Interactions among yeasts and probiotic bacteria and inhibition of the growth of Bacillus clausii by Debaryomyces hansenii

master's thesis

• Title (croatian): Interakcije između kvasaca i probiotičkih bakterija te inhibicija rasta Bacillus clausii s Debaryomyces hansenii
• Author: Ana Gabrić
• Mentor: Renata Teparić (mentor)
• Committee member: Jasna Novak (predsjednik povjerenstva)
• Committee member: Igor Stuparević (član povjerenstva)
• Committee member: Andreja Leboš-Pavunc (član povjerenstva)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Chemistry and Biochemistry); (Laboratory for Biochemistry); Zagreb
• Defense date and country: 2023-02-08, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Cross-kingdom interactions exist in many environments, including various human body niches. In order to understand these interactions better, 16 yeasts were isolated from the pear (with some rotten spots) and five bacteria cultures were isolated from the probiotic supplements. Yeast isolates were inoculated on 15 media in order to determine the optimal growth conditions for each of them. Bacteria isolated from the probiotic preparation were identified by MALDI-TOF, while the cell morphology of the yeasts was observed under the microscope. Relationships among isolated yeasts and probiotic bacteria were evaluated by contact-inhibition test, the cell-free cultivation media test and co-culturing test. According to the results of the contact-inhibition test, yeasts B5 and B10 inhibited the growth of Bacillus clausii. Both inhibitory yeast isolates were identified as Debaryomyces hansenii by 28 rDNA sequencing. This unique finding was confirmed with co-culturing of B. clausii and D. hansenii that also described how this relationship is strain-dependent.

Abstract (croatian)

Interakcije među pripadnicima različitih carstava su prisutne u mnogim staništima, uključujući različite organske sustave ljudskog tijela. Kako bi se bolje razumjele ove interakcije, 16 vrsti kvasaca je izolirano iz djelomično trule kruške i 5 bakterijskih vrsti je izolirano iz probiotičkih pripravaka. Izolati kvasaca su nacijepljeni na 15 hranjivih podloga kako bi se odredili optimalni uvjeti uzgoja za svakoga od njih. Bakterije izolirane iz probiotičkog pripravka su identificirane pomoću MALDI-TOF, dok je morfologija kvasaca potvrđena pomoću svjetlosnog mikroskopa. Interakcije između izoliranih kvasaca i probiotičkih bakterija su provjerene s nekoliko testova, uključujući kontaktni test inhibicije, test sa medijima u kojima su mikroorganizmi uzgajani te test zajedničkog uzgoja. Prema rezultatima kontaktnog testa inhibicije kvasci B5 i B10 su inhibirali rast bakterije Bacillus clausii. Oba inhibirajuća kvašćeva izolata identificirana su kao Debaryomyces hansenii 28 rDNA sekvencioniranjem. Ovo jedinstveno otkriće potvrđeno je zajedničkim uzgojem B. clausii i D. hansenii te je zaključeno kako je ova inhibicija ovisna o soju kvasca.

• Keywords: Debaryomyces hansenii; Bacillus clausii; interactions; yeasts; probiotic bacteria
• Keywords (croatian): Debaryomyces hansenii; Bacillus clausii; interakcije; kvasci; probiotičke bakterije
• Language: english
• URN:NBN: urn:nbn:hr:159:621975
• Study programme: Title: Bioprocess Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva (magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-05-17 09:19:20