Uticaj krioprotektivnog medijuma sa glicerolom na liofilizaciju bakterija mlečne kiseline

The aims of lyophilization (freeze-drying) of lactic acid bacteria are to preserve pure cultures or to prepare starters for the dairy industry. In both cases, the choice of the cryoprotectant is very important. In this work, samples of Bifidobacterium breve A71 and Bifidobacterium bifidum BbTD were freeze-dried in a new cryoprotective medium containing lactose, gelatin and glycerol (medium B). The reference medium contained saccharose, gelatin and skim milk (medium A). Before lyophilization, the eutectic points of both media were determined, because the products must be cooled to a temperature below its freezing point. The success of the cryoprotectants was estimated in terms of the number of surviving organisms after lyophilization. Bifidobacterium breve A71 and Bifidobacterium bifidum BbTD freeze-dried in media A and B showed high survival rates. Bifidobacterium breve A71 showed a greater percentage survival in combination with medium B than with medium A. These results could be utilized in the manufacture of Bifidobacterium breve A71 as a starter in the diary industry because it is a human isolate which, except for acidification, has probiotic activity.Bakterije mlečne kiseline se liofilizuju (suše u zamrznutom stanju) sa ciljem čuvanja kultura na duže vreme ili u formi startera za mlečnu industriju. U oba slučaja važan je izbor krioprotektanata. U ovom radu praćena je liofilizacija Bifidobacterium breve A71 i Bifidobacterium bifidum BbTD u novom krioprotektivnom medijumu sa laktozom, želatinom i glicerolom (medijum B). Referentni medijum sadrži saharozu, želatin i obrano mleko (medijum A). Liofilizaciji prethodi određivanje eutektičke temperature jer se faza zamrzavanja odvija na nešto nižoj temperaturi od eutektičke. Efikasnost krioprotektanata ispitivana je u smislu preživljavanja kultura nakon liofilizacije. Bifidobacterium breve A71 i Bifidobacterium bifidum BbTD liofilizovani u medijumima A i B ostaju u visokom procentu vijabilne. Obe kombinacije krioprotektanata daju relativno visok procenat preživljavanja. Bifidobacterium breve A71 u kombinaciji sa medijumom B ima veći procenat preživljavanja nego u kombinaciji sa medijumom A. Ovi rezultati mogu poslužiti u proizvodnji liofilizovanog Bifidobacterium breve A71 - startera u mlečnoj industriji jer je to humani izolat sa potencijalno dobrim probiotskim osobinama

Mineralized agar-based nanocomposite films: Potential food packaging materials with antimicrobial properties

New mineralized, agar-based nanocomposite films (Zn-carbonate and Zn-phosphate/agar) were produced by a combination of in situ precipitation and a casting method. The presence of minerals significantly influenced the morphology, properties and functionality of the obtained nanocomposites. Reinforcement with the Zn-mineral phase improved the mechanical properties of the carbonate-mineralized films, but had a negligible effect on the phosphate-mineralized samples. Both nanocomposites showed improved optical and thermal properties, better Zn(II) release potential in a slightly acidic environment and exhibited antimicrobial activity against S. aureus. These results suggest that Zn-mineralized agar nanocomposite films could be potentially used as affordable, eco-friendly and active food packaging materials.This is the peer reviewed version of the paper: Malagurski, I., Levic, S., Nesic, A., Mitric, M., Pavlovic, V., & Dimitrijevic-Brankovic, S. (2017). Mineralized agar-based nanocomposite films: Potential food packaging materials with antimicrobial properties. Carbohydrate Polymers, 175, 55–62. [https://doi.org/10.1016/j.carbpol.2017.07.064][https://www.sciencedirect.com/science/article/abs/pii/S0144861717308408?via%3Dihub

Photocatalytic Degradation of Carbofuran in Water Using Laser-Treated TiO2: Parameters Influence Study, Cyto- and Phytotoxicity Assessment

This study investigates the impact of changing parameters on the photocatalytic degradation of carbofuran (CBF) using laser-treated TiO2 nanotube arrays on a Ti mesh under simulated sunlight irradiation and assessing toxicity during photocatalytic degradation. Various parameters, including the stirring effect, light intensity, initial CBF concentration, and variation in the active surface area of laser-treated TiO2 photocatalysts, were examined to determine their impact on degradation efficiency. The photodegradation kinetics were monitored using ultra-performance liquid chromatography with a PDA detector (UPLC-PDA) and UV-Vis spectrophotometry, while mineralization was assessed by a total organic carbon (TOC) analyzer. The photocatalytic degradation of CBF is enhanced by an increase in the active surface area of the TiO2 photocatalyst, light intensity, and the introduction of stirring, but it decreases with an increase in the initial concentration of CBF. The toxicity assessments revealed that the cytotoxicity of CBF initially increased during the degradation process but decreased after further treatment, indicating the formation and subsequent breakdown of toxic intermediates. The phytotoxicity test showed that longer degradation times resulted in higher toxicity to plant growth. This study provides new insights into the photocatalytic degradation of CBF with TiO2, the importance of parameter optimization for more efficient treatment, and the use of toxicity tests to confirm the success of the photocatalytic proces

Synthesis and antimicrobial properties of Zn-mineralized alginate nanocomposites

New bioactive and antimicrobial biomaterials were produced by alginate-mediated biomineralization with Zn-mineral phase. The synthesis procedure is simple, cost-effective and resulted in. two different Zn-mineralized alginate nanocomposites, Zn-carbonate/Zn-alginate and Zn-phosphate/Zn-alginate. The presence of Zn-mineral phase and its type, have significantly affected nanocomposite morphology, stability, total metallic loading and potential to release Zn(II) in physiological environment. Antimicrobial experiments showed that both types of Zn-mineralized nanocomposites exhibit strong antimicrobial effect against Escherichia coli, Staphylococcus aureus and Candida albicans. These results suggest that alginate biomineralization, where minerals are salts of essential metallic ions like Zn(II), represents a'good strategy for designing multifunctional biomaterials for potential biomedical applications.This is the peer reviewed version of the paper: Malagurski, I., Levic, S., Pantic, M., Matijasevic, D., Mitric, M., Pavlovic, V., & Dimitrijevic-Brankovic, S. (2017). Synthesis and antimicrobial properties of Zn-mineralized alginate nanocomposites. Carbohydrate Polymers, 165, 313–321. [https://doi.org/10.1016/j.carbpol.2017.02.064

Synergy of Nd:YAG Picosecond Pulsed Laser Irradiation and Electrochemical Anodization in the Formation of TiO2 Nanostructures for the Photocatalytic Degradation of Pesticide Carbofuran

This study proposes a simple and controlled method for producing TiO2 with phase junction, oxygen vacancies, and Ti3+ by combining picosecond pulsed laser irradiation and electrochemical anodization. Ti mesh was pretreated by irradiating with a picosecond pulsed laser technique using an Nd:YAG laser (1064 nm) at two fluencies, 15 J/cm2 and 30 J/cm2 . The samples were then subjected to electrochemical anodization to form TiO2 nanotube arrays on the previously laser-treated surface. This study will investigate the possibility of forming TiO2 nanotube arrays on a pre-laser-treated Ti substrate and determine their physicochemical and photocatalytic properties. The samples were characterized by FESEM, XRD, Raman, XPS, and UV-Vis DRS. UV-Vis spectroscopy was used to observe the progress of photocatalytic degradation for all samples, and degradation products were determined using GC-MS. With the synergistic effects of phase junction, oxygen vacancies, and Ti3+, the laser-treated TiO2 with 30 J/cm2 showed a higher photocatalytic degradation rate (85.1%) of the pesticide carbofuran compared to non-laser-treated TiO2 (54.8%), remaining stable during successive degradation cycles, which has promising practical applications

Protection of probiotic microorganisms by microencapsulation

Probiotic bacteria are used in the production of fermented dairy foods, pharmaceutical products and health supplements. They play an important role in promoting and maintaining human health. In order, to produce health benefits probiotic strains should be present in a viable form at a suitable level during the product's shelf life until consumption and maintain high viability throughout the gastrointestinal tract. Despite the importance of these beneficial microorganisms many investigations have shown their poor viability and stability, especially for bifidobacteria in fermented products. The introduction of microencapsulation techniques for protection of probiotic strains has resulted in greatly enhanced viability of these microorganisms in food products as well as in the gastrointestinal tract. This paper gives an overview of available microencapsulation techniques and materials for probiotic protection and stabilization. Several methods of microencapsulation for probiotic bacteria, including extrusion, emulsification, drying (fluidized bed, spray, freeze) and spray coating techniques, are presented. The commonly used supporting materials like alginate, starch, chitosan, gelatin, waxes, biogums, and some others are also discussed

APPLICATION OF CRUDE FUNGAL LACCASE FROM GANODERMA SPP. IN DECOLORIZATION OF TRIPHENYLMETHANE DYE CRYSTAL VIOLET

Industrial dye effluents that contain triphenylmethane dyes are environment-threatening problem. The triphenylmethane dyes are one of the largest dye’s group that is discharged in large quantities to water bodies. Removing of them with fungal enzymes is big scientific challenge. The fungal laccases are promising tool for removing of these dyes from water bodies. In this study, the potential of crude fungal laccase from genus Ganoderma in decolorization of triphenylmethane dye, crystal violet was investigated. The crude fungal enzyme was produced using agroindustrial lignocellulosic waste, cereal mix. The effect of different substrate masses (15g, 25g and 50 g) and Cu2+ ions concentrations (0.25 mM, 0.75 mM, 1.0 mM, 2.5 mM и 5.0 mM) on lccase production were investigated. The obtained crude fungal laccase with the highest activity was used for decolorization of crystal violet at different concentrations from 20 mg/L to 50 mg/L. The crude fungal laccase from genus Ganoderma had the highest activity of 47.43 U/g, when the substrate mass of 50 g was used for enyzme production. The lower masses of substrate (15g and 25g) induced lower laccase activities of 45.07 U/g and 46.69 U/g, respectively. The initial addition of Cu2+ ions in concentration of 0.25 mM to agroindustrial waste led to decrease of laccase activity compared to the laccase activity of laccase obtained from agroindustrial waste that didn’t contain Cu2+ ions. On the other hand, the increase of Cu2+ concentration to 1.0 mM in the substrate led to increase the laccase activity. The highest laccase activity of 47.53 U/g was obtained when the 1.0 mM Cu2+ was added to substrate, while the decrease in laccase activity was observed when 5.0 mM Cu2+ was added to the agroindustrial waste. Decolorization of crystal violet at different concentrations (20 mg/L, 30 mg/L, 40 mg/L, 50 mg/L) was carred out at pH 5 and temperature of 50 ºC for 120 min. The highest decolorization efficiency of 14.42 % was obtained in the case of the lowest dye concentration (20 mg/L), while the lowest decolorization efficiency of 3.76 % was obtained when the highest dye concentration of 50 mg/L was decolorized with crude fungal laccase for 120 min. The obtained results show that fungal crude laccases can be used for decolorization of triphenylmethane dyes, but the detailed optimization is very important for obtaining relatively high decolorization efficiencies for short time

The evaluation of the antioxidant potential during the oxidative polymerization of polyphenol compounds induced by laccase enzyme

The polymerization and crosslinking of various phenolic compounds induced by the laccase enzyme have been in recent years increasingly used in food industry, due to the emergence of products with improved properties, especially with increased antioxidant activity. In this regard, this study has explored the laccase-induced structural changes of two types of naturally occurring polyphenols, named gallic acid and epigallocatechin gallate, and their antioxidant activity. In the first part, the effect of the laccase of different origin - laccase of white rot fungi (Ganoderma spp.), previously grown on waste cereals and commercial laccase from Novozym® 51003, were investigated. Based on the results obtained after incubation (24 h, 50ºC), the sample containing a mixture of polyphenols, rather than individually, gave visible changes in the reading of the UV-Vis spectrum and increased antioxidant activity with small differences between commercial laccase and laccase of white rot fungi, which indicates that laccase obtained by growing fungi on waste cereals may be competitive for such a purpose. Moreover, the use of such an obtained laccase is more environmentally friendly and economically viable than use of commercial one. Further process optimization of polyphenols polymerization was performed within the method of multifactor statistical analysis (Design Expert), by using of commercial laccase, where by the effect of enzyme concentrations (0.1, 0.3 and 0.5 U/ml) and incubation time (4, 14 and 24 h) were monitored. The maximal antioxidant activity, measured by both DPPH (inhibition of 58.58% of radicals) and FRAP (176.57 mmol Fe2+/ml) was achieved by a sample containing a mixture of polyphenols and 0.3 U/ml laccase enzymes, after 14 h, at 50˚C. The results of this study revealed that careful optimization of process variables during polyphenols polymerization is extremely important for obtaining the product with desirable value added properties, which may be implemented in food and pharmaceutical industry

Food products modification by direct enzymatic synthesis of fructo-oligosaccharides with purpose of reduction of sucrose content and enrichment of the products with prebiotics

Predmetni pronalazak se odnosi na "in situ" enzimski postupak sinteze frukto-oligosaharida direktnom transfruktozilacijom saharoze prisutne u prehrambenim proizvodima korišćenjem enzima fruktozil-transferaze. Na taj način sharoza prisutna u proizvodu se konvertuje u prebiotike, frukto-oligosaharide, pri čemu se dobija proizvod poboljšanih funkcionalnih svojstava, sa smanjenim sadržajem saharoze, tj. manjim glikemijskim indeksom. Takođe, predmetni postupak se odnosi i na proizvode sa prebiotskom aktivnošću proizvedene prema metodama ovog pronalask

Decolorization of azo dye Methyl Orange with crude fungal laccase obtained by growing Ganoderma spp. on cereal mix

In recent years, one of the biggest environmental problems is the pollution of water with colored wastewater which has negative effect on the environment and human health. Wastewaters contain complex structural compounds, such as azo dyes that used today in many industrial fields. Removing of azo dyes from wastewater using traditional methods is an extremely complex and in many cases ineffective process. In recent decades, there is a tendency towards the application of environmentally acceptable methods of removing synthetic dyes from wastewater. Method which has proven to be very effective, is the degradation of synthetic dyes using various fungal enzymes. In this study, the crude fungal laccase (31,42 UmL-1) obtained by growing fungal mycelium Ganoderma spp. on cereal mix was used for decolorization of Methyl Orange. Decolorization procedure was carried out at different temperatures (30-70 ºC) and pH (3-8) in order to determine the optimal conditions for dye decolorization. The incubation time was 180 min and every 15 min during the incubation time, the change in color intensity was monitored spectrophotometrically at 472 nm and decolorization efficiency (DE) was calculated. The optimal pH was 5 with DE of 57 % at 30 ºC, while in the case of other pH values, DE was lower. The lowest DE (1,2 %) was in the case of pH 8, which indicates that laccase activity decreases in the alkaline medium. The optimal temperature of decolorization was 50 ºC with DE of 62 % at pH 5, while the DE was lower at higher and lower temperatures, which is in accordance with the literature data on the laccase activity optimal temperature of the Ganoderma spp. The lowest DE was 35 % at 70 ºC and pH 5. The obtained results show that laccase with good decolorization properties can be obtained using cheap agro-industrial wastes, such as cereal mix. The low cost of laccase production as well as the relatively high DE in a short time may further broaden its application in wastewater treatment