Odgovor na stres E. coli kod in vivo hipoosmotskog šoka

master's thesis

• Title (english): Stress response of E. coli to the in vivo hypoosmotic shock
• Author: Renata Buđa
• Mentor: Božidar Šantek (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology); Zagreb
• Defense date and country: 2014-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

U ovom istraživanju proučavan je odgovor bakterije E. coli na stres izazvan hipoosmotskim šokom in vivo. E. coli je uzgajana u medijima visoke osmolarnosti (125 – 650 mM NaCl), a potom naglo prebačena u medij niske osmolarnosti (0 mM NaCl). U tu svrhu korišteni si različiti sojevi: divlji tip, dvostruki mutant (ΔmscSΔmscL) te ΔaqpZ mutant. Na osnovi rezultata fluorescentne mikroskopije i analize podataka vidljivo je da se stanicama divljeg tipa i mutanata povećava volumen proporcionalno intenzitetu šoka za 7 – 18 %. Divlji tip se uspijeva oporaviti nakon svakog hipoosmotskog šoka te nastaviti s rastom. Međutim, kod dvostrukog mutanta E. coli vidljiv je prestanak oporavka kod 450 mM NaCl kao i povećan broj odumrlih stanica kod 650 mM NaCl. Nadalje, opaženo je da se sve stanice nakon povećanja volumena, osim divljeg tipa kod hipoosmotskog šoka od 650 mM NaCl, vraćaju na početni volumen nakon određenog vremena. Hipoosmotski šok od 650 mM NaCl kod divljeg tipa izaziva prekomjerni gubitak vode (ispod početne vrijednosti), a primjenom šoka iste takve magnitude na ΔaqpZ mutanta utvrđeno je da protein Aquaporin Z nema ulogu u prekomjernom gubitku vode. Također, takve stanice postepeno regeneriraju svoj volumen uzimanjem kalija iz okoline.

Abstract (english)

In this research, the E. coli stress response on the in vivo hypoosmotic shock has been studied. E. coli was grown in a high osmolarity medium (125 mM – 650 mM sodium chloride) and then rapidly transferred into the low osmolarity medium (0 mM sodium chloride). For this purpose different strains were used: wild type, double mutant (ΔmscSΔmscL) and the ΔaqpZ mutant. Based on the single cell results of the fluorescence microscopy and the data analysis, it has been observed that wild type and the mutant cells volume was increased for 7 – 18%, proportionally to the shock magnitude. The wild type was able to recover and continue to grow after each hypoosmotic shock. However, for the E. coli double mutant the termination of the recovery was observed at 450 mM NaCl as well as the increased number of the dead cells at 650 mM NaCl. Furthermore, it was observed that all of the cells after the volume increase, except the wild type at 650 mM NaCl, were recovering their initial volume after a specific time. The hypoosmotic shock from 650 mM NaCl causes the excessive water loss in the wild type (below the initial value). By applying the shock of such magnitude on the ΔaqpZ mutant , it was established that the protein Aquaporin Z doesn’t partake in the excessive water loss. Likewise, such cells recover their volume gradually by potassium uptake.

• Keywords: Escherichia coli; hipoosmotski šok; NaCl; ΔmscSΔmscL; Aquaporin Z
• Keywords (english): Escherichia coli; hypoosmotic shock; NaCl; ΔmscSΔmscL; Aquaporin Z
• Language: croatian
• URN:NBN: urn:nbn:hr:159:292789
• Study programme: Title: Bioprocess Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva (magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-02 11:51:25