Jovana Grahovac

Process model and economic analysis of ethanol production from sugar beet raw juice as part of the cleaner production concept.

The batch fermentation process of sugar beet processing intermediates by free yeast cells is the most widely used method in the Autonomous Province of Vojvodina for producing ethanol as fuel. In this study a process and cost model was developed for producing ethanol from raw juice. The model can be used to calculate capital investment costs, unit production costs and operating costs for a plant producing 44 million l of 99.6% pure ethanol annually. In the sensitivity analysis the influence of sugar beet and yeast price, as well as the influence of recycled biomass on process economics, ethanol production costs and project feasibility was examined. The results of this study clearly demonstrate that the raw material costs have a significant influence on the expenses for producing ethanol. Also, the optimal percentage of recycled biomass turned out to be in the range from 50% to 70%.

Chemometric Approach to Prediction of Antibacterial Agent Production by Streptomyces hygroscopicus

The nutritional requirements for antimicrobial agent production using Streptomyces hygroscopicus were analyzed in shake flask experiments. Antimicrobial activity was tested against Staphylococcus aureus and Bacillus cereus. The mathematical models have been generated with relative high complexity in order to give an adequate fit to the data. All the results suggest a high dependence of produced antimicrobial agent quantities on the amount of carbon, nitrogen, and phosphorus in cultivation medium. The statistical results of the generated models reflect the high predictive ability. The derived models were validated using leave-one-out cross-validation technique, and from statistical point of view, they have significantly high values of the cross-validation parameters.

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.

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.

Production of nigericin and niphimycin by soil isolate Streptomyces sp. MS1: Anti-Candida bioassay guided response surface methodology for the optimized culture medium

Anti-Candida bioassay guided optimization of the culture medium was used in order to enhance the antifungal activity of the soil isolate MS1. Its morphological, physiological and biochemical characteristics, as well as 16S rDNA sequencing, assigned an MS1 isolate to genus Streptomyces. Optimization of the culture medium was achieved by experimental factorial design and response surface methodology. Maximal antifungal components production was obtained with starch, soybean meal and phosphates content of 40.52, 5.10 and 2.21 g/L, respectively. Chromatography and 1H and 13CNMR spectroscopy were employed for purification and structural characterization of antifungal antibiotics concurrently produced by this strain. These antibiotics were identified as polyether carboxylic antibiotic nigericin and guanidyl-polyol macrolide, niphimycin.

Optimization of the flux values in multichannel ceramic membrane microfiltration of Baker`s yeast suspension

The objective of this work was to estimate the effects of the operating parameters on the bakers yeast microfiltration through multichannel ceramic membrane. The selected parameters were transmembrane pressure, suspension feed flow, and initial suspension concentration. In order to investigate the influence and interaction effects of these parameters on the microfiltration operation, two responses have been chosen: average permeate flux and flux decline. The Box-Behnken experimental design and response surface methodology was used for result processing and process optimization. According to the obtained results, the most important parameter influencing permeate flux during microfiltration is the initial suspension concentration. The maximum average flux value was achieved at an initial concentration of 0.1 g/L, pressure around 1.25 bars and a flow rate at 16 L/h.

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.