Identifikacija aerobno mezofilnih bakterija MALDI-TOF tehnikom u mlijeku iz mljekomata

master's thesis

• Title (english): Identification of aerobic mesophilic bacteria using the maldi-tof technique in milk from milk vending machine
• Author: Monica Darrer
• Mentor: Nataša Mikulec (mentor)
• Mentor: Snježana Kazazić (komentor)
• Committee member: Nataša Mikulec (predsjednik povjerenstva)
• Committee member: Snježana Kazazić (član povjerenstva)
• Committee member: Neven Antunac (član povjerenstva)
• Committee member: Mirna Mrkonjić Fuka (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Department of Dairy Science); Zagreb
• Defense date and country: 2023-09-20, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

U mlijeku dobivenom higijenskom mužnjom zdravih krava dozvoljeno je prema
Pravilniku o kakvoći svježeg sirovog mlijeka do 100 000 mikroorganizama/mL što
predstavlja prirodnu mikrobiotu mlijeka i nema negativan utjecaj na ukupnu kvalitetu mlijeka.
Međutim, nestručnim rukovanjem tijekom i nakon mužnje ono se lako kontaminira te postaje
potencijalan medij za rast i razmnožavanje mikroorganizama od kojih mogu biti štetni po
zdravlje ljudi. Budući je broj aerobno mezofilnih bakterija u mlijeku jedan od pokazatelja
higijenske kvalitete mlijeka, njihova je brojnost i identifikacija temeljna u kontroli sirovog
mlijeka iz mljekomata. Iz pet različitih mljekomata prikupljeno je 30 uzoraka kojima je
određivan ukupni broj aerobno mezofilnih bakterija metodom protočne citometrije.
Identifikacija se provodila usporedbom MALDI-TOF spektra masa s referentnim spektrima
pohranjenim u biblioteci mikroorganizama i obradom pomoću MALDI Biotyper računalnog
programa. Uspješno je identificirano 30 rodova i 51 bakterijska vrsta. Rodovi koji
prevladavaju su Lactococcus lactis, Leuconostoc mesenteroides, Kluyveromyces lactis,
Staphylococcus aureus.

Abstract (english)

According to the Regulation on the Quality of Fresh Raw Milk, up to 100 000
microorganisms/mL are allowed in milk obtained by hygienic milking of healthy cows, which
represents the natural microbiota of milk and has no negative impact on the overall quality of
milk. However, with unprofessional handling during and after milking, it is easily
contaminated and becomes a potential medium for the growth and reproduction of
microorganisms, some of which can be harmful to human health. Since the number of aerobic
mesophilic bacteria in milk is one of the indicators of the hygienic quality of milk, their
number and identification are fundamental in the control of raw milk from milk vending
machine. From five different milk vending machines, 30 samples were collected from which
the total number of aerobic mesophilic bacteria was determined using the flow cytometry
method and the classic method of counting colonies on a nutrient medium. Identification was
performed by comparing MALDI-TOF mass spectra with reference spectra stored in the
microorganism library and processing using the MALDI Biotyper computer program. 30
genus and 51 bacterial species were successfully identified. Genus that predominate are
Lactococcus lactis, Leuconostoc mesenteroides, Kluyveromyces lactis, Staphylococcus
aureus.

• Keywords: sirovo mlijeko; aerobno mezofilne bakterije; MALDI-TOF tehnika
• Keywords (english): raw milk; aerobic mesophilic bacteria; MALDI-TOF technique
• Language: croatian
• URN:NBN: urn:nbn:hr:204:936561
• Study programme: Title: Production and Processing of Milk; Study programme type: university; Study level: graduate; Academic / professional title: magistar / magistra inženjer/inženjerka proizvodnje i prerade mlijeka (magistar / magistra inženjer/inženjerka proizvodnje i prerade mlijeka)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-10-19 06:42:57