Topography and Expansion Patterns at the Biofilm-Agar Interface in Bacillus subtilis Biofilms.

Sarah Gingichashvili,Doron Steinberg,Osnat Feuerstein

doi:10.3390/microorganisms9010084

Sarah Gingichashvili, Doron Steinberg + Show 1 more

Open Access

https://doi.org/10.3390/microorganisms9010084

Copy DOI

Journal: Microorganisms	Publication Date: Dec 31, 2020
Citations: 13	License type: CC BY 4.0

Affiliation: Hebrew University of Jerusalem

Abstract

Bacterial biofilms are complex microbial communities which are formed on various natural and synthetic surfaces. In contrast to bacteria in their planktonic form, biofilms are characterized by their relatively low susceptibility to anti-microbial treatments, in part due to limited diffusion throughout the biofilm and the complex distribution of bacterial cells within. The virulence of biofilms is therefore a combination of structural properties and patterns of adhesion that anchor them to their host surface. In this paper, we analyze the topographical properties of Bacillus subtilis’ biofilm-agar interface across different growth conditions. B. subtilis colonies were grown to maturity on biofilm-promoting agar-based media (LBGM), under standard and stress-inducing growth conditions. The biofilm-agar interface of the colony type biofilms was modeled using confocal microscopy and computational analysis. Profilometry data was obtained from the macrocolonies and used for the analysis of surface topography as it relates to the adhesion modes present at the biofilm-agar interface. Fluorescent microspheres were utilized to monitor the expansion patterns present at the interface between the macrocolonies and the solid growth medium. Contact surface analysis reveals topographical changes that could have a direct effect on the adhesion strength of the biofilm to its host surface, thus affecting its potential susceptibility to anti-microbial agents. The topographical characteristics of the biofilm-agar interface partially define the macrocolony structure and may have significant effects on bacterial survival and virulence.

Highlights

Bacterial biofilms are found in abundance in nature—these microbial communities, which are often characterized by a complex, self-secreted extracellular matrix, readily form on various natural and synthetic surfaces
We focus on biofilm surface topography directly at the interface between the macrocolony and agar substrate
In this paper we explore surface topography at the biofilm-agar interface, where it determines in part the expansion patterns and the modes of adhesion between the macrocolony and growth medium

Summary

Introduction

Bacterial biofilms are found in abundance in nature—these microbial communities, which are often characterized by a complex, self-secreted extracellular matrix, readily form on various natural and synthetic surfaces. The matrix in which bacterial cells are embedded consists of exopolysaccharides and other types of biomolecules such as lipids, proteins and nucleic acids. The interaction between components of the extracellular matrix was shown to play a role in the three-dimensional structuring of biofilms [4,5]. In B. subtilis biofilms, presence of specific biomaterials such as calcite minerals [6] and amyloid fibers [7] was shown to provide structural integrity and “robustness”. Bacteria in the biofilm microenvironment, as opposed to their planktonic state, benefit from increased resilience— due to limited diffusion of anti-microbial agents, and due to the complex bacterial organization within the biofilms.

Methods

Results

Conclusion