Project description:The objective of the study was to uncover the developmental dynamics in Bacillus subtilis biofilms on a transcriptome level. The experiment covered a developmental timeline over two months of biofilm growth.
Project description:Investigation of the kinetics of whole genome gene expression level changes in Bacillus subtilis NDmed strain during formation of submerged biofilm and pellicle. The Bacillus subtilis NDmed strain analyzed in this study is able to form thick and highly structured submerged biofilms as described in Bridier et al., (2011) The Spatial Architecture of Bacillus subtilis Biofilms Deciphered Using a Surface-Associated Model and In Situ Imaging. PLoS ONE 6(1):e16177.
Project description:Correspondence between evolution and development has been discussed for more than two centuries. Recent work reveals that phylogeny-ontogeny correlations are indeed present in developmental transcriptomes of eukaryotic clades with complex multicellularity. Nevertheless, it has been largely ignored that the pervasive presence of phylogeny-ontogeny correlations is likely a hallmark of development in eukaryotes. This perspective opens a possibility to look for similar parallelisms in biological settings where developmental logic and multicellular complexity are more obscure. For instance, it has been increasingly recognized that multicellular behavior underlies biofilm formation in bacteria. However, it remains unclear whether bacterial biofilm growth shares some basic principles with development in complex eukaryotes. Here we show that ontogeny of growing Bacillus subtilis biofilms recapitulates phylogeny at the expression level. Using finely resolved transcriptome and proteome profiles, we found that biofilm ontogeny correlates with the evolutionary measures. Early-stage biofilms expressed older and more conserved genes, while later-stage biofilms progressively used evolutionary younger and more diverged genes. Molecular and morphological signatures also revealed that biofilm growth is highly regulated and organized into discrete ontogenetic stages, similar to those of eukaryotic embryos. In conjunction this suggests that biofilm formation in Bacillus is a bona fide developmental process comparable to organismal development in animals, plants and fungi. Given that most cells on Earth reside in the form of biofilms and that biofilms represent the oldest known fossils, we anticipate that the widely-adopted vision of the first life as a single-cell and free-living organism needs rethinking.
Project description:Ravindra Garde, Bashar Ibrahim & Stefan Schuster. Extending the minimal model of metabolic oscillations in Bacillus subtilis biofilms. Scientific Reports 10, 1 (2020).
Biofilms are composed of microorganisms attached to a solid surface or floating on top of a liquid surface. They pose challenges in the field of medicine but can also have useful applications in industry. Regulation of biofilm growth is complex and still largely elusive. Oscillations are thought to be advantageous for biofilms to cope with nutrient starvation and chemical attacks. Recently, a minimal mathematical model has been employed to describe the oscillations in Bacillus subtilis biofilms. In this paper, we investigate four different modifications to that minimal model in order to better understand the oscillations in biofilms. Our first modification is towards making a gradient of metabolites from the center of the biofilm to the periphery. We find that it does not improve the model and is therefore, unnecessary. We then use realistic Michaelis-Menten kinetics to replace the highly simple mass-action kinetics for one of the reactions. Further, we use reversible reactions to mimic the diffusion in biofilms. As the final modification, we check the combined effect of using Michaelis-Menten kinetics and reversible reactions on the model behavior. We find that these two modifications alone or in combination improve the description of the biological scenario.
Project description:Biofilms offer an excellent example of ecological interaction among bacteria. Temporal and spatial oscillations in biofilms are an emerging topic. In this paper, we describe the metabolic oscillations in Bacillus subtilis biofilms by applying the smallest theoretical chemical reaction system showing Hopf bifurcation proposed by Wilhelm and Heinrich in 1995. The system involves three differential equations and a single bilinear term. We specifically select parameters that are suitable for the biological scenario of biofilm oscillations. We perform computer simulations and a detailed analysis of the system including bifurcation analysis and quasi-steady-state approximation. We also discuss the feedback structure of the system and the correspondence of the simulations to biological observations. Our theoretical work suggests potential scenarios about the oscillatory behaviour of biofilms and also serves as an application of a previously described chemical oscillator to a biological system.
Project description:Soybeans fermented by Bacillus subtilis BJ3-2 exhibits strong ammonia taste in medium temperature below 37℃ and prominent soy sauce-like aroma moderate temperatures above 45℃. The transcriptome sequencing of Bacillus subtilis BJ3-2 (incubating at 37°C and 45°C) has been completed, screening of differentially expressed genes (DEGs) through data analysis, and analyzing their metabolic pathways, laying a foundation for exploring the regulatory mechanism of soy sauce-like aroma formation.
Project description:Identification of the specific WalR (YycF) binding regions on the B. subtilis chromosome during exponential and phosphate starvation growth phases. The data serves to extend the WalRK regulon in Bacillus subtilis and its role in cell wall metabolism, as well as implying a role in several other cellular processes.
Project description:In nature, bacteria form biofilms – differentiated multicellular communities attached to surfaces. In the otherwise sessile biofilms, a subset of cells continues to express motility genes. Here, we demonstrate a biological role for this subpopulation, which enabled biofilms of Bacillus subtilis to expand on high-friction surfaces. Moreover, we show that the extracellular matrix (ECM) protein TasA was required for the expression of flagellar genes. In addition to its structural role as an adhesive fiber for cell attachment, TasA served as a developmental signal similar to ECM proteins of multicellular organisms. Transcriptomic analysis revealed that TasA regulated a specific subset of genes, inducing genes involved in motility and repressing ECM production. A screen for suppressor mutations that restore motility in the absence of TasA revealed activation of the biofilm-motility switch by the two-component system CssRS, that alleviated Spo0A repression by TasA. Our results suggest that although mostly sessile, biofilms retain a degree of motility by maintaining a motile subpopulation.
Project description:Bacillus subtilis is exposed to a wide range of transitory stress and starvation conditions. Here we investigate the expression changes observed in the B. subtilis wild type strain 168 and its isogenic sigB mutant(BSM29) with respect to each stress condition tested.
Project description:In nature, bacteria reside in biofilms - multicellular differentiated communities held together by extracellular matrix. In this work, we identified a novel subpopulation essential for biofilm formation – mineral-forming cells in Bacillus subtilis biofilms. This subpopulation contains an intracellular calcium-accumulating niche, in which the formation of a calcium carbonate mineral is initiated. As the biofilm colony develops, this mineral grows in a controlled manner, forming a functional macrostructure that serves the entire community. Consistently, biofilm development is prevented by inhibition of calcium uptake. Taken together, our results provide a clear demonstration of the orchestrated production of calcite exoskeleton, critical to morphogenesis in simple prokaryotes. We expect future research exploring this newly discovered process to shed further light on mechanisms of bacterial development.