title: 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.
authors.affiliation: Dipartimento di Fisica Università degli studi di Napoli, Complesso Universitario Monte S. Angelo, Via Cintia 80126, Napoli, Italy. Electronic address: giuseppe.pesce@fisica.unina.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pesce
authors.affiliation: Dipartimento di Fisica Università degli studi di Napoli, Complesso Universitario Monte S. Angelo, Via Cintia 80126, Napoli, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Rusciano
authors.affiliation: Dipartimento di Fisica Università degli studi di Napoli, Complesso Universitario Monte S. Angelo, Via Cintia 80126, Napoli, Italy; CNR Istituto Nazionale di Ottica - Sezione di Napoli, Via Campi Flegrei, 34 80078 Pozzuoli, Napoli, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Sasso
authors.affiliation: Dipartimento di Biologia Università degli studi di Napoli, Complesso Universitario Monte S. Angelo, Via Cintia 80126, Napoli, Italy.
authors.forename: Rachele
authors.initials: R
authors.lastname: Isticato
authors.affiliation: Dipartimento di Biologia Università degli studi di Napoli, Complesso Universitario Monte S. Angelo, Via Cintia 80126, Napoli, Italy.
authors.forename: Teja
authors.initials: T
authors.lastname: Sirec
authors.affiliation: Dipartimento di Biologia Università degli studi di Napoli, Complesso Universitario Monte S. Angelo, Via Cintia 80126, Napoli, Italy.
authors.forename: Ezio
authors.initials: E
authors.lastname: Ricca
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry*; D057446:Hydrodynamics; D052898:Optical Tweezers; D013171:Spores, Bacterial / Q000737:chemistry; D013499:Surface Properties
keywords: B. subtilis; Electric charge; Hydrodynamic coefficient; Optical tweezers; Spore