magistrsko delo
Kim Fijok (Author), Janja Trček (Mentor), Jure Škraban (Co-mentor), Iztok Dogša (Co-mentor)

Abstract

V magistrskem delu smo pri 83 sevih ocetnokislinskih bakterij (OKB) iz Zbirke mikroorganizmov Oddelka za biologijo Fakultete za naravoslovje in matematiko Univerze v Mariboru preiskali sposobnost za tvorbo zunajceličnih polisaharidov. 25 sevov je na gojišču RAE oblikovalo značilen biofilm. Štiri izbrane seve in še štiri referenčne seve smo vključili v nadaljnje analize. Z analizo PCR smo pri teh osmih sevih iskali specifične odseke ključnih genov za sintezo acetana (aceA), levana (levA) in celuloze (bscA). Pri enem sevu smo identificirali gen za sintezo acetana in levana, pri štirih gen za sintezo celuloze in acetana, pri dveh pa samo gen za sintezo celuloze. Pri enem izmed sevov nismo identificirali nobenega izmed treh iskanih genov, čeprav je sev v gojišču tvoril značilen biofilm. Po namnožitvi vsakega izmed teh sevov v dveh gojiščih, z različnima viroma ogljika, smo iz namnožene biomase izolirali vodotopne zunajcelične polisaharide. Očiščene polisaharide smo kislinsko hidrolizirali, jih ločili s tankoplastno kromatografijo ter identificirali po primerjavi s sladkornimi standardi. Zaradi drugačne monosaharidne sestave od že poznanega acetana in sposobnosti sevov, da producirajo vodotopne polisaharide v velikih količinah, smo izbrali tri seve za preiskovanje viskoelastičnih lastnosti polisaharidov. Najbolj viskozen je bil zunajcelični polisaharid pridobljen iz seva K. oboediens AV380. Bistveno nižjo viskoznost sta imela zunajcelična polisaharida, pridobljena iz sevov A. aceti LMG 1504T in A. pomorum LMG 18848T. Polisaharid seva K. oboediens AV380 je oblikoval viskoelastično trdno snov, zdržal najširše območje reverzibilnih deformacij in najkasneje razpadel, zato menimo, da ima potencialno uporabno vrednost v biotehnološki industriji in je primeren kandidat za nadaljnje raziskave.

Keywords

magistrska dela;ocetnokislinske bakterije;biofilm;zunajcelični polisaharidi;acetan;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UM FNM - Faculty of Natural Sciences and Mathematics
Publisher: [K. Fijok]
UDC: 579(043.2)
COBISS: 34651139 Link will open in a new window
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Other data

Secondary language: English
Secondary title: Influence of different carbon sources on composition and rheological properties of extracellular polysaccharides in acetic acid bacteria
Secondary abstract: In this master's thesis we analyzed the ability of 83 acetic acid bacteria (AAB) strains from the Culture Collection of Microorganisms of the Department of Biology, FNM UM, to form extracellular polysaccharides. 25 strains formed a characteristic biofilm on RAE medium. Four selected strains and four additional reference strains were included in further analyses. Using PCR analysis, we looked for specific PCR-products of key genes for the synthesis of acetan (aceA), levan (levA) and cellulose (bscA) in these eight strains. Under the applied growth conditions all 8 strains formed a biofilm of different thickness. The acetan and levan synthesis gene was identified in one strain, the cellulose and acetan synthesis gene in four, and only the cellulose synthesis gene in two. We did not identify any of the three genes in one of the strains, although the strain formed a characteristic biofilm on the medium. After cultivation of each of these strains in two media, containing different carbon sources, water-soluble extracellular polysaccharides were isolated from the harvested biomass. Purified polysaccharides were hydrolysed by acid at high temperature, separated by thin layer chromatography, and identified in comparison to sugar standards. Due to different monosaccharide composition from the already known acetan and the ability of the strains to produce water-soluble polysaccharides in large quantities, we selected three strains to investigate the viscoelastic properties of polysaccharides. The most viscous was the extracellular polysaccharide obtained from the strain K. oboediens AV380. Extracellular polysaccharides derived from strains of A. aceti LMG 1504T and A. pomorum LMG 18848T had significantly lower viscosities. The polysaccharide of the K. oboediens AV380 strain formed a viscoelastic solid, withstood the widest range of reversible deformations, and disintegrated at the latest. According to these characteristics, the polysaccharide of strain AV380 has potential useful values for biotechnological industry and is thus a suitable candidate for further research.
Secondary keywords: master theses;acetic acid bacteria;biofilm;extracellular polysaccharides;acetan;
Type (COBISS): Master's thesis/paper
Thesis comment: Univ. v Mariboru, Fak. za naravoslovje in matematiko, Oddelek za biologijo
Pages: XII, 64 str.
ID: 12011188