Določanje kakovosti prehranskih dopolnil z živimi bakterijami z masno spektrometrijo (MALDI-TOF)

Omahen, Joži (author), Bogovič Matijašić, Bojana (mentor), Kramer, Mateja (comentor)

Pri sedemnajstih prehranskih dopolnilih z živimi bakterijami, naprodaj v slovenskih lekarnah, smo preverili skladnost navedb na označbi z dejansko mikrobiološko sestavo. Število živih bakterij v izdelkih smo ugotavljali s standardno metodo štetja na selektivnih gojiščih, prisotnost označenih vrst pa z metodama PCR in MALDI-TOF MS. PCR smo izvedli na skupni DNA iz izdelka ter na DNA iz konzorcija kolonij, MALDI-TOF MS pa na posameznih kolonijah. Odkrili smo več pomanjkljivosti pri označevanju. Pri osmih izdelkih je bila navedena beseda »probiotik«, ki v EU ni dovoljena. Večinoma proizvajalci navajajo le skupno število vseh mikroorganizmov v izdelku, ne pa tudi števila posameznih sevov (neustreznih 15 od 17 vzorcev). Pri petih izdelkih je bila navedena le vrsta bakterij, ne pa tudi oznaka seva. Skupno število kolonijskih enot v enoti izdelka (KE) je bilo ustrezno v štirinajstih izdelkih, v treh (18 %) pa prenizko. Metoda MALDI-TOF MS in identifikacija z MALDI Biotyper (Bruker Daltonics) se je izkazala kot hitra in enostavna metoda, ki je dovolj zanesljiva za identifikacijo večine vrst, z izjemo vrst skupine Lacticaseibacillus (L. casei, L. zeae, L. rhamnosus). Šestnajst od 292 pregledanih kolonij (5 %) ni bilo mogoče identificirati zaradi odsotnosti spektra (11 kolonij) ali neprepoznanega spektra (5 kolonij). Z metodo PCR smo pri enajstih izdelkih uspešno identificirali vse bakterijske vrste, ki so bile navedene na označbi izdelka. Prednost PCR je zmožnost identifikacije na nivoju podvrst: Bif. animalis subsp. lactis, Streptococcus salivarius subsp. thermophilus, Bif. longum subsp. longum, Bif. longum subsp. infantis.

• Language: Slovenian
• Keywords: prehranska dopolnila, žive bakterije, označevanje živil, identifikacija bakterij, PCR, masna spektrometrija z MALDI-TOF, Lactobacillus, Bifidobacterium, Streptococcus
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: [J. Omahen]
• Year: 2021
• PID: 20.500.12556/RUL-128728
• UDC: 579.67:615.372:577.2.083
• COBISS.SI-ID: 71369731
• Publication date in RUL: 25.07.2021

OMAHEN, Joži, 2021, Določanje kakovosti prehranskih dopolnil z živimi bakterijami z masno spektrometrijo (MALDI-TOF) [online]. Master’s thesis. Ljubljana : J. Omahen. [Accessed 30 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=128728

Secondary language

• Language: English
• Title: Quality assessment of dietary supplements containing viable bacteria by mass spectrometry (MALDI-TOF)

Abstract

For seventeen dietary supplements containing viable bacteria sold in Slovenian pharmacies, we checked the consistency of the information on the label with the actual microbiological compositions. The number of live bacteria in the products was determined by the standard method of colony counting on selective media, and the presence of the labeled bacterial species by the PCR and MALDI-TOF MS methods. PCR was performed on total DNA from the product and on DNA from a consortium of colonies, and MALDI-TOF MS on individual colonies. We found several labeled irregularities. In eight cases, the labeled of the product mentioned the word "probiotic", which is not allowed for food supplements in the EU. In most cases, the labels only included the total number of all microorganisms in the product, but not the number of individual strains (incorrect in 15 out of 17 samples). In five products only the type of bacteria was indicated, the strain was not labeled. The total number of colony units per product unit (KE) was appropriate for fourteen products and too low for three products (18 %). The MALDI-TOF MS method and identification with the MALDI Biotyper (Bruker Daltonics) proved to be a rapid and simple method, reliable enough to identify most species, with the exception of the species Lacticaseibacillus (L. casei, L. zeae, L. rhamnosus). Sixteen of the 292 colonies examined (5 %) could not be identified due to missing spectrum (11 colonies) or unrecognized spectrum (5 colonies). Using the PCR method, we successfully identified all bacterial species listed on the product labeled for eleven products. The advantage of the PCR method is the ability to identify at the subspecies level: Bif. animalis subsp. lactis, Streptococcus salivarius subsp. thermophilus, Bif. longum subsp. longum, Bif. longum subsp. infantis.

• Keywords: dietary supplements, viable bacteria, food labeling, bacteria identification, PCR, MALDI-TOF mass spectrometry, Lactobacillus, Bifidobacterium, Streptococcus