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Razvoj metod za študij socialnih interakcij med bakterijami iz rodov Bacillus in Streptomyces
Sraka, Maša (Author), Danevčič, Tjaša (Mentor) More about this mentor... This link opens in a new window, Petković, Hrvoje (Co-mentor)

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Abstract
V magistrskem delu smo želeli optimizirati pogoje skupnega gojenja kultur bakterijskih vrst Streptomyces rimosus in Bacillus subtilis PS-216. Pri delu smo bakterijski vrsti gojili v kokulturi na različnih mikrobioloških trdnih in tekočih gojiščih ter spremljali njuno rast in morfologijo. Uporabili smo divji sev bakterije B. subtilis in 3 različne seve S. rimosus, ki proizvajajo različne količine antibiotika oksitetraciklina. Največji vpliv na morfologijo ene bakterijske vrste na drugo smo opazili na gojiščih MSgg in MSgM. Bakterija S. rimosus je v kokulturi z B. subtilis na teh gojiščih izločala v gojišče neznano roza pigmentirano spojino. Pigmentirano spojino je izločala v tekočih in trdnih gojiščih MSgg oz. MSgM v prisotnosti različnih mutant bakterije B. subtilis in v prisotnosti izrabljenega gojišča bakterije B. subtilis. Pigmentirano spojino je izločala v prisotnosti bakterijskih vrst B. subtilis, B. licheniformis, B. megaterium, E. coli in S. marcescens. Raziskali smo vpliv koncentracije FeCl3 na izločanje pigmentirane spojine in ugotovili, da se le-ta pojavi v koncentracijah nad 25 µM FeCl3 ter da intenzivnost pigmentacije narašča do koncentracije 125 µM, ko doseže plato. Pigment se je pojavil le takrat, kadar smo seve gojili v kokulturi. Do pigmentacije gojišča ni prišlo v odsotnosti FeCl3 in v monokulturi. Raziskali smo vpliv pH vrednosti gojišča na pojavnost roza pigmentirane spojine, kjer nismo opazili povezave med pH in pigmentiranostjo gojišča, razen pri gojišču MSgM s 50 µM FeCl3, kjer smo predhodno korigirali pH na 7 in do izločanja roza pigmentirane snovi ni prišlo. Raziskali smo tudi vpliv skupne inkubacije bakterij na izražanje promotorjev gena za sintezo surfaktina in zunajceličnih polisaharidov (EPS) pri kulturi B. subtilis v prisotnosti 5 % izrabljenega gojišča bakterije S. rimosus R7. Izražanje promotorja gena za surfaktin je bilo v prisotnosti izrabljenega gojišča nižje, zato sklepamo, da bakterija S. rimosus izloča nekaj, kar zavira izražanje promotorja gena za sintezo surfaktina pri bakteriji B. subtilis. Vpliva na izražanje promotorja gena za sintezo EPS nismo opazili.

Language:Slovenian
Keywords:Bacillus subtilis, Streptomyces rimosus, kokultivacija, socialne interakcije med bakterijami, sekundarni metaboliti
Work type:Master's thesis/paper (mb22)
Tipology:2.09 - Master's Thesis
Organization:BF - Biotechnical Faculty
Year:2019
Publisher:[M. Sraka]
UDC:579.22/.26:579.852.1+579.873.7:604.4
COBISS.SI-ID:5111928 Link is opened in a new window
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Secondary language

Language:English
Title:Development of methods to study social interactions between bacteria from the genus Bacillus and Streptomyces
Abstract:
In the master's thesis we wanted to optimize the conditions of cocultivation of cultures of bacterial species S. rimosus and B. subtilis. We cocultivated bacteria in various solid and liquid growth media and monitored their growth and morphology. We used a wild type of B. subtilis and 3 different strains of S. rimosus bacteria, that produce different amounts of antibiotic oxytetracycline. The most noticeable influence on morphology of one bacterial species on another was observed on MSgg and MSgM media. On these media S. rimosus cocultured with B. subtilis secreted an unknown pink pigmented compound. The bacterium S. rimosus secreted the pigmented compound in both liquid and solid MSgg/MsgM media in the presence of various mutants of B. subtilis and in the presence of the B. subtilis conditioned medium. S. rimosus also secreted the pink compound in the presence of bacterial species B. subtilis, B. licheniformis, B. megaterium, E. coli and S. marcescens. We examined the effect of FeCl3 concentration on the secretion of the pigmented compound and found pigmentation to occur at concentrations above 25 µM FeCl3 and that the pigmentation intensity increased up to 125 µM FeCl3, when it reached the plateau. The pigmentation appeared only when the bacteria were grown in coculture, but not in the absence of FeCl3 and in S. rimosus monoculture. We investigated the influence of the media pH on pigmentation and no correlation was observed, except that in MSgM medium with 50 µM FeCl3 and pH 7 no pigmentation was observed. We also stuided effect of cocultivation on the expression of the surfactin promoter and exopolysaccharides (EPS) promoter in B. subtilis in the presence of 5% conditioned medium of S. rimosus R7. The expression of the surfactin promoter was lower in the presence of conditioned medium. Therefore, we conclude that S. rimosus secretes an unknown compound, that inhibits the activitiy of the surfactin promoter in B. subtilis. We did not notice the effect on the expression of EPS promoter.

Keywords:Bacillus subtilis, Streptomyces rimosus, cocultivation, social interactions between bacteria, secondary metabolites

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