Search

The research focuses on developing a bioleaching procedure for red mud samples. Bacteria were isolated using red mud from three different locations, after that, grown bacteria were applied to the red mud samples from Mostar, Bosnia and Herzegovina. Samples were heated to 100°C and filtered with MiliQ water. Geochemical analysis of red mud samples with bacteria, eluates and red mud on filter papers was carried out.

Hydroxyapatite (HAp) is the most widely used calcium phosphate for hard tissue applications due to its compositional similarity to biological apatite, biocompatibility and bioactivity. As bone apatite is a multi-substituted carbonated HAp containing trace elements, one of the used approaches to improve the biological and physicochemical properties of HAp is ionic substitution. To achieve a good balance between cell biomaterial interactions and anti-bacterial properties, a Sr-substituted HAp with potential regenerative properties was co-substituted with Ag+ ions to offset the cytotoxicity of higher substitution levels of Ag+ ions and stimulate osteogenic growth. A series of single-substituted HAp with Sr2+ and Ag+ ions, and Ag/Sr-co-substituted HAp with different substitution degrees (0, 1, 2.5 and 5 mol%) were obtained by wet precipitation method from cuttlefish bone in order to obtain biomimetic multi-substituted HAp. Rietveld refinement studies revealed an increase of cell volume (Å3), a-axis (Å), b-axis (Å) and c-axis (Å) for all obtained HAp powders, due to larger ionic radius of Sr2+ (1.12 Å) and Ag+ (1.15 Å) in comparison to substituted Ca2+ (0.99 Å) ion. The element mapping reflected the uniform distribution of the Ca, P, Ag and Sr elements in the precipitated powders. The zeta-potential values of the Ag/Sr-co-substituted HAp samples revealed that all the samples were negatively charged and the obtained zeta-potential values expressed a downward trend with increasing buffer pH. The antibacterial effect was evaluated by inhibition zone and spread plate analysis, while the surface of samples was observed after inhibition zone analysis by scanning electron microscopy. The antibacterial effect was confirmed for all HAp powders substituted with Ag+ ions against Gram-positive S. aureus and Gram-negative E. coli, representative bacteria in clinical bone infections. Further, the non-cytotoxicity was confirmed by using human embryonic kidney 293 and human mesenchymal stem cells.

Bacterium Acinetobacter baumannii is nowadays an emerging hospital pathogen. From colonised or infected patients, A. baumannii is disseminated into the natural water environments. Due to the resistance of this bacterium to the conventional methods of water disinfection, alternative methods of A. baumannii removal from water are needed. There is no literature data how the hydrophobicity level of A. baumannii isolates influences the immobilization onto hydrophilic surface of natural zeolitized tuff (NZ). The immobilization of hydrophilic and hydrophobic isolate of A. baumannii onto NZ was examined. Both hydrophilic and hydrophobic isolate was successfully immobilized onto NZ, whereby hydrophobic isolate in a higher abundance than hydrophilic one. The NZ is a promising material for the capture of isolates of pathogenic bacteria A. baumannii from water, and could find application in water treatment technology.

Vatrogasci Javne vatrogasne postrojbe Grada Zagreba izrazili su želju za automatizacijom i informatizacijom određenih procesa vezanih uz logistiku obavljanja intervencija. Rad se bavi razvojem i implementacijom "ZG193HELP" sustava koji ispunjava navedene želje. Sustav povezuje tablet uređaje, koji su smješteni u vatrogasna vozila, s komandnim centrom. Klijentska aplikacija tablet uređaja na interaktivnoj karti prikazuje trenutnu poziciju tableta, lokaciju dodijeljene intervencije, lokaciju hidranata koji su blizu intervencije i tekst koji opisuje najbržu rutu od vatrogasne postaje do intervencije. Trenutna pozicija se preuzima s GPS prijemnika i šalje poslužitelju koji ju arhivira i prosljeđuje komandnom centru. Klijentska aplikacija u komandnom centru na interaktivnoj karti prikazuje trenutnu poziciju svih tablet uređaja, aktivnih intervencija i vatrogasnih postaja. Ovaj rad se bavi razvojem i implementacijom poslužiteljske strane i klijentom u komandnom centru. Razvoj i implementacija tablet klijenta nije dio ovog rada, ali je kroz suradnju navedeno ostvareno u okviru drugog rada. Firefighters from Zagreb fire brigade expressed the desire to automate and informatize certain processes related to the logistics of performing the interventions. The focus of this thesis is development and implementation of the "ZG193HELP "system that fulfills the stated desires. The system connects tablet devices that are located in firefighter vehicles with the command center. The tablet client application shows (on the interactive map) the current position of the tablet, the location of the assigned intervention, the location of the hydrants that are close to the intervention, and a text describing the fastest route from the fire station to the intervention. The current position is fetched from the GPS receiver and sent to the server that archives and forwardes it to the command center. The command center client application shows the current position of all tablet devices, active interventions, and fire stations on the interactive map. This thesis focusses on the development and implementation of the server side and the command center client. The development and implementation of the tablet client is not a part of this thesis, but it has been achieved through the collaboration as part of another thesis.

Intestinal enterococci (Ie) are well known bacterial indicators of faecal contamination in food as well as in environmental samples. In total 19 soils under the anthropogenic influence in Croatia were analysed: 15 influenced by illegal dumpsites of human solid waste and 4 agricultural soils fertilized with animal manure. Three samples were control soils without the visible anthropogenic influence. The number of Ie was measured after suspension of soil in peptone water and subsequent confirmation on Slanetz Bartley and Bile esculin azide agar. The pH was measured in soil suspension in distilled water. The pH values of soils varied from 4.9 to 9.7. Ie were not detected (˂1 CFU/g) in control soils saved from visible human activities. Ie also were not detected in agricultural soils fertilized with swine or poultry manure. All soils influenced by illegal dumpsites contained the Ie at concentration from 1.3 to 6.2 log CFU per g of wet soil. Ie could be used as indicators of illegal dumps, since they could be leached from the human solid waste by storm water and infiltrated into the underling soil. The traditional use of animal manure as a soil fertilizer has no appreciable influence on the occurrence of Ie. More stringent monitoring and prevention of illegal dumps is needed to avoid the negative human influence on the soil.

In order to improve hydrophilicity, dyeing and antimicrobial properties of wool, the potentialapplication of low-pressure oxygen plasma pretreatment was explored. After optimization of process parameters, samples of wool fabrics were dyed with natural dye extracted from Punica granatum L. The effect of plasma pretreatment and mordants on colorimetric and antibacterial properties against Staphylococcus aureus and Klebsiella pneumoniae was investigated. The results revealed a significant improvement in wicking ability and tensile strength of all tested samples. Plasma pretreatment proved to be suitable for improving color yield and even replacing the application of certain mordants in the process of dyeing wool with pomegranate dye. All samples exhibited good antibacterial activity against tested bacteria. Only a slight decrease in color strength and antibacterial activity is visible on plasma pretreated samples after 28 days of aging.

Bakterija Acinetobacter baumannii je oportunistički patogen koji izaziva infekcije imunosuprimiranih ljudi u bolničkom i izvanbolničkom okružju. Pojava sojeva višestruko rezistentnih na antibiotike te otpornost na dezinficijense i isušivanje čini ovu bakteriju velikom prijetnjom za ljudsko zdravlje. Svrstana je među „ESKAPE“ patogene za koje je potrebno pronaći nove terapijske metode te se nalazi na prvom mjestu WHO liste opasnih patogena. A. baumannii smatrao se isključivo bolničkim patogenom sve do nedavnog pronalaska u okolišu. Do danas je nepoznato koji ekološki čimbenici i u kojoj mjeri utječu na A. baumannii. Cilj rada bio je istražiti učinak temperature (-20, 4, 22, 35, 44, 50, 63°C) i pH (2, 5, 7, 10, 12 pri 22°C) na preživljavanje A. baumannii u komercijalnoj prirodnoj izvorskoj vodi i u vodi obogaćenoj nutrijentima (razrijeđeni 1:100 Nutrient broth) kako bi mogli predvidjeti ponašanje A. baumannii u okolišu. Ispitivana su 4 okolišna i jedan klinički izolat A. baumannii kroz 7 tjedana. Broj bakterija određen je kao broj kolonija (CFU) na hranjivom agaru (24h/42°C). Stopa preživljavanja izračunata je uspoređujući početni i konačni broj bakterija. Optimalni uvjeti za preživljavanje A. baumannii su sobna temperatura (22°C) i pH 7. Uspješno preživljava kroz 7 tjedana pri temperaturama od -20 do 44°C kao i pri pH 5 do 10. Također preživljava klasičan proces pasterizacije (63°C/30 min), te je tek nakon 2h uništen. Na 50°C može preživjeti do 4 dana. Pri pH 12 može preživjeti do 1 dan, dok pri pH 2 preživljava samo 1h. Preživljavanje je veće u svim slučajevima u Nutrient broth-u, u kojem je došlo do umnažanja bakterija. Jedan izolat osjetljiv na sve testirane antibiotike slabije je preživljavao u izvorskoj vodi pri različitim temperaturama od ostalih multiplo-rezistentnih izolata, što upućuje na zaključak da multiplo- rezistentni izolati A. baumannii potencijalno bolje preživljavaju nepovoljne okolišne uvjete. A. baumannii je vrlo otporna bakterija na različite uvjete temperature i pH koji su nepovoljni za većinu drugih mezofilnih nesporogenih bakterija.

Carbapenems are considered as last-resort antibiotics, and the carbapenem-resistant bacteria (CRB) are currently deemed as the biggest microbial threat to human welfare. Since soil is considered as one of the most important environments for emergence of antibiotic-resistant bacteria, we searched for cultivable CRB in soil samples from 14 locations, mainly those influenced by illegal dumps, across Croatia. We proposed cultivation of CRB from environmental samples at two temperatures to differentiate between ones that are intrinsically resistant (37°C) and ones with acquired resistance, which are presumably human-associated and clinically relevant (42°C). The Stenotrophomonas sp. were predominant among CRB37. Among CRB42 we found mostly bacteria from the family Enterobacteriaceae, Acinetobacter and Burkholderia species. The CRB37 were found in every soil, excluding one sample where pH was extremely low, and another where water content was extremely low. The CRB42 were found in most soil samples, but were absent from samples of non-contaminated pasture and forest, indicating that human-associated CRB are unlikely to be found in soils deprived of anthropogenic influence. The appropriate deposition of human solid waste is thus one of the means to prevent the spreading of CRB of clinical relevance to the soil.

Acinetobacter baumannii is an emerging human opportunistic pathogen that causes nosocomial as well as community-acquired infections. A. baumannii is assigned to ESKAPE group of pathogens due to its ability to „escape“ the biocidal activity of antibiotics. The aim of this study was to test the behaviour of A. baumannii isolates in water media under different temperature and pH conditions in order to predict its behaviour in the environment. Survival of 5 A. baumannii isolates was monitored during 7 weeks in commercially available spring water and diluted Nutrient broth. Tested temperatures at neutral pH were: -20, 4, 22, 35, 44, 50 and 63 °C. Tested pH values were 2, 7 and 12 at 22 °C. Bacterial numbers were determined on Nutrient agar and expressed as log CFU mL-1 from which survival rates were calculated. A. baumannii successfully survived at temperatures ranging from -20 to 44 °C during 7 weeks. It was able to survive classic pasteurization procedure (63 °C/30 min) and was destroyed after 2h of contact. Prolonged survival of A. baumannii at extreme temperatures and pH values indicates that this pathogen is resilient and persistent under different conditions that are unfavourable for the majority of other mesophilic non-sporogenic bacteria. Optimal conditions for the growth and survival of this pathogen are room temperature and neutral pH, which is a prerequisite for the existence of isolates in hospital environment. Multidrug-resistant isolates survive better in harsh environmental conditions than sensitive isolates, which represents a major healthcare concern.

U ovom radu uspoređeni su ISO 20743:2013 (apsorpcijska i transfer metoda) i ISO 20645:2004 (metoda difuzije u agaru) standardi za određivanje antibakterijske učinkovitosti tekstilnih materijala. Testirana je antibakterijska učinkovitost nekoliko probnih materijala načinjenih na Tekstilno-tehnološkom fakultetu u sklopu projekta „Udobnost i antimikrobna svojstva tekstila i obuće“ prema bakterijama Staphylococcus aureus i Escherichia coli. Usporedbom triju metoda može se zaključiti kako za ispitane materijale nije uvijek moguće jednoznačno utvrditi pokazuju li antibakterijsku učinkovitost ili ne. Od ispitivanih materijala samo pozitivna kontrola, antibakterijski uložak za cipele, je pokazao antibakterijsku učinkovitost u sve tri metode i prema obje testirane bakterije. Ostali materijali su u nekim metodama pokazivali učinkovitost, a u nekima ne, a razlika je bilo i s obzirom na testiranu bakteriju. Kako bi se pouzdano odredila antibakterijska učinkovitost materijala, potrebno je paralelno izvoditi nekoliko prikladnih metoda i ispitati bar dvije bakterije, jer se na temelju samo jedne bakterije i jedne metode može pogrešno zaključiti o antibakterijskoj učinkovitosti nekog materijala.

An emerging hospital pathogen, bacterium Acinetobacter baumannii occurs in the natural environment influenced by human liquid or solid waste. Bacterial biofilm formation on abiotic or biotic solid surfaces is considered as an important virulence factor of this pathogen. There are no data on the quantification of viable bacterial cells of A. baumannii (either of clinical or environmental origin) that are immobilized onto the solid surfaces. In this study, the environmental isolate of A. baumannii was immobilized onto the particles of natural zeolitizied tuff (NZ) at 20°C in the water media of different nutrient concentrations. Numbers of immobilized viable bacterial cells ranged from 6.7-9.1 log CFU/g. The intensity of bacterial immobilization onto the NZ was a function of total bacterial concentration which was statistically significantly positively correlated with the COD of surrounding water media. Immobilization of bacteria onto the NZ occurred via the bacterial extracellular substances that enable longer survival of bacteria in the environment. The presence of A. baumannii in the natural environment will possess a serious public health concern about the spread of this emerging human pathogen.

Tema ovog završnog rada je izrada sustava za logističko upravljanje mobilnim robotom „Robolog" s naglaskom na arhitekturu i dizajn tog sustava. Uz pomoć ovog sustava, korisnik bi na karti trebao moći vidjeti gdje se trenutno robot nalazi i imati mogućnost narediti robotu da se premjesti na neko drugo mjesto zadavanjem robotovog odredišta na toj istoj karti. U radu je opisano od kojih se softverskih i hardverskih dijelova sustav sastoji, koji se softverski dijelovi izvršavaju na kojem hardveru i na visokoj razini apstrakcije na koji način softverski dijelovi međusobno komuniciraju. Isto tako, u radu je obrađena organizacija koda nekih softverskih dijelova ovog sustava. The focus of this thesis is the development of a logistic mobile robot management system "Robolog" with a special focus on architecture and design. With this system, a user should be able to see and control the current robot position by issuing commands through a map interface on their screen. The thesis explores which hardware and software components the system is composed of, how the software interacts with and executes on the hardware, and how the software components communicate between each other on a high level of abstraction. The thesis also discusses how the code is organized within some of the software components.

Multi-drug resistant (MDR) Acinetobacter baumannii were found in untreated as well as in biologically or chemically treated hospital and municipal wastewaters. However, there is no evidence about the fate of A. baumannii in the wastewater treatment process. The aim of this study was to screen the sewage sludge after its stabilization by anaerobic mesophilic digestion for the presence of A. baumannii. On 9 sampling occasions at the municipal wastewater treatment plant of the City of Zagreb, 17 isolates of A. baumannii were recovered form digested sludge with MALDI-TOF MS score values ranging from 2.026-2.288. 3/17 isolates were sensitive to all antibiotics, while 14 MDR isolates shared the resistance to carbapenems and fluoroquinolones but sensitivity to colistin. Technology of anaerobic sludge digestion was performed at 36°C, neutral pH and digestion time of 21-36 days. In laboratory controlled anaerobic conditions isolates were able to survive on Nutrient agar in anaerocultA system during 30 days, after which multiplied normally in aerobic conditions. However, isolates were not able to multiply directly in anaerocultA. The finding confirms the need of proper management and disposal of sewage sludge generated at wastewater treatment plants in order to prevent the spread of MDR A. baumannii in nature.

Acinetobacter baumannii is an emerging opportunistic pathogen associated mainly with hospital infections. Since there is insufficient data regarding the successfulness of A. baumannii in the natural environment, the aim of this investigation was to examine the survival rates of A. baumannii in different types of natural water media. Multi-drug resistant (MDR) environmental isolates were cultivated on CHROMagar Acinetobacter at 42°C/24h. Bacterial suspension was inoculated into bottles containing the 100 mL of sterile spring water, seawater and effluent water from the secondary type of municipal wastewater treatment plant, and incubated at 20°C with stirring (150 rpm) during 28 days. Number of bacteria was followed by cultivation on Nutrient agar plates at 42°C/24h, from which the survival rates were calculated. In effluent water the successful multiplication of A. baumannii was evident (124% survival rate after 28 days), while in natural spring water and seawater no multiplication occurred. The survival rate in spring water was constant (100%) with a slight decrease (94%) after 21 days and 89% after 28 days, while in seawater the survival rate was constant for the first 2 days (100%), and decreased to 64% after 28 days. The chemical oxygen demand of effluent was considerably higher (24 mgO2/L) than the spring (3 mgO2/L) and seawater (4 mgO2/L). These findings indicate that MDR isolates of A. baumannii successfully persist in the natural water media and that the survival rates are dependent on the availability of nutrients.

Acinetobacter baumannii is well known emerging hospital pathogen of the 21st century. Multi- drug resistant (MDR) A. baumannii are found in untreated as well as in chemically treated hospital wastewaters. However, there is no clear evidence about their origin. The aim of this study was to screen the hospital wastewater for the presence of viable A. baumannii and to find the correlation between recovered wastewater and clinical isolates. The sampling of the hospital wastewater was done at the central manhole of the Special Hospital for Pulmonary Diseases in Zagreb, Croatia. The clinical isolate was recovered on the exact date from bronchial aspirate of patient hospital. The isolation of A. baumannii was performed on CHROMagar Acinetobacter supplemented after incubation at 42°C/48h. One clinical and six isolates from hospital wastewater gave reliable MALDI-TOF MS score values ranging from 2.021-2.271 confirming the identity of A. baumannii colonies. All isolates were MDR and shared the resistance to carbapenems and fluoroquinolones, but sensitivity to colistin. MLST analysis following Oxford scheme revealed that all isolates belong to the ST-195 clustering into the CC92 within the IC2. This study confirmed the occurrence of viable MDR A. baumannii in hospital wastewater in Zagreb. Close relatedness of isolates from hospital wastewater with the clinical isolates from the same hospital in the period of monitoring suggests the possible origin of recovered wastewater A. baumannii. This finding confirms the need for proper treatment and disposal of untreated hospital wastewaters in order to prevent the spread of MDR A. baumannii in nature.

The carbapenem resistance in Gram-negative bacteria, which is usually associated with resistance to several other classes of antibiotics, has become a global problem of this century in hospital settings. Reports regarding the occurrence of viable carbapenem- resistant bacterial population (CRBP) outside medical institutions are globally scarce. The aim of this study was to quantify the numbers of viable CRBP through the secondary type of municipal wastewater treatment process (WWTP). The study was performed at the WWTP of the Croatian capital city of Zagreb, on 20 sampling occasions from September 2015 to June 2016. The CRBP was enumerated on CHROMagar Acinetobacter supplemented with CR102, which allows the growth of carbapenem-resistant isolates after incubation at 37C/72 h. The CRBP were found in influent, effluent, fresh activated sludge, anaerobically digested sludge, but not in lime- treated stabilized sludge of pH 12. Similar abundance (p>0.05) of CRBP was detected in influent and fresh activated sludge (median value 4.0 log CFU/mL) and significant decrease (p

Disinfection implies the elimination of pathogenic microorganisms in water treatment systems that facilitates the safe discharge or reuse of wastewater. Alkaline disinfection is the inactivation of pathogenic bacteria at high pH conditions, usually above 12. Wood fly ash has been known to increase the pH when introduced to water solutions. Fly ash is an industrial by-product of the combustion of different wood materials and is mostly disposed of as waste on landfills. Proposed applications of wood ash are in agriculture and forestry where it serves as a liming agent and increases the availability of nutrients in acid soils, as a component in concrete, cement, and mortar manufacturing, and as a catalyst for biodiesel synthesis. Usage of fly ash as a disinfectant has not been reported in the literature so we tested it by monitoring the removal of typical pathogen indicators (faecal coliforms and intestinal enterococci) in effluents of urban wastewater and landfill leachate treatment plants in order to simulate the disinfection by using wood fly ash as a potential tertiary treatment method. The addition of ash at a concentration of 10 g L-1 (1 %) caused an instant increase of pH in urban wastewater (Wastewater treatment plant of Velika Gorica, Croatia) and landfill leachate (Jakuševec landfill, Zagreb, Croatia). High pH (10.1–12.7) inactivated bacterial populations in both types of wastewater and the removal of faecal coliforms and intestinal enterococci after 6 h of contact was 100 % (below the detection limit

Any natural or artificial substrate that is immersed in seawater is rapidly covered by unavoidable biofouling. Growth of such fouling also known as biofilm formation is complex and not yet thoroughly investigated. Roughly known stages of biofilm generation are: adsorption of organic and inorganic macromolecules ; migration of microbial cells to the surface ; attachment of bacteria onto surface ; production of extra-cellular polymers ; and development of a more complex 3D community with the presence of micro- and macroalgae, leading to attachment of larger macro-invertebrates. Succession of diatoms and bacteria was investigated during a one month period incubation on artificial substrate mounted above the seafloor at five meters depth. Samples were collected after 1h, 12h, 24h, 48h, 4 days, 7 days and 30 days of contact. For bacteriological analysis the biofilm was detached from plexiglass plates (polymer of methyl methacrylate) using an ultrasonic probe and samples were inoculated onto selective agar plates. Biofilm for algological analysis was scraped with adopted toothbrush and resuspended in subsamples for epiphluorescent, light and electronic microscopy, as well as for HPLC pigment analysis. During monitoring of biofilm development, abundance of all biofilm components increased and reached maximum values after one month incubation. In the bacterial community heterotrophic marine bacteria were dominant and reached 1.94x104 CFU cm-2. Faecal coliforms and faecal enterococci were not detected in the biofilm. Phototrophic component of the biofilm was dominated by diatoms and reached 6.10x105 cells cm-2, which was supported by pigment analysis with fucoxantin as dominant pigment in concentration up to 110 ng cm-2. Dominant diatoms were Cylindrotheca closterium and unidentified penate benthic diatoms. More detailed taxonomic analysis of those diatoms by electronic microscopy revealed up to 20 different taxa of diatoms. The study confirmed that the plexiglass surface in a marine environment is susceptible to biofouling within 30 days of contact.

Quercetin, a protective phenolic compound isolated from plants, exerts antibacterial activity against many strains of bacteria. It is discovered that some positive biological effects of free phenolics can be improved by their chemical derivatization with metals. Thus, we synthesized a complex of the phenolic compound quercetin (Q) with the rare earth metal europium (Eu3+) in a biological buffer, and compared its activity against Staphylococcus aureus cells with that of free Q. While free Q did not show antibacterial activity against S. aureus, its complex with Eu3+ did. Using confocal laser scanning microscope we screened for the ability of Q/Eu3+ complex, free Q and Eu3+ to penetrate into S. aureus cells. Images revealed all the three chemical forms penetrated into S. aureus cells. However, while free Q did not disrupt cell morphology, Q/Eu3+ complex and free Eu3+ caused degradation of cell structure – most of the cells were lysed, their structures were amorphous, and only few cells showed minor fluorescence signal corresponding to the Q/Eu3+ or free Eu3+. Thus, the antibacterial activity of Q/Eu3+ was attributed to degradation of complex and antibacterial effect of released free Eu3+. Confocal laser scanning microscopy was successfully employed for visualization of anti-S. aureus effect of Q/Eu3+ complex.

S ciljem uspoređivanja dvije vrste mliječnih zamjenica i mlijeka, kroz proizvodne parametre i zdravstveno stanje teladi proveden je pokus na trideset šest (36) teladi holstein pasmine u razdoblju od 1.- 63. dana. Tijekom pokusa telad je dnevno konzumirala iste količine tekuće hrane. Kontrolna skupina je napajana nepasteriziranim sirovim mlijekom, pokusna skupina teladi (P1) mliječnom zamjenicom „A“ standardne kakvoće, a pokusna skupina teladi (P2) mliječnom zamjenicom „B“ bolje nutritivne vrijednosti bjelančevina, obogaćene imunoglobulinima jajeta (do 4. tjedna). Od 4. tjedna do kraja pokusa telad pokusne skupine (P2) napajana je mliječnom zamjenicom „A“. Vrijednost završne tjelesne mase bila je najbolja kod teladi kontrolne skupine, što je bilo statistički značajno (P

Two commercially available materials, MiraCarbon® carbon fibers (CF) and CultiSpher-S® microcarrier (CS), were used as support materials for immobilization of phosphate (P)-accumulating bacterium Acinetobacter junii. The CF are filamentous microscopic fibers intended to be used for mass adhesion of activated sludge thus preventing excess of waste sludge. The CS are macroporous gelatin spheres intended to be used as support for growth of animal cells. The immobilization of A. junii was performed by aerobically incubating the pure bacterial culture and selected materials in simulative wastewater with low P concentrations (2 mg L-1) for 24 h. After the incubation the numbers of immobilized bacteria were 1.97±0.95×109 CFU g-1 of CF and 4.96±1.0×109 CFU g-1 of CS. The materials with immobilized bacteria were now transferred to simulative wastewater with high P concentrations (20 mg L-1) to test the P-removing capacity of such prepared substrate. During 24 h of aerobic incubation a part of the cells were detaching from the surface of the CF thus bioaugmenting the surrounding media while majority of the bacteria remained firmly in the biofilm ; the bacteria were metabolically active and removed 50% of starting P from the wastewater. On the other hand, the CS dissolved after 24 h of incubation resulting in blur and gelatinous solution which excluded CS for potential usage in the treatment systems, although the bacteria were still viable and metabolically active. The CF were rigid throughout the experiment, showed great potential for implementation and should further be tested in activated sludge systems.

To test new methods of activated sludge bioaugmentation we immobilised Acinetobacter junii and Pseudomonas aeruginosa onto natural zeolitic tuff and tested their ability to remove phosphates and heavy metals (copper, zinc, nickel) from synthetic and real wastewater. A. junii strain used is a known phosphate (P)-accumulating bacterium and P. aeruginosa strain was isolated from metalworking fluids. We immobilized the bacteria (bioparticle formation) by aerobically incubating pure bacterial cultures and zeolitic tuff in nutrient medium, obtaining A. junii bioparticles (AJBP) and P. aeruginosa bioparticles (PABP). We conducted four sets of experiments in order to: i) compare heavy metal tolerance of planktonic and immobilized bacteria, ii) compare their ability to remove phosphates and heavy metals from synthetic wastewater, iii) investigate if combined system with AJBP and PABP can be as efficient as systems with only AJBP or PABP, iv) test the ability of combined AJBP and PABP to remove phosphates and metals from real wastewater. Immobilised bacteria were significantly more tolerant to heavy metal stress than planktonic bacteria and removed significantly more metals. The two bacteria in form of bioparticles can survive in the same system, multiply and remove phosphates and heavy metals more successfully than when used separately. By simultaneous use of both bioparticles in real wastewater achieved values of phosphate and metal removal were from 15.2 to 17.0 mg/L P-PO4, 1.1 to 11.4 mg/L Cu2+, 1.2 to 32.8 mg/L Zn2+ and 1.0 to 39.6 mg/L Ni2+. This high efficiency gives the opportunity to use these bioparticles in wastewater treatment plants.

E. coli DSM 498 was precultivated on the Tryptic glucose yeast agar (Biolife, Italy) at 36±0.1°C/2d. Biomass was subcultured and incubated at 36±0.1°C/2d on/in 8 different commercial media suitable for the cultivation of E. coli (Biolife, Italy): Nutrient agar, EC X-GLUC agar, Endo agar, Mac Conkey agar, Mac Conkey broth, m-Faecal Coliform agar, m-LES Endo agar, TTC Tergitol 7 agar base. The culture of E. coli from each medium was stained by Gram method and examined by light microscopy with magnification of 7520x. The length and width of bacteria were determined using DinoCapture 2.0 software by measuring at least 100 cells per medium. The cells of E. coli cultivated on the media with proteins as the carbon source (Nutrient agar and EC X-GLUC agar) had an average length of 1.592±0.338 m, width 0.651±0.106 m and width/length ratio 0.422±0.086. The cells of E. coli cultivated on/in the media with proteins and lactose as the carbon sources (Endo agar, Mac Conkey agar, Mac Conkey broth, m-Faecal Coliform agar, m-LES Endo agar, TTC Tergitol 7 agar base) were statistically significant longer with an average length of 3.595±1.193 m, wider with 0.680±0.131 m and with lower width/length ratio of 0.202±0.050. In the literature the cells belonging to the genus Ecsherichia are generally described as straight cylindrical rods 2.0-6.0 x 1.1-1.5 m. The size of E. coli varies when cultivated on/in different commercial media. Although the size of E. coli is not a determinative characteristic, the variation of cell size when cultured on/in different commercial media can be of great help during routine laboratory work.

Technology of bacterial immobilization could be an alternative for improvement of biological phosphate removal from the wastewater. Immobilization of phosphate accumulating bacteria on suitable carriers offers higher density of bacterial cells and enhanced metabolic activity of desired bacteria in the bioreactors. In addition, immobilized bacteria are better adapted to survive periods of environmental stresses characteristic for wastewater treatment. The perlite, an expanded volcanic rock, and sepiolite, a naturally occurring clay mineral, were tested as carriers of phosphate-accumulating bacterium Acinetobacter junii. All three forms of tested perlite (non-expanded, semi-expanded and expanded) and both forms of tested sepiolite (original and purified) proved to be good carriers of A. junii. Highest number of immobilized bacteria was on the expanded perlite (12.65 × 109 CFU g-1) followed by semi expanded (5.57 × 109 CFU g-1) and non-expanded (1.68× 109 CFU g-1) perlite. The numbers of bacteria immobilized on sepiolite were 8.12 ×109 CFU g-1 on purified form and 5.57 × 109 CFU g-1 on original form of sepiolite. The immobilized bacteria were metabolically active and successfully removed phosphate from the simulative wastewater when incubated in pure culture or in bioaugmented activated sludge. Out of three perlite samples, the semi-expanded perlite proved to be the best carrier of A. junii in the activated sludge system due to good incorporation in the sludge. The expanded and raw perlite were, respectively, bulking and sinking in the bioreactors, thus diminishing the exposure and phosphate removal of immobilized bacteria in the wastewater. The addition of sepiolite with immobilized A. junii in activated sludge system resulted in significant improvement of phosphate removal from the wastewater, increase of biomass and better settling properties of sludge.

Biološko uklanjanje fosfata (P) iz otpadnih voda temelji se na metabolizmu P-uklanjajućih bakterija prisutnih u aktivnom mulju. Imobilizacija P-uklanjajućih bakterija na materijale koji služe kao nosači bakterija jedna je od mogućnosti unaprjeđenja ovog procesa jer se imobilizacijom postiže veća koncentracija željenih bakterija te pojačana metabolička aktivnost u bioreaktoru. U ovom radu kao nosači P-uklanjajuće bakterije Acinetobacter junii ispitani su prirodni alumosilikatni materijali (zeolitni tufovi, bentonit i perlit), jedan prirodni magnezijev-silikat (sepiolit) te jedan sintetski alumosilikat (sintetski zeolit A). U radu su utvrđeni fizikalno-kemijski čimbenici koji utječu na rast i metabolizam bakterije A. junii i na proces imobilizacije bakterija na nosače. Svi prirodni materijali pokazali su se kao dobri nosači bakterija, a sintetski zeolit A nije bio prihvatljiv nosač. Bakterije imobilizirane na nosač zadržale su metaboličku aktivnost u pokusima sa sintetskim i realnim otpadnim vodama što ukazuje na mogućnost njihovog korištenja u postrojenjima za pročišćavanje otpadne vode.

Uzgoj zdravog podmlatka predstavlja jedan od najvažnijih i najzahtjevnijih segmenata govedarske proizvodnje. Tradicionalni način uzgoja teladi podrazumijeva isključivu uporabu punomasnog mlijeka u razdoblju do odlučenja. Premda je punomasno mlijeko prirodna i nutritivno najbolje uravnotežena hrana za sisajuću telad, u suvremenim govedarskim proizvodnim sustavima široko je rasprostranjena uporaba mliječnih zamjenica. Cilj ovoga istraživanja bilo je vrednovanje učinka različito formuliranih mliječnih zamjenica i punomasnog sirovog mlijeka na proizvodne i zdravstvene pokazatelje teladi. Istraživanje je obuhvaćalo razdoblje od teljenja do odlučenja (63. dana). Za potrebe pokusa odabrano je 36 teladi Holstein pasmine, ravnomjerno zastupljenih spolova, podijeljenih u tri skupine. Telad kontrolne skupine hranjena je sirovim punomasnim mlijekom cijelo vrijeme trajanja pokusa. Telad pokusne skupine P1 napajana je mliječnom zamjenicom A, koja je sadržavala 21% sirovih bjelančevina (62, 5% bjelančevina mliječnoga i 37, 5% bjelančevina podrijetlom iz soje) i 16% sirovih masti. Telad pokusne skupine P2 je od četvrtog dana do kraja trećeg tjedna života napajana mliječnom zamjenicom B, koja je sadržavala 22, 5% ukupnih sirovih bjelančevina (100% bjelančevina mliječnog podrijetla, od čega 45% obrano mlijeko u prahu i 55% sirutka u prahu) i 18% sirovih masti. Ova mliječna zamjenica bila je obogaćena specifičnim protutijelima, dobivenim iz žumanjka jajeta, na bakterije roda Salmonella, Escherichia Coli te rota i corona viruse. Od početka četvrtog tjedna pa sve do odlučenja, telad pokusne skupine P2 napajana je mliječnom zamjenicom A, istovjetnom kao i u pokusnoj skupini P1. Obje mliječne zamjenice su bile obogaćene probiotskim bakteri sjkim kulturama Lactobacillus rhamnosus i Enterococcus faecium. Telad kontrolne skupine i pokusne skupine P2 postigla je značajno (P0, 05). Telad kontrolne skupine postigla je na kraju istraživanja statistički visoko značajno (P

Povećane količine željeza mogu ući u uređaje za biološko pročišćavanje s industrijskim i procijednim otpadnim vodama ili korištenjem željeznih soli za precipitaciju fosfata u tercijarnom stupnju pročišćavanja. U ovom radu istražen je utjecaj dodatka željeza u obliku FeSO4 na rast i metabolizam čiste kulture fosfatakumulirajuće bakterije Acinetobacter junii. Pokazalo se da je za uspješan rast i metabolizam A. junii dovoljna prisutnost Fe2+ u tragovima (≤0, 02 mg L-1). U otpadnoj vodi koncentracije Fe2+ od 1, 31 mg L-1 pokazuju negativan utjecaj na rast i metabolizam bakterija, a koncentracije veće od 24, 16 mg L-1 uzrokuju odumiranje bakterijske biomase. Postoji opasnost da povišene koncentracije Fe2+ djeluju toksično prema fosfat-akumulirajućim bakterijama i drugim mikroorganizmima u aktivnom mulju i tako dugoročno naruše sposobnost uređaja za tercijarno pročišćavanje da uspješno uklanjaju fosfate iz otpadnih voda.