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Bioactive functional nanolayers of chitosan-lysine surfactant with single- and mixed-protein-repellent and antibiofilm properties for medical implants
Urban Ajdnik, Lidija Fras Zemljič, Olivija Plohl, Lourdes Pérez, Janja Trček, Matej Bračič, Tamilselvan Mohan, 2021, izvirni znanstveni članek

Opis: Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption arethe prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer apromising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to researchand develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties incontact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-freepolyelectrolyte−surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionicsurfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria.We successfully introduced the PESC as bioactive functional nanolayers on the“model”and“real”polydimethylsiloxane (PDMS)surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly depositednanolayers (thickness: 44−61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serumalbumin,fibrinogen, andγ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartzcrystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ:−19 to−30mV at pH 7.4), water content (1628−1810 ng cm−2), and hydration (low viscosity and elastic shear modulus) correlated with themass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed thatthe charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcusaureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatingswith simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leadingto a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents).
Ključne besede: silicone implants, protein-repellent, antimicrobial, chitosan, lysine, bioactive coatings, adsorption, QCM-D
Objavljeno v DKUM: 15.04.2024; Ogledov: 133; Prenosov: 2
.pdf Celotno besedilo (4,24 MB)
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From nature to lab : sustainable bacterial cellulose production and modification with synthetic biology
Vid Potočnik, Selestina Gorgieva, Janja Trček, 2023, pregledni znanstveni članek

Opis: Bacterial cellulose (BC) is a macromolecule with versatile applications in medicine, pharmacy, biotechnology, cosmetology, food and food packaging, ecology, and electronics. Although many bacteria synthesize BC, the most efficient BC producers are certain species of the genera Komagataeibacter and Novacetimonas. These are also food-grade bacteria, simplifying their utilization at industrial facilities. The basic principles of BC synthesis are known from studies of Komagataeibacter xylinus, which became a model species for studying BC at genetic and molecular levels. Cellulose can also be of plant origin, but BC surpasses its purity. Moreover, the laboratory production of BC enables in situ modification into functionalized material with incorporated molecules during its synthesis. The possibility of growing Komagataeibacter and Novacetimonas species on various organic substrates and agricultural and food waste compounds also follows the green and sustainable economy principles. Further intervention into BC synthesis was enabled by genetic engineering tools, subsequently directing it into the field of synthetic biology. This review paper presents the development of the fascinating field of BC synthesis at the molecular level, seeking sustainable ways for its production and its applications towards genetic modifications of bacterial strains for producing novel types of living biomaterials using the flexible metabolic machinery of bacteria.
Ključne besede: acetic acid bacteria, bacterial cellulose, sustainable production, agricultural waste, food waste, genetic engineering, synthetic biology, biomaterial, Komagataeibacter, Novacetimonas
Objavljeno v DKUM: 28.03.2024; Ogledov: 130; Prenosov: 20
.pdf Celotno besedilo (5,82 MB)
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GO-enabled bacterial cellulose membranes by multistep, in situ loading : effect of bacterial strain and loading pattern on nanocomposite properties
Tobiasz Gabryś, Beata Fryczkowska, Urška Jančič, Janja Trček, Selestina Gorgieva, 2023, izvirni znanstveni članek

Opis: This paper presents the results of research on the preparation and properties of GO/BC nanocomposite from bacterial cellulose (BC) modified with graphene oxide (GO) using the in situ method. Two bacterial strains were used for the biosynthesis of the BC: Komagataeibacter intermedius LMG 18909 and Komagataeibacter sucrofermentans LMG 18788. A simple biosynthesis method was developed, where GO water dispersion was added to reinforced acetic acid-ethanol (RAE) medium at concentrations of 10 ppm, 25 ppm, and 50 ppm at 24 h and 48 h intervals. As a result, a GO/BC nanocomposite membrane was obtained, characterized by tensile strength greater by 150% as compared with the pure BC (̴ 50 MPa) and lower volume resistivity of ~4 ∙ 109 Ω × cm. Moreover, GO addition increases membrane thickness up to ~10% and affects higher mass production, especially with low GO concentration. All of this may indicate the possibility of using GO/BC membranes in fuel cell applications.
Ključne besede: bacterial cellulose, graphene oxide, nanocomposite, structural analysis
Objavljeno v DKUM: 13.03.2024; Ogledov: 190; Prenosov: 7
.pdf Celotno besedilo (6,62 MB)
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Comparative genomics and phenotypic characterization of Gluconacetobacter entanii, a highly acetic acid-tolerant bacterium from vinegars
Karin Jelenko, Eva Cepec, Francisco X. Nascimento, Janja Trček, 2023, izvirni znanstveni članek

Opis: The bacterial species Gluconacetobacter entanii belongs to a group of acetic acid bacteria. In 2000, it was described as a primary species of submerged spirit vinegar-producing bioreactors with a strict requirement of acetic acid, ethanol, and glucose for growth. Over the years, the type-strain of G. entanii deposited in international culture collections has lost the ability for revitalization and is thus not available any more in a culturable form. Here, we have systematically characterized phenotypic features and genomes of recently isolated G. entanii strains and compared them with characteristics of the type-strain available from published data. Using the functional annotation, genes gmhB and psp were identified as unique for G. entanii genomes among species in the clade Novacetimonas. The genome stability of G. entanii was assessed after 28 and 43 months of preculturing the strain Gluconacetobacter entanii AV429 twice a week. The strain G. entanii AV429 did not accumulate giant insertions or deletions but a few gene mutations. To unify further research into acetic acid bacteria systematics and taxonomy, we propose G. entanii AV429 as the neotype strain.
Ključne besede: acetic acid bacteria, vinegar, acetic acid tolerant bacteria, Gluconacetobacter, Novacetimonas, Gluconacetobacter entanii, Komagataeibacter
Objavljeno v DKUM: 14.02.2024; Ogledov: 239; Prenosov: 15
.pdf Celotno besedilo (1,59 MB)
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Bio-based processes for material and energy production from waste streams under acidic conditions
Zeynep Cetecioglu, Merve Atasoy, Adam Cenian, Gaweł Sołowski, Janja Trček, Aysenur Ugurlu, Jana Sedlakova-Kadukova, 2022, pregledni znanstveni članek

Opis: The revolutionary transformation from petrol-based production to bio-based production is becoming urgent in line with the rapid industrialization, depleting resources, and deterioration of the ecosystem. Bio-based production from waste-streams is offering a sustainable and environmentally friendly solution. It offers several advantages, such as a longer operation period, less competition for microorganisms, higher efficiency, and finally, lower process costs. In the current study, several biobased products (organic acids, biomethane, biohydrogen, and metal leachates) produced under acidic conditions are reviewed regarding their microbial pathways, processes, and operational conditions. Furthermore, the limitations both in the production process and in the scale-up are evaluated with future recommendations.
Ključne besede: bio-based production, acidogenic conditions, fermentation, organic acids, biohydrogen, biomethane, bioleaching
Objavljeno v DKUM: 24.08.2023; Ogledov: 286; Prenosov: 36
.pdf Celotno besedilo (1,39 MB)
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Antimicrobial resistance of Acetobacter and Komagataeibacter species originating from vinegars
Eva Cepec, Janja Trček, 2022, izvirni znanstveni članek

Opis: Consumers’ preference towards healthy and novel foods dictates the production of organic unfiltered bottled vinegar that still contains acetic acid bacteria. After ingesting vinegar, the bacteria come into close contact with the human microbiota, creating the possibility of horizontal gene transfer, including genetic determinants for antibiotic resistance. Due to the global spread of antimicrobial resistance (AMR), we analyzed the AMR of Acetobacter and Komagataeibacter species originating mainly from vinegars. Six antibiotics from different structural groups and mechanisms of action were selected for testing. The AMR was assessed with the disk diffusion method using various growth media. Although the number of resistant strains differed among the growth media, 97.4%, 74.4%, 56.4%, and 33.3% of strains were resistant to trimethoprim, erythromycin, ciprofloxacin, and chloramphenicol, respectively, on all three media. Moreover, 17.9% and 53.8% of all strains were resistant to four and three antibiotics of different antimicrobial classes, respectively. We then looked for antimicrobial resistance genes in the genome sequences of the reference strains. The most common genetic determinant potentially involved in AMR encodes an efflux pump. Since these genes pass through the gastrointestinal tract and may be transferred to human microbiota, further experiments are needed to analyze the probability of this scenario in more detail.
Ključne besede: acetic acid bacteria, Acetobacter, Komagataeibacter, antimicrobial resistance, trimethoprim resistance, erythromycin resistance, ciprofloxacin resistance, chloramphenicol resistance, ampicillin resistance, gentamicin resistance
Objavljeno v DKUM: 24.08.2023; Ogledov: 370; Prenosov: 32
.pdf Celotno besedilo (444,89 KB)
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Description of Komagataeibacter melaceti sp. nov. and Komagataeibacter melomenusus sp. nov. isolated from apple cider vinegar
Leon Marič, Ilse Cleenwerck, Tomaž Accetto, Peter Vandamme, Janja Trček, 2020, izvirni znanstveni članek

Opis: Two novel strains AV382 and AV436 were isolated from a submerged industrial bioreactor for production of apple cider vinegar in Kopivnik (Slovenia). Both strains showed very high (≥98.2%) 16S rRNA gene sequence similarities with Komagataeibacter species, but lower 16S–23S rRNA gene internal transcribed spacer (ITS). The highest similarity of the 16S–23S rRNA gene ITS of AV382 was to Komagataeibacter kakiaceti LMG 26206$^T$ (91.6%), of AV436 to Komagataeibacter xylinus LMG 1515$^T$ (93.9%). The analysis of genome sequences confirmed that AV382 is the most closely related to K. kakiaceti (ANIb 88.2%) and AV436 to K. xylinus (ANIb 91.6%). Genome to genome distance calculations exhibit for both strains ≤47.3% similarity to all type strains of the genus Komagataeibacter. The strain AV382 can be differentiated from its closest relatives K. kakiaceti and Komagataeibacter saccharivorans by its ability to form 2-keto and 5-keto-D-gluconic acids from glucose, incapability to grow in the presence of 30% glucose, formation of C$_{19:0}$ cyclo ω8c fatty acid and tolerance of up to 5% acetic acid in the presence of ethanol. The strain AV436 can be differentiated from its closest relatives K. xylinus, Komagataeibacter sucrofermentans, and Komagataeibacter nataicola by its ability to form 5-keto-D-gluconic acid, growth on 1-propanol, efficient synthesis of cellulose, and tolerance to up to 5% acetic acid in the presence ethanol. The major fatty acid of both strains is C$_{18:1}$ ω7c. Based on a combination of phenotypic, chemotaxonomic and phylogenetic features, the strains AV382$^T$ and AV436$^T$ represent novel species of the genus Komagataeibacter, for which the names Komagataeibacter melaceti sp. nov. and Komagataeibacter melomenusus are proposed, respectively. The type strain of Komagataeibacter melaceti is AV382$^T$ (= ZIM B1054$^T$ = LMG 31303$^T$ = CCM 8958$^T$) and of Komagataeibacter melomenusus AV436$^T$ (= ZIM B1056$^T$ = LMG 31304$^T$ = CCM 8959$^T$).
Ključne besede: Acetic acid bacteria, Acetobacteraceae, Komagataeibacter, Komagataeibacter melaceti, Komagataeibacter melomenusus, vinegar
Objavljeno v DKUM: 02.09.2022; Ogledov: 398; Prenosov: 13
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Acetan and acetan-like polysaccharides: genetics, biosynthesis, structure, and viscoelasticity
Janja Trček, Iztok Dogša, Tomaž Accetto, David Stopar, 2021, pregledni znanstveni članek

Opis: Bacteria produce a variety of multifunctional polysaccharides, including structural, intracellular, and extracellular polysaccharides. They are attractive for the industrial sector due to their natural origin, sustainability, biodegradability, low toxicity, stability, unique viscoelastic properties, stable cost, and supply. When incorporated into different matrices, they may control emulsification, stabilization, crystallization, water release, and encapsulation. Acetan is an important extracellular water-soluble polysaccharide produced mainly by bacterial species of the genera Komagataeibacter and Acetobacter. Since its original description in Komagataeibacter xylinus, acetan-like polysaccharides have also been described in other species of acetic acid bacteria. Our knowledge on chemical composition of different acetan-like polysaccharides, their viscoelasticity, and the genetic basis for their production has expanded during the last years. Here, we review data on acetan biosynthesis, its molecular structure, genetic organization, and mechanical properties. In addition, we have performed an extended bioinformatic analysis on acetan-like polysaccharide genetic clusters in the genomes of Komagataeibacter and Acetobacter species. The analysis revealed for the first time a second acetan-like polysaccharide genetic cluster, that is widespread in both genera. All species of the Komagataeibacter possess at least one acetan genetic cluster, while it is present in only one third of the Acetobacter species surveyed.
Ključne besede: extracellular polysaccharide, acetan, acetan genetic cluster, acetan synthesis, acetan viscoelasticity, applications of acetan, Komagataeibacter, Acetobacter
Objavljeno v DKUM: 02.09.2022; Ogledov: 532; Prenosov: 8
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Vpliv sestave gojišča na odpornost ocetnokislinskih bakterij proti antibiotikom : magistrsko delo
Eva Cepec, 2021, magistrsko delo

Opis: Zaradi vse večje ozaveščenosti potrošnikov o pomenu uživanja naravnih živil se povečuje tudi povpraševanje po jabolčnem nefiltriranem kisu, tako imenovanem motnem jabolčnem kisu. Motni jabočlni kis poleg ostalih sestavin vsebuje tudi ocetnokislinske bakterije. Povečan trend uporabe takšnega kisa pa pred proizvajalca in potrošnika postavlja vprašanje o potencialni odpornosti ocetnokislinskih bakterij proti antibiotikom. V tem delu smo zato preiskali odpornost različnih vrst in rodov ocetnokislinskih bakterij proti klinično pomembnim antibiotikom (ampicilinu, kloramfenikolu, ciprofloksacinu, trimetoprimu, eritromicinu in gentamicinu) na treh rastnih gojiščih (RAE, MA in GY). Odpornost smo analizirali z disk-difuzijsko metodo glede na prisotnost/odsotnost cone inhibicije okoli diskov z antibiotiki. Preiskali smo 12 sevov iz rodu Acetobacter in 22 predstavnikov iz rodu Komagateibacter. Delež odpornih sevov proti posameznemu antibiotiku se je med rastnimi gojišči razlikoval, na vseh gojiščih pa so bili preiskani sevi v visokem deležu odporni proti trimetoprimu (97,1 %), eritromicinu (73,5 %), ciprofloksacinu (50,0 %) in kloramfenikolu (32,4 %). Rezistenco proti štirim antibiotikom smo ugotovili pri kar 17,6 % sevov, 29,4 % testiranih sevov pa je bilo odpornih proti trem antibiotikom. Ker ocetnokislinske bakterije ali pa njihova DNA po zaužitju kisa, kefirja in drugih živilskih proizvodov, pri katerih sodelujejo ocetnokislinske bakterije, lahko pride v kontakt z mikrobioto prebavil človeka, bi bilo v nadaljevanju potrebno preučiti možnost horizontalnega prenosa genov za odpornost proti antibiotikom iz ocetnokislinskih bakterij v bakterije, ki sestavljajo mikrobioto prebavil človeka.
Ključne besede: ocetnokislinske bakterije, odpornost proti antibiotikom
Objavljeno v DKUM: 20.12.2021; Ogledov: 1349; Prenosov: 102
.pdf Celotno besedilo (1,32 MB)

Funkcionalizacija celuloznih vlaken z uporabo protimikrobnih sredstev in/ali probiotikov za novo generacijo tamponov : magistrsko delo
Larisa Spasković, 2021, magistrsko delo

Opis: To magistrsko delo temelji na razvoju in funkcionalizaciji tamponov z dodano vrednostjo. Tampone smo funkcionalizirali s probiotično bakterijo Lactobacillus. gasseri K7. S pomočjo tamponov nove generacije želimo tako pomagati ženskam pri preprečevanju okužb z bakterijami in glivami na način ohranjanjanje zdrave vaginalne mikrobiote v času menstrualnih krvavitev. Lastnosti funkcionaliziranih tamponov bodo ovrednotene s pomočjo različnih testnih metod, ki temeljijo na uporabnih lastnostih tamponov. Magistrska naloga zajema nanos liofiliziranih in svežih probiotikov, ujetih v hidroksi β ciklodekstrine s pomočjo tehnike elektropredenja na nosilni material. V tem magistrskem delu sem probiotike, tako sveže kot tudi liofilizirane ujela v ciklodekstrine in iz dobljene koloidne raztopine izpredla kot nanovlakna z elektropredenjem, najprej na polipropilen, na koncu pa še na tamponski trak podjetja Tosama d.o.o. Funkcionaliziran material sem analizirala s pomočjo metod (elementna sestava: XPS, ATR-FTIR, morfologija: SEM mikroskopija, bioaktivnost: določanje antioksidativnosti po metodi ABTS in sproščanje probiotikov ). Rezultati uporabljenih analiz kažejo, da se pri elektropredenju tvorijo nanovlakna, ki se naložijo na površino nosilnega materiala. Dokazali smo tudi, da se probiotiki ujamejo v ciklodekstrine in se obdržijo tako na polipropilenski kopreni, kot tudi na bombažnem tamponskem traku. Sproščanje probiotikov iz obeh uporabljenih nosilnih materialov je pokazalo, da se bakterija sprošča iz materiala še do 4 ure, kar je zelo obetajoč rezultat Antioksidativni potencial smo merili z namenom preverjanja protivnetnega učinka funkcionaliziranega nosilnega materiala. Rezultati so pokazali da imajo le - tega vzorci, katere smo funkcionalizirali z liofiliziranimi bakterijami.
Ključne besede: funkcionalizacja, tamponi, probiotiki, elektropredenje, ciklodekstrini
Objavljeno v DKUM: 04.10.2021; Ogledov: 953; Prenosov: 159
.pdf Celotno besedilo (3,44 MB)

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