Vpliv sorodstvenega razlikovanja med izolati Bacillus subtilis na interakcijo s patogeno bakterijo Salmonella enterica v biofilmu

Jensterle, Katja (author), Mandić Mulec, Ines (mentor), Kovačec, Eva (comentor)

S. enterica je s hrano prenosljiva patogena bakterija, ki že izkazuje odpornost na medicinsko pomembne antibiotike. Odličen alternativni pristop h konvencionalni antibiotični terapiji je probiotična terapija. Med probiotike uvrščamo tudi bakterije iz rodu Bacillus, vendar so interakcije med bakterijo S. enterica in temi probiotiki v biofilmu slabo raziskane. Ni znano kako vplivajo interakcije med sevi ene vrste na interakcije z drugimi vrstami bakterij. Znano pa je, da bakterije B. subtilis lahko razlikujejo med filogenetsko visoko in manj sorodnimi sevi. V nalogi smo preučevali kako to sorodstveno razlikovanje med sevi B. subtilis vpliva na rast in prostorsko razporeditev S. enterica. Uporabili smo seve, označene z genom za odpornost proti antibiotiku (AmpR, SpR ali CmR) in s fluorescenčnim označevalcem (GFPmut3, mKate2 ali CFP), kar nam je omogočilo spremljanje sprememb rasti in razporeditve celic S. enterica. Testirali smo izrabljena gojišča različnih kombinacij sevov B. subtilis in interakcije s S. enterica ob sogojenju obeh vrst v tekočem in na trdnem gojišču. Ugotovili smo, da izrabljeno gojišče sevov B. subtilis, ne glede na tip mešanice sevov, ne zavira rasti S. enterica, temveč jo spodbuja, tako v tekočem kot tudi na trdnem gojišču. Sogojenje S. enterica z enim ali z mešanico sevov B. subtilis je negativno vplivalo na rast S. enterica, pri čemer v tekočem gojišču nismo zaznali značilnega vpliva sorodnosti. V kolonijah na trdnem gojišču so bile mešanice visoko sorodnih sevov B. subtilis nekoliko uspešnejše v zmanjševanju števila celic S. enterica, v primerjavi z manj sorodnimi mešanicami. Prostorska razporeditev S. enterica se tako v kolonijah kot v tekočem gojišču ni spreminjala v odvisnosti od sorodnosti in števila sevov B. subtilis. Ugotovili smo, da ima sorodnost med sevi B. subtilis značilen vpliv tudi na odpornost S. enterica na antibiotike. Bakterija S. enterica postane bolj občutljiva na tetraciklin in kotrimoksazol ter manj občutljiva na spektinomicin po inkubaciji z visoko sorodnimi sevi B. subtilis, v primerjavi z enovrstnim biofilmom.

• Language: Slovenian
• Keywords: mikrobne združbe, Bacillus subtilis, Salmonella enterica, sorodstveno razlikovanje, socialne interakcije, odpornost proti antibiotikom, biofilm, izrabljeno gojišče
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: [K. Jensterle]
• Year: 2022
• PID: 20.500.12556/RUL-135731
• UDC: 579.22/.26
• COBISS.SI-ID: 102529283
• Publication date in RUL: 30.03.2022

Secondary language

• Language: English
• Title: The influence of kin discrimination between isolates of Bacillus subtilis on interaction with pathogenic bacteria Salmonella enterica in biofilm

Abstract

A food-borne pathogen Salmonella enterica is already showing resistance to antibiotics and new approaches are needed to combat this problem. An excellent alternative approach to the conventional antibiotic therapy is the probiotic therapy. Strains of the Bacillus genus are in use as probiotics, but the interactions between S. enterica probiotic strains in biofilms are poorly understood. Even less is known about how intraspecific bacterial interactions influence interactions with another bacterial species. B. subtilis has been recently recognized for its ability to discriminate between less and more related strains. In order to study how relatedness between B. subtilis strains affects the growth and spatial distribution of S. enterica, we used mixtures of highly related and less related B. subtilis strains and cocultured them with S. enterica. Each strain was labelled with an antibiotic resistance gene (AmpR, SpR or CmR) and a fluorescent marker (GFPmut3, mKate2 or CFP). We aimed to determine whether and how the growth and distribution of S. enterica was changing in co-culture with B. subtilis and how kin discrimination between strains of B. subtilis impacts S. enterica. In experiments with spent media of B. subtilis strain mixtures and their relatedness have not inhibited growth of S. enterica, on contrary, spent media contained components that promoted the growth of S. enterica in liquid and on solid media. On the other hand, co-cultivation with B. subtilis mixtures had a negative impact on S. enterica growth, with no correlation with the strain number or relatedness. In colonies on a solid medium, the mixtures of highly-related strains of B. subtilis seemed to be more effective in reducing number of S. enterica cells, however, the size of Salmonella's colony has not changed. We also found that the relatedness between B. subtilis strains had a significant impact on antibiotic resistance of S. enterica, which became more susceptible to tetracycline and cotrimoxazole and less susceptible to spectinomycin after incubation with highly-related B. subtilis strains.

• Keywords: microbial communities, Bacillus subtilis, Salmonella enterica, kin discrimination, social interactions, antibiotic resistence, biofilm, spent media