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Substantial agricultural losses resulting from plant diseases caused by different plant pathogens are one of the worldwide challenges today. Among these, Botrytis cinerea, responsible for gray mold disease, stands out for its capacity to devastate significant quantities of diverse valuable crops. Utilization of biocontrol agents for suppressing phytopathogens has become imperative, and bacteria from the genus Bacillus hold an immense potential due to their rapid replication rate, resistance to adverse environmental conditions, enhanced effectiveness in promoting plant growth and broad-spectrum activity. The objective of this study was to determine the best sources of carbon, nitrogen and phosphorus in cultivation media with the aim of maximizing both antimicrobial activity against B. cinerea and plantgrowth-promoting (PGP) potential during the early stages of cucumber plant development, exhibited by Bacillus sp. isolate Par 3. Antimicrobial activity was tested using the well diffusion method. The influence of Bacillus sp. isolate Par 3 on plant germination was tested on cucumber seeds. The largest inhibition zones were achieved in two cases, with 1) sucrose as carbon source, ammonium nitrate as nitrogen source, and diammonium hydrogen phosphate as phosphorus source and 2) glycerol as carbon source, ammonium nitrate as nitrogen source and dipotassium hydrogen phosphate as phosphorus source. Seeds treated with a culture liquid of Bacillus sp. isolate Par 3 using the optimized medium exhibited the best results in terms of cucumber germination percentage (100%), root length (53.09 mm) and shoot length (13.26 mm). Bacillus sp. Par 3 isolate was identified as Bacillus subtilis using 16S rRNA gene sequencing. The results of this study underscore the significance of media optimization for the production of biocontrol agents, taking into account both antimicrobial efficacy and PGP characteristics.

This work illustrates the prediction of frost action mechanisms on ceramic compacts and their biocorrosion resistance to fungus action. The ceramic compacts were produced from two raw materials: coal fly ash (40 wt.%) and clay material (60 wt.%). The ceramics models were made in laboratory conditions by pressing (P = 45 MPa), drying (105°C, 3h), and sintering (1100°C, 1 h; heating rates 3°C/min and 10°C/min.). The mechanisms responsible for the deterioration of the designed ceramic compacts were defined based on the values of the total porosity, pore size distribution, pore critical radius, and the Maage factor, as well as on the values of water permeability. The biocorrosion process was investigated using Aspergillus niger fungus as a model microorganism. The different degrees of fungus colonization on the designed compacts were comparatively analyzed based on the Scanning Electron Microscopy investigation results. The gained results are encouraging as they show that the utilization of fly ash (40 wt.%) in ceramic composites is possible without significant deterioration of their durability (frost action and microbiological corrosion resistance) compared with the ones whose production was based only on clay material.

Kombucha as a tea-based fermented beverage has become progressively widespread, mainly in the functional food market, because of health-improving benefits. As part of a daily diet for adults and children, kombucha was a valuable non-alcoholic drink containing beneficial mixtures of organic acids, minerals, vitamins, proteins, polyphenols, etc. The influence of the specific surface area of the vessel, the inoculum size, and the initial tea concentration as operating factors and fermentation time as output variable on the efficiency of kombucha fermentation was examined. The focus of this study is optimization and standardization of kombucha fermentation conditions using Box-Behnken experimental design and applying an artificial neural network (ANN) predictive model for the fermentation process. The Broyden-Fletcher-Goldfarb-Shanno iterative algorithm was used to accelerate the calculation. The obtained ANN models for the pH value and titratable acidity showed good prediction capabilities (the r2 values during the training cycle for output variables were 0.990 and 0.994, respectively). Predictive ANN modeling has been proven effective and reliable in establishing the optimum kombucha fermentation process using the selected operating factors.

In this research, chicken meat was inoculated with selected microorganisms and subjected to the osmotic dehydration process in two osmotic solutions, in an effort to investigate the effect of storage time duration on its microbiological and chemical characteristics. Total viable counts, numbers of Enterobacteriaceae, Salmonella spp., Listeria monocytogenes, Escherichia coli, proteolytic bacteria, psychotropic bacteria, of microbiological, and biogenic amine content, TBARS and DPPH, and chemical analyses were conducted on meat samples stored at 22°C, during 14 days. During storage, the number of all tested microorganisms on meat samples decreased. The highest reduction occurred in the first 4 days. The meat dehydrated in molasses achieved better results of microbiological profile during storage. Results of TBARS and DPPH analyses indicated lipid oxidation after 14 days of storage, while the results after 10 days were satisfactory. Developed mathematical models allows good prediction of microbiological and chemical responses of dehydrated chicken meat during the investigated storage duration.

As one of the main non-covalent relations in microbiological-based systems, cell surface hydrophobicity (CSH) can be observed as a relevant parameter for biodegradation capability and suggested bacterial behaviour and biofilm formation during a bioremediation process. On the other hand, the role of ureolytic bacteria in bioremediation has subsequently led to the examination of this bacterial type in different engineering fields. In order to optimize the operating parameters of microbial adhesion to hydrocarbons test (MATH) for ureolytic bacteria, Box–Behnken experimental design was conducted for five ureolytic bacteria isolated from soils, as well as for the reference strain Sporosarcina pasteurii DSM 33. The optimization was completed with and without the essential substrate for the targeted metabolic reaction, with the aim to compare differences in bacterial hydrophobicity. A vortex time of 2 min, a hydrocarbon volume of 0.5 mL, and a phase separation time of 15 min are recommended as MATH operating parameters for all tested ureolytic bacteria. Although all bacteria are hydrophobic, lower CSH values in the presence of urea were observed for the same bacterium, which could be explained by the interaction of urea with the organic phase of the separation system, as well as a rapid ureolysis process that also occurs during the application of ureolytic bacteria in biotechnology systems.

In the past decades, the bioremediation process based on denitrification by aerobic heterotrophic bacteria was extensively studied for different engineering approaches. Besides the fact that only non-pathogenic and non-biofilm forming bacteria must be used, it is very important to isolate bacteria or a group of bacteria in nature with the capacity to remove completely nitrate without accumulation of nitrogen oxides or ammonia as intermediates. In this article, the denitrification capacity of 43 bacterial strains isolated from slightly alkaline and calcite soils along the Danube River were investigated by artificial neural network (ANN) modelling. According to the obtained results, an ANN model was developed for the prediction of denitrification capacity of bacterial soil strains based on six signification denitrification indicators: biomass and N2 gas production, nitrate and nitrite concentration as well as nitrite and ammonia formation. The ANN model showed a reasonably good predictive capability of the outputs (overall R2 for prediction was 0.958). In addition, the experimental verification of the ANN in laboratory testing indicated that the ANN could predict the denitrification capacity of soil bacteria during the denitrification process in laboratory conditions.

Increased consumption, big production units and very efficient delivery service networks of fresh vegetables and salads caused a higher number of foodborne illnesses in the last two decades all over the world. In this study 15 fresh vegetable salads from different marketplaces in Novi Sad were tested by reference microbiological methods (detection of Salmonella spp., enumeration of Listeria monocytogenes, mesophilic aerobic bacteria, yeasts and molds, sporogenic mesophilic aerobic bacteria, sporogenic sulfite-reducing bacteria, Bacillus cereus, Enterobacteriaceae, Escherichia coli and coagulase positive staphylococci). Salmonella spp. was found in one sample which, according to the safety criteria for such a product (if treated as ready-to-eat), was considered to be microbiologically unsafe. The number of Listeria monocytogenes in all tested samples was

In this paper, influence of increasing concentrations of beeswax on the antimicrobial activity of chitosan-caraway essential oil biofilm was investigated. Selected microorganisms for the test were Salmonella Typhimurium and Listeria monocytogenes. Reduction of S. Typhimurium and L. monocythogenes viable counts in bacterial suspension in the presence of chitosan films with or without added beeswax amounted over 80 % after 24 h contact time, and over 95 % after 3 h of contact time, respectively and influence of added beeswax on growth reduction was not detected. However, when number of S. Typhimurium viable cells was analyzed (log CFU/ml), it was shown that addition of beeswax led to increased activity of films, especially for the films with 36 kg/m3 and 54 kg/m3of beeswax. When films were transferred, after 24 h in bacterial suspension, onto Petri dishes with nutrient agar and incubated for 24 h on 37°C, results also showed beeswax contribution to growth inhibition of S. Typhimurium.

In the recent years, extensive studies have been conducted on the application of bioremediation in order to prevent and solve the global problem of nitrate accumulation especially in water and soil. In the studies related to the biological denitrification, Pseduomonas stutzeri is usually used as a model microorganism due to its ability of performing a complete reduction of nitrate. The aim of this work is to establish a culture medium at a laboratory level for maximizing the biomass production of Pseduomonas stutzeri ATCC 17588 and Pseudomonas stutzeri D1, previously isolated from the Danube (Novi Sad, Serbia) by using a Box-Bhenken experimental design and response surface methodology. The selected independent variables (+, 0, - levels) were: glucose (0, 1 and 2 g/L), KNO3 (1, 2 and 3 g/L), and peptone (0.4, 2 and 4 g/L), while the number of viable cells (log/mL) was chosen as a dependent factor (response). Based on the obtained results, it can be noticed that the maximum number of P. stutzeri ATCC 17588 viable cells is achieved when the initial content of glucose, KNO3 and peptone in the medium are 0 g/L, 2 g/L and 4 g/L, respectively. In the case of P. stutzeri D1, the most appropriate media for enhancing the biomass production consists of glucose (1 g/L), KNO3 (3 g/L) and peptone (4 g/L). Тhe obtained results can be used for further technoeconomic analysis and scale up of the P. stutzeri biomass production. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45008]

A large volume of industrial waste of biological origin is produced annually worldwide, causing a serious disposal problem even though it is a huge source of beneficial compounds which may be used for their high nutritional and bioactive properties. The bio-potential of blackberry pomace (waste) obtained after juice separation from the Čačanska bestrna and Thornfree cultivars was evaluated. Higher amounts of total and monomeric anthocyanins, total phenolics, and total flavonoids were found in Thornfree pomace extract and demonstrated stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (2.12 mmol TEAC g-1) than Čačanska bestrna pomace extract (1.03 mmol TEAC g-1). Both extracts highly increased apoptosis/necrosis ratios in all investigated cell lines. The highest cell growth inhibition effects (EC50=52.5 - 64.7 μg mL-1) and the highest increase of apoptosis (AI=12.2) were obtained in breast adenocarcinoma cell line. Both blackberry pomace extracts inhibited the growth of all tested microorganisms. In the reference and wild bacterial strains MIC and MBC/MFC were achieved in the 0.39-25 mg mL-1 and 0.78-25 mg mL-1 range, respectively. Blackberry cultivar pomaces are rich source of phytochemicals with significant health promoting properties that could be further utilized as beneficial food ingredients. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31044]

This study investigated properties of starch-based edible films with oregano and black cumin essential oil addition. Essential oils addition positively affected film swelling (decreased due to essential oil addition), mechanical properties (tensile strength decreased while elongation at break increased), and water vapor barrier properties (decreased along with essential oils addition). Control film did not have any biological activity, which proves the need for essential oils addition in order to obtain active packaging. Oregano oil was more effective in terms of biological activity. Endothermal peak, above 200°C, represents total thermal degradation of edible films. Diffraction pattern of control film showed significant destruction of A-type crystal structure. Addition of essential oils resulted in peak shape change: diffraction peaks became narrower. Principal Component Analysis has been used to assess the effect of essential oils addition on final starch-based edible films characteristics with the aim to reveal directions for the film characteristics improvement, since the next phase will be optimal film application for food packaging.

The aim of this study was to evaluate bioactivity of chitosan film with incorporated caraway essential oil by measuring antioxidant and antimicrobial activity. A Fourier transform infrared spectroscopy was used to determine the potential interaction of functional groups of chitosan film and incorporated caraway essential oil. New detected peaks and main shifts in the peaks of chitosan spectra are attributed mainly to presence of s-(+)-carvone and limonene, the main components of caraway essential oil. The antioxidant activity of chitosan film was analyzed by DPPH method. Chitosan film without incorporated caraway essential oil showed the lowest scavenging ability (29.95%, after 24 h). The addition of different concentrations of caraway essential oil into chitosan film significantly enhanced antioxidant activity of pure chitosan film, reaching the maximum of 95%. ASTM E 2149 - 01 method was performed to evaluate the antimicrobial activity of chitosan films. The reduction of bacteria cell number in contact with examined films was tested on Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes and Gram-negative bacteria Escherichia coli and Salmonella Typhimurium. The most sensitive bacteria was Staphylococcus aureus and the most resistant bacteria was Salmonella Typhimurium for all tested films. These results suggested that incorporation of caraway essential oil into chitosan film significantly improved its antioxidant and antimicrobial activity. The film showed a great potential to be used as an active packaging material.

Kombucha is a traditional beverage obtained by fermenting sweetened black tea with tea fungus, which represents a consortium of acetic acid bacteria and yeasts. Also, CoffeeBerry® products, which derived from the whole fruit of the coffee plant, are valuable ingredients with nutritional and health-enhancing potential. Samples of fermentation broths enriched with CoffeeBerry® extract and traditional Kombucha were analysed. The fermentation was performed in a bioreactor at 28±1°C for nine days. The results showed that the CoffeeBerry® extract has contributed to a faster fermentation of cultivation medium. Some individual polyphenolic compounds and catehins in fermentation broth samples were identified and quantified by High Performance Liquid Chromatography (HPLC). Among the bioactive compounds present in investigated samples obtained during Kombucha fermentation of the sweetened black tea enriched with CoffeeBerry® extract, chlorogenic acid (188.94-458.56 μg/mL) was the predominant. The antioxidant activity of investigated samples was tested by measuring their ability to scavenge DPPH and reactive hydroxyl radicals by electron spin resonance (ESR) spectroscopy. The scavenging activities on DPPH and hydroxyl radicals were increased with duration of fermentation. IC50 values for Kombucha fermentation broth enriched with CoffeBerry®, based on DPPH and hydroxyl radical scavenging activities, were in the range 26.33-170.13 μL/mL and 11.33-102.22 μL/mL, respectively.

Reducing the costs of repairing concrete structures damaged due to the appearance of cracks and reducing the number of people involved in the process of their repair is the subject of a multitude of experimental studies. Special emphasis should be placed on research involving industrial by-products, the disposal of which has a negative environmental impact, as is the case in the research presented in this paper. The basic idea was to prepare a mortar with added granulated blast furnace slag from Smederevo Steel Mill and then treat artificially produced cracks with a Sporosarcina pasteurii DSM 33 suspension under the conditions of both sterile demineralized water and water from the Danube river in order to simulate natural conditions. The results show a bio-stimulated healing efficiency of 32.02% in sterile demineralized water and 42.74% in Danube river water already after 14 days. The SEM images clearly show calcium carbonate crystals as the main compound that has started to fill the crack, and the crystals are much more developed under the Danube river water conditions. As a special type of research, microscopic images of cracks were classified into those with and without the presence of bacterial culture. By applying convolutional neural networks (ResNet 50), the classification success rate was 91.55%. [ABSTRACT FROM AUTHOR]

The main chemical composition, i.e. the total content of bioactive compounds (phenolics 2209.86 ± 70.32 mg GAE/100g FDR, flavonoids 831.87 ± 12.61 mg R/100g FDR and anthocyanins 144.55 ± 0.39 mg CGE/100g FDR), in freeze-dried raspberry (FDR) was evaluated spectrophotometrically. Vitamin C content was determined by HPLC analysis (88.81 ± 4.38 mg vit C/100g FDR). Antioxidant activities of FDR extract were evaluated spectrophotometrically on stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and by electron spin resonance spectroscopy (ESR) method on hydroxyl radicals (•OH). EC50 values were evaluated. EC50 DPPH• was 0.127 ± 0.013 mg/ml, while EC50 •OH was 1.366 ± 0.026 mg/ml. Antiproliferative activity of the FDR extract was evaluated in vitro in three human cell lines by colorimetric sulphorhodamine B (SRB) assay. The most pronounced effects were obtained in the breast adenocarcinoma cell line (MCF7). EC50 value was 395.07 ± 96.38 μg/ml. Antimicrobial activity was determined by disk diffusion method. The FDR extract produced a clear inhibition zone (without visible colonies) only toward Staphylococcus aureus. The minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations of FDR extract were evaluated. The values MIC were in the range of 4.7 - 100 mg/ml, and of MBC in the range of 6.3 - > 100 mg/ml.[ Projekat Ministarstva nauke Republike Srbije, br. TR 31044]

In recent years, a lot of commercial TiO2 photocatalyst products have been developed and extensively studied for prospective and safe antimicrobial application in daily life, medicine, laboratories, food and pharmaceutical industry, waste water treatments and in development of new self-cleaning and antimicrobial materials, surfaces and paints. This paper reviews the studies published worldwide on killing microorganisms, methods for testing the antimicrobial activity, light sources and intensities, as well as calculation methods usually used when evaluating the antimicrobial properties of the TiO2-based products. Additionally, some strengths and weaknesses of the available methods for testing the antimicrobial activity of TiO2 photocatalyst products have been pointed out.[Projekat Ministarstva nauke Republike Srbije, br. III45008]

In this work, caraway or oregano essential oils were added to the cast chitosan film in an attempt to design a natural, biodegradable, bioactive (antioxidant and antimicrobial) packaging film. When the structure of the tested films was analyzed with Fourier transform infrared spectroscopy, no significant differences were found between the chitosan film with and without essential oils of caraway or oregano. The lowest antioxidant activity, based on the scavenging of the stable DPPH• free radical, was detected for the chitosan film without oil addition, going from 11.64%, after 2.5 h to 28.96%, after 24 h. When the caraway essential oil was added to the chitosan film, the antioxidant activity was increased (p

The significance of the conservation of cultural heritage objects has led to a greater interest in the appearance of biocorrosion. The aim of this paper is to point out the correlation between the growth of fungi isolated from the fortress of Bač and the contact angle value of the bricks from the fortress in order to determine the brick susceptibility to biodegradation. Three types of bricks (red, yellow and roan) and three isolates of Penicillium spp., as well as one isolate of Cladosporium sp., were used during the experiments. A suspension of fungi in soil extract solution was inflicted on the surface of the bricks and then the samples were incubated. The study showed that the red bricks with cut surface and the roan bricks with broken surface are the most susceptible to the biocorrosion process. Based on the obtained results, Cladosporium sp. can be considered as the most important biodeteriogenic factor on the bricks built in the walls of the Bač fortress. [Projekat Ministarstva nauke Republike Srbije, br. III45008]

This study is concerned with the testing of antimicrobial activity of triticale stillage obtained after lactic fermentation by Lactobacillus fermentum PL-1. The antimicrobial tests were performed using the disc-diffusion and agar well diffusion methods. It was found that fermented triticale stillage after lactic acid fermentation exhibited an inhibitory effect towards tested Gram positive and Gram negative bacteria: Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, and Enterococcus faecalis. The triticale stillage without addition of CaCO3 before fermentation showed a stronger antimicrobial effect in comparison with the triticale stillage with added CaCO3. Triticale stillage after lactic acid fermentation did not show any antifungal effect on the growth of tested moulds (Alternaria alternata, Aspergillus versicolor, Penicillium brevicompactum, and Fusarium subglutinans). [Projekat Ministarstva nauke Republike Srbije, br. TR-31017]

Commercial extracts of three spices (lemon, caraway and basil) against Listeria monocytogenes, L. innocua and L. welshimeri were investigated using disc diffusion method. Lemon and basil extracts inhibited all the organisms at the level of ≥ 5 μl (lemon) and 20 μl (basil). These extracts produced inhibitory zones of 9-19 mm (lemon) and 8-11.5 mm (basil). The extract of caraway showed activity only against L. innocua at the highest level (20 μl), producing an inhibitory zone of 14.7 mm. Generally, the lemon extract was the most effective. This extract exhibited greater inhibitory activity against L. monocytogenes, while the basil extract had the strongest effect on L. welshimeri. [Projekat Ministarstva nauke Republike Srbije, br. TR 31017]

Antibacterial activity of fruit and pomace extracts (concentration 50 mg/ml) of two raspberry (Rubus idaeus L.) cultivars (Meeker and Willamette) was tested against selected Gram-positive and Gram-negative bacteria (reference and wild strains). Disc diffusion method with 15 μl of extracts and agar-well diffusion method with 50 and 100 μl were used. Antibiotic (cefotaxime/clavulanic acid) was used as a control. Both raspberry fruit extracts showed the strongest antibacterial activity against Pseudomonas aeruginosa (wild strain) and Bacillus cereus, where the largest clear zones (without growth) appeared. Escherichia coli was the most resistant strain, with only zone of reduced growth. The highest antibacterial activity of pomace extracts was against Staphylococcus aureus and Staphylococcus saprophyticus. There were no differences in the antibacterial activity between cultivars for both fruit and pomace extracts. [Projekat Ministarstva nauke Republike Srbije, br. TR 31044]

The wettability of clay roofing tiles as a surface phenomenon plays a key role considering their deterioration process during exploitation. The experimental investigations in this paper were performed combining the data of the material-relevant parameters and the surface wetting properties in order to assess clay roofing tiles biodurability. The fungus Aspergillusniger was used as a model microorganism whose colonization and growth, during a period of 28 days on the tiles fired at two temperatures (900 and 1020ºC), was analyzed. The paper confirms that the colonization of the tiles with the fungus goes through two stages: up to the 18th day, based on the surface characteristics, and after the 18th day when the textural characteristics (values of water absorption) are the dominant parameters.

Antibacterial activity of Beta vulgaris L. (beetroot) pomace extract (concentration 100 mg/ml) was tested against five Gram positive and seven Gram negative bacterial strains (reference cultures and natural isolates). Disc diffusion method with 15 µl of extract and agar-well diffusion method with 50 and 100 µl were used. Antibiotic (cefotaxime/clavulanic acid) was used as a control sample. The tested extract showed the highest activity against Staphylococcus aureus and Bacillus cereus, where clear zones (without growth) appeared. There was no any activity against other tested Gram-positive bacteria, except for Staphylococcus epidermidis, with a small zone of reduced growth. Growth of all tested Gram-negative bacteria was inhibited usually with 100 µl of extract. The most susceptible were Citrobacter freundii and Salmonella typhymurium. The tested antibiotic gave clear, usually large zones for all tested strains except for Staphylococcus cohni spp. cohni, where only a zone of reduced growth appeared.

Listeria spp. are Gram positive, short, non-sporing rods, microaerophilic. Of the six species currently recognized, Listeria monocytogenes is the most important as it causes a range of infections in humans and animals. The organism can be found in a wide variety of habitats including the soil, food processing environments and raw foods. The ability of the organism to grow at refrigeration temperatures is of major importance in food production. This study examines the presence of Listeria species in fresh meat. 29 samples (chicken, pork and beef) meat. This bacteria was found in 82.7% of analyzed samples; 7 L. innocua, 8 L. monocytogenes and 9 L. welshimeri (of all isolates). L. innocua prevailed in pork meat (40%), L. monocytogenes in chicken and pork meat (30%), and L. welshimeri in beef meat (44.4%).

Kombucha is a beverage traditionally produced by metabolic activity of yeasts and acetic acid bacteria. The antimicrobial activity of lemon balm kombucha as well as of particular control samples was determined by agar-well diffusion method. Antioxidant activity on stable 1,1-diphenyl-2-picrylhydrazyl radicals of lemon balm kombucha and lemon balm tea was determined by electron spin resonance spectroscopy. Acetic acid, Kombucha samples and heat-denaturated kombucha showed significant antimicrobial activity against bacteria. However, there was no activity against yeasts and moulds. Kombucha showed higher antioxidant activity than tea sample for all applied sample volumes.

The work is concerned with the possibility of preparing kombucha beverage from sweetened winter savory (local name Rtanj tea) inoculated with the pellicle in a quantity of 2 -51 in the vessels (glass containers) volume of 2 - 6 l. It was found that the process lasts a few days (2 - 5) longer than the traditional process of biotransformation of black tea into kombucha. It was also concluded that the rate of the process depends mostly on the volume container: medium ratio. In the subsequent kombucha fermentations the metabolic activity of the yeast and acetic fermentation cells did not change. The rate of the process was not influenced by the physiological state of the cells in the pellicle with the capacities larger than 31.

Diacetyl and 2,3-pentanedione are important constituents of beer sensory properties. A new GC/MS method for diacetyl and 2,3-pentanedione content determination was developed. This method was applied for the determination of diacetyl and 2,3-pentanedione contents during beer fermentation (primary fermentation and maturation). Primary fermentations were carried out at different temperatures (8°C and 14°C). Primary fermentation temperature had a great influence on diacetyl and 2,3-pentanedione formation and reduction. Formation and reduction rates increased with the primary fermentation temperature increasment. Diacetyl and 2,3-pentanedione contents also increased with the corn grits increasment. Fermentations were carried out with Saccharomyces cerevisiae pure culture, specially prepared for each fermentation. This GC/MS method for diacetyl and 2,3-pentanedione determination was valuable for analysing the influence of wort composition or fermentation conditions such as primary fermentation temperature on their formation and reduction.

The possibility of obtaining kombucha from winter savory tea has been tested in the laboratory bioreactor by applying starter cultures and traditional way of inoculation. On the basis of the obtained results, it can be concluded that applying the inoculating method with the beverage from the previous process of biotransformation yielded kombucha beverage (capacity 15 I) from winter savory tea in the laboratory bioreactor. The application of defined starter culture from the isolate of yeast and acetic acid bacteria of local tea in the glass jar (capacity 5 I) gave 3 litres of kombucha beverage, which is acceptable according to the basic parameters and sensory characteristics. However, the application of the same starter culture in the laboratory bioreactor did not result in synchronized activity of yeast and bacteria.

Kombucha is a beverage with special therapeutic properties produced by the metabolic activity of yeasts and acetic acid bacteria in sweetened black tea (traditional cultivation medium). The antimicrobial activity of kombucha (for consumption) made from black tea and Rtanj tea, as well as particular control samples, was examined by the modified disc diffusion method. Salmonella enteritidis, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa Staphylococcus aureus, Bacillus sp., Sarcina lutea, Penicillium aurantiogriseum, Aspergilus niger, Aspergilus flavus, Rhodotorula sp. Candida pseudotropi-calis and Saccharomyces cerevisae have been used as test organisms. Acetic acid and kombucha samples show significant antimicrobial activity against all bacteria except Sarcina lutea. The other control samples (neutralized kombucha, tea and a "model sistem") show less bacteriostatic activity. Kombucha and acetic acid solution show borderline inhibitory activity against some moulds, while was no activity against yeasts.