Kin discrimination modifies strain distribution, spatial segregation and incorporation of extracellular matrix polysaccharide mutants of Bacillus subtilis strains into mixed floating biofilms

Microorganisms in nature form multicellular groups called biofilms. In biofilms, bacteria embedded in the extracellular matrix (ECM) interact intensely due to their proximity. Most studies have investigated genetically homogeneous biofilms, leaving a gap in knowledge on genetically heterogeneous biofilms. Recent insights show that a Gram-positive model bacterium, Bacillus subtilis, discriminates between strains of high (kin) and low (nonkin) genetic similarity, reflected in merging (kin) and boundaries (nonkin) between swarms. However, it is unclear how kinship between interacting strains affects their fitness, the genotype assortment, and incorporation of the mutant lacking the main structural ECM polysaccharide (EpsA-O) into floating biofilms (pellicles). We cultivate Bacillus subtilis strains as mixtures of isogenic, kin and nonkin strain combinations in the biofilm-promoting medium (MSgg) in static conditions, allowing them to form pellicles. We show that in nonkin pellicles, the dominant strain strongly reduced the frequency of the other strain. Segregation of nonkin mixtures in pellicles increased and invasion of nonkin EpsA-O-deficient mutants into pellicles decreased compared to kin and isogenic floating biofilms. Kin and isogenic strains had comparable relative frequencies in pellicles and showed more homogenous cell mixing. Overall, our results emphasize kin discrimination as a social behavior that shapes strain distribution, spatial segregation and ECM mutant ability to incorporate into genetically heterogenous biofilms of B. subtilis. Soavtorji: Barbara Kraigher, Iztok Dogsa, Barbara Jerič Kokelj, Ines Mandic-Mulec. Nasl. z nasl. zaslona. Opis vira z dne 10. 8. 2022. Bibliografija: str. 12-14. Abstract. ARRS, Programi, Sl, Mikrobiologija in biotehnologija živil in okolja ARRS, Projekti, Sl, Raziskave medceličnih komunikacij v večceličnih skupnostih različnih izolatov bakterije iz rodu Bacillus ARRS, Projekti, Sl, Razvoj mikropretočnih sistemov za analizo, izbor in uporabo bakterijskih celic ARRS, Projekti, SI, Platforma osnovana na sintetičnih biofilmih za preučevanje in razvoj novih proti biofilmskih pristopov European Union, H2020, Chair Of Micro Process Engineering and TEchnology, COMPETE