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Bharathan G, Mundra S, Darwich DM, Saeed MM, Al Hafri ASA, Alsalmi MMSM, Maqsood S, Mudgil P, Fanning S, Srikumar S. Regulation of iron metabolism is critical for the survival of Salmonella Typhimurium in pasteurized milk. Food Microbiol 2023; 115:104326. [PMID: 37567619 DOI: 10.1016/j.fm.2023.104326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 08/13/2023]
Abstract
Salmonella is known to survive in raw/pasteurized milk and cause foodborne outbreaks. Lactoferrin, present in milk from all animal sources, is an iron-binding glycoprotein that limits the availability of iron to pathogenic bacteria. Despite the presence of lactoferrins, Salmonella can grow in milk obtained from different animal sources. However, the mechanism by which Salmonella overcomes iron scarcity induced by lactoferrin in milk is not evaluated yet. Salmonella employs the DNA binding transcriptional regulator Fur (ferric update regulator) to mediate iron uptake during survival in iron deplete conditions. To understand the importance of Fur in Salmonella milk growth, we profiled the growth of Salmonella Typhimurium Δfur (ST4/74Δfur) in both bovine and camel milk. ST4/74Δfur was highly inhibited in milk compared to wild-type ST4/74, confirming the importance of Fur mediated regulation of iron metabolism in Salmonella milk growth. We further studied the biology of ST4/74Δfur to understand the importance of iron metabolism in Salmonella milk survival. Using increasing concentrations of FeCl3, and the antibiotic streptonigrin we show that iron accumulates in the cytoplasm of ST4/74Δfur. We hypothesized that the accumulated iron could activate oxidative stress via Fenton's reaction leading to growth inhibition. However, the inhibition of ST4/74Δfur in milk was not due to Fenton's reaction, but due to the 'iron scarce' conditions of milk and microaerophilic incubation conditions which made the presence of the fur gene indispensable for Salmonella milk growth. Subsequently, survival studies of 14 other transcriptional mutants of ST4/74 in milk confirmed that RpoE-mediated response to extracytoplasmic stress is also important for the survival of Salmonella in milk. Though we have data only for fur and rpoE, many other Salmonella transcriptional factors could play important roles in the growth of Salmonella in milk, a theme for future research on Salmonella milk biology. Nevertheless, our data provide early insights into the biology of milk-associated Salmonella.
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Affiliation(s)
- Greeshma Bharathan
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates
| | - Sunil Mundra
- Department of Biology, College of Science, United Arab Emirates University, Al Ain, 15551, United Arab Emirates; Khalifa Centre for Genetic Engineering and Biotechnology, United Arab Emirates University, Al Ain, 15551, United Arab Emirates
| | - Dania Mustafa Darwich
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates
| | - Maitha Mohammad Saeed
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates
| | - Ahad Saeed Ali Al Hafri
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates
| | | | - Sajid Maqsood
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates
| | - Priti Mudgil
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates
| | - Séamus Fanning
- UCD-Centre for Food Safety, Science Centre South, University College Dublin, Dublin, D04 N2E5, Ireland
| | - Shabarinath Srikumar
- Department of Food Science, College of Agriculture and Veterinary Medicine, UAE University, Al Ain, 15551, United Arab Emirates.
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Quan LQ, Wang Y, Tang JX, Zhou Y, Liao CC, Liu D, Zhao XD, Li RT, Li HM. Valeridoids G - Q, Eleven seco-Iridoids from Valeriana jatamansi and Their Bioactivites. Chem Biodivers 2022; 19:e202200609. [PMID: 35997664 DOI: 10.1002/cbdv.202200609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/08/2022] [Indexed: 11/09/2022]
Abstract
Eleven new seco-iridoids, valeridoids G-Q (1-6 and 8-12), along with four known products, 9-epi-valtral C (7), desacylbaldrinal (13), 11-methoxyviburtinal (14) and baldrinal (15), were obtained from Valeriana jatamansi. Among them, the new compounds were identified by their NMR, HR-ESI-MS spectroscopic data and ECD calculation. Moreover, valeridoid N and O were a pair of C3 epimers, whose ether bonds between C-1 and C-3 opened, and new ether bonds formed between C-3 and C-6. Valeridoid Q belonged to the C-1 degradation of seco-iridoids. As a result, 9-epi-valtral C displayed significant inhibition on Streptococcus agalactiae, Staphylococcus aureus, Staphylococcus argenteus, Shigella flexneri and Klebsiella pneumoniae, and valeridoid Q exhibited the most significant inhibition against Salmonella enteritidis. 9-Epi-valtral C and baldrinal selectively inhibited the growth of human glioma stem cells. Valeridoid Q exhibited significant anti-influenza activity, while valeridoid O inhibited nitric oxide production.
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Affiliation(s)
- Li-Qiu Quan
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Yun Wang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Jian-Xian Tang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Yan Zhou
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Cai-Cen Liao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Dan Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Xu-Dong Zhao
- Laboratory of Animal Tumor Models, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, P. R. China
| | - Rong-Tao Li
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
| | - Hong-Mei Li
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, Yunnan, P. R. China
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Chen W, Zhang J, Li D, Wang Y. Application of Isothermal Signal Amplification Technique in the Etiological Diagnosis of Gonorrhea and Drug Resistance Gene Detection. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2022; 2022:5989889. [PMID: 35813416 PMCID: PMC9270114 DOI: 10.1155/2022/5989889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/07/2022] [Accepted: 06/11/2022] [Indexed: 11/18/2022]
Abstract
Background: Isothermal signal amplification technique is developed based on the rolling ring amplification mechanism of cyclic DNA molecules in nature. This technique plays an extremely beneficial role in gonorrhea pathogen identification and drug resistance gene detection. Aims: This study analyzes the isothermal signal amplification techniques in the etiological diagnosis of gonorrhea and drug resistance gene detection. Materials and Methods: Urethral, cervical secretion, or prostatic fluid samples from 322 cases of gonorrhea collected from January 2018 to December 2021 at the STD clinic of our hospital dermatology department were selected for direct smear examination and gonococcal culture examination; DNA was extracted from urethral, cervical secretion, or prostatic fluid samples and then used for pathogen identification by SAT assay and rolling loop nucleic acid amplification technique, smear examination and pathogen culture examination methods, SAT assay, and isothermal signal amplification technique for comparative sensitivity and specificity analysis. Results: The highest rate of gonorrhea positivity was for the urine rolling loop nucleic acid amplification technique, followed by the swab rolling loop nucleic acid amplification technique, and the lowest rate of gonorrhea positivity was for the urine SAT test. The difference in the positivity rate between the two urine testing methods was statistically significant (P < 0.05). The highest sensitivity of the urine rolling loop nucleic acid amplification technique method for the detection of gonorrhea pathogens and the lowest sensitivity of the urine SAT method were statistically significant (P < 0.01). The differences in sensitivity and specificity between the swab rolling loop nucleic acid amplification technique and the swab SAT method were not statistically significant (P > 0.05). ROC curves were plotted based on sensitivity and specificity, with swab SAT assay (AUC = 0.998) > rolling loop nucleic acid amplification technique (AUC = 0.981). Comparing the negative rates of urine and swab rolling loop nucleic acid amplification technique and urine SAT assay, the differences were not statistically significant (P > 0.05). Conclusion: The isothermal signal amplification technique improves the shortcomings of gonorrhea pathogen identification means and drug resistance gene detection methods, with good detection sensitivity and specificity, simple operation, low price, and easy promotion, which has obvious advantages in clinical applications and epidemiological studies.
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Affiliation(s)
- Wei Chen
- Wuhan Fourth Hospital, Oncology Department, China
| | | | - Dongsheng Li
- Wuhan No.1 Hospital, Department of Dermatology, China
| | - Yue Wang
- Wuhan No.1 Hospital, Department of Dermatology, China
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