Staphylococcus aureus parmesan tüüpi juustu soolveevannide biokiles

Staphylococcus aureus on tuntud kui toidupatogeen, olles võimeline produtseerima termotolerantseid enterotoksiine, mistõttu toiduainete tööstustes on vajalik jälgida, et selliseid tüvesid tootmiskeskkonnas ei esineks ega moodustaks seadmete pindadele biokilesid. Bakalaureusetöö raames uuriti, kas parmesan tüüpi juustu sooveevannide biokilest on võimalik tuvastada S. aureus’t ning anti ülevaade juustu soolveevannide biokiles esineda võivate mikroobide kohta ning teostati mikrobioloogiline ja molekulaarne uuring S. aureus’e esinemise kohta ühe Eesti piimatööstuse parmesan tüüpi juustude soolveevannide biokileproovides. Kirjanduse andmetel selgus, et S. aureus’t on juustu soolveevannidest varem leitud ning on võimalik, et teda esineb ka soolveevannide biokiles. Uuritud biokileproovidest (n=24) saadi mikrobioloogilise analüüsi käigus esmane ülevaade neis sisalduvate mikroobide kohta ning moodustati proovide valim (n=57) gram- ja katalaas-positiivsetest kobarkokkidest, kes oma rakumorfoloogialt sarnanesid stafülokokkidega. Antud isolaatidest ja otse biokilede proovimaterjalist eraldati DNA ning teostati PCR analüüs S. aureus’e tuvastamiseks. Biokileproovidest eraldatud DNA proovid on saadetud sekveneerimisele Tartu Ülikooli genoomika instituuti. Töö tulemusena leiti, et uuritud biokileproovides S. aureus’t ei esinenud, ehkki võib kirjanduse andmete kohaselt sisaldada stafülokokkide enterotoksiine, mida käesolevas töös ei määratud.

Staphylococcus aureus is known as food pathogen that is capable of producing thermotolerant enterotoxins. Therefore, it is essential to ensure that such strains do not occur in the production environment and consequently do not form biofilms on the surface of the equipment in the food industry. This thesis focused on the research and analysis of whether S. aureus could be distinguished from the biofilm of parmesan type cheese brine tanks as well as to provide an overview of the microbes that may be present in chees brine, and lastly, to conduct a microbiological and molecular study of the presence of S. aureus in samples of biofilms on 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 microbes in these and gram- and catalase-positive clusters that resembled staphylococci in their cell morphology (n=57) were selected for further studies. DNA was extracted from these isolates and from directly from the biofilm in order to identify S. aureus in samples by the PCR analysis. DNA samples isolated from biofilm samples were sent to the Institute of Genomics 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 the studied biofilm samples, although, according to the literature, staphylococcal enterotoxins which were not identified in this work may be present.