0000000000177042
AUTHOR
Pauline Loison
Viscosity mapping of the structures of Bacillus subtilis spores by fluorescence lifetime imaging
International audience; L’état de la membrane plasmique des cellules est un élément essentiel pour connaitre la conditionphysiologique des cellules. Sur des microorganismes, cette connaissance permet de mesurer l’impact d’uneperturbation sur la structure cellulaire et sur sa survie ultérieure. La fluidité membranaire résulte tout à lafois de la composition en phospholipides, de la présence et du rôle de certaines molécules comme lesstérols, les protéines transmembranaires mais aussi des conditions thermodynamiques et physico-chimiquesextérieures (P, T, aw). La bactérie Bacillus subtilis est capable dans des conditions défavorables de passerd’un état actif végétatif à l’état de spore, état d…
Study of Bacillus subtilis spore's : characterication of stuctures implied in its resistance
The bacterial spore is a multilayer microbial form which is extremely resistant to environmental perturbations. This resistance is especially due to its unique structure which is particularly compact and weakly permeable. This work aims to identify and characterize the spore structures involved in these properties. Overall investigation methods, such as NMR and fluorescence anisotropy, have shown that the cortex of Bacillus subtilis spores is modified by temperature for level similar to that of the activation of germination. This will result in changes to the access to the inner membrane. A tool at the spore’s scale, the fluorescence lifetime imaging microscopy (FLIM) in conjunction with th…
Physico-chemical state influences in vitro release profile of curcumin from pectin beads
International audience; Curcumin is a polyphenolic compound with diverse effects interesting to develop health benefit products but its formulation in functional foods or in food supplement is hampered by its poor water solubility and susceptibility to alkaline conditions, light, oxidation and heat. Encapsulation of curcumin could be a mean to overcome these difficulties. In this paper, curcumin was encapsulated by ionotropic gelation method in low methoxyl pectin beads associated with different surfactants: Solutol®, Transcutol® and sodium caseinate. After encapsulation, physico-chemical properties of encapsulated curcumin such as its solubility, physical state, tautomeric forms and encaps…
Direct investigation of viscosity of an atypical inner membrane of Bacillus spores: A molecular rotor/FLIM study
Abstract We utilize the fluorescent molecular rotor Bodipy-C12 to investigate the viscoelastic properties of hydrophobic layers of bacterial spores Bacillus subtilis. The molecular rotor shows a marked increase in fluorescence lifetime, from 0.3 to 4 ns, upon viscosity increase from 1 to 1500 cP and can be incorporated into the hydrophobic layers within the spores from dormant state through to germination. We use fluorescence lifetime imaging microscopy to visualize the viscosity inside different compartments of the bacterial spore in order to investigate the inner membrane and relate its compaction to the extreme resistance observed during exposure of spores to toxic chemicals. We demonstr…