Bojana Ž. Bajić

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.

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.