Zorana Z. Rončević

Wastewaters from rose wine production as substrate for xanthan production

Wineries and other grape processing industries annually generate large amounts of solid and liquid waste streams. Winery wastewaters are the waste product of many independent processing and cleaning operations in wineries. As a consequence of the working period and the winemaking technologies, as well as the cleaning practices, volumes and composition of winery wastewaters greatly vary over the year. Due to high organic load, the disposal of these effluents in the environment causes several issues. The bioconversions of winery wastewaters in valuable products are an important alternative to overcome these ecological problems. The aim of this study was to examine the possibility of xanthan production from media based on four wastewaters obtained from different stages of the rose wine production process, i.e. wastewaters collected during the washing of the crusher, press and tanks after clarification of must and fermentation. Process efficacy was estimated based on raw xanthan yield and rheological characteristics of media. In applied experimental conditions, raw xanthan yields were in the range between 8.03 g/L and 17.52 g/L. Also, all cultivation media showed pseudoplastic behavior. Obtained results suggest that wastewaters from rose wine production have a great potential to be used as a substrate for production of this high value biopolymer.

Optimization of cultivation medium composition for production of bioactive compounds effective against Penicillium sp.

Biological control is one of the best alternatives to pesticides as it avoids their weak points in plant disease control. In this study, the composition of cultivation medium for production of bioactive compounds by Bacillus subtilis ATCC 6633 was optimized. The produced bioactive compounds were tested against a phytopathogenic Penicillium sp. known for infesting different agricultural products and causing substantial crop losses. Antimicrobial activity assaying was carried out using the diffusion-disc method, and inhibition zone diameters were measured as direct indicators of antifungal activity. The response surface methodology (RSM) was used to evaluate the effects of different contents of initial nutrients (glycerol, NaNO2 and K2HPO4) in cultivation medium on inhibition zone diameter. Optimization was carried out using the desirability function method in order to maximize bioactive compounds yield and to minimize residual nutrients contents. The optimized concentrations of the selected nutrients in cultivation medium for production of bioactive compounds were: glycerol 20 g/l, NaNO2 1 g/l and K2HPO4 15 g/l.

Formulation of medium for bactericides biosynthesis using wild type Streptomyces sp.

The aim of this study was formulation of medium for the production of bactericide effective against Staphylococcus aureus and Escherichia coli using Streptomyces sp. isolated from the soil. Biosynthesis of antibacterial compounds was performed on media prepared in accordance with Box-Behnken design with three factors on three levels and three repetitions in the central point where the contents of the carbon source (10.0-50.0 g/L), soybean meal (5.0-25.0 g/L) and phosphates (0.5-2.5 g/L) were varied. Fructose, lactose, sucrose, starch and glycerol were used as carbon sources. Since the cultivation broths showed activity only against Staphylococcus aureus, the values of inhibition zone diameters for this microorganism were statistically processed using response surface methodology and desirability function approach in order to optimize relations of varied nutrients. Media with glucose were not used in these experiments, but the mathematical model defined in previous research was applied for optimization. The developed models predict that optimal concentrations of carbon source, soybean meal and phosphates are about 10.0, 5.0 and 0.5 g/L, respectively, except in the lactose-containing medium, where the optimal phosphate content is 0.9 g/L. Performing the bioprocess in optimal media, the maximum inhibition zone diameter against Staphylococcus aureus was formed by the medium with fructose (34.5 mm).

Mogućnost primene ksantana za uklanjanje jona metala iz otpadnih voda

Biopolimeri poseduju sposobnost apsorpcije velike kolicine vode ili bioloskih fluida pri cemu bubre i formiraju hidrogelove. Zahvaljujuci tome nasli su siroku primenu u razlicitim granama industrije, a između ostalog koriste se i za uklanjanje jona metala iz vode. Zbog svoje jedinstvene strukture i izuzetnih reoloskih karakteristika, ksantan, komercijalno najznacajniji mikrobioloski biopolimer,mogao bi se primenjivati i za preciscavanje otpadnih voda jer bi se strukture formirane u prisustvu metala mogle lako odvojiti mehanickim putem. Stoga su istraživanja iz okvira ovog rada izvedena u cilju ispitivanja mogucnosti umrežavanja sirovog ksantana razlicitim jonima metala. Na osnovu uspesnosti umrežavanja i stabilnosti formiranih strukturaprocenjeno je daje primenomovog biopolimera moguce ukloniti jone olova i gvožđa iz otpadnih voda.

Optimization of the medium composition for production of antimicrobial substances by bacillus subtilis ATCC 6633

In the effort to overcome the increase in antimicrobial resistance of different pathogens, natural products from microbial sources appear to be the most favorable alternative to current antibiotics. Production of antimicrobial compounds is highly dependent on the nutritional conditions. Hence, in order to achieve high product yields, selection of the media constituents and optimization of their concentrations are required. In this research, the possibility of antimicrobial substances production using Bacillus subtilis ATCC 6633 was investigated. Also, optimization of the cultivation medium composition in terms of contents of glycerol, sodium nitrite and phosphates was done. Response surface methodology and the method of desirability function were applied for determination of optimal values of the examined factors. The developed model predicts that the maximum inhibition zone diameters for Bacillus cereus ATCC 10876 (33.50 mm) and Pseudomonas aeruginosa ATCC 27853 (12.00 mm) are achieved when the initial contents of glycerol, sodium nitrite and phosphates were 43.72 g/L, 1.93 g/L and 5.64 g/L, respectively. The results of these experiments suggest that further research should include the utilization of crude glycerol as a carbon source and optimization of composition of such media and cultivation conditions in order to improve production of antimicrobial substances using Bacillus subtilis ATCC 6633.

Environmental biotechnology for the treatment of waste effluents from biofuels production

Bioethanol, biodiesel and biogas represent very significant alternatives to fossil fuels in order to reduce carbon- dioxide emissions, so there is a need to develop energy efficient technologies, equipment and waste management procedures to make production profitable by reducing production costs. One way to accomplish this is to solve the problem of waste effluents by using them to obtain high-value products. All biotechnological processes are energy intensive to some extent, so saving energy becomes one of the main goals of all biotechnological processes in addition to preserving the environment and the management or reuse of waste. The availability of waste effluents from the production of biofuels, such as distillery stillage and crude glycerol, will increase over the next few years due to the growth of the biofuel industry and will provide a great possibility for the biotechnological production of high-value products.

Biosynthesis of components with antifungal activity against Aspergillus spp. using Streptomyces hygroscopicus

Losses of apple fruit during storage are mainly caused by fungal phytopathogens. Traditionally, postharvest fungal disease is controlled by the application of synthetic fungicides. However, the harmful impact on environment as well as human health largely limits their application. To reduce these problems in agrochemicals usage, new compounds for plant protection, which are eco-friendly, should be developed. The aim of this study is optimization of medium composition in terms of glucose, soybean meal and phosphates content, by applying response surface methodology, for the production of agents with antifungal activity against Aspergillus spp. For biosynthesis was used strain of Streptomyces hygroscopicus isolated from the environment. Experiments were carried out in accordance with Box-Behnken design with three factors on three levels and three repetitions in the central point. Antifungal activity of the obtained cultivation mediums against Aspergillus oryzae and Aspergillus niger was determined, in vitro, using the diffusion - disc method. For determination optimal medium components desirability function was used. Achieved model predicts that the maximum inhibition zone diameter (40.93 mm) against test microorganisms is produced when the initial content of glucose, soybean meal and phosphates are 47.77 g/l, 24.54 g/l and 0.98 g/l, respectively. To minimize the consumption of medium components and costs of effluents processing, additional three sets of optimization were made. The chosen method for optimization of medium components was efficient, relatively simple and time and material saving. Obtained results can be used for the further techno-economic analysis of the process to select optimal medium composition for industrial application.