Vpliv pogojev gojenja bakterij vrste Escherichia coli v kontinuirnem bioprocesu na nastajanje bakteriofagov z lizogenim ciklom

Pevec, Polona (author), Podgornik, Aleš (mentor)

Bakteriofag λ je temperatni bakteriofag, kar pomeni, da lahko izbira med dvema različnima strategijama razmnoževanja, litičnim in lizogenim ciklom. Med našim delom smo opazovali, kako se bakteriofag prilagaja na spremembo količine hranil in temperature ter kako vpliva prisotnost bakteriofaga na njegovega gostitelja. Osnovne parametre gojenja smo testirali šaržno ter s pomočjo eno ter dvostopenjskega miniaturnega bioreaktorskega sistema z bakterijo E. coli. Okarakterizirali smo gostitelja in revitalizirali liofiliziran bakteriofag, ob spreminjanju pogojev smo določili specifiko rasti kulture in preverili delovanje bakteriofaga. Statistično in grafično smo analizirali podatke in identificirali rastne parametre gostitelja. Vpliv temperature na bakteriofag in gostitelja smo preverili s serijo šaržnih eksperimentov pri različnih temperaturah. Povišanje temperature je v testiranem območju pozitivno vplivalo na rast bakterijske kulture, rast bakteriofagov je bila sorazmerno pogojena z rastjo gostitelja, rast (μmax) je bila mnogo počasnejša v primerjavi z eksperimenti, kjer bakteriofag ni bil dodan v sistem. Raziskave v mejnem območju limitnega dejavnika in preklop med dvema cikloma smo izvajali preko omejevanja pretoka hranil skozi sistem. Ugotovili smo, da ima spreminjanje temperature mnogo večji vpliv na rasti gostitelja, kot uravnavanje pretoka in posledično večji vpliv na rast bakteriofagov. Da bi ustvarili zanesljiv model napovedi preklopa razmnoževalnega cikla, bi bilo treba izvesti še mnogo uspešnih ponovitev eksperimentov.

• Language: Slovenian
• Keywords: bakteriofag, lizogenija, kemostat, bakterije, preklop
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [P. Pevec]
• Year: 2020
• PID: 20.500.12556/RUL-119809
• UDC: 602.3:578.347:602.42(043.2)
• COBISS.SI-ID: 30317059
• Publication date in RUL: 11.09.2020

PEVEC, Polona, 2020, Vpliv pogojev gojenja bakterij vrste Escherichia coli v kontinuirnem bioprocesu na nastajanje bakteriofagov z lizogenim ciklom [online]. Master’s thesis. P. Pevec. [Accessed 19 May 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=119809

Secondary language

• Language: English
• Title: Effect of environmental conditions on growth of bacterial species Escherichia coli in continuous bioprocess and production of bacteriophages with lysogenic cycle

Abstract

λ is a temperate bacteriophage, that means that it can interchangeably choose between any of two lifecycle strategies lysogeny or lysis. Through our reaserch, we observed how the bacteriophage adapts to changes in nutrients availability and temperature, and how the presence of the bacteriophage affects its host. The basic culture parameters were tested in batches and later with the help of one- and two-stage miniature chemostat bioreactor systems with E. coli. We characterized the host and revitalized the lyophilized bacteriophage, determined the specificity of culture growth and checked the activity of the bacteriophage. Statistical and graphical analysis of the data was performed and the growth parameters of the host identified. The effect of temperature on the bacteriophage and the host was tested in a series of batch experiments at different temperatures. The increase in temperature in the tested area had a positive effect on bacterial culture growth, bacteriophage growth was proportional to host growth, μmax was much slower compared to experiments where bacteriophage was not added to the system. Research of the limiting factors of switching between the two cycles was performed by restricting the flow of nutrients through the system. We found that temperature change has a much greater impact on host growth than flow regulation and consequently a greater impact on bacteriophage growth. In order to create a reliable predictive model for the switching of the reproductive cycle, many more successful experiments would need to be performed.

• Keywords: bacteriophage, lysogeny, chemostat, bacteria, switch