Essential oils are known to exhibit diverse antimicrobial properties, showing their value as a natural resource. Our work aimed to investigate the primary mode of action of Cuban
(Kunth) essential ...oil (EO) against
subsp.
serovar Typhimurium (
ser. Typhimurium). We assessed cell integrity through various assays, including time-kill bacteriolysis, loss of cell material with absorption at 260 and 280 nm, total protein leakage, and transmission electron microscopy (TEM). The impact of
EO on membrane depolarization was monitored and levels of intracellular and extracellular ATP were measured by fluorescence intensity. The minimum inhibitory and bactericidal concentrations (MIC and MBC) of
EO were 0.4 and 0.8 mg/mL, respectively. This EO exhibited notable bactericidal effects on treated cells within 15 min without lysis or leakage of cellular material. TEM showed distinct alterations in cellular ultrastructure, including membrane shrinkage and cytoplasmic content redistribution. We also observed disruption of the membrane potential along with reduced intracellular and extracellular ATP concentrations. These findings show that
EO induces the death of
ser. Typhimurium, important information that can be used to combat this foodborne disease-causing agent.
The synthesis of silver nanoparticles (SNP) from plants is a simple, fast and environmentally safe route. In the present study, the aqueous extract of fresh leaves from
Leea coccinea
L. was evaluated ...as a possible source of reducing and stabilizing agents to obtain SNP. The synthesized SNP were characterized by spectroscopic techniques such as UV–visible spectrophotometry and Fourier transform infrared spectroscopy (FTIR), scanning electron and confocal microscopies and the antimicrobial activity against
Xanthomonas phaseoli
pv.
phaseoli
was evaluated using agar diffusion methods. The results showed that the evaluated extract was promising for the green synthesis of the SNP, which was visually identified by the formation of a dark-brown complex and the presence of a peak of maximum absorption at 470 nm in a UV–VIS spectrum. FTIR spectrum of SNP showed main characteristic signals of aromatic compounds, carboxylic group among others confirmed by phytochemical screening that made evident the presence of flavonoids, phenols, leucoanthocyanidins, terpenes and steroids groups. Fluorescent SNP with high degree of agglomeration were observed by the microscopical technics used. A promising antibacterial activity of SNP was shown by a zone of microbial growth inhibition. These results suggested the need for going deeper in the physico-chemical characterization and kinetic studies, as well as the biological evaluations to make possible the use of this plant source in the future development of antibacterial formulations for bean seed protection.
Essential oils are known to exhibit diverse antimicrobial properties, showing their value as a natural resource. Our work aimed to investigate the primary mode of action of Cuban Lippia graveolens ...(Kunth) essential oil (EO) against Salmonella enterica subsp. enterica serovar Typhimurium (S. enterica ser. Typhimurium). We assessed cell integrity through various assays, including time-kill bacteriolysis, loss of cell material with absorption at 260 and 280 nm, total protein leakage, and transmission electron microscopy (TEM). The impact of L. graveolens EO on membrane depolarization was monitored and levels of intracellular and extracellular ATP were measured by fluorescence intensity. The minimum inhibitory and bactericidal concentrations (MIC and MBC) of L. graveolens EO were 0.4 and 0.8 mg/mL, respectively. This EO exhibited notable bactericidal effects on treated cells within 15 min without lysis or leakage of cellular material. TEM showed distinct alterations in cellular ultrastructure, including membrane shrinkage and cytoplasmic content redistribution. We also observed disruption of the membrane potential along with reduced intracellular and extracellular ATP concentrations. These findings show that L. graveolens EO induces the death of S. enterica ser. Typhimurium, important information that can be used to combat this foodborne disease-causing agent.
RESUMEN Las infecciones ocasionadas por Staphylococcus aureus constituyen una problemática para la salud animal y humana. El objetivo de este trabajo fue determinar la concentración mínima ...inhibitoria (CMI) y la concentración mínima bactericida (CMB) de nanopartículas de plata (NpAg) obtenidas por síntesis verde con extracto de hojas de Leea coccinea sobre cepas de Staphylococcus aureus y aislados resistentes a meticilina. Se evaluaron tres lotes de NpAg de Leea coccinea sobre dos cepas S. aureus y dos aislados resistentes a meticilina, por el método de diluciones seriadas, para la determinación de CMI y CMB. Las NpAg de Leea coccinea mostraron actividad antibacteriana sobre las cepas y los aislados resistentes de S. aureus, con valores de CMI para los tres lotes que coincidieron en su mayoría en 0,03 mg/mL para todas las cepas y los aislados. En los valores de CMB en los tres lotes concordaron y se observaron diferencias entre los valores para los aislados resistentes (0,485 mg/mL) y las cepas (0,12 mg/mL). Estos resultados demuestran la actividad antibacteriana de las NpAg de Leea coccinea sobre este patógeno, destacan sus potencialidades como alternativa ante la resistencia a antibióticos y crean las bases para otros estudios con vista a una futura aplicación como antibacteriano.
RESUMEN Las infecciones por Salmonella spp. (salmonelosis) son la segunda causa mayoritaria de enfermedades transmitidas por alimentos a nivel mundial. Ante la creciente emergencia de cepas ...resistentes a antibióticos, se buscan alternativas para el tratamiento; los aceites esenciales son productos que se destacan por sus potencialidades como antimicrobianos. El objetivo de este trabajo fue determinar la actividad antibacteriana de aceites esenciales de plantas cultivadas en Cuba sobre cepas de Salmonella enterica. Los aceites esenciales se obtuvieron por hidrodestilación o expresión. Se realizó la evaluación de la acción antibacteriana de 15 aceites por difusión en agar; se seleccionaron los promisorios y se les determinó la concentración mínima inhibitoria (CMI) y mínima bactericida (CMB) por la técnica de diluciones seriadas. Los aceites esenciales de Ocimum gratissimum L., Lippia graveolens (Kunth) y Thymus vulgaris L. inhibieron el crecimiento de las cepas de Salmonella enterica, incluyendo cepas resistentes a antibióticos. Los valores de CMI y CMB de los aceites oscilaron entre 0,5 mg/mL y 1 mg/mL, respectivamente. Estos aceites esenciales son candidatos promisorios para el desarrollo de productos antibacterianos destinados al control de la salmonelosis.
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