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The main goal of this work was to optimize the method of processing wound dressing products (like gauzes, sanitary pads, cotton wool, compresses, and bandages) with a commercial silver colloidal solution (Koloid doo, Belgrade, Serbia) and then to examine the antimicrobial properties of the obtained items in order to potentially reach the market with new improved wound dressing products. The influence of different silver concentrations used for treatment on antimicrobial activity was investigated only against Escherichia coli. The antimicrobial activity of different types of materials treated with silver solutions of 30 ppm was investigated against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, Gram-positive bacteria Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis, as well as the fungus Candida albicans. The microbial reduction of the tested materials loaded with a silver solution of 30 ppm (15-20 µg of Ag on 1 g of fabric) against the Gram-negative bacteria E. coli and P. aeruginosa was almost maximal after 2 h of contact (i.e. 95 and 99 %, respectively). In the case of Gram-positive bacteria S. aureus, B. subtilis, and E. faecalis, a longer time is needed to completely eradicate bacteria (over 99 %). Antifungal activity testing against the fungus C. albicans gave moderate antifungal activity results., Cilj ovog rada je ispitivanje antimikrobne efikasnosti pamučnih materijala kao što su gaza, higijenski ulošci, vata, komprese i zavoji obrađeni komercijalnim koloidnim rastvorom srebra (kompanija Koloid doo). Ispitan je uticaj koncentracije koloidnog rastvora srebra kojim je obrađena tkanina na antimikrobnu aktivnost prema Gram-negativnim bakterijama Escherichia coli i Pseudomonas aeruginosa, Gram-pozitivnim bakterijama Staphylococcus aureus, Bacillus subtilis i Enterococcus faecalis i gljivici Candida albicans. Redukcija bakterija postignuta testiranim materijalima obrađenim rastvorom srebra koncentracije 30 ppm (15 do 20 µg Ag na 1 g materijala) prema Gram-negativnim bakterijama E. coli i P. aeruginosa je skoro maksimalna nakon dva sata kontakta, 95 i 99 %, redom. U slučaju Gram-pozitivnih bakterija S. aureus, B. subtilis i E. faecalis, potrebno je duže vreme za potpunu redukciju broja bakterija, osim za B. subtilis, gde je dovoljno dva sata kontakta za maksimalno smanjenje početnog broja bakterija. Antifungalna aktivnost prema gljivici C. albicans je umerena.

Antibacterial and antifungal ability of silver nanoparticles (Ag NPs) supported by functionalized magnetite (Fe 3 O 4 ) with 5-aminosalicylic acid (5-ASA) was tested against Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus and yeast Candida albicans. Characterization of materials including transmission electron microscopy, X-ray diffraction analysis, and inductively coupled plasma optic emission spectroscopy technique followed each step during the course of nanocomposite preparation. The synthesized powder consists of 30–50 nm in size silver particles surrounded by clusters of smaller (∼10 nm) Fe 3 O 4 particles. The content of silver in the nanocomposite powder was found to be slightly above 40 wt.–%. Concentration-dependent and time-dependent bacterial reduction measurements in dark indicated that use of Ag NPs leads to the complete reduction of E. coli and S. aureus even at the concentration level of silver as low as 40 μg/mL. However, the negligible antifungal ability of synthesized nanocomposite was found against yeast C. albicans in the entire investigated concentration range (0.1-2.0 mg/mL of the nanocomposite, i. e., 40–800 μg/mL of silver). Complete inactivation of E. coli and S. aureus was achieved in five repeated cycles indicated that synthesized nanocomposite can perform under long-run working conditions. From the technological point of view, magnetic separation is the additional advantage of synthesized nanocomposite for potential use as an antibacterial agent. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Predmet ove disertacije je iskorišćenje otpadnih sirovina, poljoprivrednog i industrijskog porekla, za proizvodnju enzima celulaza i amilaza pomoću novoizolovanog bakterijskog soja Paenibacillus chitinolyticus CKS1. Optimizacija procesa proizvodnje hidrolitiĉkih enzima celulaza i amilaza vršena je korišćenjem komercijalnih supstrata i otpadnih sirovina ivariranjem uticaja pojedinaĉnih parametara primenom metode planiranog eksperimenta i matematiĉko-statistiĉka obrade eksperimentalnih podataka – metode odzivnih površina (RSM). Proces proizvodnje celulalaza (endoglukanaza i egzoglukanaza) je optimizovan na razliĉitim komercijalnim podlogama ali i na otpadnim sirovinama. Soj CKS1 je pokazao predominantnu aktivnost egzoglukanaza (iskazanih kao Avicelazna aktivnost) što je netipiĉno za većinu bakterijskih vrsta. Rezultati su pokazali da se P. chitinolyticus CKS1 moţe koristiti za dobijanje celulazau komercijalnoj podlozi (maksimalna CMC-azna i Avicelazna aktivnost iznose 0,532 U/mL i 1,83 U/mL, pojedinaĉno), ali i na otpadnim sirovinama: otpadnom lekovitom bilju (maksimalna CMC-azna i Avicelazna aktivnost iznose 0,203 U/mL i 1,94 U/mL, pojedinaĉno) i piljevini (maksimalna CMC-azna i Avicelazna aktivnost iznose 0,145 U/mL i 1,75 U/mL, pojedinaĉno). Soj CKS1 je pokazao mogućnost rasta i proizvodnje dve vrste celulaza: endoglukanaza (iskazanih kao karboksimetil celulazna (CMC-azna) aktivnost i egzoglukanaza (iskazanih kao Avicelazna) aktivnost tokom svog rasta na ĉvrstom otpadnom supstratu- repinom rezancu (maksimalna CMC-azna i Avicelazna aktivnost iznosi 3,159 U/g i 4,840 U/g). Metodom odzivnih površina optimizovana je proizvodnja endoglukanaza i egzoklukanaza u podlozi obogaćenoj jeĉmenim mekinjama (maksimalna CMC-aza i Avicelazna aktivnost iznosi 0,405 U/mL i 0,433 U/mL, pojedinaĉno). Dobijena je nešto niţa vrednostAvicelazne aktivnosti, ali optimizovani procesi jasno ukazuju na mogućnost njihovog korišćenja, pošto su u skladu sa principima odrţive proizvodnje i brige o, The subject of this thesis is the utilization of waste materials of agricultural and industrial origin, for the production of enzymes cellulases and amylases using a novel isolated bacterial strain Paenibacillus chitinolyticus CKS1. Optimization of the process of production of hydrolytic enzymes cellulases and amylases was performed using commercial substrates and waste materials by varying the influence of individual parameters but also by employing the method of the planned experiment and mathematical-statistical processing of experimental data - Response Surface Methodology (RSM). The process of producing cellulase (CMC-ase and Avicelase) was optimized using various commercial substrates but also using waste materials.The strain CKS1 showed predominant exoglucanase (Avicelase) activity which is not typical for most bacterial species. Results showed that P.chitinolyticus CKS1 could be used for cellulase (CMC-ase and Avicelase) production, in a liquid medium with comercial substrates (with maximum CMCase and Avicelase activity of 0,532 U/mL and 1,83 U/mLrespectively), but also in a medium with waste substrates: waste medicinal herbs (with maximum CMCase and Avicelase activityof 0,203 U/mL and 1,94 U/mL, respectively) and sawdust (with maximum CMCase and Avicelase activity of 0,145 U/mL and 1,75 U/mL, respectively)...

Studies related to the synthesis of nanosized ZnO as the antibacterial agent have become an interdisciplinary area gathering chemists, physicists, biologists, and medics. The broad scope of materials based on ZnO resulted in the development of various techniques for its preparation. Considering the dependence of particle shape and size onto physical and chemical properties of ZnO, the synthesis procedure is of major importance. In this work, an unconventional methodology of synthesis is proposed for obtaining nanosized ZnO. Polymeric zinc complex containing 2,2’-dipyridylamine (dipya) and dianion of 1,3-benzenedicarboxylic acid (ipht), [Zn(dipya)(ipht)]n, was used as precursor. Besides the crystal structure of [Zn(dipya)(ipht)]n which was already published [1], the luminescent properties are presented in this work. Also, the amazing antibacterial activity of this precursor prompted us to investigate the relationship between the crystal structure and thermal properties, especially if we bear in mind the lack of similar studies in the literature. Therefore, the mechanism and kinetics of its degradation was investigated under nonisothermal conditions in nitrogen and air atmospheres. Degradation enthalpies, thermodynamic activation parameters, pre-exponential factor, A, and the apparent activation energy, Ea, were determined for each step using Kissinger’s and Ozawa’s equations. The complexity of degradation steps has been analyzed using isoconversional methods. TG/DCS data were collected at four different heating rates: 10, 15, 20 and 25 ºC min –1 , while the formation of nanosized ZnO was confirmed using XRPD and FESEM techniques. The influence of precursor on the crystallite size and morphology of the resulting ZnO along with its antibacterial activity was examined. The obtained results will be discussed and compared.

Sugar beet pulp (SBP) and molasses, by-products from sugar industry were used as a substrate for cellulase production in this study. Solid state fermentation (SSF) was performed by a natural isolate Paenibacillus chitinolyticus CKS1. Data showed that cellulose in SBP could be used as a substrate to produce both cellulases, CMCase and Avicelase. An optimum solid: moisture ratio for maximum cellulase production was investigated. Maximum CMCase 3.159 U/g and Avicelase activity 4.840 U/g was obtained at the fourth day of incubation with 10% of inoculum. The cellulase production during SSF on SBP indicates that this process is economically very justified.