Primjena hladne plazme na inaktivaciju Escherichia coli MG1655

master's thesis

• Title (english): Application of cold plasma on inactivation of Escherichia coli MG1655
• Author: Ivona Vukoje
• Mentor: Zoran Herceg (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Food Processes Engineering); Zagreb
• Defense date and country: 2016-07-19, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Cilj ovog rada bio je istražiti inaktivacijski učinak hladne plazme generirane u plinskoj fazi na čistu kulturu Escherichia coli MG1655 te oksidacijski stres na stanice E. coli nakon provedenog tretmana hladnom plazmom. Parametri koji su se promatrali bili su vrijeme izloženosti (5 i 10 min), frekvencija (60, 90 i 120 Hz), plin (zrak i argon), polaritet (+ i -) i električna provodljivost (100 i 800 μScm-1). Broj stanica izražen kao log CFUmL-1 određivan je prije i nakon tretiranja. Na tretiranim uzorcima određivano je stvaranje slobodnih radikala (H2O2), rekuperacija stanica, promjena temperature, stvaranje biofilma te istjecanje staničnog sadržaja pri valnim duljinama od 260 i 280 nm. Učinci pet varijabli i njihovih kombinacija na inaktivaciju Escherichie coli MG1655 su statistički analizirani metodom odzivne površine (RSM). Rezultati su pokazali bolju inaktivaciju i manju revitalizaciju primjenom argona i dužeg vremena tretiranja. Bolja inaktivacija je postignuta uz električnu provodljivost 100 μScm-1, ali je kod svih tretiranih uzoraka došlo do rekuperacije stanica nakon 18 h inkubacije pri 30 °C.

Abstract (english)

The aim of this study was to investigate the effect of cold plasma generated in gas phase on inactivation of Escherichia coli MG1655 and to determine the oxidative stress of cells after the treatment. The processing parameters were exposure time (5 and 10 min), frequency (60, 90 and 120 Hz), gas (air or argon), polarity (+ or -) and electrical conductivity (100 μScm-1 and 800 μScm-1). The number of cells expressed as log CFUmL-1 was determined before and after treatment. In treated samples forming of free radicals (H2O2), recuperation of cells, change of temperature, biofilm assay and leakage of cells macromolecules on wave lenghts of 260 and 280 nm was determined. The effects of five variables and their combinations on inactivation of Escherichia coli MG1655 were statistically analyzed through response surface methodology (RSM). The results showed better inactivation and reduced recuperation with applied argon, and longer exposure time with the electrical conductivity of 100 μScm-1. After the treatment and incubation for 18 h at 30 °C all samples were recuperated.

• Keywords: hladna plazma; Escherichia Coli; inaktivacija; oksidacijski stres; rekuperacija
• Keywords (english): cold plasma; Escherichia Coli; oxidative stress; inactivation; recuperation
• Language: croatian
• URN:NBN: urn:nbn:hr:159:037704
• Study programme: Title: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka prehrambenog inženjerstva (magistar/magistra inženjer/inženjerka prehrambenog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-04-27 08:35:26