Title WapAI mediated competition in Bacillus subtilis swarms and biofilms
Title (croatian) WapAI posreduje kompeticiju kod rojenja i stvaranje biofilma Bacillus subtilis
Author Ivona Viduka
Mentor Ines Mandić-Mulec (mentor)
Mentor Igor Jurak (komentor)
Committee member Željka Maglica (predsjednik povjerenstva)
Committee member Ivana Ratkaj (član povjerenstva)
Committee member Ines Mandić-Mulec (član povjerenstva)
Committee member Igor Jurak (član povjerenstva)
Granter University of Rijeka (Faculty of Biotechnology and Drug Development) Rijeka
Defense date and country 2019-09-27, Croatia
Scientific / art field, discipline and subdiscipline BIOTECHNICAL SCIENCES Biotechnology
Abstract Bacteria are unicellular organisms but nonetheless they engage in multicellular behaviours like swarming motility and biofilm formation. Essential for their survival in such communities are mechanisms responsible for cooperation and competition. Moreover, bacteria are able to discriminate between strains based on the relatedness and treat less related strains differently than those that are genetically identical (clones) or highly related. This behaviour, referred to as kin discrimination, has been recently described for environmental strains of Bacillus subtilis and the tRNase toxin WapA has been identified as a potential kin discrimination locus. However, the mechanisms behind this process are not sufficiently known. Here, we characterize a role of the WapAI toxin-immunity system in competition between isogenic or non-kin strains. We studied their interactions in pellicles and swarming communities by determining their fitness by colony forming units. We also documented spatial distribution of two types of cells in pellicles by confocal microscopy. Our results show that the fitness of the toxin sensitive strain is significantly reduced compared to the toxin producing strain, regardless whether it is competed against parental or non-kin strain during swarming. In pellicles, parental strain did not outcompete the isogenic wapAI mutant, but the fitness of the non-kin mutant was reduced. Interestingly, mutant and parental cells co-aggregated into larger patches while two differentially labelled but otherwise isogenic strains mixed very well. Patchiness was not observed in non-kin combination, where the wild type outcompeted the mutant strain, which was undetectable by fluorescent microscopy. We conclude that competition in swarms is fiercer than in pellicles, probably due to less intense mixing of genotypes in pellicles.
Abstract (croatian) Bakterije su jednostanični organizmi koji stupaju u višestanične interakcije kao što su rojenje (engl. swarming) i formacija biofilmova. Za njihovo preživljenje u spomenutim zajednicama su nužni mehanizmi odgovorni za kooperaciju i kompeticiju. Nadalje, bakterije imaju sposobnost diskriminacije (razlikovanja) sojeva na temelju povezanosti gdje manje srodne sojeve tretiraju drugačije od genetički identičnih sojeva (klonovi) ili visoko srodnih. Spomenuto ponašanje se naziva diskriminacija srodnika (engl. kin discrimination), nedavno opisano u okolišnim sojevima bakterije Bacillus subtilis, a toksin WapA (tRNaza) kao potencijalni lokus za navedenu diskriminaciju. Međutim, mehanizmi iza ovog procesa nisu dovoljno znani. U ovom radu smo opisali ulogu WapAI sistema u kompeticiji između izogenih ili nesrodnih sojeva. Proučavali smo interakcije u peliklima i u zajednicama rojenja brojanjem kolonija na ploči (engl. colony forming units, CFU). Istražili smo prostornu distribuciju dvije vrste stanica u peliklima konfokalnom mikroskopijom. Rezultati su pokazali da je sposobnost razmnožavanja soja osjetljivog na toksin značajno smanjena u usporedbi sa sojem koji stvara toksin bez obzira je li u kompeticiji s roditeljskim ili nesrodnim sojem tijekom rojenja. U peliklima, roditeljski soj nije prevladao izogenu wapAI mutantu, ali je frekvencija nesrodne mutante bila značajno reducirana. Također, stanice mutante i roditeljskog soja su agregirale u veće nakupine dok su različito obilježeni, ali izogeni sojevi iskazali vrlo dobro miješanje. Nakupljanje stanica nije bilo zabilježeno u nesrodnim kombinacijama, gdje je divlji tip prevladao mutantu koju nije bilo moguće zapaziti fluorescentnim mikroskopom. Zaključno, kompeticija tijekom rojenja je snažnija nego u peliklima vjerojatno zbog slabijeg miješanja genotipova u peliklima.
Keywords
Bacillus subtilis
kin discrimination
WapA toxin
pellicles
swarms
Keywords (croatian)
Bacillus subtilis
diskriminacija srodnika
WapA toksin
pelikli
rojenje
Language english
URN:NBN urn:nbn:hr:193:337886
Study programme Title: Biotechnology in medicine Study programme type: university Study level: graduate Academic / professional title: magistar/magistra biotehnologije u medicini (magistar/magistra biotehnologije u medicini)
Type of resource Text
File origin Born digital
Access conditions Embargoed access Embargo expiration date: 2029-12-01
Terms of use
Repository Repository of the University of Rijeka, Faculty of Biotechnology and Drug Development
Created on 2019-09-29 19:30:13