Staphylococcus aureus parmesan tüüpi juustu soolveevannide biokiles

English. Staphylococcus aureus is known as food pathogen that is capable of producingthermotolerant enterotoxins. Therefore, it is essential to ensure that such strains do notoccur in the production environment and consequently do not form biofilms on the surfaceof the equipment in the food industry.This thesis focused on the research and analysis of whether S. aureus could bedistinguished from the biofilm of parmesan type cheese brine tanks as well as to providean overview of the microbes that may be present in chees brine, and lastly, to conduct amicrobiological and molecular study of the presence of S. aureus in samples of biofilmson the parmesan type cheese brine tanks in one Estonian dairy industry.According to the literature S. aureus has been previously found in the cheese brine tanks,and therefore may also exist in biofilms of the cheese brine tanks. Biofilm samples (n =24) were subjected to microbiological analysis to obtain the first overview of the microbesin these and gram- and catalase-positive clusters that resembled staphylococci in their cellmorphology (n=57) were selected for further studies. DNA was extracted from theseisolates and from directly from the biofilm in order to identify S. aureus in samples by thePCR analysis. DNA samples isolated from biofilm samples were sent to the Institute ofGenomics of the University of Tartu for sequencing.As a result of the research, it was concluded that S. aureus was not present in any of thestudied biofilm samples, although, according to the literature, staphylococcal enterotoxinswhich were not identified in this work may be present.

Staphylococcus aureus on tuntud kui toidupatogeen, olles võimeline produtseerimatermotolerantseid enterotoksiine, mistõttu toiduainete tööstustes on vajalik jälgida, etselliseid tüvesid tootmiskeskkonnas ei esineks ega moodustaks seadmete pindadelebiokilesid.Bakalaureusetöö raames uuriti, kas parmesan tüüpi juustu sooveevannide biokilest onvõimalik tuvastada S. aureus’t ning anti ülevaade juustu soolveevannide biokiles esinedavõivate mikroobide kohta ning teostati mikrobioloogiline ja molekulaarne uuring S.aureus’e esinemise kohta ühe Eesti piimatööstuse parmesan tüüpi juustudesoolveevannide biokileproovides.Kirjanduse andmetel selgus, et S. aureus’t on juustu soolveevannidest varem leitud ningon võimalik, et teda esineb ka soolveevannide biokiles. Uuritud biokileproovidest (n=24)saadi mikrobioloogilise analüüsi käigus esmane ülevaade neis sisalduvate mikroobidekohta ning moodustati proovide valim (n=57) gram- ja katalaas-positiivsetestkobarkokkidest, kes oma rakumorfoloogialt sarnanesid stafülokokkidega. Antudisolaatidest ja otse biokilede proovimaterjalist eraldati DNA ning teostati PCR analüüs S.aureus’e tuvastamiseks. Biokileproovidest eraldatud DNA proovid on saadetudsekveneerimisele Tartu Ülikooli genoomika instituuti.Töö tulemusena leiti, et uuritud biokileproovides S. aureus’t ei esinenud, ehkki võibkirjanduse andmete kohaselt sisaldada stafülokokkide enterotoksiine, mida käesolevastöös ei määratud.