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Zeng Y, Li P, Liu S, Shen M, Liu Y, Zhou X. Salmonella enteritidis acquires phage resistance through a point mutation in rfbD but loses some of its environmental adaptability. Vet Res 2024; 55:85. [PMID: 38970094 PMCID: PMC11227202 DOI: 10.1186/s13567-024-01341-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 04/07/2024] [Indexed: 07/07/2024] Open
Abstract
Phage therapy holds promise as an alternative to antibiotics for combating multidrug-resistant bacteria. However, host bacteria can quickly produce progeny that are resistant to phage infection. In this study, we investigated the mechanisms of bacterial resistance to phage infection. We found that Rsm1, a mutant strain of Salmonella enteritidis (S. enteritidis) sm140, exhibited resistance to phage Psm140, which was originally capable of lysing its host at sm140. Whole genome sequencing analysis revealed a single nucleotide mutation at position 520 (C → T) in the rfbD gene of Rsm1, resulting in broken lipopolysaccharides (LPS), which is caused by the replacement of CAG coding glutamine with a stop codon TAG. The knockout of rfbD in the sm140ΔrfbD strain caused a subsequent loss of sensitivity toward phages. Furthermore, the reintroduction of rfbD in Rsm1 restored phage sensitivity. Moreover, polymerase chain reaction (PCR) amplification of rfbD in 25 resistant strains revealed a high percentage mutation rate of 64% within the rfbD locus. We assessed the fitness of four bacteria strains and found that the acquisition of phage resistance resulted in slower bacterial growth, faster sedimentation velocity, and increased environmental sensitivity (pH, temperature, and antibiotic sensitivity). In short, bacteria mutants lose some of their abilities while gaining resistance to phage infection, which may be a general survival strategy of bacteria against phages. This study is the first to report phage resistance caused by rfbD mutation, providing a new perspective for the research on phage therapy and drug-resistant mechanisms.
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Affiliation(s)
- Yukun Zeng
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, China
| | - Ping Li
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, China
| | - Shenglong Liu
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, China
| | - Mangmang Shen
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, China
| | - Yuqing Liu
- Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, 250100, China.
| | - Xin Zhou
- College of Veterinary Medicine, Institute of Comparative Medicine, Yangzhou University, Yangzhou, 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China.
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, China.
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Porwollik S, Chu W, Desai PT, McClelland M. A genome-wide collection of barcoded single-gene deletion mutants in Salmonella enterica serovar Typhimurium. PLoS One 2024; 19:e0298419. [PMID: 38452024 PMCID: PMC10919679 DOI: 10.1371/journal.pone.0298419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/24/2024] [Indexed: 03/09/2024] Open
Abstract
Genetic screening of pools of mutants can reveal genetic determinants involved in complex biological interactions, processes, and systems. We previously constructed two single-gene deletion resources for Salmonella enterica serovar Typhimurium 14028s in which kanamycin (KanR) and chloramphenicol (CamR) cassettes were used to replace non-essential genes. We have now used lambda-red recombination to convert the antibiotic cassettes in these resources into a tetracycline-resistant (TetR) version where each mutant contains a different 21-base barcode flanked by Illumina Read1 and Read2 primer sequences. A motility assay of a pool of the entire library, followed by a single-tube processing of the bacterial pellet, PCR, and sequencing, was used to verify the performance of the barcoded TetR collection. The new resource is useful for experiments with defined subsets of barcoded mutant strains where biological bottlenecks preclude high numbers of founder bacteria, such as in animal infections. The TetR version of the library will also facilitate the construction of triple mutants by transduction. The resource of 6197 mutants covering 3490 genes is deposited at Biological and Emerging Infections Resources (beiresources.org).
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Affiliation(s)
- Steffen Porwollik
- Dept. of Microbiology and Molecular Genetics, University of California, Irvine, Irvina, CA, United States of America
| | - Weiping Chu
- Dept. of Microbiology and Molecular Genetics, University of California, Irvine, Irvina, CA, United States of America
| | - Prerak T. Desai
- GSK Computational Biology, Upper Providence, PA, United States of America
| | - Michael McClelland
- Dept. of Microbiology and Molecular Genetics, University of California, Irvine, Irvina, CA, United States of America
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Jacob C, Student J, Bridges DF, Chu W, Porwollik S, McClelland M, Melotto M. Intraspecies competition among Salmonella enterica isolates in the lettuce leaf apoplast. FRONTIERS IN PLANT SCIENCE 2024; 15:1302047. [PMID: 38352648 PMCID: PMC10861783 DOI: 10.3389/fpls.2024.1302047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/08/2024] [Indexed: 02/16/2024]
Abstract
Multiple Salmonella enterica serovars and strains have been reported to be able to persist inside the foliar tissue of lettuce (Lactuca sativa L.), potentially resisting washing steps and reaching the consumer. Intraspecies variation of the bacterial pathogen and of the plant host can both significantly affect the outcome of foliar colonization. However, current understanding of the mechanisms underlying this phenomenon is still very limited. In this study, we evaluated the foliar fitness of 14 genetically barcoded S. enterica isolates from 10 different serovars, collected from plant and animal sources. The S. enterica isolates were vacuum-infiltrated individually or in pools into the leaves of three- to four-week-old lettuce plants. To estimate the survival capacity of individual isolates, we enumerated the bacterial populations at 0- and 10- days post-inoculation (DPI) and calculated their net growth. The competition of isolates in the lettuce apoplast was assessed through the determination of the relative abundance change of barcode counts of each isolate within pools during the 10 DPI experimental period. Isolates exhibiting varying apoplast fitness phenotypes were used to evaluate their capacity to grow in metabolites extracted from the lettuce apoplast and to elicit the reactive oxygen species burst immune response. Our study revealed that strains of S. enterica can substantially differ in their ability to survive and compete in a co-inhabited lettuce leaf apoplast. The differential foliar fitness observed among these S. enterica isolates might be explained, in part, by their ability to utilize nutrients available in the apoplast and to evade plant immune responses in this niche.
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Affiliation(s)
- Cristián Jacob
- Departamento de Ciencias Vegetales, Facultad de Agronomía y Sistemas Naturales, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Joseph Student
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Horticulture and Agronomy Graduate Program, University of California, Davis, Davis, CA, United States
| | - David F. Bridges
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
- Plant Biology Graduate Group, University of California, Davis, Davis, CA, United States
| | - Weiping Chu
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Maeli Melotto
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
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4
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Lin Z, Jiang S, Zwe YH, Zhang K, Li D. Glycogen plays a key role in survival of Salmonella Typhimurium on dry surfaces and in low-moisture foods. Food Res Int 2024; 175:113714. [PMID: 38128983 DOI: 10.1016/j.foodres.2023.113714] [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: 10/05/2023] [Revised: 11/16/2023] [Accepted: 11/22/2023] [Indexed: 12/23/2023]
Abstract
Salmonella enterica is known to survive in desiccate environments and is often associated with low-moisture foods (LMFs). In this work, S. Typhimurium ATCC 14028 was found to survive better by achieving the least reductions (3.17 ± 0.20 Log CFU reduction) compared to S. Tennessee ATCC 10722 (3.82 ± 0.13 Log CFU reduction) and S. Newport ATCC 6962 (6.03 ± 0.36 Log CFU reduction) after 30 days on surfaces with a relative humidity of 49% at ambient temperature. A metabolomic analysis revealed that S. Typhimurium was still active in energy metabolism after 24 h in the desiccate environment and glycogen, an energy reserve, was drastically reduced. We followed up on the glycogen levels over 30 days and found indeed a sharp decline on the first day. However, the glycogens detected on day 7 were significantly higher (P < 0.05) and thereafter remained stable above the original levels until day 30. The expression levels of both glycogen anabolism- and catabolism-related genes (csrA, glgA, glgC, glgX) were significantly up-regulated at all tested points (P < 0.05). The glgA and glgC insertion mutants displayed weaker survivability on both dry surfaces and in representative LMFs (flour and milk powder) compared to the wild-type strain. This work highlights the role of glycogen during different periods of desiccation, which may bring novel insight into mitigating Salmonella by disrupting glycogen metabolism.
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Affiliation(s)
- Zejia Lin
- Department of Food Science & Technology, National University of Singapore, Singapore 117543, Singapore
| | - Shaoqian Jiang
- Department of Food Science & Technology, National University of Singapore, Singapore 117543, Singapore
| | - Ye Htut Zwe
- Department of Food Science & Technology, National University of Singapore, Singapore 117543, Singapore; National Centre for Food Science, Singapore Food Agency, 7 International Business Park, Singapore 609919, Singapore
| | - Kexin Zhang
- Department of Food Science & Technology, National University of Singapore, Singapore 117543, Singapore
| | - Dan Li
- Department of Food Science & Technology, National University of Singapore, Singapore 117543, Singapore.
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Liu S, Xue R, Qin W, Yang X, Ye Q, Wu Q. Performance and transcriptome analysis of Salmonella enterica serovar Enteritidis PT 30 under persistent desiccation stress: Cultured by lawn and broth methods. Food Microbiol 2023; 115:104323. [PMID: 37567618 DOI: 10.1016/j.fm.2023.104323] [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: 02/13/2023] [Revised: 06/04/2023] [Accepted: 06/13/2023] [Indexed: 08/13/2023]
Abstract
Lawn-harvest method uses a solid medium (e.g., tryptic soy agar, TSA) to produce bacterial lawns and is widely accepted for the culture of microorganisms in microbial studies of low-moisture foods (LMFs, foods with water activity less than 0.85). It produces desiccation-tolerant cells with higher D-values in LMFs; however, little is known about the molecular mechanisms underlying bacterial resistance. Salmonella enterica Enteritidis PT 30 (S. Enteritidis), the most pertinent pathogen in LMFs, was cultured in TSA and tryptic soy broth (TSB). Cells were harvested and inoculated on filter papers to assess their performance under a relative humidity of 32 ± 2%. Transcriptome analysis of cultured cells during long-term desiccation (24, 72, and 168 h) was conducted in TruSeq PE Cluster Kit (Illumina) by paired-end methods. Lawn-cultured S. Enteritidis cells have stronger survivability (only decreased by 0.78 ± 0.12 log after 130 d of storage) and heat tolerance (higher D/β value) than those from the broth method. More desiccation genes of lawn-cultured cells were significantly upregulated from growth to long-term desiccation. Differentially expressed genes were the most enriched in the ribosome and sulfur metabolism pathways in the lawn- and broth-cultured groups. This study tracked the transcriptomic differences between two cultured groups in response to long-term desiccation stress and revealed some molecular mechanisms underlying their different suitability in microbial studies of LMFs.
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Affiliation(s)
- Shuxiang Liu
- College of Food Science, Sichuan Agricultural University, Ya'an, 625014, China; Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China.
| | - Ruimin Xue
- College of Food Science, Sichuan Agricultural University, Ya'an, 625014, China
| | - Wen Qin
- College of Food Science, Sichuan Agricultural University, Ya'an, 625014, China
| | - Xiaojuan Yang
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China
| | - Qinghua Ye
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China
| | - Qingping Wu
- Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China.
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Liu X, Pang X, Wu Y, Wu Y, Xu L, Chen Q, Niu J, Zhang X. New Insights into the Lactic Acid Resistance Determinants of Listeria monocytogenes Based on Transposon Sequencing and Transcriptome Sequencing Analyses. Microbiol Spectr 2023; 11:e0275022. [PMID: 36541787 PMCID: PMC9927151 DOI: 10.1128/spectrum.02750-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Listeria monocytogenes is a foodborne pathogen that can tolerate a variety of extreme environments. In particular, its acid resistance (AR) capability is considered one of the key factors threating food safety. Here, we employed a microbial functional genomic technology termed transposon sequencing (Tn-seq), leading to the identification of two genes involved in cell wall peptidoglycan biosynthesis (murF) and phosphate transport (lmo2248) that play key roles in lactic acid resistance (LAR) of L. monocytogenes. Deletion of lmo2248 significantly impaired the ability of LAR in L. monocytogenes, demonstrating the accuracy of the Tn-seq results. Transcriptome analysis revealed that 31.7% of the L. monocytogenes genes on the genome were differentially expressed under lactic acid (LA) treatment, in which genes involved in phosphate transport were influenced most significantly. These findings shed light on the LAR mechanisms of L. monocytogenes, which may contribute to the development of novel strategies against foodborne pathogens. IMPORTANCE Listeria monocytogenes is a Gram-positive foodborne pathogen with high lethality and strong stress resistance, and its strong acid tolerance leads to many foodborne illnesses occurring in low-pH foods. Lactic acid is a generally recognized as safe (GRAS) food additive approved for use by the FDA. However, the genetic determinants of lactic acid resistance in L. monocytogenes have not been fully identified. In this study, the lactic acid resistance determinants of L. monocytogenes were comprehensively identified by Tn-seq on a genome-wide scale. Two genes, murF (cell wall peptidoglycan biosynthesis) and lmo2248 (phosphate transport), were identified to play an important role in the lactic acid resistance. Moreover, genome-wide transcriptomic analysis showed that phosphotransferase system (PTS)-related genes play a key role at the transcriptional level. These findings contribute to a better understanding of the lactic acid resistance mechanism of L. monocytogenes and may provide unique targets for the development of other novel antimicrobial agents.
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Affiliation(s)
- Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xinxin Pang
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yansha Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Linan Xu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Qihe Chen
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Jianrui Niu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinglin Zhang
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
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Qiu Y, Ozturk S, Cui X, Qin W, Wu Q, Liu S. Increased heat tolerance and transcriptome analysis of Salmonella enterica Enteritidis PT 30 heat-shocked at 42 ℃. Food Res Int 2023; 167:112636. [PMID: 37087231 DOI: 10.1016/j.foodres.2023.112636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 02/15/2023] [Accepted: 02/21/2023] [Indexed: 02/26/2023]
Abstract
In this study, we compared the heat tolerance parameter (D65℃) values of Salmonella enterica serovar Enteritidis PT 30 (S. Enteritidis ) heat adapted at different degrees (at 42 ℃ for 20-180 min) and cultivated using two methods. The treated group with the highest D65℃ value (LP-42 ℃-60 min) and the untreated groups (Control-TSB and Control-TSA) were subjected to transcriptome analysis. Heat-adaptation increased the D65℃ values of S. Enteritidis by 24.5-60.8%. The D65℃ values of the LP-42 ℃-60 min group (1.85 ± 0.13 min, 7.7% higher) was comparable to that of the Control-TSA. A total of 483 up- and 443 downregulated genes of S. enteritidis were identified in the LP-42 ℃-60 min group (log2fold change > 1, adjusted p-value < 0.05). Among these genes, 5 co-expressed and 15 differentially expressed genes in the LP-42 ℃-60 min and Control-TSA grops possibly contributed to the high D65℃ values of S. Enteritidis . The Rpo regulon was involved in the heat adaptation of S. Enteritidis , as evidenced by the significant upregulation of rpoS, rpoN, and rpoE. KEGG enrichment pathways, such as biosynthesis of secondary metabolites, tricarboxylic acid, and ribosomes were identified and mapped to reveal the molecular mechanisms of S. enteritidis during heat adaptation. This study quantified the enhanced heat tolerance of S. Enteritidis heat adapted at different degrees of heat-adaptation. The results of this study may serve as a basis for elucidating the molecular mechanisms underlying the enhanced heat tolerance at the transcriptome level.
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Affiliation(s)
- Yan Qiu
- College of Food Science, Sichuan Agricultural University, Ya'an, China
| | - Samet Ozturk
- Department of Food Engineering, Gümüşhane University, Gümüşhane, Turkey
| | - Xinyao Cui
- College of Food Science, Sichuan Agricultural University, Ya'an, China
| | - Wen Qin
- College of Food Science, Sichuan Agricultural University, Ya'an, China; Food Processing and Safety Institute, Sichuan Agricultural University, Ya'an, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou 510070, China
| | - Shuxiang Liu
- College of Food Science, Sichuan Agricultural University, Ya'an, China; Food Processing and Safety Institute, Sichuan Agricultural University, Ya'an, China; State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou 510070, China.
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Davies CP, Jurkiw T, Haendiges J, Reed E, Anderson N, Grasso-Kelley E, Hoffmann M, Zheng J. Changes in the genomes and methylomes of three Salmonella enterica serovars after long-term storage in ground black pepper. Front Microbiol 2022; 13:970135. [PMID: 36160197 PMCID: PMC9507087 DOI: 10.3389/fmicb.2022.970135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/16/2022] [Indexed: 11/28/2022] Open
Abstract
Low moisture foods (LMFs) have traditionally been recognized as safe for consumption, as most bacteria require higher water content to grow. However, outbreaks due to LMF foods are increasing, and the microbial pathogen Salmonella enterica is frequently implicated. S. enterica can survive in LMFs for years, but few serovars have been studied, and the mechanisms which underlie this longevity are not well understood. Here, we determine that S. enterica serovars S. Tennessee, S. Anatum, and S. Reading but not S. Oranienburg can survive in the ground black pepper for 6 years. S. Reading was not previously associated with any LMF. Using both Illumina and Pacific Biosciences sequencing technologies, we also document changes in the genomes and methylomes of the surviving serovars over this 6-year period. The three serovars acquired a small number of single nucleotide polymorphisms (SNPs) including seven substitutions (four synonymous, two non-synonymous, and one substitution in a non-coding region), and two insertion-deletions. Nine distinct N6-methyladenine (m6A) methylated motifs across the three serovars were identified including five which were previously known, Gm6ATC, CAGm6AG, BATGCm6AT, CRTm6AYN6CTC, and CCm6AN7TGAG, and four novel serovar-specific motifs, GRTm6AN8TTYG, GAm6ACN7GTA, GAA m6ACY, and CAAm6ANCC. Interestingly, the BATGCAT motif was incompletely methylated (35–64% sites across the genome methylated), suggesting a possible role in gene regulation. Furthermore, the number of methylated BATGCm6AT motifs increased after storage in ground black pepper for 6 years from 475 to 657 (S. Tennessee), 366 to 608 (S. Anatum), and 525 to 570 (S. Reading), thus warranting further study as an adaptive mechanism. This is the first long-term assessment of genomic changes in S. enterica in a low moisture environment, and the first study to examine the methylome of any bacteria over a period of years, to our knowledge. These data contribute to our understanding of S. enterica survival in LMFs, and coupled with further studies, will provide the information necessary to design effective interventions which reduce S. enterica in LMFs and maintain a healthy, safe food supply.
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Affiliation(s)
- Cary P. Davies
- Animal Biosciences and Biotechnology Laboratory, Beltsville Agricultural Research Center, NEA, U.S. Department of Agriculture, Beltsville, MD, United States
- *Correspondence: Cary P. Davies,
| | - Thomas Jurkiw
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - Julie Haendiges
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - Elizabeth Reed
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - Nathan Anderson
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, Bedford Park, IL, United States
| | - Elizabeth Grasso-Kelley
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, Bedford Park, IL, United States
| | - Maria Hoffmann
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - Jie Zheng
- Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
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Pan X, You J, Tang M, Zhang X, Xu M, Yang T, Rao Z. Improving prodigiosin production by transcription factor engineering and promoter engineering in Serratia marcescens. Front Microbiol 2022; 13:977337. [PMID: 35992721 PMCID: PMC9382025 DOI: 10.3389/fmicb.2022.977337] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 07/12/2022] [Indexed: 11/13/2022] Open
Abstract
Prodigiosin (PG), a red linear tripyrrole pigment produced by Serratia marcescens, has attracted attention due to its immunosuppressive, antimicrobial, and anticancer properties. Although many studies have been used to dissect the biosynthetic pathways and regulatory network of prodigiosin production in S. marcescens, few studies have been focused on improving prodigiosin production through metabolic engineering in this strain. In this study, transcription factor engineering and promoter engineering was used to promote the production of prodigiosin in S. marcescens JNB5-1. Firstly, through construing of a Tn5G transposon insertion library of strain JNB5-1, it was found that the DNA-binding response regulator BVG89_19895 (OmpR) can promote prodigiosin synthesis in this strain. Then, using RNA-Seq analysis, reporter green fluorescent protein analysis and RT-qPCR analysis, the promoter P17 (PRplJ) was found to be a strong constitutive promoter in strain JNB5-1. Finally, the promoter P17 was used for overexpressing of prodigiosin synthesis activator OmpR and PsrA in strain JNB5-1 and a recombinant strain PG-6 was obtained. Shake flask analysis showed that the prodigiosin titer of this strain was increased to 10.25 g/L, which was 1.62-times that of the original strain JNB5-1 (6.33 g/L). Taken together, this is the first well-characterized constitutive promoter library from S. marcescens, and the transcription factor engineering and promoter engineering can be also useful strategies to improve the production of other high value-added products in S. marcescens.
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10
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Morasi RM, Rall VLM, Dantas STA, Alonso VPP, Silva NCC. Salmonella spp. in low water activity food: Occurrence, survival mechanisms, and thermoresistance. J Food Sci 2022; 87:2310-2323. [PMID: 35478321 DOI: 10.1111/1750-3841.16152] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 03/04/2022] [Accepted: 03/22/2022] [Indexed: 01/17/2023]
Abstract
The occurrence of disease outbreaks involving low-water-activity (aw ) foods has gained increased prominence due in part to the fact that reducing free water in these foods is normally a measure that controls the growth and multiplication of pathogenic microorganisms. Salmonella, one of the main bacteria involved in these outbreaks, represents a major public health problem worldwide and in Brazil, which highlights the importance of good manufacturing and handling practices for food quality. The virulence of this pathogen, associated with its high ability to persist in the environment, makes Salmonella one of the main challenges for the food industry. The objectives of this article are to present the general characteristics, virulence, thermoresistance, control, and relevance of Salmonella in foodborne diseases, and describe the so-called low-water-activity foods and the salmonellosis outbreaks involving them.
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Affiliation(s)
- Rafaela Martins Morasi
- Department of Food Sciences And Nutrition, Faculty of Food Engineering, State University of Campinas (UNICAMP), Monteiro Lobato Street, 80, Campinas, São Paulo, Brazil
| | - Vera Lúcia Mores Rall
- Sector of Microbiology and Immunology, Department of Chemical and Biological Sciences, Institute of Biosciences of Botucatu, São Paulo State University (UNESP), Botucatu, Brazil
| | - Stéfani Thais Alves Dantas
- Sector of Microbiology and Immunology, Department of Chemical and Biological Sciences, Institute of Biosciences of Botucatu, São Paulo State University (UNESP), Botucatu, Brazil
| | - Vanessa Pereira Perez Alonso
- Department of Food Sciences And Nutrition, Faculty of Food Engineering, State University of Campinas (UNICAMP), Monteiro Lobato Street, 80, Campinas, São Paulo, Brazil
| | - Nathália Cristina Cirone Silva
- Department of Food Sciences And Nutrition, Faculty of Food Engineering, State University of Campinas (UNICAMP), Monteiro Lobato Street, 80, Campinas, São Paulo, Brazil
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11
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Liu X, Liu G, Wu Y, Pang X, Wu Y, Qinshu, Niu J, Chen Q, Zhang X. Transposon sequencing: A powerful tool for the functional genomic study of food-borne pathogens. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2021.06.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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12
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Genetic Determinants of Stress Resistance in Desiccated Salmonella enterica. Appl Environ Microbiol 2021; 87:e0168321. [PMID: 34586905 DOI: 10.1128/aem.01683-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteric pathogens, including Salmonella, are capable of long-term survival after desiccation and resist heat treatments that are lethal to hydrated cells. The mechanisms of dry-heat resistance differ from those of wet-heat resistance. To elucidate the mechanisms of dry-heat resistance in Salmonella, screening of the dry-heat resistance of 108 Salmonella strains, representing 39 serotypes, identified the 22 most resistant and the 8 most sensitive strains for comparative genome analysis. A total of 289 genes of the accessory genome were differently distributed between resistant and sensitive strains. Among these genes, 28 proteins with a putative relationship to stress resistance were selected for to quantify relative gene expression before and after desiccation and expression by solid-state cultures on agar plates relative to cultures growing in liquid culture media. Of these 28 genes, 15 genes were upregulated (P < 0.05) after desiccation or by solid-state cultures on agar plates. These 15 genes were cloned into the low-copy-number vector pRK767 under the control of the lacZ promoter. The expression of 6 of these 15 genes increased (P < 0.05) resistance to dry heat and to treatment with pressure of 500 MPa. Our finding extends the knowledge of mechanisms of stress resistance in desiccated Salmonella to improve control of this bacterium in dry food. IMPORTANCE This study directly targeted an increasing threat to food safety and developed knowledge and targeted strategies that can be used by the food industry to help reduce the risk of foodborne illness in their dry products and thereby reduce the overall burden of foodborne illness. Genomic and physiological analyses have elucidated mechanisms of bacterial resistance to many food preservation technologies, including heat, pressure, disinfection chemicals, and UV light; however, information on bacterial mechanisms of resistance to dry heat is scarce. Mechanisms of tolerance to desiccation likely also contribute to resistance to dry heat, but this assumption has not been verified experimentally. It remains unclear how mechanisms of resistance to wet heat relate to dry-heat resistance. Thus, this study will fill a knowledge gap to improve the safety of dry foods.
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Induction of the Viable but Non-Culturable State in Salmonella Contaminating Dried Fruit. Appl Environ Microbiol 2021; 88:e0173321. [PMID: 34731057 PMCID: PMC8788685 DOI: 10.1128/aem.01733-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Salmonella can become viable but nonculturable (VBNC) in response to environmental stressors, but the induction of the VBNC state in Salmonella contaminating ready-to-eat dried fruit is poorly characterized. Dried apples, strawberries, and raisins were mixed with a five-strain cocktail of Salmonella at 4% volume per weight of dried fruit at 109 CFU/g. The inoculated dried fruit were then dried in desiccators at 25°C until the water activity (aw) approximated that of the uninoculated dried fruit. However, Salmonella could not be recovered after drying, not even after enrichment, suggesting a population reduction of approximately 8 log CFU/g. To assess the potential impact of storage temperature on survival, dried apples were spot-inoculated with the Salmonella cocktail, dried under ambient atmosphere at 25°C, and stored at 4 and 25°C. Spot inoculation permitted recovery of Salmonella on dried apple after drying, with the population of Salmonella decreasing progressively on dried apples stored at 25°C until it was undetectable after about 46 days, even following enrichment. The population decline was noticeably slower at 4°C, with Salmonella being detected until 82 days. However, fluorescence microscopy and laser scanning confocal microscopy with the LIVE/DEAD BacLight bacterial viability system at time points at which no Salmonella could be recovered on growth media even following enrichment showed that a large proportion (56 to 85%) of the Salmonella cells on the dried fruit were viable. The data suggest that the unique combination of stressors in dried fruit can induce large numbers of VBNC cells of Salmonella. IMPORTANCESalmonella is a leading foodborne pathogen globally causing numerous outbreaks of foodborne illnesses and remains the leading contributor to deaths attributed to foodborne disease in the United States and other industrialized nations. Therefore, efficient detection methods for Salmonella contaminating food are critical for public health and food safety. Culture-based microbiological methods are considered the gold standard for the detection and enumeration of Salmonella in food. Findings from this study suggest that unique stressors on dried fruit can induce the VBNC state in Salmonella, thus rendering it undetectable with culture-based methods even though the bacteria remain viable. Therefore, strong consideration should be given to using, in addition to culture-based methods, microscopic and molecular methods for the accurate detection of all viable and/or culturable cells of Salmonella contaminating dried fruit, as all of these cells have the potential to cause human illness.
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Vaid RK, Thakur Z, Anand T, Kumar S, Tripathi BN. Comparative genome analysis of Salmonella enterica serovar Gallinarum biovars Pullorum and Gallinarum decodes strain specific genes. PLoS One 2021; 16:e0255612. [PMID: 34411120 PMCID: PMC8375982 DOI: 10.1371/journal.pone.0255612] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 07/19/2021] [Indexed: 12/27/2022] Open
Abstract
Salmonella enterica serovar Gallinarum biovar Pullorum (bvP) and biovar Gallinarum (bvG) are the etiological agents of pullorum disease (PD) and fowl typhoid (FT) respectively, which cause huge economic losses to poultry industry especially in developing countries including India. Vaccination and biosecurity measures are currently being employed to control and reduce the S. Gallinarum infections. High endemicity, poor implementation of hygiene and lack of effective vaccines pose challenges in prevention and control of disease in intensively maintained poultry flocks. Comparative genome analysis unravels similarities and dissimilarities thus facilitating identification of genomic features that aids in pathogenesis, niche adaptation and in tracing of evolutionary history. The present investigation was carried out to assess the genotypic differences amongst S.enterica serovar Gallinarum strains including Indian strain S. Gallinarum Sal40 VTCCBAA614. The comparative genome analysis revealed an open pan-genome consisting of 5091 coding sequence (CDS) with 3270 CDS belonging to core-genome, 1254 CDS to dispensable genome and strain specific genes i.e. singletons ranging from 3 to 102 amongst the analyzed strains. Moreover, the investigated strains exhibited diversity in genomic features such as virulence factors, genomic islands, prophage regions, toxin-antitoxin cassettes, and acquired antimicrobial resistance genes. Core genome identified in the study can give important leads in the direction of design of rapid and reliable diagnostics, and vaccine design for effective infection control as well as eradication. Additionally, the identified genetic differences among the S. enterica serovar Gallinarum strains could be used for bacterial typing, structure based inhibitor development by future experimental investigations on the data generated.
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Affiliation(s)
- Rajesh Kumar Vaid
- Bacteriology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Zoozeal Thakur
- Bacteriology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Taruna Anand
- Bacteriology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Sanjay Kumar
- Bacteriology Laboratory, ICAR-National Research Centre on Equines, Hisar, Haryana, India
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Uelze L, Becker N, Borowiak M, Busch U, Dangel A, Deneke C, Fischer J, Flieger A, Hepner S, Huber I, Methner U, Linde J, Pietsch M, Simon S, Sing A, Tausch SH, Szabo I, Malorny B. Toward an Integrated Genome-Based Surveillance of Salmonella enterica in Germany. Front Microbiol 2021; 12:626941. [PMID: 33643254 PMCID: PMC7902525 DOI: 10.3389/fmicb.2021.626941] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 01/21/2021] [Indexed: 02/03/2023] Open
Abstract
Despite extensive monitoring programs and preventative measures, Salmonella spp. continue to cause tens of thousands human infections per year, as well as many regional and international food-borne outbreaks, that are of great importance for public health and cause significant socio-economic costs. In Germany, salmonellosis is the second most common cause of bacterial diarrhea in humans and is associated with high hospitalization rates. Whole-genome sequencing (WGS) combined with data analysis is a high throughput technology with an unprecedented discriminatory power, which is particularly well suited for targeted pathogen monitoring, rapid cluster detection and assignment of possible infection sources. However, an effective implementation of WGS methods for large-scale microbial pathogen detection and surveillance has been hampered by the lack of standardized methods, uniform quality criteria and strategies for data sharing, all of which are essential for a successful interpretation of sequencing data from different sources. To overcome these challenges, the national GenoSalmSurv project aims to establish a working model for an integrated genome-based surveillance system of Salmonella spp. in Germany, based on a decentralized data analysis. Backbone of the model is the harmonization of laboratory procedures and sequencing protocols, the implementation of open-source bioinformatics tools for data analysis at each institution and the establishment of routine practices for cross-sectoral data sharing for a uniform result interpretation. With this model, we present a working solution for cross-sector interpretation of sequencing data from different sources (such as human, veterinarian, food, feed and environmental) and outline how a decentralized data analysis can contribute to a uniform cluster detection and facilitate outbreak investigations.
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Affiliation(s)
- Laura Uelze
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Natalie Becker
- Department of Food, Feed and Commodities, Federal Office of Consumer Protection and Food Safety, Berlin, Germany
| | - Maria Borowiak
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Ulrich Busch
- Bavarian Health and Food Safety Authority, Oberschleißheim, Germany
| | - Alexandra Dangel
- Bavarian Health and Food Safety Authority, Oberschleißheim, Germany
| | - Carlus Deneke
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Jennie Fischer
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Antje Flieger
- Unit of Enteropathogenic Bacteria and Legionella (FG11) – National Reference Centre for Salmonella and Other Bacterial Enteric Pathogens, Robert Koch Institute, Wernigerode, Germany
| | - Sabrina Hepner
- Bavarian Health and Food Safety Authority, Oberschleißheim, Germany
| | - Ingrid Huber
- Bavarian Health and Food Safety Authority, Oberschleißheim, Germany
| | - Ulrich Methner
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Jörg Linde
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut, Jena, Germany
| | - Michael Pietsch
- Unit of Enteropathogenic Bacteria and Legionella (FG11) – National Reference Centre for Salmonella and Other Bacterial Enteric Pathogens, Robert Koch Institute, Wernigerode, Germany
| | - Sandra Simon
- Unit of Enteropathogenic Bacteria and Legionella (FG11) – National Reference Centre for Salmonella and Other Bacterial Enteric Pathogens, Robert Koch Institute, Wernigerode, Germany
| | - Andreas Sing
- Bavarian Health and Food Safety Authority, Oberschleißheim, Germany
| | - Simon H. Tausch
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Istvan Szabo
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
| | - Burkhard Malorny
- Department of Biological Safety, German Federal Institute for Risk Assessment, Berlin, Germany
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16
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Li Y, Salazar JK, He Y, Desai P, Porwollik S, Chu W, Paola PSS, Tortorello ML, Juarez O, Feng H, McClelland M, Zhang W. Mechanisms of Salmonella Attachment and Survival on In-Shell Black Peppercorns, Almonds, and Hazelnuts. Front Microbiol 2020; 11:582202. [PMID: 33193218 PMCID: PMC7644838 DOI: 10.3389/fmicb.2020.582202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/27/2020] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica subspecies I (ssp 1) is the leading cause of hospitalizations and deaths due to known bacterial foodborne pathogens in the United States and is frequently implicated in foodborne disease outbreaks associated with spices and nuts. However, the underlying mechanisms of this association have not been fully elucidated. In this study, we evaluated the influence of storage temperature (4 or 25°C), relative humidity (20 or 60%), and food surface characteristics on the attachment and survival of five individual strains representing S. enterica ssp 1 serovars Typhimurium, Montevideo, Braenderup, Mbandaka, and Enteritidis on raw in-shell black peppercorns, almonds, and hazelnuts. We observed a direct correlation between the food surface roughness and S. enterica ssp 1 attachment, and detected significant inter-strain difference in survival on the shell surface under various storage conditions. A combination of low relative humidity (20%) and ambient storage temperature (25°C) resulted in the most significant reduction of S. enterica on shell surfaces (p < 0.05). To identify genes potentially associated with S. enterica attachment and survival on shell surfaces, we inoculated a library of 120,000 random transposon insertion mutants of an S. Enteritidis strain on almond shells, and screened for mutant survival after 1, 3, 7, and 14 days of storage at 20% relative humidity and 25°C. Mutants in 155 S. Enteritidis genes which are involved in carbohydrate metabolic pathways, aerobic and anaerobic respiration, inner membrane transport, and glutamine synthesis displayed significant selection on almond shells (p < 0.05). Findings of this study suggest that various food attributes, environmental factors, and an unexpectedly complex metabolic and regulatory network in S. enterica ssp 1 collectively contribute to the bacterial attachment and survival on low moisture shell surface, providing new data for the future development of knowledge-based intervention strategies.
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Affiliation(s)
- Ye Li
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL, United States
| | - Joelle K Salazar
- Division of Food Processing Science and Technology, U.S. Food and Drug Administration, Bedford Park, IL, United States
| | - Yingshu He
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL, United States
| | - Prerak Desai
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Weiping Chu
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Palma-Salgado Sindy Paola
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Mary Lou Tortorello
- Division of Food Processing Science and Technology, U.S. Food and Drug Administration, Bedford Park, IL, United States
| | - Oscar Juarez
- Department of Biology, Illinois Institute of Technology, Chicago, IL, United States
| | - Hao Feng
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Wei Zhang
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL, United States
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