1. Harnessing environmental yeasts - Pichia kudriavzevii strain ZMUM_K002 : the quest for isolates with properties for efficient biotechnological applicationsTadeja Vajdič, Marjanca Starčič Erjavec, 2025, izvirni znanstveni članek Opis: The environment hosts a diversity of microorganisms whose potential for biotechnological applications has not yet been exhausted. The quest of our study was to find isolates of Pichia kudriavzevii from the environment that could be used as new biotechnological agents. Moreover, we aimed to explore the resource efficiency for microbial cultivation, in particular the efficiency of spent coffee grounds (SCG), an easily accessible waste coffee product with a high unutilized organic content. In this study, Pichia kudriavzevii strain ZMUM_K002, a yeast strain isolated from a grape pomace compost, was investigated. Antifungal susceptibility, particularly fluconazole susceptibility, was assessed, and the strain’s biotechnological potential by comparing its ability to utilize low-cost carbon sources, including SCG, with a natural isolate of Saccharomyces cerevisiae (strain ZMUM_K003) was assessed. The P. kudriavzevii strain ZMUM_K002 exhibited higher fluconazole susceptibility and yielded more than 30% more biomass in optimized media formulations compared to S. cerevisiae ZMUM_K003. These findings demonstrate that P. kudriavzevii ZMUM_K002 has the potential for efficient biomass production in sustainable industrial biotechnology, particularly in processes requiring high biomass yields on alternative substrates.
Ključne besede: Pichia kudriavzevii, Candida krusei, environmental sampling, biomass production, sauerkraut, safety assessment, spent coffee grounds
Objavljeno v DKUM: 21.03.2025; Ogledov: 0; Prenosov: 6
 Celotno besedilo (1,93 MB)
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2. Genetic diversity of exopolysaccharides from acetic acid bacteria isolates originating from apple cider vinegarsTadeja Vajdič, 2022, izvirni znanstveni članek Opis: Acetic acid bacteria (AAB) produce acetic acid but are also gaining importance as safe microorganisms for producing extracellular polysaccharides (EPSs). The best-known homopolysaccharides among them are cellulose and levan. In addition, acetic acid bacteria also produce heteropolysaccharides, water-soluble acetans. Isolates from the broth of organic and conventional apple cider vinegar production were screened for biofilm production. Phenotypic and genomic diversity of EPS-producing isolates was assessed. The diversity of phenotypically different EPSs of apple cider vinegar isolates was investigated at the gene level for the following novel strains:
Komagataeibacter (K.) melomenusus SI3083, K. oboediens SI3053, K. pomaceti SI3133, and Gluconacetobacter (Ga.) entanii SI2084. Strain K. melomenusus SI3083 possesses cellulose operons bcs1, bcs2, and bcs4 together with the type I acetan cluster in the absence of the levan operon, strain K. oboediens SI3053 has the operons bcs1, bcs2, bcs3, and bcs4, the levan operon, and the acetan cluster (type I), and the strains K. pomaceti SI3133 and Ga. entanii SI2084 both contain recently described novel ace-type II cluster in addition to the incomplete operon bcs1. A comparison of the genetic diversity of these EPSs to those of the reference strains suggests that the studied EPSs are not species-descriptive. The results of this study deepen our understanding of the genetic variability of the EPS genes in AAB, thereby enabling us to better characterize and exploit the various insoluble and soluble exopolysaccharides produced by AAB for biotechnological applications in the future.
Ključne besede: acetic acid bacteria genomes, apple cider vinegar microbiota, biofilm production, bacterial cellulose, acetan, Acetobacter, Komagataeibacter
Objavljeno v DKUM: 26.09.2024; Ogledov: 0; Prenosov: 16
Celotno besedilo (2,45 MB)
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3. Analiza fenolov v listih murv (Morus sp.) in njihov protibakterijski učinek : magistrsko deloŠpela Jelen, 2022, magistrsko delo Opis: V sklopu magistrskega dela smo analizirali vsebnost skupnih in posameznih fenolov v listih genotipov različnih vrst murv (Morus alba, M. alba × rubra, M. nigra, M. australis). Na podlagi fenolnega profila smo odbrali genotipe z največjimi vsebnostmi in proučili protibakterijski učinek murvovih ekstraktov na rast dveh bakterij, grampozitivne Staphylococcus aureus in gramnegativne Escherichia coli. Skupne fenole vseh genotipov smo analizirali s Folin-Ciocalteujevo metodo, posamezne fenole smo analizirali s tekočinsko kromatografijo z UV/VIS-detekcijo. Protibakterijski učinek etanolnih ekstraktov smo določali s Kirby-Bauerjevo disk difuzijsko metodo in z difuzijskim antibiogramom z vdolbinicami. Vpliv protibakterijskega učinka vodnih murvovih ekstraktov na kinetiko rasti obeh bakterij smo preučevali s pomočjo spektrofotometra na mikrotitrski ploščici. Najvišje vrednosti skupnih fenolov (21,51 ± 2 mg GAE/g SS), klorogenske kisline (14,9 ± 0,86 mg/g SS), 4-kafeoilkininske kisline (4,36 ± 0,22 mg/g SS), 5-p-kumaroilkininske kisline (2,2 ± 1,21 mg/g SS), kvercetin glikozida (0,74 ± 0,01 mg/g SS) in kemferol-acetil-heksozida (4,42 ±0,01 mg/g SS) so dosegali sadni genotipi (M. alba × rubra, M. nigra, M. australis), medtem ko so genotipi bele murve (M. alba) vsebovali največ rutina (2,67 ± 0,7 mg/g SS) in kvercetin-malonil-heksozida (1,59 ± 0,39 mg/g SS). Pri difuzijskem antibiogramu z diski inhibicijskih con pri E. coli ni bilo, medtem ko je bil pri difuzijskem antibiogramu z vdolbinicami učinek bakteriostatičen. Pri poskusu s S. aureus se je inhibicijska cona izrazila pri vseh koncentracijah murvovih ekstraktov, a je bila bakteriostatična. Na podlagi spektrofotometričnih rezultatov lahko sklepamo, da murvov ekstrakt nekaj ur zavira rast bakterij S. aureus in E. coli, nato pa jo vzpodbudi, kar lahko pripišemo proteinom in ogljikovim hidratom v ekstraktu. Za nadaljnje raziskave bi bilo smiselno uporabiti čisti fenolni ekstrakt brez beljakovin in ogljikovih hidratov, saj slednji dve snovi predstavljata hranilo za bakterije.
Ključne besede: Murve (Morus sp.), fenolni profil listov, protibakterijski učinek, S. aureus, E. coli
Objavljeno v DKUM: 07.12.2022; Ogledov: 852; Prenosov: 168
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