEC from 87/292 (29.8 %). Of the 205 that were cultured, 106 (51.7 %) were detected on both MacConkey agar and CHROMagar STEC and 99 (48.3 %) were detected on MacConkey agar only. All 106 (100 %) isolates that grew on CHROMagar STEC had the ter gene cassette, known to be associated with resistance to tellurite, compared to 13/99 (13.1 %) that were not detected on CHROMagar STEC. CHROMagar STEC supported the growth of 36/40 (90 %) isolates harbouring stx2a or stx2d, the subtypes most frequently associated with progression to HUS. Of the 92 isolates harbouring eae, an important STEC virulence marker, 77 (83.7 %) grew on CHROMagar STEC. CHROMagar STEC is a useful selective media for the rapid, near-patient detection of STEC that have the potential to cause HUS.

Background: Traditional culture of nontuberculous mycobacteria (NTMs) has involved egg-based formulations (Lowenstein–Jensen medium) or defined media (Middlebrook formulations), which have disadvantages of composition complexity, availability, and cost. This study quantitatively compared three non-selective, non-blood based basal agars with Columbia blood agar (CBA), to enumerate Mycobacterium abscessus complex organisms in pure culture. Methods: M. abscessus subsp. massiliense, M. abscessus subsp. bolletii, and M. abscessus subsp. abscessus were employed. Inocula of each of these were counted on three basal agar media, including (i) standard plate count agar (SPCA), (ii) tryptone soya agar (TSA), and (iii) Mueller–Hinton agar (MHA) and compared to counts on CBA. Results: All NTM isolates of all subspecies grew successfully on all four media examined. The growth was most profuse on SPCA, with a mean colony diameter of 3 mm, whereas the mean colony diameter on all other media was 1 mm. Statistically, there was no significant difference in counts when comparing CBA with SPCA or MHA (P > 0.05), whereas there was a statistically significant difference between CBA and TSA (P = 0.01). There was no statistically significant difference between SPCA and MHA (P = 0.53). Conclusion: This study indicates that SPCA and MHA are equally effective as CBA, when enumerating of M. abscessus complex organisms. Employment of TSA gave significantly lower counts than CBA (P = 0.01) and therefore should not be employed when enumerating these organisms. SPCA yielded the most profuse growth of all media examined. In addition to these advantages, given that SPCA does (i) not require blood as a medium constituent, (ii) is simple to reconstitute, (iii) is relatively cheap, and (iv) is widely available commercially, this study endorses employment of SPCA for the nonselective culture of M. abscessus complex organisms, including enumeration.

Vibrio parahemolyticus is a halophilic bacterium which causes widespread seafood poisoning pathogenicity. Although the incidence of disease caused by V. parahemolyticus was stepwise increased, the pathogenic mechanism remained unclear. Herein, the difference of V. parahemolyticus's metabonomic which on blood agar and seawater beef extract peptone medium was detected via nuclear magnetic resonance and 55 metabolites were identified. Among them, 40 kinds of metabolites were upregulated in blood agar group, and 12 kinds were downregulated. Nine pathways were verified by enrichment analysis which were predicted involved in amino acids and protein synthesis, energy metabolism, DNA and RNA synthesis and DNA damage repair. We supposed that the metabolic pathway obtained from this study is related to V. parahemolyticus pathogenicity and our findings will aid in the identification of alternative targets or strategies to treat V. parahemolyticus-caused disease.

The research carried out so far for phage-antibiotic synergy (PAS) differs as regards the technique of modifying the double-layer agar (DLA) method to show the PAS effect on Petri plates, which may contribute to non-uniform research results. Therefore, there is a need to unify the method to effectively detect the PAS effect, at its most basic in vitro test. In this study, bacteriophage T45 and 43 antibiotics belonging to different antibiotic classes were used. Seven different DLA method modifications were tested, in terms of antibiotic addition placement and presence or absence of the base agar. The overall number of phage plaques per plate mainly depended on the antibiotic used. Differences in plaque quantity depended on the type of the DLA method modification. The largest total number of plaques was obtained by the addition of an antibiotic to a bottom agar with the presence of a top agar. This indicates that even though an antibiotic could manifest the PAS effect by a standard disk method, it would be worth examining if the effect is equally satisfactory when applying antibiotics directly into the agar, with regards to using the same bacteriophage and bacterial host.

Due to the increase of bacteria that develop resistance to classical antibiotics in recent years, fosfomycin has become one of the antibiotics gaining importance again. Fosfomycin exerts its bactericidal effect on many bacteria by binding to a cytoplasmic enzyme, MurA, and inhibiting the enzyme enopurivil transferase, which is involved in peptidoglycan synthesis. Bacteria producing ESBL are common pathogens in nosocomial infections and resistance is frequently encountered in their treatment. Fosfomycin is considered as an alternative drug in these infections. With its reintroduction, it is important to establish reliable and reproducible susceptibility testing methods for fosfomycin. In this study, it was aimed to evaluate the utility of disk diffusion, agar dilution kit and automated MicroScan methods (Beckman Coulter, Brea, CA, ABD) for fosfomycin susceptibility of ESBL-producing enteric bacteria. The study included 120 ESBL positive isolates of enteric bacteria (89 Escherichia coli, 31 Klebsiella pneumoniae) cultivated from the samples sent to the Microbiology Laboratory of the Mersin University Medical Faculty of Medicine Hospital between May 2019 and November 2019. Fosfomycin susceptibilities of the isolates included in the study were tested by disk diffusion, automated MicroScan and the commercial agar dilution kit. In the study, 37 (30.8%) of 120 isolates were determined as resistant to fosfomycin by disk diffusion method and six (5%) of the isolates were found to be resistant to fosfomycin with the MicroScan automatized system. With the agar dilution kit, 11 (9.1%) of 120 isolates were found to be resistant as the minimum inhibitory concentration (MIC) values were > 32 µg/ml. Fosfomycin resistance was significantly higher in K.pneumoniae isolates than E.coli isolates by agar dilution method (p= 0.006). Ertapenem resistance was detected in seven of 120 isolates. All seven isolates that were resistant to ertapenem were susceptible to fosfomycin by agar dilution method. All three isolates, which were found resistant to colistin, were susceptible to fosfomycin by agar dilution method. In the study, the categorical agreement of the disk diffusion and MicroScan methods in E.coli isolates with the agar dilution was high and the error rates were low. For K.pneumoniae, categorical concordance was calculated as 22.5% for disk diffusion test and 74.1% for MicroScan, while major and minor error rates were found to be quite high. As a result; fosfomycin is thought to be an alternative drug option in the treatment of infections caused by especially carbapenem and colistin resistant bacteria, with its high activity on ESBL-producing enteric bacteria. It has been determined that there is a great agreement between the agar dilution, which is the reference method for the determination of fosfomycin resistance for E.coli, and the MicroScan and disk diffusion methods, and that the disk diffusion method which provides ease of use in terms of cost and labor compared to the agar dilution method, can be used as a reliable method. However, it has been demonstrated that the agar dilution method should be used in K.pneumoniae isolates. Nevertheless; It was concluded that if the automatized system is used in laboratories where agar dilution cannot be performed, the results should be interpreted carefully, since the error rates are very high.

In this study, Pb(Mg1/3Nb2/3)0.65Ti0.35O3 (PMNT) ceramics were prepared by a water-based gel-casting method. The gel-cast mixtures were dried through soaking in acetone with different soaking times...

Aim. This study aimed to evaluate the antibacterial effect of sodium hypochlorite gel and four types of intracanal medicaments. Materials and Methods. The agar diffusion method was used to evaluate the antibacterial effect of five medicaments (sodium hypochlorite gel (NaOCl), chlorhexidine gel (CHX), calcium hydroxide paste (CH), Ledermix, and Diapex plus) against Enterococcus faecalis (E. faecalis), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli). The zone of inhibition around each medicament was measured in millimeters, after 48 hours of incubation at 37°C. The antibacterial effects of medicaments against each microbial strain and the sensitivity of microorganisms towards each medicament were compared using the one-way ANOVA and Games–Howell post hoc tests. The level of significance was set to p < 0.05 . Results. All medicaments showed variable inhibition zones for all bacterial strains except Diapex Plus which showed no antibacterial activity. NaOCl gel exhibited the most significant inhibition zones for all bacterial strains followed by CHX gel, Ledermix, and CH. However, the effect of CHX and CH paste against S. aureus was statistically similar, while the effect of CH against E. faecalis was significantly higher than the Ledermix. Conclusion. Sodium hypochlorite gel displayed the highest antibacterial activity among tested medicaments and can be recommended as a potent intracanal medicament. Chlorhexidine gel showed a significantly higher antibacterial effect when compared with Ledermix and calcium hydroxide. Calcium hydroxide demonstrated stronger antibacterial activity against E. faecalis than Ledermix. Diapex Plus exhibited no antibacterial effect.

Aureobasidium pullulans α-amylase (ApAmy) mixed with melted agar-agar solution and drop-wisely added to a mixture of organic solvent solution allowed for the entrapment of the α-amylase in the agar-agar organic matrix as beads. The immobilized ApAmy’s characteristics and wash performance were elucidated in comparison with the soluble ApAmy. Agar-agar at 2.0 % (w/v) and toluene: chloroform at 3:1 resulted in the highest immobilization yield retaining about 98% residual activity after ten catalytic cycles. The optimum temperature and pH for the immobilized enzyme were 60ºC and 6.5 respectively. The immobilized ApAmy hydrolysed branched and linear substrates thus establishing its broad substrate specificity. Relatively, the immobilized ApAmy (iApAmy) was more tolerant to organic solvents than the free enzyme. The iApAmy was mildly inhibited by cobalt but metals such as zinc, manganese, calcium and sodium enhanced the free and immobilized ApAmy activity. The iApAmy had a higher washing efficiency (77%) in the presence of detergents than the free enzyme (68%) and control (36%). The iApAmy showed good potentials as a detergent additive and from its characteristics, it could be useful in other industrial applications.

Copper complexes with different ligands (ethylenediaminetetraacetic acid, EDTA, ammonium citrate tribasic, TAC, and alanine, ALA) were studied in aqueous solutions and hydrogels with the aim of setting the optimal conditions for copper stain removal from marble by agar gels, with damage minimization. The stoichiometry and stability of copper complexes were monitored by ultraviolet-visible (UV-Vis) spectroscopy and the symmetry of Cu(II) centers in the different gel formulations was studied by electron paramagnetic resonance (EPR) spectroscopy. Cleaning effectiveness in optimized conditions was verified on marble laboratory specimens through color variations and by determining copper on gels by inductively coupled plasma-mass spectrometry (ICP-MS). Two copper complexes with TAC were identified, one having the known stoichiometry 1:1, and the other 1:2, Cu(TAC)2, never observed before. The stability of all the complexes at different pH was observed to increase with pH. At pH 10.0, the gel’s effectiveness in removing copper salts from marble was the highest in the presence of ALA, followed by EDTA, TAC, and pure agar gel. Limited damage to the marble surface was observed when gels with added EDTA and TAC were employed, whereas agar gel with ALA was determined to be the most efficient and safe cleaning material.

Carboxymethyl cellulose/agar-based functional halochromic films were fabricated by adding alizarin and grapefruit seed extract (GSE). The fillers were evenly dispersed in the polymer matrix to form compatible composite films. The addition of alizarin has improved the film's mechanical strength (20%) and water resistance (40%) with potent antioxidant and excellent color indicating properties. In contrast, GSE has imparted strong antibacterial and antioxidant activities to the film. Also, the addition of alizarin and GSE slightly improved the water vapor barrier properties but did not affect the thermal stability of the film. The composite film also exhibited UV blocking properties with adequate transparency. The composite film showed an excellent pH-dependent color change with color reversibility and color stability and a volatile gas detection function. The film also showed potent antimicrobial activity against foodborne pathogenic bacteria

Hydrogel films composed of chitosan and agar or chitosan, agar and honey/bee pollen were prepared; they could be used as active wound dressings. During this study, various types of gel films were prepared using chitosan with different molecular weights and ratios of the two biopolymers. In addition, compositions with different amounts of honey or bee pollen were obtained. The selected samples were characterized by determining typical properties that are important for wound dressings. The best twocomponent films had a chitosan to agar weight ratio of 2:1. From among the examined tri-component films, the 2:1:0.5 weight ratio of chitosan, agar and 50 wt% honey solution was the best composition.

Pseudomonas aeruginosa is one among the leading nosocomial pathogens worldwide. It is therefore necessary to decrease and to prevent a rebound of growth. Comparison of novel suspension testing method and agar cup diffusion method results in determination of the sensitive method to identify effectiveness of disinfectants against microbial activity. This study was carried out to determine the effectiveness among novel suspension testing and agar cup diffusion method to determine disinfectant susceptibility and also to identify the efficacy of ethanol and chlorhexidine gluconate at manufacturer’s concentration against Pseudomonas aeruginosa. In this study 50 isolates of Pseudomonas aeruginosa were included. Each isolate was subjected to novel suspension testing method and agar cup diffusion method with ethanol and chlorhexidine gluconate, the results were observed and recorded. The 50 isolates, sensitive strains showed 100% sensitivity to chlorhexidine gluconate and 95% to ethanol. Whereas resistant strains showed 100% sensitivity to chlorhexidine gluconate, 75% were sensitive to ethanol. Both agar cup diffusion method and novel suspension method yielded similar results. With the advantage of easy processing and less time consumption, agar cup diffusion method can be routinely used for determining the disinfectant susceptibility testing.

AIMS Several acidophilic bacteria have not been cultured, primarily owing to the lack of suitable culture methods under strong acidic conditions. This study aimed to quantitatively evaluate the strengths of the agar plates (AP) and gellan gum plates (GP), and optimal culture periods under strong acidic conditions. METHODS AND RESULTS To define the lower limit of plate strength for bacterial isolation culture, the diameter of Escherichia coli K12 colonies and the breaking stress of plates at different concentrations of gelling agents, medium composition and pH conditions were determined. The lower limit of available strength of AP and GP was 19·6 and 14·8 kPa, respectively. Medium composition slightly affected AP breaking stress, although GP with a high cationic concentration medium could not be prepared. CONCLUSIONS Assessment of the strength limits of AP and GP revealed that AP is not suitable for prolonged bacterial culture (≥72 h). Furthermore, GP was completely ineffective for bacterial culture under highly acidic conditions (≤pH 1·0). SIGNIFICANCE AND IMPACT OF THE STUDY Our quantitative evaluation method based on breaking stress is a potentially valuable tool to understand the state and the suitable limit of plate culture methods in more detail under various conditions.

Borax-agar gel has been used recently in the deacidification and other conservation processes for paper manuscripts. However, the residues of borax-agar can be damaging to the cellulose fibers. Conservators are trying to solve this problem, especially with the great success achieved by the borax / agar based gel in the acidity neutralization and improve the mechanical properties of the paper manuscripts. The current study considers whether the use of paper barriers such as Japanese gampi, linen, and rayon can reduce harmful borax-agar residues. Historical paper specimens were treated with 3% and 6% of agar poultice with different barriers such as rayon, pure linen, and Japanese gampi paper. After drying, the treated paper samples were exposed to hot-moist ageing at 80 °C and 65% relative humidity for 72 h. The role of different barriers used in the reduction of residues from agar poultice and the effect of these residues on cellulose fibers were studied via some analytical techniques, such as digital optical microscopy, scanning electron microscopy, pH, color change, and Fourier-transform infrared spectroscopy (FTIR), were used. The results showed that 3% of the agar poultice-borax with a linen barrier gave the best results with no residue left after treatment.

Full-thickness burns pose a major challenge for clinicians to handle because of their restricted self-healing ability. Even though several approaches have been implemented for repairing these burnt skin tissue defects, all of them had unsatisfactory outcomes. Moreover, during recent years, skin tissue engineering techniques have emerged as a promising approach to improve skin tissue regeneration and overcome the shortcomings of the traditional approaches. Although previous literatures report the wound healing effects of the squalene oil, in the current study, for the first time, we developed a squalene-loaded emulgel-based scaffold as a novel approach for potential skin regeneration. This squalene-loaded agar-based emulgel scaffold was fabricated by using physical cross-linking technique using lecithin as an emulsifier. Characterization studies such as X-ray diffraction, Fourier-transform infrared spectroscopy, and field emission scanning electron microscopy revealed the amorphous nature, chemical interactions, and cross-linked capabilities of the developed emulgel scaffold. The squalene-loaded emulgel scaffold showed excellent wound contraction when compared with the agar gel and negative control. In case of the histopathology and recent immunohistochemistry findings, it was clearly evidenced that squalene-loaded emulgel promoted faster rate of the revascularization and macrophage polarization in order to enhance the burn wound healing. Moreover, the findings also revealed that the incorporation of squalene oil into the formulation enhances collagen deposition and accelerates the burnt skin tissue regeneration process. Finally, we conclude that the squalene-loaded emulgel scaffold could be an effective formulation used in the treatment of the burnt skin tissue defects.

Biodegradable films based on agar with glycerol (GLY) as a plasticizer were developed by incorporating hydroalcoholic garlic extract (HGE) on the film surface. The effect of GLY content (0, 15, or 30 wt%) and different concentrations of HGE (0, 0.5, 1, or 1.5 μg/mL) on the physicochemical and transport properties of the films was evaluated. The optical (color and transparency), mechanical (tensile test), transport (diffusion and water vapor transmission rate), thermal (thermogravimetric analysis) structural (infrared spectroscopy and X-ray diffraction), and morphological (scanning electron microscope) properties were analyzed. The impregnation of HGE increased the transparency values and decreased the luminosity, tensile strength, elastic modulus, and crystallinity of the agar films. The formulation of 30 wt% GLY with 1.5 μg/mL HGE, identified as 30 GLY [1.5], showed a similar thermal stability that of a neat agar film. The agar films with 30 wt% GLY showed the lowest diffusion coefficient and water vapor transmission rate, indicating that volatile compounds are slowly released. From the results the formulation 30 GLY [1.5] could be used as a film to transport and to release HGE which is supported by a biodegradable matrix and this system has a potential use as insect semiochemical for plague control.