Osamitev in morfološka karakterizacija mikroorganizmov iz tal Ljubljanskega barja : magistrsko delo

Založnik, Mojca (author), Mandić-Mulec, Ines (mentor)

Ekološka raznolikost in pogostost vrst v različnih habitatih in združbah je ena osrednjih tem ekologije. Študije, ki se osredotočajo na mikrobno raznolikost v odvisnosti od časa izrasti kolonij na ploščah so redke, in bakterijska združba, ki je izrasla iz tal Ljubljanskega barja, še ni bila preučevana. V okviru te naloge smo spremljali izrast bakterijske združbe tal nizkega barja na polimernem gojišču z gelanom v obdobju 12 tednov. Spremljali smo čas izrasti kolonije (čas retardacije), redčitev izhodiščnega vzorca tal iz katerega izvira in vsak izolat morfološko opisali. Med 323 morfotipi je 37 morfotipov zraslo v drugem mesecu, 18 morfotipov v tretjem mesecu, preostali morfotipi so izrasli v prvem mesecu inkubacije. S pomočjo metode UPGMA in Jaccardovega koeficienta smo skonstruirali drevo v 48 korakih, s pomočjo katerega smo razložili povezavo časovno ločenih treh morfoloških skupin in časa retardacije. Verjetnost, da bi naključno drevo razložilo njihovo povezavo z 48 koraki ali manj, je bila manjša ali enaka 0,003 (P  0,005). Korelacija med izrisanim drevesom povezave morfotipov in časom retardacije je bila zato signifikantna, čeprav ne zelo velika. Bogatost morfotipov in raznolikost, določeni na podlagi Shannonovega indeksa, sta padali s časom izrasti kolonije. Sevi prvega meseca so bili bolj raznoliki tudi po barvi kolonij, medtem ko so bili počasi rastoči sevi na splošno brez pigmenta oziroma prozorni do rumenkasti. Izolate smo ponovno združili v združbe na podlagi retardacijskega časa in izhodne redčitve ter ovrednotili njihov metabolni potencial na Biolog ECOploščah. Iz študije lahko zaključimo, da je združba hitro rastočih sevov (prvi mesec) metabolno bolj raznolika kot počasneje rastoči združbi drugega in tretjega meseca. Na število in tip razgrajenih substratov najbolj vpliva čas retardacije (pojasni 59 % variance podatkov), kar smo potrdili tudi z analizo glavnih komponent (angl. PCA-analysis), na referenčno združbo iz HC-tal pa redčitev, saj število razgrajenih substratov referenčne združbe pada z višanjem redčitve. Najpomembnejši dejavnik ločevanja znotraj posameznih časovnih združb 1. in 2. meseca je čas inkubacije, znotraj 3. meseca pa redčitev.

• Language: Slovenian
• Keywords: Ljubljansko barje, mikroorganizmi, tla, mikrobna raznolikost, talni ekosistemi, bakterijske združbe, nizko barje, kolonije, retaradacijski čas, morfotipi, fiziološki potencial, multivariatna analiza, ekologija
• Work type: Master's thesis
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: M. Lešnjak
• Year: 2012
• Number of pages: XIX, 89 str., [36] str. pril.
• PID: 20.500.12556/RUL-171055
• UDC: 579.26:631.4(497.4Ljubljansko barje)(043.2)=163.6
• COBISS.SI-ID: 753271
• Publication date in RUL: 30.07.2025

Secondary language

• Language: English
• Title: Isolation and morphological characterisation of microorganisms from Ljubljana marsh soil : M. Sc. thesis

Abstract

Ecological diversity and frequency of species in different habitats and communities is one of the central themes of ecology. Studies that focus on the microbial diversity in relation to colony retardation time are rare, and the culturable microbial community in Ljubljana marsh soil has not yet been studied. In this study we followed the outgrowth of degraded peat soil bacterial community on a polymeric substrate-based medium in the period of 12 weeks. We determined the colony retardation time (i.e. the time the isolate needs to form a visible colony on solid plate), which was also evaluated in relation to the dilution of the original soil sample, and morphologically described each isolate. Among the 323 morphotypes, 37 were categorised into the group with the retardation time of 2 months, while 18 morphotypes had the retardation time of 3 months. Other morphotypes grew out within the 1st month. We explained the connection of time groups with morphological characteristics with the construction of a tree in 48 steps using the UPGMA method and the Jaccard coefficient. Because the probability that a random tree with 48 steps would explain the connection is less than 0,003 (P0,005), this means that the correlation between a given tree and time group of morphotypes according to retardation time is very significant, although not very large. Richness and diversity (as defined by the Shannon diversity index) decreased with retardation time. Fast-growing morphotypes were more similar to each other than to the slow-growing morphotypes, which had less pigmented colonies. Communities constructed from the faster-growing strains exhibited higher metabolic diversity than communities of slow growers. The number and type of degraded substrates is most affected by retardation time factor (explained 59 % of the data variance), which was confirmed by principal component analysis (PCA). The reference HC-community, on the other hand, was more affected by dilution factor, as the number of degraded substrates decreased with increased dilution. The most important factor of separation among different retardation time groups of the 1st and 2nd month is incubation time, and dilution among the 3rd month isolates.

• Keywords: Ljubljana marsh, microorganisms, soil, microbial diversity, soil ecosystems, bacterial community, colony, retradation time, morphotype, physiological potential, multivariate analysis, ecology