Flow cytometric assessment of the effect of simulated gastric fluid (SGF) on the survival of Salmonella typhimurium, Shigella dysenteriae and Shigella flexneri

Salmonella Typhimurium is a widely distributed foodborne pathogen and is tolerant of various environmental conditions. It can cause intestinal fever, gastroenteritis and bacteremia. The aim of this research was to explore the effect of illumination with 405 nm light-emitting diodes (LEDs) on the resistance of S. Typhimurium to environmental stress. Beef slices contaminated with S. Typhimurium were illuminated by 405 nm LEDs (18.9 ± 1.4 mW/cm2) for 8 h at 4 °C; controls were incubated in darkness at 7 °C. Then, the illuminated or non-illuminated (control) cells were exposed to thermal stress (50, 55, 60 or 65 °C); oxidative stress (0.01% H2O2 [v/v]); acid stress (simulated gastric fluid [SGF] at pH 2 or 3); or bile salts (1%, 2%, or 3% [w/v]). S. Typhimurium treated by 405 nm LED irradiation showed decreased resistance to thermal stress, osmotic pressure, oxidation, SGF and bile salts. The transcription of eight environmental tolerance-related genes were downregulated by the illumination. Our findings suggest the potential of applying 405 nm LED-illumination technology in the control of pathogens in food processing, production and storage, and in decreasing infection and disease related to S. Typhimurium.

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Comparative survival of Salmonella typhimurium DT 104, Listeria monocytogenes, and Escherichia coli O157:H7 in preservative-free apple cider and simulated gastric fluid

International Journal of Food Microbiology ◽

10.1016/s0168-1605(98)00198-6 ◽

1999 ◽

Vol 46 (3) ◽

pp. 263-269 ◽

Cited By ~ 75

Author(s):

A Roering

Keyword(s):

Escherichia Coli ◽

Listeria Monocytogenes ◽

Salmonella Typhimurium ◽

Gastric Fluid ◽

Simulated Gastric Fluid ◽

Escherichia Coli O157 ◽

Apple Cider ◽

Preservative Free

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Formulation of Quaternized Aminated Chitosan Nanoparticles for Efficient Encapsulation and Slow Release of Curcumin

Molecules ◽

10.3390/molecules26020449 ◽

2021 ◽

Vol 26 (2) ◽

pp. 449

Author(s):

Ahmed M. Omer ◽

Zyta M. Ziora ◽

Tamer M. Tamer ◽

Randa E. Khalifa ◽

Mohamed A. Hassan ◽

...

Keyword(s):

Slow Release ◽

Sodium Tripolyphosphate ◽

Chitosan Nanoparticles ◽

Gastric Fluid ◽

Release Profile ◽

Simulated Gastric Fluid ◽

Maximum Value ◽

Structure Surface ◽

Drug Encapsulation Efficiency

An effective drug nanocarrier was developed on the basis of a quaternized aminated chitosan (Q-AmCs) derivative for the efficient encapsulation and slow release of the curcumin (Cur)-drug. A simple ionic gelation method was conducted to formulate Q-AmCs nanoparticles (NPs), using different ratios of sodium tripolyphosphate (TPP) as an ionic crosslinker. Various characterization tools were employed to investigate the structure, surface morphology, and thermal properties of the formulated nanoparticles. The formulated Q-AmCs NPs displayed a smaller particle size of 162 ± 9.10 nm, and higher surface positive charges, with a maximum potential of +48.3 mV, compared to native aminated chitosan (AmCs) NPs (231 ± 7.14 nm, +32.8 mV). The Cur-drug encapsulation efficiency was greatly improved and reached a maximum value of 94.4 ± 0.91%, compared to 75.0 ± 1.13% for AmCs NPs. Moreover, the in vitro Cur-release profile was investigated under the conditions of simulated gastric fluid [SGF; pH 1.2] and simulated colon fluid [SCF; pH 7.4]. For Q-AmCs NPs, the Cur-release rate was meaningfully decreased, and recorded a cumulative release value of 54.0% at pH 7.4, compared to 73.0% for AmCs NPs. The formulated nanoparticles exhibited acceptable biocompatibility and biodegradability. These findings emphasize that Q-AmCs NPs have an outstanding potential for the delivery and slow release of anticancer drugs.

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Modelling inactivation of wild‐type and clinical Escherichia coli O26 strains using UV‐C and thermal treatment and subsequent persistence in simulated gastric fluid

Journal of Applied Microbiology ◽

10.1111/jam.14397 ◽

2019 ◽

Vol 127 (5) ◽

pp. 1564-1575 ◽

Cited By ~ 5

Author(s):

V.S. Castro ◽

D.K.A. Rosario ◽

Y.S. Mutz ◽

A.C.C. Paletta ◽

E.E.S. Figueiredo ◽

...

Keyword(s):

Escherichia Coli ◽

Thermal Treatment ◽

Gastric Fluid ◽

Simulated Gastric Fluid ◽

Wild Type ◽

Uv C

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Fabrication of Multi-Layered Microspheres Based on Phase Separation for Drug Delivery

Micromachines ◽

10.3390/mi12060723 ◽

2021 ◽

Vol 12 (6) ◽

pp. 723

Author(s):

He Xia ◽

Ang Li ◽

Jia Man ◽

Jianyong Li ◽

Jianfeng Li

Keyword(s):

Aqueous Solution ◽

Phase Separation ◽

Gastric Fluid ◽

Simulated Gastric Fluid ◽

Sustained Drug Release ◽

Simulated Intestinal Fluid ◽

Glycol Diacrylate ◽

Emulsion Droplets ◽

Collection Tube ◽

Poly Ethylene

In this work, we used a co-flow microfluidic device with an injection and a collection tube to generate droplets with different layers due to phase separation. The phase separation system consisted of poly(ethylene glycol) diacrylate 700 (PEGDA 700), PEGDA 250, and sodium alginate aqueous solution. When the mixture droplets formed in the outer phase, PEGDA 700 in the droplets would transfer into the outer aqueous solution, while PEGDA 250 still stayed in the initial droplet, breaking the miscibility equilibrium of the mixture and triggering the phase separation. As the phase separation proceeded, new cores emerged in the droplets, gradually forming the second and third layers. Emulsion droplets with different layers were polymerized under ultraviolet (UV) irradiation at different stages of phase separation to obtain microspheres. Microspheres with different layers showed various release behaviors in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The release rate decreased with the increase in the number of layers, which showed a potential application in sustained drug release.

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