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Xu L, Wu Y, Yang X, Pang X, Wu Y, Li X, Liu X, Zhao Y, Yu L, Wang P, Ye B, Jiang S, Ma J, Zhang X. The Fe-S cluster biosynthesis in Enterococcus faecium is essential for anaerobic growth and gastrointestinal colonization. Gut Microbes 2024; 16:2359665. [PMID: 38831611 DOI: 10.1080/19490976.2024.2359665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 05/21/2024] [Indexed: 06/05/2024] Open
Abstract
The facultative anaerobic Gram-positive bacterium Enterococcus faecium is a ubiquitous member of the human gut microbiota. However, it has gradually evolved into a pathogenic and multidrug resistant lineage that causes nosocomial infections. The establishment of high-level intestinal colonization by enterococci represents a critical step of infection. The majority of current research on Enterococcus has been conducted under aerobic conditions, while limited attention has been given to its physiological characteristics in anaerobic environments, which reflects its natural colonization niche in the gut. In this study, a high-density transposon mutant library containing 26,620 distinct insertion sites was constructed. Tn-seq analysis identified six genes that significantly contribute to growth under anaerobic conditions. Under anaerobic conditions, deletion of sufB (encoding Fe-S cluster assembly protein B) results in more extensive and significant impairments on carbohydrate metabolism compared to aerobic conditions. Consistently, the pathways involved in this utilization-restricted carbohydrates were mostly expressed at significantly lower levels in mutant compared to wild-type under anaerobic conditions. Moreover, deletion of sufB or pflA (encoding pyruvate formate lyase-activating protein A) led to failure of gastrointestinal colonization in mice. These findings contribute to our understanding of the mechanisms by which E. faecium maintains proliferation under anaerobic conditions and establishes colonization in the gut.
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Affiliation(s)
- Linan Xu
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xiangpeng Yang
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinxin Pang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yansha Wu
- Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Xingshuai Li
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yuzhong Zhao
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Lumin Yu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Peikun Wang
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Bin Ye
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Shijin Jiang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Junfei Ma
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinglin Zhang
- College of Agriculture and Forestry, Linyi University, Linyi, China
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Song D, Su Q, Jia A, Fu S, Ma X, Li T, Man C, Yang X, Jiang Y. A Method to Directly Identify Cronobacter sakazakii in Liquid Medium by MALDI-TOF MS. Foods 2023; 12:foods12101981. [PMID: 37238798 DOI: 10.3390/foods12101981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/11/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry has been widely used as an emerging technology for the rapid identification of microorganisms. Cronobacter sakazakii (C. sakazakii) is a food-borne pathogen of particular importance to the powdered infant formula (PIF) processing environment due to its high lethality in infants. However, the traditional solid spotting detection method of pretreating samples for MALDI-TOF MS leads only to qualitative detection of C. sakazakii. We developed a new, low-cost, robust liquid spotting pretreatment method and used a response surface methodology to optimize its parameters. The applicability, accuracy, and quantitative potential were measured for different types of samples. The optimal parameters of this method were as follows: a volume of 70% formic acid of 25 μL, treatment with ultrasound at 350 W for 3 min, and a volume of acetonitrile added of 75 μL. These conditions led to the highest identification score for C. sakazakii (1926.42 ± 48.497). This method was found to detect bacteria accurately and reproducibly. When 70 strains of C. sakazakii isolates were analyzed with this method, the identification accuracy was 100%. The detection limit of C. sakazakii in environmental and PIF samples was 4.1 × 101 cfu/mL and 2.72 × 103 cfu/mL, respectively.
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Affiliation(s)
- Danliangmin Song
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
| | - Qunchao Su
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
| | - Ai Jia
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
| | - Shiqian Fu
- Key Laboratory of Animal Protein Food Deep Processing Technology of Zhejiang Province, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo 315800, China
| | - Xiaoming Ma
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
| | - Tiantian Li
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
| | - Chaoxin Man
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
| | - Xinyan Yang
- Key Laboratory of Dairy Science, Ministry of Education, Harbin 150030, China
| | - Yujun Jiang
- Department of Food Science, Northeast Agricultural University, Harbin 150038, China
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Han M, Schierstaedt J, Duan Y, Trotereau J, Virlogeux-Payant I, Schikora A. Novel method to recover Salmonella enterica cells for Tn-Seq approaches from lettuce leaves and agricultural environments using combination of sonication, filtration, and dialysis membrane. J Microbiol Methods 2023; 208:106724. [PMID: 37054820 DOI: 10.1016/j.mimet.2023.106724] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 04/05/2023] [Accepted: 04/08/2023] [Indexed: 04/15/2023]
Abstract
Salmonella enterica in agricultural environments has become an important concern, due to its potential transmission to humans and the associated public health risks. To identify genes contributing to Salmonella adaptation to such environments, transposon sequencing has been used in recent years. However, isolating Salmonella from atypical hosts, such as plant leaves, can pose technical challenges due to low bacterial content and the difficulty to separate an adequate number of bacteria from host tissues. In this study, we describe a modified methodology using a combination of sonication and filtration to recover S. enterica cells from lettuce leaves. We successfully recovered over a total of 3.5 × 106Salmonella cells in each biological replicate from two six-week old lettuce leaves, 7 days after infiltration with a Salmonella suspension of 5 × 107 colony forming units (CFU)/mL. Moreover, we have developed a dialysis membrane system as an alternative method for recovering bacteria from culture medium, mimicking a natural environment. Inoculating 107 CFU/mL of Salmonella into the media based on plant (lettuce and tomato) leaf and diluvial sand soil, a final concentration of 109.5 and 108.5 CFU/mL was obtained, respectively. One millilitre of the bacterial suspension after 24 h incubation at 28 °C using 60 rpm agitation was pelleted, corresponding to 109.5 and 108.5 cells from leaf- or soil-based media. The recovered bacterial population, from both lettuce leaves and environment-mimicking media, can adequately cover a presumptive library density of 106 mutants. In conclusion, this protocol provides an effective method to recover a Salmonella transposon sequencing library from in planta and in vitro systems. We expect this novel technique to foster the study of Salmonella in atypical hosts and environments, as well as other comparable scenarios.
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Affiliation(s)
- Min Han
- Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
| | - Jasper Schierstaedt
- Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany; Leibniz Institute of Vegetable and Ornamental Crops (IGZ), Department Plant-Microbe Systems, Theodor-Echtermeyer Weg 1, Großbeeren 14979, Germany
| | - Yongming Duan
- Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany
| | - Jérôme Trotereau
- INRAE Val de Loire, Université de Tours, UMR ISP, Nouzilly 37380, France
| | | | - Adam Schikora
- Julius Kühn Institute (JKI) - Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, Braunschweig 38104, Germany.
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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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Park DG, Ha ES, Kang B, Choi I, Kwak JE, Choi J, Park J, Lee W, Kim SH, Kim SH, Lee JH. Development and Evaluation of a Next-Generation Sequencing Panel for the Multiple Detection and Identification of Pathogens in Fermented Foods. J Microbiol Biotechnol 2023; 33:83-95. [PMID: 36457187 PMCID: PMC9895999 DOI: 10.4014/jmb.2211.11009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/08/2022] [Accepted: 11/10/2022] [Indexed: 12/03/2022]
Abstract
These days, bacterial detection methods have some limitations in sensitivity, specificity, and multiple detection. To overcome these, novel detection and identification method is necessary to be developed. Recently, NGS panel method has been suggested to screen, detect, and even identify specific foodborne pathogens in one reaction. In this study, new NGS panel primer sets were developed to target 13 specific virulence factor genes from five types of pathogenic Escherichia coli, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium, respectively. Evaluation of the primer sets using singleplex PCR, crosscheck PCR and multiplex PCR revealed high specificity and selectivity without interference of primers or genomic DNAs. Subsequent NGS panel analysis with six artificially contaminated food samples using those primer sets showed that all target genes were multi-detected in one reaction at 108-105 CFU of target strains. However, a few false-positive results were shown at 106-105 CFU. To validate this NGS panel analysis, three sets of qPCR analyses were independently performed with the same contaminated food samples, showing the similar specificity and selectivity for detection and identification. While this NGS panel still has some issues for detection and identification of specific foodborne pathogens, it has much more advantages, especially multiple detection and identification in one reaction, and it could be improved by further optimized NGS panel primer sets and even by application of a new real-time NGS sequencing technology. Therefore, this study suggests the efficiency and usability of NGS panel for rapid determination of origin strain in various foodborne outbreaks in one reaction.
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Affiliation(s)
- Dong-Geun Park
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea
| | - Eun-Su Ha
- Research and Development Center, Sanigen Co., Ltd, Anyang 14059, Republic of Korea
| | - Byungcheol Kang
- Research and Development Center, Sanigen Co., Ltd, Anyang 14059, Republic of Korea
| | - Iseul Choi
- Research and Development Center, Sanigen Co., Ltd, Anyang 14059, Republic of Korea
| | - Jeong-Eun Kwak
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea
| | - Jinho Choi
- Research and Development Center, Sanigen Co., Ltd, Anyang 14059, Republic of Korea
| | - Jeongwoong Park
- Research and Development Center, Sanigen Co., Ltd, Anyang 14059, Republic of Korea
| | - Woojung Lee
- Division of Food Microbiology, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju 28159, Republic of Korea
| | - Seung Hwan Kim
- Division of Food Microbiology, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju 28159, Republic of Korea
| | - Soon Han Kim
- Division of Food Microbiology, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Cheongju 28159, Republic of Korea
| | - Ju-Hoon Lee
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea,Corresponding author Phone: +82-2-880-4854 Fax: +82-2-873-5095 E-mail:
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Cui Q, Zhong Y, Shang W, Deng F, Wang B, Wu J, Wang P, Wan L, Wang K, Fang L, Dai R, Zhang H, Ledesma-Amaro R, Zhang Y, Huang J. Fluorescent Probe Combined with Photoelectric Analysis Technology for Detection of Escherichia coli. BIOSENSORS 2023; 13:150. [PMID: 36831916 PMCID: PMC9953772 DOI: 10.3390/bios13020150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/10/2023] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
Food safety is facing great challenges in preventing foodborne diseases caused by pathogenic pollution, especially in resource-limited areas. The rapid detection technique of microorganisms, such as immunological methods and molecular biological methods, plays a crucial key in timely bioanalysis and disease treatment strategies. However, it is difficult for these methods to simultaneously meet the criteria of simple operation, high specificity, and sensitivity, as well as low cost. Coconut water is known as the "water of life" in Hainan. It is a refreshing and nutritious beverage which is widely consumed due to its beneficial properties to health. Coconut water processing is an important pillar industry in Hainan. The detection of pathogenic microorganisms, such as Escherichia coli, in coconut water has become an important factor which has restricted the upgrading and development of this industry. Based on the needs of industrial development, we developed a microbial photoelectric detection system which was composed of a fluorescent probe detection reagent and a photoelectric sensor detection device. This system combined microbial enzyme targets, selective fluorescent substrate metabolism characteristics, and a photoelectric sensor signal transduction mechanism, which produce a strong signal with a high signal-to-noise ratio. The microbial detection system developed here has a simple structure, simple and convenient operation, short detecting time (≥2 h), and high sensitivity (1 CFU/mL). This system may also enable early warning and monitoring programs for other pathogenic microorganisms in order to promote the overall competitiveness of the Hainan coconut water industry.
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Affiliation(s)
- Qian Cui
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Yongjie Zhong
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Wenkai Shang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Fuming Deng
- Coconut Research Center, Coconut Research Institute, Chinese Academy of Tropical Agricultural Science (CATAS), Haikou 570228, China
| | - Buhua Wang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Jiajia Wu
- CAS Key Laboratory of Marine Environmental Corrosion and Bio-Fouling Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Peng Wang
- CAS Key Laboratory of Marine Environmental Corrosion and Bio-Fouling Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Liudang Wan
- Insititue of Biotechnology, ViewKr, Haikou 570228, China
| | - Keling Wang
- Insititue of Biotechnology, ViewKr, Haikou 570228, China
| | - Lingchen Fang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Rui Dai
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Han Zhang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Rodrigo Ledesma-Amaro
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London SW7 2AZ, UK
| | - Yunuo Zhang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
| | - Jiaomei Huang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China
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Liu X, Pang X, Wu Y, Wu Y, Shi Y, Zhang X, Chen Q. Synergistic Antibacterial Mechanism of Mannosylerythritol Lipid-A and Lactic Acid on Listeria monocytogenes Based on Transcriptomic Analysis. Foods 2022; 11:foods11172660. [PMID: 36076848 PMCID: PMC9455235 DOI: 10.3390/foods11172660] [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: 07/26/2022] [Revised: 08/26/2022] [Accepted: 08/28/2022] [Indexed: 11/21/2022] Open
Abstract
Mannosylerythritol lipids-A (MEL-A) is a novel biosurfactant with multiple biological effects. The synergistic antibacterial activity and mechanism of MEL-A and lactic acid (LA) against Listeria monocytogenes were investigated. The synergistic effect resulted in a significant increase in the antibacterial rate compared to LA treatment alone. Genome-wide transcriptomic analysis was applied to deeply investigate the synergistic antibacterial mechanism. Gene Ontology (GO) enrichment analysis showed that the synergy between MEL-A and LA affected many potential cellular responses, including the sugar phosphotransferase system, carbohydrate transport, and ribosomes. KEGG enrichment analysis showed that the PTS system and ribosome-related pathways were significantly enriched. In addition, synergistic treatment affected locomotion and membrane-related cellular responses in GO enrichment analysis and carbohydrate metabolism and amino acid metabolism pathways in KEGG enrichment analysis compared to LA treatment alone. The accuracy of the transcriptome analysis results was verified by qPCR (R2 = 0.9903). This study will provide new insights for the prevention and control of L. monocytogenes.
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Affiliation(s)
- Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
| | - Xinxin Pang
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
| | - Yansha Wu
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
| | - Ying Shi
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
| | - Xinglin Zhang
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
- College of Agriculture and Forestry, Linyi University, Linyi 276005, China
| | - Qihe Chen
- Department of Food Science and Nutrition, Zhejiang University, Yuhangtang Rd. 866, Hangzhou 310058, China
- Correspondence: ; Tel.: +86-571-86984316
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Functional Genomics Identified Novel Genes Involved in Growth at Low Temperatures in Listeria monocytogenes. Microbiol Spectr 2022; 10:e0071022. [PMID: 35735974 PMCID: PMC9431668 DOI: 10.1128/spectrum.00710-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Listeria monocytogenes (Lm) is a foodborne pathogen that can cause severe human illness. Standard control measures for restricting bacterial growth, such as refrigeration, are often inadequate as Lm grows well at low temperatures. To identify genes involved in growth at low temperatures, a powerful functional genomics method Tn-seq was performed in this study. This genome-wide screening comprehensively identified the known and novel genetic determinants involved in low-temperature growth. A novel gene lmo1366, encoding rRNA methyltransferase, was identified to play an essential role in Lm growth at 16°C. In contrast, the inactivation of lmo2301, a gene encoding the terminase of phage A118, significantly enhanced the growth of Lm at 16°C. The deletion of lmo1366 or lmo2301 resulted in cell morphology alterations and impaired the growth rate in milk and other conditions at low temperatures. Transcriptomic analysis revealed that the Δlmo1366 and Δlmo2301 mutants exhibited altered transcriptional patterns compared to the wild-type strain at 16°C with significant differences in genes involved in ribosome structural stability and function, and membrane biogenesis, respectively. This work uncovered novel genetic determinants involved in Lm growth at 16°C, which could lead to a better understanding of how bacteria survive and multiply at low temperatures. Furthermore, these findings could potentially contribute to developing novel antibacterial strategies under low-temperature conditions. IMPORTANCEListeria monocytogenes is a Gram-positive pathogen that contributes to foodborne outbreaks due to its ability to survive at low temperatures. However, the genetic determinants of Lm involved in growth at low temperatures have not been fully defined. Here, the genetic determinants involved in the low-temperature growth of Lm were comprehensively identified on a genome-wide scale by Tn-seq. The gene lmo1366, encoding rRNA methyltransferase, was identified essential for growth under low-temperature conditions. On the other hand, the gene lmo2301, encoding terminase of phage A118, plays a negative role in bacterial growth at low temperatures. The transcriptomic analysis revealed the potential mechanisms. These findings lead to a better understanding of how bacteria survive and multiply at low temperatures and could provide unique targets for novel antibacterial strategies under low-temperature conditions.
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Pang X, Wu Y, Liu X, Wu Y, Shu Q, Niu J, Chen Q, Zhang X. The Lipoteichoic Acid-Related Proteins YqgS and LafA Contribute to the Resistance of Listeria monocytogenes to Nisin. Microbiol Spectr 2022; 10:e0209521. [PMID: 35196823 PMCID: PMC8865564 DOI: 10.1128/spectrum.02095-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/24/2022] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes is a major pathogen contributing to foodborne outbreaks with high mortality. Nisin, a natural antimicrobial, has been widely used as a food preservative. However, the mechanisms of L. monocytogenes involved in nisin resistance have not yet to be fully defined. A mariner transposon library was constructed in L. monocytogenes, leading to the identification of 99 genes associated with the innate resistance to nisin via Transposon sequencing (Tn-seq) analysis. To validate the accuracy of the Tn-seq results, we constructed five mutants (ΔyqgS, ΔlafA, ΔvirR, ΔgtcA, and Δlmo1464) in L. monocytogenes. The results revealed that yqgS and lafA, the lipoteichoic acid-related genes, were essential for resistance to nisin, while the gtcA and lmo1464 mutants showed substantially enhanced nisin resistance. Densely wrinkled, collapsed surface and membrane breakdown were shown on ΔyqgS and ΔlafA mutants under nisin treatment. Deletion of yqgS and lafA altered the surface charge, and decreased the resistance to general stress conditions and cell envelope-acting antimicrobials. Furthermore, YqgS and LafA are required for biofilm formation and cell invasion of L. monocytogenes. Collectively, these results reveal novel mechanisms of nisin resistance in L. monocytogenes and may provide unique targets for the development of food-grade inhibitors for nisin-resistant foodborne pathogens. IMPORTANCE Listeria monocytogenes is an opportunistic Gram-positive pathogen responsible for listeriosis, and is widely present in a variety of foods including ready-to-eat foods, meat, and dairy products. Nisin is the only licensed lantibiotic by the FDA for use as a food-grade inhibitor in over 50 countries. A prior study suggests that L. monocytogenes are more resistant than other Gram-positive pathogens in nisin-mediated bactericidal effects. However, the mechanisms of L. monocytogenes involved in nisin resistance have not yet to be fully defined. Here, we used a mariner transposon library to identify nisin-resistance-related genes on a genome-wide scale via transposon sequencing. We found, for the first time, that YqgS and LafA (Lipoteichoic acid-related proteins) are required for resistance to nisin. Subsequently, we investigated the roles of YqgS and LafA in L. monocytogenes stress resistance, antimicrobial resistance, biofilm formation, and virulence in mammalian cells.
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Affiliation(s)
- Xinxin Pang
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yansha Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Qin Shu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Jianrui Niu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Qihe Chen
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xinglin Zhang
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
- College of Agriculture and Forestry, Linyi University, Linyi, China
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