scholarly journals Effects of 405 ± 5-nm LED Illumination on Environmental Stress Tolerance of Salmonella Typhimurium in Sliced Beef

Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 136
Author(s):  
Du Guo ◽  
Yichen Bai ◽  
Shengyi Fei ◽  
Yanpeng Yang ◽  
Jiahui Li ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Environmental Stress ◽  
Salmonella Typhimurium ◽  
Bile Salts ◽  
Foodborne Pathogen ◽  
Acid Stress ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Pressure Oxidation ◽  
Light Emitting

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.

scholarly journals A Novel LysR Family Factor STM0859 is Associated with The Responses of Salmonella Typhimurium to Environmental Stress and Biofilm Formation

2021 ◽  
Vol 70 (4) ◽  
pp. 479-487
Author(s):  
ZHONGMEI MA ◽  
NA LI ◽  
CHENGCHENG NING ◽  
YUCHENG LIU ◽  
YUN GUO ◽  
...  
Keyword(s):  
Environmental Stress ◽  
Salmonella Typhimurium ◽  
Biofilm Formation ◽  
Wild Strain ◽  
Acid Stress ◽  
Environmental Stresses ◽  
Pcr Analysis ◽  
Mobility Shift ◽  
Complementation Strain ◽  
Lysr Family

Salmonella enterica subsp. enterica serovar Typhimurium (ST) is an intracellularly parasitic bacterium. This zoonotic pathogen causes food poisoning and thus imposes a severe threat to food safety. Here, to understand the regulatory roles of the novel transcription factor STM0859 on the response of ST to environmental stress and biofilm formation, the STM0859 gene-deficient strain and the complementation strain ΔSTM0859/STM0859 were generated, respectively. Then, its capacity of responding to environmental stresses and biofilm (BF) formation ability under different stresses, including acid, alkali, high salt, cholate, and oxidative stresses was tested. We further analyzed the interaction between the STM0859 protein and the promoter of the acid stress response-related gene rcsB by performing an electrophoresis mobility shift assay (EMSA). The results showed that acid resistance and BF formation capacities of ST-ΔSTM0859 strain were significantly weaker, as compared with those of Salmonella Typhimurium SL1344 (ST-SL1344) wild strain (p < 0.01). Quantitative qRT-PCR analysis showed that the expression levels of acid stress and BF formation-related genes, rcsB and rpoS, of ST-ΔSTM0859 strain were significantly reduced at the transcription levels, while the transcription levels of these genes were fully restored in complementation strain ST-ΔSTM0859/STM0859. The results of EMSA showed that STM0859 was capable of binding the promoter DNA fragments of the rcsB gene, suggesting that STM0859 can promote the transcription of the rcsB gene through interaction with its promoter, thereby exerting an indirectly regulatory role on the adaptive responses to acid stress and BF formation of ST. This study provided new insights into the regulatory mechanisms of the LysR family factors on the tolerances of ST under adverse environmental stresses.

scholarly journals Nanosized Liposomes Containing Bile Salt: A Vesicular Nanocarrier for Enhancing Oral Bioavailability of BCS Class III Drug

2017 ◽  
Vol 20 ◽  
pp. 305 ◽  
Author(s):  
Mosab Arafat ◽  
Cathrin Kirchhoefer ◽  
Momir Mikov ◽  
Muhammad Sarfraz ◽  
Raimar Löbenberg
Keyword(s):  
Bile Salt ◽  
Oral Bioavailability ◽  
Bile Salts ◽  
Structural Integrity ◽  
Sodium Deoxycholate ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Class Iii ◽  
Simulated Intestinal Fluid ◽  
Fed State

PURPOSE: Liposomes have been studied as a colloidal carrier in drug delivery systems, especially for oral administration. However, their low structural integrity in the gut is still a major shortcoming. Membrane disruptive effects of physiological bile salts in the small intestine result in premature drug release prior to intestinal absorption. Thus, we analyzed the stabilizing effect of sodium deoxycholate when incorporated into nano-sized liposomes. METHOD: Cefotaxime-loaded liposomes were prepared with different sodium deoxycholate concentrations (3.75- 30 mM) by rotary film evaporation followed by nano-size reduction. The physical integrity of liposomes was evaluated by monitoring cefotaxime leakage, particle sizes in different simulated physiological media. The oral bioavailability and pharmacokinetics of cefotaxime was assessed in rats (n = 6 per group) after single dose of drug-encapsulated in liposomes containing bile salt, drug in conventional liposomes, and cefotaxime solution (oral and intravenous). RESULTS: Simulated gastric fluid with low pH showed less effect on the stability of liposomes in comparison to media containing physiological bile salts.  Liposomes containing 15 mM sodium deoxycholate were most stable in size and retained the majority of encapsulated cefotaxime even in fed state of simulated intestinal fluid being the most destructive media. Pharmacokinetics data showed an increase in Cmax and AUC0-inf in the following order: cefotaxime solution < conventional liposomes < liposomes made with bile salts. The total oral bioavailability of cefotaxime in liposomes containing bile salt was found to be 5-times higher compared to cefotaxime solution and twice as much as in conventional liposomes. CONCLUSION: Incorporation of bile salts, initially used as membrane permeation enhancer, also acted as a stabilizer against physiological bile salts. The nano-sized liposomes containing sodium deoxycholate were able to reduce the leakage of encapsulated cefotaxime in the gut due to the improved vesicle stability and to enhance the oral bioavailability of acid-labile drugs up to 5-fold. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

scholarly journals Prior Exposure to Dry-Cured Meat Promotes Resistance to Simulated Gastric Fluid in Salmonella Typhimurium

Foods ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 603 ◽  
Author(s):  
Yhan S. Mutz ◽  
Denes K. A. Rosario ◽  
Vinicius S. Castro ◽  
Patricia C. Bernardes ◽  
Vania M. F. Paschoalin ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Salmonella Enterica ◽  
Meat Product ◽  
Foodborne Pathogen ◽  
Acid Tolerance ◽  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
Pathogen Inactivation ◽  
Cured Meat

This study assessed if exposure of foodborne Salmonella enterica in Brazilian dry-cured loin (BDL) affects pathogen inactivation in simulated gastric fluid (SGF). The acid tolerance responses of three Salmonella enterica serovars, Typhimurium, Derby and Panama, were assessed by an acid challenge trial at pH 3.0 for 4 h following pre-adaptation to three conditions: neutral pH, acidic pH (4.5) or BDL matrix. The influence of Salmonella exposure temperature and time in the BDL on pathogen gastric fluid resistance was evaluated by the response surface methodology. The Salmonella serovars acquired acid tolerance when exposed to the BDL matrix and their response to acid stress was strain-dependent, with S. Typhimurium being the most tolerant strain. S. Typhimuirum exposed to temperatures >25 °C in the BDL matrix displayed increased resistance to SGF. By using the response surface methodology, it was determined that S. Typhimurium becomes less resistant against SGF if maintained in the BDL matrix at temperatures <7 °C, reinforcing the recommendation to store dry-cured meat under refrigeration in order to minimize consumer risks. The results presented herein point to a novel aspect of hurdle technology that should be taken into account to further understand the risks associated with hurdle-stable meat product, such as dry-cured meats, concerning foodborne pathogen contamination.

Listeria monocytogenes ArcA contributes to acid tolerance

2013 ◽  
Vol 62 (6) ◽  
pp. 813-821 ◽  
Author(s):  
Changyong Cheng ◽  
Jianshun Chen ◽  
Ying Shan ◽  
Chun Fang ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Bacterial Load ◽  
Foodborne Pathogen ◽  
Acid Stress ◽  
Intestinal Barrier ◽  
Systemic Infection ◽  
Acid Tolerance ◽  
Gastric Fluid ◽  
Arginine Deiminase

The foodborne pathogen Listeria monocytogenes is able to colonize the human and animal intestinal tracts and subsequently crosses the intestinal barrier, causing systemic infection. For successful establishment of infection, L. monocytogenes must survive and adapt to the low pH environment of the stomach. Gene sequence analysis indicates that lmo0043, an orthologue of arcA, encodes a protein containing conserved motifs and critical active amino acids characteristic of arginine deiminase that mediates an arginine deimination reaction. We attempted to characterize the role of ArcA in acid tolerance in vitro and in mice models. Transcription of arcA was significantly increased in L. monocytogenes culture subjected to acid stress at pH 4.8, as compared with that at pH 7.0. Deletion of arcA impaired growth of L. monocytogenes under mild acidic conditions at pH 5.5, and reduced its survival in synthetic human gastric fluid at pH 2.5 and in the murine stomach. Bacterial load in the spleen of mice intraperitoneally inoculated with an arcA deletion mutant was significantly lower than that of the wild-type strain. These phenotypic changes were recoverable by genetic complementation. Thus, we conclude that L. monocytogenes arcA not only mediates acid tolerance in vitro but also participates in gastric survival and virulence in mice.

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

Molecules ◽  
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.

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

2019 ◽  
Vol 127 (5) ◽  
pp. 1564-1575 ◽  
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

scholarly journals Isolation, Identification and Function of Pichia anomala AR2016 and Its Effects on the Growth and Health of Weaned Pigs

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1179
Author(s):  
Yajun Ma ◽  
Zhihong Sun ◽  
Yan Zeng ◽  
Ping Hu ◽  
Weizhong Sun ◽  
...  
Keyword(s):  
Oral Administration ◽  
Relative Abundance ◽  
Bile Salts ◽  
Average Daily Gain ◽  
Pichia Anomala ◽  
Simulated Gastric Fluid ◽  
Transferase Activity ◽  
Mrna Levels ◽  
Weaned Pigs ◽  
Intestinal Juice

This study isolates and identifies Pichia anomala (P. anomala) AR2016, and studies its effect on the growth and health of weaned pigs. A P. anomala strain from solid wine koji is isolated and identified using 26S rDNA analysis, and its culture conditions are optimized. Heat tolerance, bile salt tolerance, artificial gastric, and intestinal juice tolerance are evaluated. In our methodology, thirty 28 d Large White × Landrace × Rongchang weaned pigs were randomly divided into three groups with 10 barrows in each, and fed a maize-soybean meal diet and orally administered 0.85% saline (CK), 1 mL 1 × 109 cfu/mL Candida utilis (C. utilis), and 1 mL 1 × 109 cfu/mL P. anomala once daily for 28 days. A P. anomala strain was identified and named P. anomala AR2016. P. anomala AR2016 grew best in yeast extract peptone dextrose medium with pH 5.0 at 28 °C, 180 r/min and could tolerate 45 °C for 0.5 h, 0.2% pig bile salts, simulated gastric fluid, and 1.0% simulated intestinal fluid. Our results show that compared with the CK group, orally administered P. anomala AR2016 increases average daily gain, the ileal villus height, the ileal mucosal concentrations of occludin and zonula occluens-1, the serum glucose and total protein concentration, total superoxide dismutase, glutathione peroxidase, and total antioxidative capacity activity, the trypsin and lipase activity in jejunal and ileal contents, the jejunal and ileal mucosa mRNA levels of ALP, TNF-α, and TLR-2, and the relative abundance of Bacteroidetes, Actinobacteria, Succinivibrionaceae, Lachnospiraceae, and Prevotellaceae (p < 0.05). Compared with the CK group, oral administration of P. anomala AR2016 decreased the incidence of diarrhea, aspartate aminotransferase activity, alanine amino-transferase-activity, malondialdehyde, D-lactic acid and endotoxin content in serum, the mRNA level of aminopeptidase N of ileum mucosa, and the relative abundance of Proteobacteria, Clostridiaceae, Campylobacteraceae, Vibrionaceae, Bacillus, and Pseudon (p < 0.05). Collectively, the study indicates that P. anomala AR2016 can tolerate high acidity and high bile salts, and has high survivability in the artificial gastric intestinal juice environment. Oral administration of P. anomala AR2016 improves the growth performance, reduces the incidence of diarrhea, enhances intestinal barrier function, and improves microflora in weaned pigs.

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