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Primjena biomase za razvoj biobaziranih proizvoda postala je svakodnevica u evolucijskom metaboličkom inženjeringu. Bakterijska nanoceluloza (BNC) koju proizvodi združena kultura kvasca i bakterija je nova alternativa polimerima fosilnog podrijetla. Zahvaljujući tome proizvodnja BNC postala je izrazito popularna zbog svojih ekološki prihvatljivih svojstava. BNC je obnovljiv prirodni polisaharid zbog jedinstvenih karakteristika poput visokog stupnja kristaliničnosti, visoke čistoće, visokog kapaciteta zadržavanja vode, visoke mehaničke čvrstoće i poboljšane biokompatibilnosti. Zbog tih izvanrednih svojstava, BNC može poslužiti kao idealna sirovina za razvoj različitih indrustrijskih proizvoda. Celulozni nanomaterijali pružaju novu i održivu platformu za proizvodnju materijala visokih performansi koje omogućava nanotehnologija. BNC je visoko kristalična sirovina i građena je od čiste celuloze bez lignina, hemiceluloze i pektina. Ovaj ekstracelularni biopolimer ima specifičnu ulogu kao izvor rezervne energije, zaštitni biofilm, pomaže u uspostavljanju simbioze, osmotskoj prilagodbi i omogućuje različitim rodovima mikroorganizmima da djeluju, prilagode se, umnožavaju i učinkovito opstanu u promjenjivim okolišnim uvjetima. Application of biomass for the development of biobased products has become a routine agenda in evolutionary metabolic engineering. Bacterial nanocellulose (BNC), which is produced by a symbiotic culture of yeast and bacteria, is a new alternative to conventional polymers based on petroleum. Because of that, the production of BNC is becoming increasingly popular owing to its environmentally friendly properties. BNC is renewable natural polysaccharide due to its remarkable properties such as a high degree of crystallinity, high purity, high water retention capacity, high mechanical strength, and enhanced biocompatibility. Favoured with those extraordinary properties, BC could serve as ideal biomass for the development of various industrial products. Cellulosic nanomaterials provide a novel and sustainable platform for the production of high performance materials enabled by nanotechnology. BNC is a highly crystalline material and contains pure cellulose without lignin, hemicellulose, and pectin. These extracellular biopolymer plays specific roles as energy reserve material, protective agent, aid in cell functioning, the establishment of symbiosis, osmotic adaptation and supports the microbial genera to function, adapt, multiply and survive efficiently under changing environmental conditions.

Polilaktidna kiselina (PLA) i bakterijska nanoceluloza (BNC) zbog svoje biorazgradljivosti, biokompatibilnosti i netoksičnosti imaju velik potencijal za primjenu u biomedicini. Cilj ovog rada bio je pripraviti i ispitati biokompozit PLA/BNC. Istražen je utjecaj BNC-a na morfološku strukturu, kemijski sastav, toplinska svojstva, toplinsku postojanost i hidrofobnost PLA te zasijavanje i rast stanica biokompozita PLA/BNC primjenom pretražnog elektronskog mikroskopa (SEM), infracrvene spektroskopije (FTIR), diferencijalne pretražne kalorimetrije (DSC) i termogravimetrijske analize (TGA) te određivanjem kontaktnog kuta i metodom MTT. Dodatkom BNC-a u PLA dolazi do pomaka staklišta (Tg) prema nižim temperaturama, što ukazuje na veću pokretljivost amorfne faze PLA te porasta stupnja kristalnosti zbog nukleacijskog učinka celuloze. Početak toplinske razgradnje pomaknut je na niže temperature u odnosu na čisti PLA, što ukazuje na smanjenje toplinske postojanosti PLA dodatkom BNC-a. Biokompozit PLA/BNC pokazuje poroznu, vlaknastu strukturu. Test zasijavanja stanica pokazao je da je biokompozit PLA/BNC pogodan za prihvaćanje i rast humanih stanica, pa je prema tome potencijalno primjenjiv u regenerativnoj medicini i tkivnom inženjerstvu. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna., Polylactic acid (PLA) and bacterial nanocellulose (BNC) are promising materials in medicine due to their biodegradability, biocompatibility, and non-toxicity. The aim of this work was to prepare and characterize the PLA/BNC biocomposite. Morphology, chemical composition, thermal properties, thermal stability, hydrophobicity and cell seeding, and growth of the PLA/BNC biocomposite were characterized by means of scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle, and MTT method. DSC showed that the glass transition temperature (Tg) of PLA decreased with the addition of BNC due to higher mobility of amorphous PLA phase. The degree of crystallinity increased due to nucleation effect of cellulose. With the addition of BNC, the thermal stability of biocomposite decreased. The PLA/BNC biocomposite exhibited a porous, fibrous structure. The cell seeding test showed the PLA/BNC biocomposite to be suitable for growth of human cells, and therefore, potentially applicable in regenerative medicine and tissue engineering. This work is licensed under a Creative Commons Attribution 4.0 International License.

Celuloza je fascinantna i obnovljiva prirodna polimerna sirovina koju karakteriziraju izvrsna svojstva poput hidrofilnosti, kiralnosti, biorazgradivosti, širokog spektra svojstava kemijskih modifikacija, te stvaranja različitih morfologija polukristaliničnih vlakana. U ovom je radu istraživan uzgoj kombuche u aerobnim uvjetima tijekom 14 dana fermentacije u kokosovoj vodi, na sobnoj temperaturi, uz dodatak različitih koncentracija saharoze. Praćene su promjene pH vrijednosti, koncentracije etanola, octene, glukonske i mliječne kiseline, kao i prinos bakterijske nanoceluloze (BNC). Istraživana je kinetika otpuštanja vode iz sintetizirane BNC, a rezultati su potvrdili da su uzorci pogodni za ublaživanje rana. Antimikrobna aktivnost je BNC testirana je na bakterijama Escherichia coli, Staphylococcus aureus, Salmonella typhimurium i Bacillus subtilis, te kvascu vrste Candida albicans. Uočena je antimikrobna aktivnost kombuche na bakterije, no ne i na kvasac Candida albicans. Cellulose is a fascinating and sustainable natural polymeric raw material characterized by exciting properties such as hydrophilicity, chirality, biodegradability, broad chemical-modifying capacity, and the formation of different semicrystalline fibre morphologies. This work studies cultivation of kombucha in aerobic conditions over a period up to 14 days of fermentation in coconut water, at room temperature with different sucrose concentrations added. Changes in pH value, ethanol, acetic acid, gluconic acid, and lactic acid were observed, as well as yield of bacterial nanocellulose (BNC). The water release rate (WRR) were investigated, and the results supported its anticipated use as antimicrobial wound dressing material. The antimicrobial activity of BNC was tested against bacteria Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Bacillus subtilis, as well as yeast Candida albicans. Antimicrobial activities were observed in the fermented samples against all the investigated bacteria strains, but Candida albicans was not inhibited by kombucha.

Kefir i kombucha su tradicionalni fermentirani napitci proizvedeni simbiotičkim djelovanjem kultura bakterija mliječne i octene kiseline te kvasaca. U ovom je radu proučavan uzgoj kokulture vodenih kefirnih zrnaca i kombuche u kokosovoj vodi tijekom 14 dana fermentacije na sobnoj temperaturi uz dodatak različitih koncentracija saharoze. Praćene su promjene pH vrijednosti, koncentracija etanola, octene, glukonske i mliječne kiseline, kao i prinos bakterijske nanoceluloze (BNC) u kokulturi. Svojstva, kristaliničnost i strukturna karakterizacija BNC proučavane su pomoću difrakcije rendgenskim zrakama (XRD), FT-IR spektroskopije i skenirajuće elektronske mikroskopije (SEM). Antimikrobna aktivnost BNC testirana je na bakterijama Staphylococcus aureus i Bacillus subtilis te na kvascima vrsta Candida albicans i Schizosaccharomyces pombe. Rezultati određivanja kapaciteta zadržavanja vode (WHC) i otpuštanja vode (WRR) dokazali su moguću primjenu BNC kao antimikrobnog pokrovnog materijala za rane. Bakterijska nanoceluloza (BNC) dobivena djelovanjem kokulture vodenih kefirnih zrnaca i kombuche, sa svojim jedinstvenim svojstvima mikrofibrilne strukture, može se smatrati mnogostranim biomaterijalom za različita područja primjene. Kefir and kombucha are traditional fermented drinks produced by adding symbiotic cultures of lactic and acetic acids and yeasts to medium. This work studies cultivation of coculture of water kefir grains and kombucha in aerobic conditions over a period up to 14 days of fermentation in coconut water, at room temperature with different sucrose concentrations added. Changes in pH value, ethanol, acetic acid, gluconic acid, and lactic acid were observed, as well as yield of bacterial nanocellulose (BNC) in coculture. Properties, crystallinity and structural characterization of BNC produced from coculture were evaluated by employing X-ray diffractometry, FT-IR and SEM. The antimicrobial activity of BNC was tested against bacteria Staphylococcus aureus and Bacillus subtilis, as well as yeasts Candida albicans and Schizosaccharomyces pombe. The water holding capacity (WHC) and release rate (WRR) were calculated, and the results supported its anticipated use as antimicrobial wound dressing material. Bacterial nanocellulose (BNC) produced from coculture of water kefir grains and kombucha shown its unique microfibril characteristic properties, which make it a versatile biomaterial for application in various domains.