Razvoj eksperimentalnog sustava za proučavanje utjecaja oblića Caenorhabditis elegans na miješanu populaciju bakterija Escherichia coli i Bacillus subtilis

master's thesis

• Title (english): Development of experimental system for studying effect of nematode Caenorhabtiditis elegans on mixed population of Escherichia coli and Bacillus subtilis
• Author: Darja Dubravčić
• Mentor: Ivan Matić (mentor)
• Mentor: Krunoslav Brčić-Kostić (sumentor)
• Committee member: Krunoslav Brčić-Kostić (predsjednik povjerenstva)
• Committee member: Dubravka Hranilović (član povjerenstva)
• Committee member: Željka Vidaković Cifrek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2009, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Kompeticija i predacija među najvažnijim su silama u oblikovanju organizama i ekosistema. Oba proces snažno utječu na bioraznolikost, diferencijaciju niše i stjecanje novih adaptacija. U većini slučajeva njihov utjecaj na organizme proučavan je odvojeno. U kojoj mjeri i pod kojim uvjetima pojedini proces ima prevladavajuću ulogu često je nepoznato ili nedovoljno razjašnjeno. Tijekom ovog istraživanja razvila sam eksperimentalni sustav za laboratorijsko proučavanje zajedničkog djelovanja kompeticije i predacije na dobro poznatim modelnim organizmima; Bacillus subtilis, Escherichia coli i Caenorhabditis elegans. Optimalni uvjeti za praćenje interakcija pokazali su se oni s bakterijskim sojevima B. subtilis ATCC 21332 (sfp+) i JH642 (sfp-) i E. coli MG1665 na krutoj NGM podlozi, pri temperaturi od 28°C, te β-galaktozidaza test za praćenje bakterijske dinamike. Ishod kompeticije ovisio je o početnom omjeru E.coli : B. subtilis, pri čemu je u 1:1 omjeru E. coli pokazao inhibitorni učinaka na ATCC 1332 soj, dok su omjeri 1:13, 1:40 i 1:180 pokazali inhibicijsko djelovanje ATCC 21332 na MG1665. Neovisno o omjeru u kojem su se nalazili JH642 i MG1665 nisu pokazali kompetitivan odnos. Predacijska stopa od jednog C. elegans pokazala se preniskom da bi djelovala na dinamiku sustava i na broj bakterija u sustavu.

Abstract (english)

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.

• Keywords: predacija; kompeticija; surfaktin; Escherichia coli; Bacillus subtilis; Caenorhabditis elegans
• Keywords (english): predation; competition; surfactin; Escherichia coli; Bacillus subtilis; Caenorhabditis elegans
• Language: croatian
• URN:NBN: urn:nbn:hr:217:896242
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra molekularne biologije (magistar/magistra molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-03-07 12:17:08