Development of experimental system for studying effect of nematode Caenorhabtiditis elegans on mixed population of Escherichia coli and Bacillus subtilis

Dubravčić, Darja (2009) Development of experimental system for studying effect of nematode Caenorhabtiditis elegans on mixed population of Escherichia coli and Bacillus subtilis. Diploma thesis, Faculty of Science > Department of Biology.

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Abstract

Competition and predation are among the most important types of interactions between species and are strong forces that shape ecological communities. Both processes have a major impact on biodiversity, niche differentiation and promote new adaptations. In most cases their impact has been studied separately. To what extent and under which conditions one of these interactions has greater impact on the system is often unknown or not clear enough. During this study I have developed an experimental system for studies of interactions between predation and competition on well known model organisms; Bacillus subtilis, Escherichia coli and Caenorhabditis elegans. I have found that the optimal conditions for measurements were achieved by using B. subtilis ATCC 21332 (sfp+) and JH642 (sfp-) and E.coli MG1665 bacterial strains on NGM agar plates and 28°C temperature. Outcome of the competition depended on the initial ratio of E. coli : B. subtilis as 1:1 ratio showed inhibitory effects of E. coli MG1665 on B. subtilis ATCC 21332, while initial rations of 1:13, 1:40 and 1:180 showed inhibitory effect of B. subtilis ATCC 21332 on E. coli MG1665. B. subtilis JH642 and E. coli MG1665, independent of initial ratios, did not exibit competitive interactions. Predation rate of one C. elegans has proven to be too low and did not influence the population dynamics and the number of bacteria in the system.

Item Type: Thesis (Diploma thesis)
Keywords: predation, competition, surfactin, Escherichia coli, Bacillus subtilis, Caenorhabditis elegans
Supervisor: Matić, Ivan
Co-supervisor: Brčić-Kostić, Krunoslav
Date: 2009
Number of Pages: 75
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 09 Sep 2014 10:23
Last Modified: 09 Sep 2014 10:23
URI: http://digre.pmf.unizg.hr/id/eprint/2671

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