Carvacrol and 1,8-cineole alone or in combination at sublethal concentrations induce changes in the cell morphology and membrane permeability of Pseudomonas fluorescens in a vegetable-based broth.
This study aimed to investigate the effects of sublethal concentrations of carvacrol (CAR) and 1,8-cineole (CIN) alone and in combination on the morphology, cell viability and membrane permeability of Pseudomonas fluorescens ATCC 11253 cultivated in a vegetable-based broth. Transmission and scanning electron microscopy images of bacterial cells exposed to CAR and CIN alone or in combination showed marked ultrastructural changes after 1h of exposure. These changes included shrunken protoplasm, discontinuity of the outer and cytoplasmic membranes and leakage of the intracellular material. Confocal scanning laser microscopy images corroborated the electron microscopy data, showing a decrease in the number of SYTO-9 cells (intact cells) with a concomitant increase in the number of PI-positive cells (dead cells). All of these morphological changes are indicative of increased membrane permeability and the loss of bacterial envelope integrity, which ultimately lead to cell death. The combination of sublethal concentrations of CAR and CIN could be applied to inhibit the growth of P. fluorescens on vegetables.
Department of Nutrition, Health Sciences Center, Federal University of Pernambuco, Recife, Brazil.
Jossana Pereira
JP
de Sousa
Rayanne de Araújo
Rde A
Torres
Geíza Alves
GA
de Azerêdo
Regina Célia Bressan Queiroz
RC
Figueiredo
Margarida Angélica da Silva
MA
Vasconcelos
Evandro Leite
EL
de Souza
D001419:Bacteria / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003511:Cyclohexanols / Q000494:pharmacology*; D000081007:Cymenes; D000077591:Eucalyptol; D005506:Food Contamination / Q000517:prevention & control; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D039821:Monoterpenes / Q000378:metabolism / Q000494:pharmacology*; D053140:Organelle Shape / Q000187:drug effects; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D014675:Vegetables / Q000382:microbiology*
D003511:Cyclohexanols; D000081007:Cymenes; D039821:Monoterpenes; C073316:carvacrol; D000077591:Eucalyptol