Surface charge and hydrodynamic coefficient measurements of Bacillus subtilis spore by optical tweezers

Abstract

In this work we report on the simultaneous measurement of the hydrodynamic coefficient and the electric charge of single Bacillus subtilis spores. The latter has great importance in protein binding to spores and in the adhesion of spores onto surfaces. The charge and the hydrodynamic coefficient were measured by an accurate procedure based on the analysis of the motion of single spores confined by an optical trap. The technique has been validated using charged spherical polystyrene beads. The excellent agreement of our results with the expected values demonstrates the quality of our procedure. We measured the charge of spores of B. subtilis purified from a wild type strain and from two isogenic mutants characterized by an altered spore surface. Our technique is able to discriminate the three spore types used, by their charge and by their hydrodynamic coefficient which is related to the hydrophobic properties of the spore surface.

Non-Stokes drag coefficient in single-particle electrophoresis: New insights on a classical problem

“…The physical picture underlying this phenomenon, known as electrophoresis [1][2][3][4][5] , dates back to Smoluchowski [6] in which the crucial element is the electroosmotic fluid flow in the Debye layer. Through clever mathematical manipulations, Smoluchowski has shown rigorously that electrophoretic mobility of the charged particle, E µ , is directly proportional to the zeta potential ζ (which is directly related to the surface charge density) on the surface of the solid particle, i.e., There have been extensive theoretical [6][7][8][9][10][11][12][13][14] and experimental [15][16][17][18][19][20] studies of a charged particle under the simultaneous effect of an electric field ∞ E and a non-electric force ext F . In particular, the electrophoretic drag coefficient E γ is of interest.…”

Electrical-charge accumulation enables integrative quality control duringB. subtilissporulation

“…We next aimed to understand the sources of negative surface potential build-up during late sporulation. The negative surface potential of developed endospores is known to be implicated with the spore-coat layers (29). Therefore, we hypothesized that the attraction of positively charged dyes to forespore surfaces is also due to the outer coat layers.…”

“…If ThT alters the yield and quality of other medically important spore-forming bacteria, such as B. anthracis, B. cereus , and C. difficile , it may offer benefits in the medical sectors as well. Spores of these species are also negatively charged on their surfaces (28, 29), which suggest the mechanism may be conserved among those species. As such, systematic investigation of the impact of ThT in various spore-forming bacterial species would be an important avenue of further research.…”

The Exosporium of Bacillus megaterium QM B1551 Is Permeable to the Red Fluorescence Protein of the Coral Discosoma sp.

“…In Bacillus subtilis , the model system for spore formers, the spore surface is organized in a multilayered coat and in a crust, a recently discovered layer that surrounds the spore coat (McKenney et al, 2012). B. subtilis spores are negatively charged (Huang et al, 2010; Pesce et al, 2014) and have a relative hydrophobicity that is in part due to the glycosylation of some spore surface proteins (Cangiano et al, 2014; Rusciano et al, 2014). In several Bacillus and Clostridium species, including B. cereus, B. anthracis, B. megaterium , and C. difficile , the outermost spore structure is the exosporium, a morphologically distinct layer composed of proteins and glycoproteins that surrounds the coat (Díaz-González et al, 2015; Manetsberger et al, 2015b; Stewart, 2015).…”