Phenotypic heterogeneity and population dynamics in biofilms

• Applicant: Professorin Dr. Erika Kothe, since 7/2017
• Subject Area: Microbial Ecology and Applied Microbiology ; Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 276408659

• Final Report Year: 2019

Final Report Abstract

The aim of the SPP was to characterize phenotypic heterogeneity and sociobiology of bacterial populations. Our project fully followed these aims and explored phenotypic heterogeneity and sociobiology of B. subtilis biofilms. While B. subtilis has become a widely studied model for the biofilm development field in the last decades, the social and experimental evolution aspects have been mainly explored within this DFG-funded project. The project was initiated by summarizing the knowledge on experimental evolution of laboratory biofilms, on bacterial differentiation and on the functions of biofilm matrix. This project has revealed how genetic division of labor benefits biofilm establishment, while being sensitive to evolution of individuality in a longer time scale. Interestingly, the benefit from genetic division of labor (i.e. the separation of matrix production to genetically distinct cells) surpasses the advantage resulted from phenotypic heterogeneity in expression of biofilm matrix components. The project discovered genetic differentiation in experimentally evolved biofilm populations of B. subtilis and demonstrated that such genetic differentiation promotes higher productivity of biofilms. To explore the influence of phenotypic heterogeneity on sociobiology of biofilms, this project described how temporal and spatial heterogeneity of matrix production determines biofilm robustness. The project also examined the ability of cheaters to exploit the biofilm matrix. While mutants lacking both matrix components could not incorporate into the biofilm produced by the wild type biofilms, their abundance was influenced by de novo competition explained through bacteriophages. In contrast, mutant strains that lacked only one of the matrix components could incorporate into the biofilm produced by the wild type cells and shift phenotypic heterogeneity in these matrix producing cells. The project promoted collaborations with numerous researchers providing different expertise, including theoretical modeling biofilm imaging, biofilm biophysics, protein biophysics, genomics, electron microscopy, and evolution. Finally, the obtained results were summarized in a review publication within the SPP special issue.

Publications

• (2016) Laboratory evolution of microbial interactions in bacterial biofilms. Journal of Bacteriology 198(19): 2564-2571
  Martin M, Hölscher T, Dragoš A, Cooper VS, Kovács ÁT
  
• (2017) De novo evolved interference competition promotes the spread of biofilm defectors. Nature Communications 8: 15127
  Martin M, Dragoš A, Hölscher T, Maroti G, Balint B, Westermann M, Kovács ÁT
  
• (2018) Collapse of genetic division of labor and evolution of autonomy in pellicle biofilms. Nature Microbiology 3(12):1451-1460
  Dragoš A, Martin M, Falcón García C, Kricks L, Pausch P, Heimerl T, Bálint B, Maróti G, Bange G, López D, Lieleg O, Kovács ÁT
  
• (2018) Division of labor during biofilm matrix production. Current Biology 28(12): 1903-1913
  Dragoš A, Kiesewalter HT, Martin M, Hsu CY, Hartmann R, Wechsler T, Drescher K, Stanley- Wall N, Kümmerli R, Kovács ÁT
  
• (2019) Evolved Biofilm: review on the experimental evolution studies of Bacillus subtilis pellicles. Journal of Molecular Biology
  Kovács ÁT, Dragoš A