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Ljubičaste nesumporne bakterije zanimljive su s ekološkog i ekonomskog stajališta u održivim biotehnološkim procesima proizvodnje biogoriva, biokemikalija, biopolimera, biomase odnosno sintezi specifičnih spojeva kao što su npr. karotenoidi i pigmenti. Za uspostavu ekološki i ekonomski održivih bioprocesa nužan je adekavatan odabir radnih mikroorganizama, sirovina i uvjeta kultivacije, a dobar primjer za to je razvoj bioprocesa na obnovljivim sirovinama kao što su to lignocelulozne sirovine. U ovom istraživanju proučavan je fotoheterotrofni uzgoj ljubičaste nesumporne bakterije Rhodovulum adriaticum DSM 2781 na tekućim hranjivim podlogama koje sadrže glukozu i/ili ksilozu kao izvore ugljika s ciljem dobivanja bakterijske biomase i fotosintetskih pigmenata. Rezultati istraživanja pokazuju da su najveće vrijednosti pokazatelja uspješnosti bioprocesa (YX = 2,095 g L-1; YX/S = 0,54 g g-1i Pr = 0,022 g L-1h-1) vezanih u dobivanje biomase ostvareni kod uzgoja na hranjivoj podlozi s 5 g L-1 glukoze. Uzgoj R. adriaticum DSM 2781 na hranjivoj podlozi s 3 g L-1 glukoze i ksiloze pokazao se najuspješnji za dobivanje fotosintetskih pigmenata (ukupni pigmenti 13,27 mg g-1 biomase) uz zadovoljavajuće ostale pokazatelje uspješnosti bioprocesa (YX = 1,507 g L-1; YX/S = 0,22 g g-1i Pr = 0,017 g L-1h-1)., Purple non-sulphur bacteria are interesting from ecologic and economic point of view in sustainable biotechnological production of biofuels, biochemicals, biopolymers and biomass as well as specific compounds such as carotenoids and pigments. In order to establish ecological and economic sustainable bioprocesses it is necessary to select adequate working microorganisms, raw materials and cultivation conditions. Development of bioprocesses on the renewable raw materials (e.g. lignocellulose containing feedstocks) are good example for such bioprocess types. In this research, the photoheterotrophic cultivation of purple non-sulfur bacteria Rhodovulum adriaticum DSM 2781 was studied on the liquid media containing glucose or /and xylose as a carbon sources in order to produce bacterial biomass and photosynthetic pigments. Results obtained in this study show that the highest values of bioprocess efficiency parameters (YX = 2,095 g L-1; YX/S = 0,54 g g-1i Pr = 0,022 g L-1h-1) related to the biomass production were observed during bacterial cultivation on media with 5 g L-1. Cultivation of R. adriaticum DSM 2781 on the media with 3 g L-1 glucose and xylose shows the highest total photosynthetic pigments content (13,27 mg g-1 biomass) together with satisfy other bioprocess efficiency parameters (YX = 1,507 g L-1; YX/S = 0,22 g g-1i Pr = 0,017 g L-1h-1).

Za proizvodnju bioetanola iz lignoceluloznih hidrolizata potreban je proizvodni soj koji dobro podnosi prisutnost inhibitora rasta i fermentacije te veliku koncentraciju etanola. Stoga smo konstruirali hibridne diploide kvasca Saccharomyces cerevisiae međusobnim križanjem dvaju prirodnih izolata, Yllcl 7_E5 i UWOPS87-2421. Soj Yllcl 7_E5 izoliran je iz vina kao dobar proizvođač etanola, a soj UWOPS87-2421 izoliran je iz cvijeta kaktusa Opuntia megacantha i otporan je na inhibitore koji se mogu naći u lignoceluloznim hidrolizatima. Hibridni sojevi rasli su brže od ishodnih sojeva u odsutnosti i prisutnosti octene i levulinske kiseline te 2-furaldehida, koji se često nalaze kao inhibitori rasta u lignoceluloznim hidrolizatima, a pojačana ekspresija gena YAPI povećala je preživljenje testiranih sojeva. Također, pojedini su hibridni sojevi, iako potječu od dvaju istih ishodnih sojeva, pokazali različit fermentativni potencijal u testu proizvodnje C02, što upućuje na njihovu genetičku varijabilnost koja omogućava daljnju selekciju poželjnih svojstava. Iz naših se rezultata može zaključiti da se kombiniranjem konstrukcije hibridnih sojeva i metoda genetičkog inženjerstva mogu oplemeniti i razviti novi biotehnološki relevantni sojevi kvasca S. cerevisiae. Osim toga, utvrđeno je da je uspješnost ciljanja gena u prirodnim izolatima S. cerevisiae (Yllcl 7_E5a and UWOPS87-2421 a) daleko manja nego u laboratorijskim sojevima, a najčešći aberantni događaj bio je duplikacija ciljanog kromosoma., Bioethanol production from lignocellulosic hydrolysates requires a producer strain that tolerates both the presence of growth and fermentation inhibitors and high ethanol concentrations. Therefore, we constructed heterozygous intraspecies hybrid diploids of Saccharomyces cerevisiae by crossing two natural S. cerevisiae isolates, YIIc17_E5 and UWOPS87-2421, a good ethanol producer found in wine and a strain from the flower of the cactus Opuntia megacantha resistant to inhibitors found in lignocellulosic hydrolysates, respectively. Hybrids grew faster than parental strains in the absence and in the presence of acetic and levulinic acids and 2-furaldehyde, inhibitors frequently found in lignocellulosic hydrolysates, and the overexpression of YAP1 gene increased their survival. Furthermore, although originating from the same parental strains, hybrids displayed different fermentative potential in a CO2 production test, suggesting genetic variability that could be used for further selection of desirable traits. Therefore, our results suggest that the construction of intraspecies hybrids coupled with the use of genetic engineering techniques is a promising approach for improvement or development of new biotechnologically relevant strains of S. cerevisiae. Moreover, it was found that the success of gene targeting (gene targeting fidelity) in natural S. cerevisiae isolates (YIIc17_E5α and UWOPS87-2421α) was strikingly lower than in laboratory strains and the most frequent off-targeting event was targeted chromosome duplication.

U ovom je radu ispitana metodologija proizvodnje mikroreaktora iz akrilne smole pomoću PolyJet Matrix 3D ispita. PolyJet Matrix tehnologija koristi različite materijale ili kombinacije materijala radi tiskanja jednostavnih ili složenih 3D struktura različitih svojstava. korištene su Za procjenu geometrije, postupaka proizvodnje i hidrodinamičku karakterizaciju mikroreaktora upotrijebljene su eksperimentalne i numeričke metode. Na osnovi hidrodinamičke karakterizacije određene su procesne granice jednofaznog protoka u mikrokanalima, te je ispitana mogućnost daljnjih poboljšanja i primjene mikroreaktora., This work investigates the methodology of producing a 3D-printed microreactor from the acrylic resin by PolyJet Matrix process. The PolyJet Matrix technology employs different materials or their combinations to generate 3D-printed structures, from small ones to complex geometries, with different material properties. Experimental and numerical methods served for the evaluation of the geometry and production of the microreactor and its hydrodynamic characterization. The operational limits of the single-phase flow in the microchannels, further improvements and possible applications of the microreactor were assessed based on the hydrodynamic characterization.

Bioetanol je proizveden procesom istodobne saharifikacije i fermentacije (eng. Simultaneous saccharification and fermentation, SSF) s kvascem Saccharomyces cerevisiae na enzimskom hidrolizatu predobrađenih kukuruznih oklasaka. Istraživan je učinak trajanja predhidrolize kukuruznih oklasaka na učinkovitost procesa proizvodnje bioetanola te je uspoređen s konvencionalnim procesom SSF. Dvije smjese komercijalno dostupnih enzima rabljene su za hidrolizu sirovine; prva je sadržavala Celluclast 1.5L (Sigma) i β-glukozidazu (Carl Roth), a druga smjesa Celluclast 1.5L (Sigma) i Viscozyme L (Sigma). Dva dana predhidrolize imala su pozitivan učinak na prinos bioetanola, dok je dulje trajanje predhidrolize smanjilo prinos bioetanola. Najveća koncentracija etanola od 41,24 g dm–3 postignuta je u procesu SSF uz dva dana predhidrolize koja je iznosila 63,15 % teoretskog iskorištenja izračunatog na neobrađeni kukuruzni oklasak. Najveća ukupna produktivnost procesa od 0,36 g dm–3 h–1 postignuta je konvencionalnim SSF-om uz enzimsku smjesu koja je sadržavala Celluclast 1.5L (Sigma) i Viscozyme L (Sigma). Koncentracija etanola iznosila je 36,6 g dm–3, što je 56,02 % teoretskog prinosa etanola na neobrađeni kukuruzni oklasak. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., Bioethanol was produced from cellulase-hydrolysed pretreated corn cobs by simultaneous saccharification and fermentation (SSF) with yeast Saccharomyces cerevisiae. The effect of the duration of the corn cob prehydrolysis step on ethanol yield by SSF process was studied and compared to the conventional SSF process. Two mixtures of commercially available enzyme preparations were used for biomass hydrolysis; the first contained Celluclast 1.5L (Sigma) and ß-glucosidase (Carl Roth), and the second mixture contained Celluclast 1.5L (Sigma) and Viscozyme L (Sigma). Two days of prehydrolysis had a positive effect on ethanol yield, while the yield decreased with longer prehydrolysis. The highest ethanol concentration of 41.24 g dm–3 was obtained by SSF process with two days of prehydrolysis, which corresponded to 63.15 % of the theoretical yield based on untreated corn cobs. However, the highest total productivity of 0.36 g dm–3 h–1 was observed in conventional SSF process using enzyme mixture containing Celluclast 1.5L (Sigma) and Viscozyme L (Sigma). Concentration of ethanol was 36.6 g dm–3 which corresponded to 56.02 % of the theoretical yield based on untreated corn cobs. This work is licensed under a Creative Commons Attribution 4.0 International License.

Proizvodnja biogoriva iz obnovljivih sirovina privukla je pažnju znanstvenika jer može poslužiti za opskrbu energijom i alternativnim gorivima. Bioetanol je jedno od najzanimljivijih biogoriva zbog njegovog pozitivnog utjecaja na okoliš. Najčešće se proizvodi iz sirovina koje sadržavaju šećer i škrob. Međutim, razni izvori lignocelulozne biomase, kao što su poljoprivredni i šumski ostaci te zeljasti energetski usjevi, također mogu poslužiti kao sirovine za proizvodnju bioetanola, energije, topline i kemikalija s dodanom vrijednošću. Lignoceluloza je složena mješavina ugljikohidrata, koju treba učinkovito prethodno obraditi da bi se oslobodili biotransformacijski putevi u kojima enzimi proizvode fermentabilne šećere što nakon hidrolize fermentiraju u etanol. Unatoč tehničkim i ekonomskim poteškoćama, obnovljive lignocelulozne sirovine imaju nisku cijenu te ne utječu na hranu i prehrambeni lanac, čime potiču održivost. Za proizvodnju bioetanola iz obnovljivih sirovina razvijeni su različiti načini rada bioprocesora. Osim toga, intenzivno se razvijaju i alternativni postupci odvajanja i pročišćavanja bioetanola. Ovaj rad daje pregled novih trendova u proizvodnji bioetanola iz različitih obnovljivih sirovina, te postupaka njegovog odvajanja i pročišćavanja., Production of biofuels from renewable feedstocks has captured considerable scientific attention since they could be used to supply energy and alternative fuels. Bioethanol is one of the most interesting biofuels due to its positive impact on the environment. Currently, it is mostly produced from sugar- and starch-containing raw materials. However, various available types of lignocellulosic biomass such as agricultural and forestry residues, and herbaceous energy crops could serve as feedstocks for the production of bioethanol, energy, heat and value-added chemicals. Lignocellulose is a complex mixture of carbohydrates that needs an efficient pretreatment to make accessible pathways to enzymes for the production of fermentable sugars, which after hydrolysis are fermented into ethanol. Despite technical and economic difficulties, renewable lignocellulosic raw materials represent low-cost feedstocks that do not compete with the food and feed chain, thereby stimulating the sustainability. Different bioprocess operational modes were developed for bioethanol production from renewable raw materials. Furthermore, alternative bioethanol separation and purification processes have also been intensively developed. This paper deals with recent trends in the bioethanol production as a fuel from different renewable raw materials as well as with its separation and purification processes.

Biodizel i bioplin dva su vrlo važna izvora obnovljive energije širom svijeta, a posebice u zemljama EU. Biodizel se gotovo isključivo koristi kao transportno gorivo, dok se bioplin uglavnom koristi za proizvodnju električne energije i topline. Primjena sofisticiranijih tehnika pročišćavanja u proizvodnji čistog biometana iz bioplina omogućuje njegovo uvođenje u mrežu prirodnog plina i daljnju uporabu kao transportno gorivo. Dok se bioplin uglavnom proizvodi od otpadnih materijala (materijal s odlagališta otpada, gnojivo, talog zaostao pročišćavanjem otpadnih voda, poljoprivredni otpad), biodizel se u EU uglavnom dobiva iz repice ili drugih uljarica koje se koriste kao hrana, što dovodi u pitanje njihovu ulogu kao hrane ili goriva. Kako bi se ublažio ovaj problem, napravljeni su značajni napori u korištenju neprehrambenih sirovina za proizvodnju biodizela. To uključuje sve vrste otpadnih ulja i masti, no od nedavno se više pažnje posvećuje proizvodnji mikrobnih ulja uzgojem mikroorganizama koji mogu akumulirati velike količine lipida u biomasi. Obećavajući kandidati za mikrobnu proizvodnju lipida mogu se pronaći među različitim sojevima filamentoznih plijesni, kvasaca, bakterija i mikroalgi. Sirovine od interesa su i poljoprivredni otpad bogat ugljikohidratima te različite lignocelulozne sirovine, za čiju se uporabu još uvijek moraju riješiti neka tehnička pitanja. Također, u ovom su radu razmatrane metode izdvajanja i pročišćavanja biodizela i bioplina., Biodiesel and biogas are two very important sources of renewable energy worldwide, and particularly in the EU countries. While biodiesel is almost exclusively used as transportation fuel, biogas is mostly used for production of electricity and heat. The application of more sophisticated purification techniques in production of pure biomethane from biogas allows its delivery to natural gas grid and its subsequent use as transportation fuel. While biogas is produced mostly from waste materials (landfills, manure, sludge from wastewater treatment, agricultural waste), biodiesel in the EU is mostly produced from rapeseed or other oil crops that are used as food, which raises the ‘food or fuel’ concerns. To mitigate this problem, considerable efforts have been made to use non-food feedstock for biodiesel production. These include all kinds of waste oils and fats, but recently more attention has been devoted to production of microbial oils by cultivation of microorganisms that are able to accumulate high amounts of lipids in their biomass. Promising candidates for microbial lipid production can be found among different strains of filamentous fungi, yeast, bacteria and microalgae. Feedstocks of interest are agricultural waste rich in carbohydrates as well as different lignocellulosic raw materials where some technical issues have to be resolved. In this work, recovery and purification of biodiesel and biogas are also considered.

Wild strains of purple non-sulphur bacteria: Rhodospirillum rubrum B-6505, Rhodopseudomonas palustris B-6506, Rhodobacter capsulatus B-6508 and Rhodobacter spheroides B-6509 were studied as 5-ALA (5 aminolevulinic acid) producers. Selected strains were subjected to mutagenesis with N-methyl-N-nitro-N-nitrosoguanidine to obtain a strain with high 5-ALA producing capacity. After mutagenesis 19 stable mutant strains were selected from Rhodobacter capsulatus B-6508 and Rhodobacter sphaeroides B-6509. On the basis of obtained results, mutant strain of Rhodobacter capsulatus B-6508 has shown the highest potential for 5-ALA production. The most favorable conditions for growth and 5-ALA production by mutant strain R. capsulatus B-6508 were observed in media composed of glutamate and malate, light at 2000 Lux, microaerophilic conditions and temperature of 28 °C. In these conditions, the highest 5-ALA concentration (179 mg/L) was detected together with the highest bacterial physiological activity. The prolongation of mutant strain R. capsulatus B-6508 cultivation time after glycine, succinate and levulinic acid addition is related to the reduction of 5-ALA concentrations (e.g. 124.5 mg/L after 48 h and 89.5 mg/L after 72 hours). In the light/aerobic conditions R. capsulatus B-6508 produced only 58.1 mg/L of 5 ALA. Furthermore, in dark conditions even lower biomass and 5-ALA concentrations were observed during R. capsulatus B-6508 cultivation.

Zbog velike rasprostranjenosti u prirodi i relativno niske cijene, lignocelulozne sirovine postaju zanimljive za primjenu u različitim biotehnološkim procesima. Međutim, zbog svoje kompleksne strukture, te sirovine moraju proći postupak predobradbe u kojem uglavnom nastaju nuspodukti koji imaju inhibitorno djelovanje na proizvodni mikroorganizam i time utječu na ukupnu učinkovitost bioprocesa. U ovom istraživanju ispitivana je mogućnost korištenja hidrolizata pšenične slame i kukuruzovine za anaerobni uzgoj kvasca S. cerevisiae odnosno s ciljem proizvodnje etanola. Postupak blago kisele predobrade lignoceluloznih sirovina u visokotlačnom reaktoru (pri 210°C; 20 bara; vrijeme zadržavanja 1 - 10 minuta; do 1,0 % H2SO4) korišten je za dobivanje hidrolizata lignoceluloznih sirovima pri čemu je najveći udjel ukupnih fermentabilnih šećera zabilježen kod postupka predobrade s 1,0 % H2SO4 i vremenom zadržavanja od 5 minuta. Anaerobni uzgoj kvasca na hranjivim podlogama s hidrolizatima lignoceluloznih sirovina proveden je u Erlenmeyer tikvicama, te dodatno testiran u horizontalnom rotirajućem cijevnom bioreaktoru (HRCB). Rezultati ovog istraživanja pokazuju da su veće vrijednosti pokazatelja uspješnosti anaerobnog uzgoja kvasca zabilježene na hranjivoj podlozi s hidrolizatom pšenične slame (u odnosu na hidrolizat kukuruzovine) u HRCB-u pri čemu su ostvarene ove vrijednosti pokazatelja uspješnosti bioprocesa: YP/S = 0,261 g g-1, Pr = 0,0678 g L-1h-1 i E= 42 %. Na osnovi rezultata ovog istraživanja vidljivo je da je potrebno dodatno optimizirati postupak predobrade lignoceluloznih sirovina kao i selekcionirati novi soj mikroorganizma koji ima sposobnost korištenja heksoza i pentoza odnosno visoku tolerantnost na nusprodukte koji nastaju postupkom predobrade lignoceluloznih sirovina.

Povećanje emisije stakleničkih plinova, energetska ovisnost i nestabilnost isporuke energenata posljedica su ubrzane potrošnje fosilnih goriva zbog ubrzanog rasta svjetske populacije i industrijalizacije. Bioetanol je postao atraktivno zamjensko biogorivo jer se proizvodi iz obnovljivih sirovina i ekološki je prihvatljiv. Upotrebljava se kao pogonsko gorivo i to kao hidrirani (96 %) ili bezvodni (u mješavinama s benzinom). Bioetanol se proizvodi fermentacijom s kvascem S. cerevisiae ili nekim drugim mikroorganizmom iz ugljikohidrata kao što su jednostavni šećeri, škrob i celuloza. Nakon fermentacije, bioetanol se izdvaja i pročišćava destilacijom i dehidracijom. Sastav je propisan specifikacijama za primjenu u motornim gorivima. Uobičajeni usjevi, kao što su kukuruz, šećerna repa i trska, zasad su osnovne sirovine za proizvodnju bioetanola. Međutim, proizvodnja bioetanola iz ovih sirovina ne može zadovoljiti globalne potrebe za bioetanolom, zbog njihove primarne uloge u prehrani ljudi i životinja. Lignoceluloza je pogodna sirovina za proizvodnju bioetanola jer je široko rasprostranjena, obnovljiva i ne upotrebljava se u prehrani. Proizvodnja bioetanola iz lignoceluloznih sirovina je složen proces, koji se u mnogim aspektima razlikuje od proizvodnje iz šećernih ili škrobnih sirovina. U ovom radu prikazane su dosadašnje i nove tehnologije u proizvodnji bioetanola uključujući primjenu različitih sirovina, postupaka proizvodnje i radnih mikroorganizama. Nadalje, navedene su mogućnosti integracije osnovnih koraka u bioprocesima proizvodnje s ciljem povećanja produktivnosti i smanjenja troškova proizvodnje., Rapidly growing fossil energy consumption, due to population and industrial growth, has caused increasing greenhouse-gas emissions, growing energy dependency and supply insecurity. Bioethanol has become an attractive alternative biofuel because of its environmental benefits and the fact that it is made from renewable resources. Ethanol is widely used as transport fuel, pure hydrous ethanol or anhydrous ethanol in mixtures with gasoline (Fig. 1). Bioethanol is produced from carbohydrates such as sugar, starch and cellulose by fermentation with yeast S. cerevisiae or other microorganisms. Thereupon, ethanol is separated and purifyed by distillation-rectification-dehydration to meet fuel specifications. Currently, conventional crops such as corn or sugarcane are the main feedstock for bioethanol production. Bioethanol production from the sucrose-containing feedstock is simpler compared to the starchy materials and the lignocellulosic biomass due to an additional step – feedstock hydrolysis. The process of ethanol production from starchy materials includes the hydrolysis of starch to glucose using α-amylase (1,4-α-D-glucan-4-glucanohydrolase) and glucoamylase (1,4-α-D-glucanglucohydrolase). Finally, the glucose is fermented to ethanol by yeast cells. Enzymatic hydrolysis of starch and fermentation of glucose can be carried out in different process configurations, such as separate hydrolysis and fermentation (SHF), and simultaneous saccharification and fermentation (SSF, Fig. 2). In consolidated bioprocessing (CBP), the conversion of starch into ethanol is performed in one step without added enzymes. This process configuration has potential to lower the cost of biomass processing due to elimination of operating and capital costs associated with dedicated enzyme production. Current bioethanol production from corn and sugarcane is unable to meet the global demand for bioethanol, due to their primary value as livestock feed and human food. The lignocellulosic biomass such a

Prekomjerno pjenjenje piva (engl. beer gushing) definira se kao naglo i nekontrolirano pjenjenje piva odmah po otvaranju ambalaže, bez prethodnog izlaganja ambalaže trešnji ili visokoj temperaturi. Ta je pojava uzrok velikim gubitcima u sladarama i pivovarama širom svijeta te se smatra iznimno nepoželjnom. Razlikujemo primarno i sekundarno prekomjerno pjenjenje piva. Fungalne kontaminacije ječma, posebno kontaminacija plijesnima roda Fusarium, izravno se povezuju s pojavom primarnog prekomjernog pjenjenja piva. Ove plijesni sintetiziraju male proteine nazvane hidrofobini, koji se navode kao glavni uzročnici prekomjernog pjenjenja piva. Uzročnici sekundarnog prekomjernog pjenjenja piva su brojniji i uključuju različite kemikalije i postupke koji se upotrebljavaju tijekom proizvodnje piva. Sekundarno pjenjenje piva uglavnom se može izbjeći primjenom dobre proizvođačke prakse, dok je problem učinkovitog suzbijanja primarnog prekomjernog pjenjenja piva još uvijek predmet brojnih istraživanja.

Biomasa mikroalgi predstavlja vrijednu sirovinu za proizvodnju farmaceutskih, prehrambenih i kozmetičkih proizvoda (proteina, masnih kiselina, vitamina, anti-oksidansa, pigmenata, lijekova i imunostimulansa), te proizvodnju biogoriva (biodizela). Temelj učinkovite proizvodnje biomase mikroalgi za dobivanje biogoriva primjena je bioprocesno inženjerskih znanja povezanih s izborom mikroalge, hranjive podloge, uvjeta i postupka vođenja bioprocesa u različitim bioreaktorskim sustavima, te metode izdvajanja i pročišćavanja biomase mikroalgi. Kriteriji izbora mikroalge određeni su fiziološkim potencijalom i mogućnošću mikroalge da uspješno nakuplja lipide tijekom bioprocesa. Izbor hranjive podloge, uvjeta i postupka vođenja bioprocesa ključni su za proizvodnju biomase mikroalgi s velikim udjelom lipida. Za dobivanje što veće količine biomase mikroalgi s ciljem proizvodnje biogoriva koriste se različiti bioreaktorski sustavi s jednom ili više podjedinica koji su opremljeni različitim sustavima za nadzor bioprocesa. Osim uvjeta i postupka vođenja bioprocesa u bioreaktoru za uspješnu proizvodnju biogoriva potrebno je izabrati i adekvatne metode za izdvajanje i pročišćavanje biomase odnosno lipida iz biomase mikroalgi. Stoga je u ovom radu dan i pregled metoda za izdvajanje i pročišćavanje biomase odnosno lipida iz biomase mikroalgi nakon uzgoja u bioreaktoru., Microalgal biomass represents valuable raw material for pharmaceuticals, food and cosmetic industry (proteins, fatty acids, vitamins, antioxidants, pigments, pharmaceuticals and immunostimulant) as well as for biofuels production (biodiesel). A base of efficient microalgal biomass production for biofuels production is the use of bioprocess engineering knowledge related to the selection of microalgae species, cultivation medium and conditions, bioprocess cultivation techniques in different bioreactor systems as well as microalgal biomass separation and purification. Selection criteria for microalgae species has to be related to the microalgae physiological potentials and its abilities to accumulate lipids during bioprocess. Cultivation medium and conditions as well as bioprocess cultivation techniques in bioreactor system are key parameters for successful production of microalgal biomass with high lipid content. In order to produce large quantities of microalgal biomass for biofuels production different bioreactor systems with one or more subunits (equipped with different monitoring systems) are used. Beside cultivation conditions and bioprocess cultivation techniques in bioreactor system for efficient biofuels production it is necessary to select appropriate methods for biomass as well as lipid separation and purification from microalgal biomass. Therefore, in this work the overview of different methods for biomass and lipids separation and purification from microalgal biomass is also presented.

In the future, due to limited resources, a crisis of energy storing molecules (fuels), which are currently produced from crude mineral oil, is expected. One strategy to compensate a part of the oil deficiency is the production of biodiesel from microalgal lipids. As model microorganism for lipid production microalgae Euglena gracilis was selected and photo mixotrophic cultivation was performed in the stirred tank photobioreactor. During this research, medium composition and operational conditions of photo-bioreactor were optimized in order to define adequate cultivation conditions for algae biomass and lipid production. As low-cost and available complex carbon/ nitrogen source, corn steep liquor (CSL) was used to promote E. gracilis growth and lipid production. Due to the optimization of medium composition and cultivation conditions, lipid production was increased up to 29% of biomass dry weight in a two stage cultivation process inside one photo-bioreactor. Promising results obtained in this research encouraged us for further investigation.

In the future, due to limited resources, a crisis of energy storing molecules (fuels), which are currently produced from crude mineral oil, is expected. One strategy to compensate a part of the oil deficiency is the production of biodiesel from microalgal lipids. As model microorganism for lipid production microalgae Euglena gracilis was selected and photo mixotrophic cultivation was performed in the stirred tank photobioreactor. During this research, medium composition and operational conditions of photo-bioreactor were optimized in order to define adequate cultivation conditions for algae biomass and lipid production. As low-cost and available complex carbon/ nitrogen source, corn steep liquor (CSL) was used to promote E. gracilis growth and lipid production. Due to the optimization of medium composition and cultivation conditions, lipid production was increased up to 29% of biomass dry weight in a two stage cultivation process inside one photo-bioreactor. Promising results obtained in this research encouraged us for further investigation.

U ovom istraživanju proveden je uzgoj alge Euglena gracilis s ciljem proizvodnje vitamina A i vitamina E. U svrhu određivanja najpovoljnijih parametara za proizvodnju vitamina u bioreaktoru s mješalom provedena je optimizacija sastava hranjive podloge i uvjeta uzgoja E. gracilis, u Erlenmeyer tikvicama na laboratorijskoj tresilici. Tijekom uzgoja alge E. gracilis u bioreaktoru s mješalom primijenjen je dvostupanjski uzgoj. U prvom stupnju proveden je fotoheterotrofni uzgoj na Hutner-ovoj podlozi, a u drugom stupnju miksotrofni uzgoj na podlozi s ograničenim izvorom ugljika. Primjena dvostupanjskog procesa osigurala je relativno visoku produktivnost proizvodnje vitamina A (PrA = 0,07 mg/Lh) i vitamina E (PrE= 0,27 mg/Lh), a prinosi su iznosili vitamina A (YA = 6,53 mg/L) odnosno vitamina E (YE = 26,26 mg/L). Visoki prinosi vitamina E ukazuju na mogućnost primjene dvostupanjskog procesa njegove proizvodnje u industrijskom mjerilu., In this research, cultivation of algae Euglena gracilis was studied in order to produce vitamin A and vitamin E. The optimization of medium composition and cultivation conditions, in Erlenmeyer flasks on laboratory shaker, was done to define the most appropriate parameters for vitamin production in the stirred tank bioreactor. During cultivation of E. gracilis in the stirred tank bioreactor two-step process was examined. In the first step photoheterotrofic cultivation on the Hutner medium was done and in the second step photomixotrophically cultivation on the limited carbon source medium. In the two step process following bioprocess efficiency parameters were observed: productivity for vitamine A (PrA = 0.07 mg/Lh) and vitamin E (PrE= 0.27 mg/Lh) production as well as vitamin A (YA = 6.53 mg/L) and vitamin E (YE = 26.26 mg/L) yield. High vitamin E yield indicate potential of two-step processes for this vitamin industrial scale production.

U ovom istraživanju proučavana je proizvodnja bioetanola na svježem soku šećerne repe s pomoću kvasca Saccharomyces cerevisiae. Za vođenje procesa proizvodnje bioetanola primjenjene su ove tehnike: šaržni proces, šaržni proces s pritokom supstrata i polukontinuirani proces. Tijekom šaržnog procesa proizvodnje bioetanola stupanj konverzije supstrata u produkt (YP/S) je iznosio 0,375 g/g, učinkovitost bioprocesa (E) 69.70 %, te produktivnost (Pr) procesa 0,53 g/Lh. U šaržnom procesu s pritokom supstrata dobivene su ove vrijednosti pokazatelja uspješnosti bioprocesa: YP/S = 0,502 g/g, E = 93,40 % i Pr = 0,50 g/Lh. Nadalje, tijekom polukontinuirane proizvodnje bioetanola pokazatelji uspješnosti bioprocesa su imali ove vrijednosti: YP/S = 0,360 g/g, E = 66,91 % i Pr = 0,66 g/Lh. Na osnovi prethodno prikazanih rezultata jasno je da šaržni proces s pritokom supstrata i polukontinuirani proces imaju značajno veći potencijal za primjenu u industrijskoj proizvodnji bioetanola iako je potrebna daljnja optimizacija polukontinuirane tehnike vođenja bioprocesa., In this investigation, the production of bioethanol on the raw sugar beet juice by Saccharomyces cerevisiae was studied. Following cultivation techniques for bioethanol productions were used: batch, fed batch and repeated batch. In batch process substrate conversion coefficient (YP/S) was 0,375 g/g, bioprocess effi eciency (E) 69,70 % and productivity (Pr) 0,53 g/Lh, respectively. During fed batch process bioprocess efficiency parameters have following values: YP/S = 0,502 g/g, E = 93,4 % and Pr = 0,50 g/Lh. Furthermore, in repeated batch process bioprocess efficiency parameters have following values: YP/S = 0,360 g/g, E = 66,91 % and Pr = 0,66 g/Lh. On the basis of previously presented results it is clear that fed batch and repeated batch processes have considerably higher potential for use in the industrial bioethanol production although further optimization of repeated batch cultivation techniques has to be performed.

U ovom istraživanju provedeno je ispitivanje utjecaja ukupne koncentracije kisika u staklenoj boci na kakvoću piva donjeg vrenja tijekom skladištenja. Pivo je bilo skladišteno na temperaturi od 22 - 25°C u tamnoj prostoriji, a u pivu je bio prisutan kisik u tri različite ukupne početne koncentracije: 0,09 mg/L, 0,29 mg/L i 0,63 mg/L. Tijekom skladištenja (98 dana) u pivu je praćena promjena koncentracije trans-2-nonenala kao indikatora procesa oksidacije (starenja) piva, a dobiveni rezultati pokazuju da koncentracija trans-2-nonenala nije direktno ovisna o ukupnoj koncentraciji kisika u boci piva. U ovom istraživanju provedena je i senzorska analiza uzoraka piva koja je pokazala da povećane ukupne koncentracije kisika u boci izravno utječu na ocjenu kakvoće piva., In this research the effect of total packaging oxygen on the quality of bottled (glass bottle) lager beer during storage was studied. The beer was stored in a dark room at temperature of 22 - 25°C and it contained three different concentrations of total packaging oxygen: 0,09, 0,29 and 0,63 mg/L. During the 98 days storage period the concentration of trans-2-nonenal, a well known indicator of oxidation processes in the beer, was monitored. The results obtained in this research clearly show that the concentration of trans-2-nonenal is not directly related to the total oxygen concentration in the bottled beer. Sensory analysis of beer was also performed and obtained results clearly show that higher concentrations of total packaging oxygen directly effects beer quality and flavour.

Batch cultivation of monoculture of Lactobacillus sp. and two–strain mixed culture of Lactobacillus sp. and Lactobacillus amylovorus DSM 20531T was carried out with the aim of producing L-(+)- and D-(–)/L-(+)-lactic acid to be implemented in poly(lactic acid) polymer production. Metabolic capacity of two Lactobacillus strains to ferment different carbon sources (glucose, sucrose or soluble starch) during cultivation in MRS medium at 40 °C, in a laboratory-scale stirred tank bioreactor was defined. Lactobacillus sp. showed similar affinity towards mono- and disaccharide substrates, which were homofermentatively converted mostly to L-(+)-lactic acid. L. amylovorus DSM 20531T has been characterized as a D/L-lactate producer and it is capable of conducting simultaneous saccharification and fermentation. Due to the interaction of Lactobacillus sp. with L. amylovorus DSM 20531T, starch was hydrolysed and fermented to the mixture of L-(+)- and D-(–)-lactic acid. Modified Luedeking-Piret kinetics used for the description of substrate utilization, growth of mono- and mixed cultures and production of lactic acid stereoisomers showed good agreement with experimental data., Proveden je šaržni uzgoj čiste kulture Lactobacillus sp. i združene kulture bakterija Lactobacillus sp. i Lactobacillus amylovorus DSM 20531T radi proizvodnje L-(+)- i D-(-)/L-(+)-mliječne kiseline i njihove primjene u proizvodnji polilaktida. Definirana je metabolička aktivnost dvaju sojeva iz roda Lactobacillus koji mogu fermentirati različite izvore ugljika (glukozu, saharozu ili topljivi škrob) tijekom uzgoja u MRS podlozi pri 40 °C u laboratorijskom bioreaktoru s miješalom. Bakterija Lactobacillus sp. sličnom brzinom homofermentativno konvertira monosaharide i disaharide do L-(+)-mliječne kiseline (od 89 do 93 %). Bakterija L. amylovorus DSM 20531T okarakterizirana je kao proizvođač D/L-mliječne kiseline i može provoditi simultanu saharifikaciju i fermentaciju. S pomoću združene kulture Lactobacillus sp. i L. amylovorus DSM 20531T škrob je hidroliziran i fermentiran do L-(+)- i D-(-)-mliječne kiseline. Potrošnja supstrata, rast čiste i združene kulture te proizvodnja stereoizomera mliječne kiseline opisani su prilagođenom Luedeking-Piret kinetikom, a dobiveni su rezultati u skladu s eksperimentalnim podacima.

In this investigation, the production of ethanol from the raw sugar beet juice and raw sugar beet cossettes has been studied. For ethanol production from the raw sugar beet juice, batch and fed-batch cultivation techniques in the stirred tank bioreactor were used, while batch ethanol production from the raw sugar beet cossettes was carried out in horizontal rotating tubular bioreactor (HRTB). In both cases, Saccharomyces cerevisiae was used as a production microorganism. During batch ethanol production from the raw sugar beet juice, ethanol yield was 59.89 g/L and production efficiency 78.8 %, and in fed-batch process the yield was 92.78 g/L and efficiency 93.4 %. At the same time, ethanol production in HRTB from the raw sugar beet cossettes with inoculum of 16.7 % V/m (raw sugar beet cossettes) resulted in the highest ethanol yield of 54.53 g/L and production efficiency of 79.5 %. The obtained results clearly show that both intermediates of sugar beet processing can be successfully used for ethanol production., U ovom je istraživanju proučavan proces proizvodnje etanola iz sirovoga soka i sirovih rezanaca šećerne repe. Tijekom proizvodnje etanola iz sirovoga soka u bioreaktoru s miješalom primijenjeni su ovi načini vođenja bioprocesa: šaržni i šaržni proces s pritokom supstrata. Pri proizvodnji etanola iz sirovih rezanaca u horizontalnom rotirajućem cijevnom bioreaktoru primijenjena je šaržna tehnika vođenja bioprocesa. U oba je ova istraživanja kao radni mikroorganizam upotrijebljen kvasac Saccharomyces cerevisiae. Tijekom šaržnog procesa proizvodnje etanola iz sirovoga soka prinos je etanola iznosio 59,89 g/L, a učinkovitost bioprocesa bila 78,8 %. U šaržnom procesu s pritokom supstrata dobiven je prinos etanola od 92,78 g/L uz učinkovitost bioprocesa od 93,4 %. Istodobno je pri proizvodnji etanola iz sirovih rezanaca šećerne repe u horizontalnom rotirajućem cijevnom bioreaktoru s inokulumom od 16,7 % (V/m) dobiven najveći prinos etanola od 54,53 g/L uz učinkovitost bioprocesa od 79,5 %. Rezultati istraživanja jasno pokazuju da se oba međuproizvoda obrade šećerne repe mogu uspješno primijeniti u proizvodnji etanola.

Amylolytic lactic acid bacterium Lactobacillus amylovorus DSM 20531T utilised glucose, sucrose and starch as a sole carbon and energy source. The three substrates were completely depleted from MRS medium during batch cultivations carried out in a laboratory scale stirred tank bioreactor at constant temperature (40 °C) and pH value (5.5). Under the tested conditions, the bacterium was capable of conducting simultaneously starch hydrolysis and fermentation. A mixture of two stereoisomers, D-(–)- and L-(+)-lactic acid, was produced in all cases by highly efficient homofermentative bioprocess with 0.93 to 1 g of lactate produced per g of total (consumed) substrate. The effect of temperature on the kinetics of cell growth and lactic acid production by the amylolytic strain in the starch-containing medium was also investigated. Efficient simultaneous saccharification and fermentation (SSF) was obtained at 35, 40 and 45 °C with completely degraded complex carbohydrate in 8 to 12 h and the product yield coefficient in the range from 0.91 to 0.93 g/g. Maximum values for substrate consumption rate (0.89 h^–1), maximum specific growth rate (0.87 h^–1), product formation rate (2.01 h^–1), and productivity of lactic acid (1.45 g/(L·h)) were obtained at 45 °C, while maximum biomass concentration (4.38 g/L) was attained at 40 °C. The ratio of the two stereoisomeric forms of produced lactic acid was strongly affected by the temperature. Unstructured kinetic model was used to describe the consumption of the three substrates, bacterial biomass formation and lactic acid production by L. amylovorus DSM 20531T. The dependence of biokinetic parameters on temperature was described by cardinal temperature model. The applied models successfully predicted all experimental data., Amilolitička bakterija mliječne kiseline Lactobacillus amylovorus DSM 20531T može koristiti glukozu, saharozu ili škrob kao jedini izvor ugljika i energije. Tijekom šaržnog uzgoja bakterije u laboratorijskom bioreaktoru s miješalom pri konstantnoj temperaturi (40 °C) i pH-vrijednosti (5,5) iz MRS podloge iskorištena su sva tri supstrata. U odabranim uvjetima bakterija provodi simultanu hidrolizu škroba i fermentaciju. U sva tri slučaja homofermentativnim bioprocesom proizvedena je smjesa dvaju stereoizomera mliječne kiseline, D-(-)- i L-(+)-mliječne kiseline, uz učinkovitost od 0,93 do 1 g laktata po gramu ukupnog supstrata. U hranjivoj podlozi sa škrobom istraživan je i utjecaj temperature uzgoja na kinetiku rasta stanica i proizvodnju mliječne kiseline. Učinkovita simultana saharifikacija i fermentacija (SSF) odvijale su se pri temperaturama uzgoja od 35, 40 i 45 °C, kada je kompleksni ugljikohidrat potpuno razgrađen tijekom 8-12 h uzgoja uz koeficijent konverzije supstrata u proizvod od 0,91 do 0,93 g/g. Maksimalna brzina potrošnje supstrata (0,89 h^-1), maksimalna specifična brzina rasta (0,87 h^-1), brzina nastajanja proizvoda (2,01 h^-1) i produktivnost proizvodnje mliječne kiseline (1,45 g/(L·h)) postignute su pri temperaturi uzgoja od 45 °C, dok je maksimalna koncentracija biomase dobivena pri 40 °C. Temperatura uzgoja uvelike utječe na omjer dvaju proizvedenih stereoizomera mliječne kiseline. Potrošnja triju supstrata, rast bakterijske biomase i proizvodnja mliječne kiseline s pomoću L. amylovorus DSM 20531T definirani su nestrukturiranim kinetičkim modelom. Ovisnost biokinetičkih parametara o temperaturi definirana je osnovnim temperaturnim modelom koji dobro opisuje odvijanje bioprocesa.

Parallel brewing trials were performed in laboratory brewery. For beer wort hopping, hop pellets of different age (“slightly aged” and “strongly aged” one) and storage indexes (0.35 and 0.59, respectively) were used. During brewing were measured bitterness, utilization of α-acids and index of α –acids isomerization. Mature beers were evaluated by panel taste testing. The results of panel testing, based on beer bitterness, drink ability and aroma, by universal flexible system of product quality evaluation, showed no significant difference between two beers. Therefore it was concluded that old hop pellets with high hop storage index values (0.59) could be used for beer wort hopping when fresh hop supply is missing. However such solution needs prolonged wort boiling, more energy consumption and colour of hopped wort and final beer is more intensive.