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Identifikacija mlečnokislinskih bakterij iz naravne mikrobiote fermentiranih mlečnih izdelkov iz Slovenije in sosednjih regij
ID Avsec, Nina (Author), ID Čanžek Majhenič, Andreja (Mentor) More about this mentor... This link opens in a new window

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Abstract
Območje JV Evrope je zaradi klimatske in geografske pestrosti ter dolge zgodovine izdelave tradicionalnih mlečnih izdelkov bogat vir avtohtone mikrobiote. Namen magistrskega dela je bilo osamiti in identificirati čim več različnih mlečnokislinskih bakterij (MKB) iz tradicionalnih mlečnih izdelkov slovenskih, srbskih in ruskih lokalnih proizvajalcev, izdelanih iz surovega ali toplotno obdelanega mleka ter brez ali z dodatkom starterskih kultur (SK). V ta namen smo pridobili 37 vzorcev mlečnih izdelkov in 2 vzorca surovega mleka od različnih vrst živali. Iz vzorcev, ki so bili izdelani bodisi iz toplotno obdelanega ali surovega mleka ter večinoma fermentirani z naravno mikrobioto, smo naključno osamili 706 kolonij, jih prečistili in na nivoju vrste identificirali z metodo MALDI-TOF. Pomemben delež mikrobiote so predstavljali predstavniki rodu Lactobacillus, s prevladujočimi vrstami Lb. paracasei, Lb. plantarum in Lb. kefiri, ter predstavniki iz rodu Lactococcus z vrsto Lac. lactis. Pomembni so bili tudi enterokoki, predvsem vrsti Ec. faecalis in Ec. faecium, ki pa so bili bolj značilni za tradicionalne sire, medtem ko je bila za fermentirana mleka in kajmake najbolj značilna vrsta Leuc. mesenteroides. Poleg najbolj značilnih MKB smo v mlečnih izdelkih identificirali tudi manj značilne ne-MKB. Ker običajno velja, da je avtohtona mikrobiota sevno bolj raznolika od SK, smo z analizo RAPD-PCR testirali izolate iz vrst Lac. lactis in Lb. paracasei 16-ih različnih izdelkov. Ugotovili smo večjo sorodnost sevov v izdelkih z dodanimi SK in iz toplotno obdelanega mleka, poleg tega pa na sestavo mikrobiote vpliva tudi vrsta mlečnega izdelka, čas zorenja in geografsko območje izdelave.

Language:Slovenian
Keywords:tradicionalni mlečni izdelki, mikrobiota, mlečnokislinske bakterije, Lactobacillus paracasei, Lactococcus lactis, identifikacija mikroorganizmov, osamitev, molekularne genetske metode, MALDI-TOF MS, RAPD-PCR, sevna sorodnost
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:BF - Biotechnical Faculty
Publisher:[N. Avsec]
Year:2020
PID:20.500.12556/RUL-122266 This link opens in a new window
UDC:637.136+637.146:602.3:579.864:543.51
COBISS.SI-ID:41221635 This link opens in a new window
Publication date in RUL:02.12.2020
Views:1243
Downloads:128
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Secondary language

Language:English
Title:Isolation and species identification of lactic acid bacteria, members of native microbiota of fermented dairy product from Slovenia and neighboring regions
Abstract:
Due to its climatic and geographical diversity as well as long history of production of traditional dairy products, SE Europe is a rich source of indigenous microbiota. The aim of our thesis was to isolate and identify as many as possible diverse lactic acid bacteria (LAB) from traditional dairy products of Slovenian, Serbian and Russian local dairy product producers, made from raw or heat-treated milk and with or without the addition of starter cultures (SC). Therefore, we obtained 37 samples of dairy products and 2 samples of raw milk, from different species of animals. From samples, made from either heat-treated or raw milk and mostly fermented with natural microbiota, 706 colonies were randomly isolated, purified and identified to the species level by the MALDI-TOF MS method. A significant proportion of identified microbiota was represented by the genus Lactobacillus, with predominant species of Lb. paracasei, Lb. plantarum and Lb. kefiri, and by the genus Lactococcus represented with Lac. lactis species. Enterococci, especially Ec. faecalis and Ec. faecium were also important, but more typical for traditional cheeses, while Leuc. mesenteroides was more typical for fermented milks and kajmaks. In addition to the typical LAB, we also identified less typical non-LAB representatives. Because the native microbiota is generally considered to be more diverse at the strain level than SC, we investigated Lac. lactis and Lb. paracasei isolates with RAPD-PCR analysis, isolated from 16 different dairy products. We determined bigger strain similarity in products with added SC and from heat-treated milk. Microbiota diversity is also influenced by the type of dairy product, ripening time and geographical area of production.

Keywords:traditional dairy products, lactic acid bacteria, Lactobacillus paracasei, Latococcus lactis, microbiota identification, isolation, molecular genetic methods, MALDI-TOF MS, RAPD PCR, strain similarity

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