Das Leben auf der Oberfläche: Populationswachstum von Bacillus subtilis
Stoffwechselphysiologie, Biochemie und Genetik der Mikroorganismen
Zusammenfassung der Projektergebnisse
Fluorescent markers represent excellent tools to follow the spatial distribution of different strains throughout an experiment. This is not only possible at microscale, but also at lower magnification so that the analysis of an entire surface colonizing colony is possible. Since spatial segregation is an important mechanism in social interactions, especially as a means to promote cooperation, this method can lead to discoveries about the impact of spatial dynamics on microbial sociality, here applied for the soil dwelling and plant promoting bacterium, Bacillus subtilis. In this project, it was examined how cells not contributing to a cooperative behavior might influence microbial population structure. A simple bacterial system was employed, bacterial sliding to demonstrate how the diffusion properties of cooperative goods and their synthesis costs define shareability to clonemates. We demonstrated that although certain compounds are secreted to the cells’ environment, not all shareable goods can be qualified as truly “public”. In general, compounds produced by bacteria should be defined as a public good only after analyses of the social properties and the possible production costs. It is also important to be aware of the investigated environment and the possibility that a substance that is publicly available in condition A, but might be privatized in condition B. These experiments enhance our understanding of bacterial population biology and guide us to develop microbial community-based biocontrol agents with improved or more efficient protective function. Further, the project revealed the interaction of various bacterial differentiation pathways, motility, ability of extracellular DNA uptake, and biofilm formation. We demonstrated that inhibiting one differentiation pathway (e.g. reducing the ability of B. subtilis cell to move) will alter DNA transfer and will promote the evolution of biofilm matrix overexpression. In addition, the project examined how motility plays an important role on structuring the establishment of biofilms, suggesting an additional physical feedback loop promoting the conservation of diverse differentiation pathways. These insights highlight the importance of careful targeting of a specific differentiation pathway during antimicrobial compound design. One might develop novel bacteria targeting compound that reduce bacterial spreading, but this might promote other survival strategies in the bacterium. In sum, the project resulted numerous publications that all aid understanding the population biology of microbes, including the impact of spatial structure, secreted compounds diffusion and fitness, in addition to the intertwinement of regulatory pathways governing bacterial differentiation.
Projektbezogene Publikationen (Auswahl)
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(2016) Monitoring spatial segregation in surface colonizing microbial populations. Journal of Visualized Experiments 116: e54752
Hölscher T, Dragoš A, Gallegos-Monterrosa R, Martin M, Mhatre E, Richter A, Kovács ÁT
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(2017) Sliding on the surface: bacterial spreading without an active motor. Environmental Microbiology 19(7): 2537-2545
Hölscher T, Kovács ÁT
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(2017) The peculiar functions of bacterial extracellular matrix. Trends in Microbiology 25: 257-266
Dragoš A, Kovács ÁT
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(2018) Hampered motility promotes the evolution of wrinkly phenotype in Bacillus subtilis. BMC Evolutionary Biology 18: 155
Richter A, Hölscher T, Pausch P, Sehrt T, Brockhaus F, Bange G, Kovács ÁT
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(2018) Impaired competence in flagellar mutants of Bacillus subtilis is connected to the regulatory network governed by DegU. Environmental Microbiology Reports 10(1): 23-32
Hölscher T, Schiklang T, Dragoš A, Dietel AK, Kost C, Kovács ÁT
