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Wynne JW, Rusu AG, Maynard BT, Rigby ML, Taylor RS. Dead reckoning of protist viability with propidium monoazide (PMA)-quantitative PCR; a case study using Neoparamoeba perurans. Protist 2024; 175:126068. [PMID: 39341117 DOI: 10.1016/j.protis.2024.126068] [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: 03/26/2024] [Revised: 09/05/2024] [Accepted: 09/20/2024] [Indexed: 09/30/2024]
Abstract
The ability to distinguish between viable and non-viable protozoan parasites is central to improved human and animal health management. While conceptually simple, methods to differentiate cell viability in situ remain challenging. Amoebic gill disease, caused by Neoparamoeba perurans is a parasitic disease impacting Atlantic salmon aquaculture globally. Although commercial freshwater treatments alleviate AGD, viable amoebae remain on gills or in used treatment water. Existing PCR-based assays are able to quantify N. perurans abundance but cannot discriminate amoeba viability. We investigated the use of propidium monoazide (PMA) application, prior to real-time PCR, to distinguish between alive and dead cells. We demonstrate that 200 μM PMA can significantly reduce amplification from non-viable (isopropanol treated) cultured amoebae across at least three logs of cell concentrations. Using a serial dilution of viable and non-viable cells, we show that non-PMA PCR amplifies both viable and non-viable amoebae, while PMA exposure suppresses (but does not completely inhibit) amplification from non-viable amoebae. The effect of freshwater treatment on N. perurans viability was assessed using the PMA-PCR. Following PMA exposure, amplification from freshwater treated amoebae was reduced by approximately 94-97 %. Taken together this study demonstrates that PMA combined with traditional real-time PCR can estimate amoeba viability.
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Affiliation(s)
| | - Anca G Rusu
- CSIRO Agriculture and Food, St Lucia 4067, Australia
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2
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Wang P, Liu Y, Li X, Li C, Li G. A ratiometric SERS aptasensor based on catalytic hairpin self-assembly mediated cyclic signal amplification strategy for the reliable determination of E. coli O157:H7. Mikrochim Acta 2024; 191:441. [PMID: 38954045 DOI: 10.1007/s00604-024-06475-1] [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: 05/02/2024] [Accepted: 05/31/2024] [Indexed: 07/04/2024]
Abstract
A ratiometric SERS aptasensor based on catalytic hairpin self-assembly (CHA) mediated cyclic signal amplification strategy was developed for the rapid and reliable determination of Escherichia coli O157:H7. The recognition probe was synthesized by modifying magnetic beads with blocked aptamers, and the SERS probe was constructed by functionalizing gold nanoparticles (Au NPs) with hairpin structured DNA and 4-mercaptobenzonitrile (4-MBN). The recognition probe captured E. coli O157:H7 specifically and released the blocker DNA, which activated the CHA reaction on the SERS probe and turned on the SERS signal of 6-carboxyl-x-rhodamine (ROX). Meanwhile, 4-MBN was used as an internal reference to calibrate the matrix interference. Thus, sensitive and reliable determination and quantification of E. coli O157:H7 was established using the ratio of the SERS signal intensities of ROX to 4-MBN. This aptasensor enabled detection of 2.44 × 102 CFU/mL of E. coli O157:H7 in approximately 3 h without pre-culture and DNA extraction. In addition, good reliability and excellent reproducibility were observed for the determination of E. coli O157:H7 in spiked water and milk samples. This study offered a new solution for the design of rapid, sensitive, and reliable SERS aptasensors.
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Affiliation(s)
- Panxue Wang
- School of Food Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, P. R. China
| | - Ying Liu
- School of Food Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, P. R. China
| | - Xiang Li
- School of Food Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, P. R. China
| | - Cen Li
- School of Food Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, P. R. China
| | - Guoliang Li
- School of Food Science and Engineering, Shaanxi University of Science & Technology, Xi'an, 710021, P. R. China.
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3
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Zhuang L, Gong J, Zhao Y, Yang J, Liu G, Zhao B, Song C, Zhang Y, Shen Q. Progress in methods for the detection of viable Escherichia coli. Analyst 2024; 149:1022-1049. [PMID: 38273740 DOI: 10.1039/d3an01750h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2024]
Abstract
Escherichia coli (E. coli) is a prevalent enteric bacterium and a necessary organism to monitor for food safety and environmental purposes. Developing efficient and specific methods is critical for detecting and monitoring viable E. coli due to its high prevalence. Conventional culture methods are often laborious and time-consuming, and they offer limited capability in detecting potentially harmful viable but non-culturable E. coli in the tested sample, which highlights the need for improved approaches. Hence, there is a growing demand for accurate and sensitive methods to determine the presence of viable E. coli. This paper scrutinizes various methods for detecting viable E. coli, including culture-based methods, molecular methods that target DNAs and RNAs, bacteriophage-based methods, biosensors, and other emerging technologies. The review serves as a guide for researchers seeking additional methodological options and aiding in the development of rapid and precise assays. Moving forward, it is anticipated that methods for detecting E. coli will become more stable and robust, ultimately contributing significantly to the improvement of food safety and public health.
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Affiliation(s)
- Linlin Zhuang
- School of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, P. R. China.
- State Key Laboratory of Digital Medical Engineering, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering & Basic Medicine Research and Innovation Center of Ministry of Education, Zhongda Hospital, Southeast University, Nanjing 211102, P. R. China.
| | - Jiansen Gong
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou 225125, P. R. China
| | - Ying Zhao
- State Key Laboratory of Digital Medical Engineering, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering & Basic Medicine Research and Innovation Center of Ministry of Education, Zhongda Hospital, Southeast University, Nanjing 211102, P. R. China.
| | - Jianbo Yang
- School of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, P. R. China.
| | - Guofang Liu
- School of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, P. R. China.
| | - Bin Zhao
- School of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, P. R. China.
| | - Chunlei Song
- School of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, P. R. China.
| | - Yu Zhang
- State Key Laboratory of Digital Medical Engineering, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering & Basic Medicine Research and Innovation Center of Ministry of Education, Zhongda Hospital, Southeast University, Nanjing 211102, P. R. China.
| | - Qiuping Shen
- School of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, P. R. China.
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4
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Liu W, Xiang P, Ji Y, Chen Z, Lei Z, Huang W, Huang W, Liu D. Response of viable bacteria to antibiotics in aerobic granular sludge: Resistance mechanisms and behaviors, bacterial communities, and driving factors. WATER RESEARCH 2023; 245:120656. [PMID: 37748345 DOI: 10.1016/j.watres.2023.120656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/31/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023]
Abstract
The assessment of antimicrobial resistance (AMR) risk by DNA-based techniques mainly relies on total bacterial DNA. In this case, AMR risk recognition is restricted to the genotype level, lacking crucial phenotypic information, such as the distribution of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in dead and viable bacteria. This limitation hinders the recognition of AMR behavior. Herein, based on propidium monoazide (PMA) shielding method, this work firstly quantified the intracellular ARGs/MGEs in viable and dead bacteria, and the impact of viable bacteria composition on the formation of intracellular/extracellular polymeric substance-related /cell-free ARGs (i/e/cARGs) and MGEs (i/e/cMGEs) in aerobic granular sludge (AGS). The shielding efficiency of PMA against dead bacteria was optimized to be as high as 97.5% when the MLSS of AGS was 2.0 g/L. Under antibiotic stimulation, 29.0% ∼ 49.0% of iARGs/iMGEs were carried by viable bacteria, and the remaining proportion were carried by dead bacteria. 18 out of the top 20 dominant genera showed a change in abundance by more than 1% after PMA treatment. 29 viable hosts were identified to associate with 52 iARGs, of which 28 and 15 hosts were also linked to 40 eARGs and 26 cARGs. Also, partial least-squares path model and variance partitioning analysis disclosed that viable bacteria and i/e/cMGEs had a positive effect on i/e/cARGs, with both contributing as much as 64.5% to the total ARGs enrichment. These results better visualized the AMR risk carried by viable bacteria and the categories of viable hosts. This work provides a novel insight into analyzing the actual AMR risk and viable hosts, helping to the reduction and control of AMR in wastewater treatment plants.
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Affiliation(s)
- Wenhao Liu
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Peng Xiang
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yuan Ji
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zeyou Chen
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhongfang Lei
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Weiwei Huang
- Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province, Hainan University, Renmin Road, Haikou 570228, China
| | - Wenli Huang
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Dongfang Liu
- Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
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Codony F, Dangla C, Ventolà L, Sabaté N. Phase change materials for portable isothermal incubators as a solution to shorten effective analysis times in microbiological quality control of drinking water. ENVIRONMENTAL MONITORING AND ASSESSMENT 2023; 195:1105. [PMID: 37642879 DOI: 10.1007/s10661-023-11742-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 08/17/2023] [Indexed: 08/31/2023]
Abstract
The microbiological quality control of water for human consumption of parameters relevant as E.coli and total coliforms does not start on the field despite the existence of test methods that could make it possible. One of the things that makes this difficult is the possibility of initiating an effective and reliable incubation at the sampling site. The appearance of isothermal media with phase change materials solves this limitation. When phase change materials combine a relatively high melting heat with a suitable melting temperature adapted to the application temperature, they become excellent materials for thermal protection and for thermal energy storage. Starting the test at the same sampling point means that the effective times to obtain a result are shorter, improving water quality control. On the other hand, operationally, it also allows longer sampling routes. Both aspects are essential for managers responsible for controlling water quality for human consumption. In this work, the evidence that demonstrates the feasibility of this approach is presented.
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Affiliation(s)
- F Codony
- Laboratori d'Aigües de Mataró, carrer Hèl·lade, 17-19, 08304, Mataró, Barcelona, Spain.
| | - C Dangla
- Laboratori d'Aigües de Mataró, carrer Hèl·lade, 17-19, 08304, Mataró, Barcelona, Spain
| | - L Ventolà
- LVM Thermal Solutions, Carretera Vic n° 20 Nau 8, 17176 Sant Esteve d'en Bas, Barcelona, Spain
| | - N Sabaté
- Laboratori d'Aigües de Mataró, carrer Hèl·lade, 17-19, 08304, Mataró, Barcelona, Spain
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Yi J, Wisuthiphaet N, Raja P, Nitin N, Earles JM. AI-enabled biosensing for rapid pathogen detection: From liquid food to agricultural water. WATER RESEARCH 2023; 242:120258. [PMID: 37390659 DOI: 10.1016/j.watres.2023.120258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/17/2023] [Accepted: 06/20/2023] [Indexed: 07/02/2023]
Abstract
Rapid pathogen detection in food and agricultural water is essential for ensuring food safety and public health. However, complex and noisy environmental background matrices delay the identification of pathogens and require highly trained personnel. Here, we present an AI-biosensing framework for accelerated and automated pathogen detection in various water samples, from liquid food to agricultural water. A deep learning model was used to identify and quantify target bacteria based on their microscopic patterns generated by specific interactions with bacteriophages. The model was trained on augmented datasets to maximize data efficiency, using input images of selected bacterial species, and then fine-tuned on a mixed culture. Model inference was performed on real-world water samples containing environmental noises unseen during model training. Overall, our AI model trained solely on lab-cultured bacteria achieved rapid (< 5.5 h) prediction with 80-100% accuracy on the real-world water samples, demonstrating its ability to generalize to unseen data. Our study highlights the potential applications in microbial water quality monitoring during food and agricultural processes.
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Affiliation(s)
- Jiyoon Yi
- Department of Biological & Agricultural Engineering, University of California, Davis, CA 95616, United States of America; Department of Biosystems & Agricultural Engineering, Michigan State University, East Lansing, MI 48824, United States of America
| | - Nicharee Wisuthiphaet
- Department of Food Science & Technology, University of California, Davis, CA 95616, United States of America; Department of Biotechnology, Faculty of Applied Science, King Mongkut's University of Technology North Bangkok, Bangkok, 10800, Thailand
| | - Pranav Raja
- Department of Biological & Agricultural Engineering, University of California, Davis, CA 95616, United States of America
| | - Nitin Nitin
- Department of Biological & Agricultural Engineering, University of California, Davis, CA 95616, United States of America; Department of Food Science & Technology, University of California, Davis, CA 95616, United States of America
| | - J Mason Earles
- Department of Biological & Agricultural Engineering, University of California, Davis, CA 95616, United States of America; Department of Viticulture & Enology, University of California, Davis, CA 95616, United States of America.
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Liu F, Lu H, Dong B, Huang X, Cheng H, Qu R, Hu Y, Zhong L, Guo Z, You Y, Xu ZZ. Systematic Evaluation of the Viable Microbiome in the Human Oral and Gut Samples with Spike-in Gram+/– Bacteria. mSystems 2023; 8:e0073822. [PMID: 36971593 PMCID: PMC10134872 DOI: 10.1128/msystems.00738-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
The functions and phenotypes of microbial communities are largely defined by viable microbes. Through advanced nucleic acid sequencing technologies and downstream bioinformatic analyses, we gained an insight into the high-resolution microbial community composition of human saliva and feces, yet we know very little about whether such community DNA sequences represent viable microbes.
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8
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Wang Y, Fang W, Wang X, Zhou L, Zheng G. Spatial distribution of fecal pollution indicators in sewage sludge flocs and their removal and inactivation as revealed by qPCR/viability-qPCR during potassium ferrate treatment. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130262. [PMID: 36327846 DOI: 10.1016/j.jhazmat.2022.130262] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/11/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
Sludge reuse and utilization is one of important routines of disseminating fecal pollution to surface water and groundwater. However, it remains unclear the spatial distribution of fecal pollution indicators in sludge flocs and their reductions during sludge treatment processes. In this study, the abundances of fecal pollution indicators including cross-assembly phage (crAssphage), JC and BK polyomavirus (JCPyV, BKPyV), human adenovirus (HAdV), the human-specific HF183 Bacteroides (HF183) and Escherichia coli (EC) in soluble extracellular polymeric substances (S-EPS), loosely-bound EPS (LB-EPS), tightly-bound EPS (TB-EPS), and pellets of sludge flocs were determined, and the effect of potassium ferrate (PF) treatment on their removal and inactivation was investigated by using both qPCR and viability-qPCR. Results showed that all investigated indicators were detected in each fraction of sludge flocs. The PF treatment led to a great migration of indicators from sludge pellets to sludge EPS and some extent of their inactivation in each fraction of sludge flocs. The overall reductions of human fecal indicators in sludge determined by qPCR were 0-1.30 logs, which were 0-2 orders of magnitude lower than those of 0.69-2.39 logs detected by viability-qPCR, implying their inactivation by PF treatment to potentially alleviate the associated human health risks.
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Affiliation(s)
- Yuhang Wang
- Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; College of Materials and Chemical Engineering, Pingxiang University, Pingxiang 337055, China
| | - Wenhao Fang
- Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinxin Wang
- Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Lixiang Zhou
- Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China
| | - Guanyu Zheng
- Department of Environmental Engineering, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
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Shi A, Li S, Ma H, Du XJ, Wang S, Lu X. Survival of Salmonella in Tea Under Different Storage Conditions and Brewing Methods. Front Microbiol 2022; 13:816667. [PMID: 35369509 PMCID: PMC8971837 DOI: 10.3389/fmicb.2022.816667] [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: 11/17/2021] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Salmonella is one of the leading causes of bacterial gastroenteritis. High prevalence of Salmonella in environment is partially due to its ability to enter the “viable but non-culturable” (VBNC) state when they encounter unfavorable conditions. Dried teas are traditionally believed to have a low risk of causing salmonellosis. This study investigated the survival of Salmonella in four types of dried teas under different storage conditions and brewing methods. A method that coupled propidium monoazide (PMA) and quantitative PCR was optimized to quantify VBNC Salmonella cells to assess the risk of Salmonella contamination in teas after brewing. Each tea sample was inoculated with Salmonella at an 8 log CFU/ml concentration and stored at 4, 10, and 25°C. Under three storage conditions, the number of survived Salmonella was highest in teas stored at 4°C and lowest in teas stored at 25°C. After storage of 120 days, culturable Salmonella was detected from all samples ranging from 6–7 log CFU/g (4°C storage) to 3–4 log CFU/g (25°C storage). The effectiveness of brewing methods in inactivating Salmonella was assessed by brewing inoculated teas at room temperature, 55, 75, and 100°C for 10 min. Brewing teas at 75 and 100°C significantly (P < 0.05) reduced the number of viable Salmonella, but VBNC Salmonella formed when brewed at 75°C. Altogether, Salmonella can persist in dried teas for over 3 months at a temperature ranging from 4 to 25°C, and thermal treatment delivered during home brewing may not eradicate Salmonella in teas.
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Affiliation(s)
- Aiying Shi
- Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, Tianjin University of Science and Technology, Tianjin, China
| | - Shenmiao Li
- Department of Food Science and Agricultural Chemistry, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Hui Ma
- Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, Tianjin University of Science and Technology, Tianjin, China
| | - Xin-Jun Du
- Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, Tianjin University of Science and Technology, Tianjin, China
| | - Shuo Wang
- Key Laboratory of Food Nutrition and Safety, Ministry of Education of China, Tianjin University of Science and Technology, Tianjin, China
- Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin, China
- *Correspondence: Shuo Wang,
| | - Xiaonan Lu
- Department of Food Science and Agricultural Chemistry, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
- Xiaonan Lu,
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10
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Wisuthiphaet N, Yang X, Young GM, Nitin N. Quantitative Imaging of Bacteriophage Amplification for Rapid Detection of Bacteria in Model Foods. Front Microbiol 2022; 13:853048. [PMID: 35308341 PMCID: PMC8931685 DOI: 10.3389/fmicb.2022.853048] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
Rapid detection of bacteria in water and food samples is a critical need. The current molecular methods like real-time PCR can provide rapid detection after initial enrichment. However, these methods require significant preparation steps, specialized facilities to reduce contamination, and relatively expensive reagents. This study evaluates a novel approach for detecting bacteria based on imaging of bacteriophage amplification upon infection of the target host bacteria to mitigate some of these constraints and improve the specificity of discriminating live vs. dead bacteria. Thus, this research leverages the natural ability of lytic bacteriophages to rapidly amplify their genetic material and generate progeny phages upon infecting the host bacterium. This study uses a nucleic acid staining dye, a conventional fluorescence microscope, and quantitative image analysis for imaging the amplification of bacteriophages. The sensitivity and assay time for imaging-based quantification of phage amplification for detecting Escherichia coli were compared with RT-PCR and the standard plaque-forming assay for detection phage amplification in model systems, including coconut water and spinach wash water. The results demonstrate that the imaging approach matches both the sensitivity and speed for detecting E. coli using the RT-PCR method without requiring isolation of nucleic acids, expensive reagents, and specialized facilities. The quantitative imaging results demonstrate the detection of 10 CFU/ml of E. coli in coconut water and simulated spinach wash water with a chemical oxygen demand (COD) of 3,000 ppm within 8 h, including initial enrichment of the bacteria. In summary, the results of this study illustrate a novel phage amplification-based approach for detecting target bacteria in complex food and water samples using simple sample preparation methods and low-cost reagents.
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Affiliation(s)
- Nicharee Wisuthiphaet
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States
| | - Xu Yang
- Nutrition and Food Science Department, California State Polytechnic University Pomona, Pomona, CA, United States
| | - Glenn M. Young
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States
| | - Nitin Nitin
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States
- Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA, United States
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11
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Mu D, Zhou D, Xie G, Liu J, Wang Z, Xiong Q, Xu H. Real-time recombinase-aided amplification with PMAxx for the rapid detection of viable Escherichia coli O157:H7 in milk. J Dairy Sci 2022; 105:1028-1038. [PMID: 34998542 DOI: 10.3168/jds.2021-21074] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022]
Abstract
Escherichia coli O157:H7, the causative agent of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome in humans, generates a effective harm to community health because of its high pathogenicity. A real-time recombinase-aided amplification (rRAA) is an emerging method for nucleic acid detection. However, genomic DNA of bacteria could exist in food and the environment for a long time after death and could be amplified by rRAA assay, resulting in false-positive signal; thus, developing a fast and sensitive method is necessary to detect viable foodborne pathogens in food products. In our research, rRAA assay coupled with an enhanced nucleic acid binding dye named improved propidium monoazide (PMAxx) was established and applied in viable E. coli O157:H7 identification in skim milk. The PMAxx could eliminate interference from dead bacteria by permeating impaired membranes and covalently linking to DNA to prevent DNA amplification. The PMAxx-rRAA assay was performed with high sensitivity and good specificity. The PMAxx-rRAA assay could detect as low as 5.4 × 100 cfu/mL of viable E. coli O157:H7 in pure culture, and 7.9 × 100 cfu/mL of viable E. coli O157:H7 in skim milk. In addition, the PMAxx-rRAA assay was performed in the presence of a high concentration of dead bacteria or nontarget bacteria in skim milk to verify the capacity to resist interference from dead bacteria and nontarget bacteria. Therefore, the established PMAxx-rRAA assay is a valuable tool for the identification of viable E. coli O157:H7 in complex food matrix.
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Affiliation(s)
- Dan Mu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Donggen Zhou
- Ningbo International Travel Healthcare Center (Ningbo Customs Port Outpatient Department), Ningbo, 315010, PR China
| | - Guoyang Xie
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Ju Liu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Zhengzheng Wang
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Qin Xiong
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Hengyi Xu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China.
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12
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Ren Q, Wei F, Yuan C, Zhu C, Zhang Q, Quan J, Sun X, Zheng S. The effects of removing dead bacteria by propidium monoazide on the profile of salivary microbiome. BMC Oral Health 2021; 21:460. [PMID: 34551743 PMCID: PMC8456568 DOI: 10.1186/s12903-021-01832-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 09/16/2021] [Indexed: 12/22/2022] Open
Abstract
Background Oral microbiome played an important role in maintaining healthy state and might exhibit certain changes under circumstances of diseases. However, current microbiological research using sequencing techniques did not regard dead bacteria as a separate part, causing findings based on subsequent analyses on dynamic equilibrium and functional pathways of microbes somewhat questionable. Since treatment by propidium monoazide (PMA) was able to remove dead bacteria effectively, it would be worth studying how the sequencing results after PMA treatment differed from those focusing on the whole microbiota. Methods Unstimulated whole saliva samples were obtained from 18 healthy people from 3 age groups (children, adults, and the elderly). After removal of dead bacteria by propidium monoazide (PMA), changes in the profile of salivary microbiome were detected using 16S rRNA sequencing technology, and differences among age groups were compared subsequently. Results Dead bacteria accounted for nearly a half of the whole bacteria flora in saliva, while freezing had little effect on the proportion of deaths. After treatment with PMA, the numbers of OTUs reduced by 4.4–14.2%, while the Shannon diversity indices decreased significantly (P < 0.01). Only 35.2% of positive and 6.1% of negative correlations were found to be shared by the whole microbiota and that with dead bacteria removed. Differences in significantly changed OTUs and functional pathways among different age groups were also observed between the group of PMA and the control. Conclusions It was necessary to take the influence of living state of bacteria into account in analytic studies of salivary microbiome. Supplementary Information The online version contains supplementary material available at 10.1186/s12903-021-01832-5.
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Affiliation(s)
- Qidi Ren
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China
| | - Fangqiao Wei
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China
| | - Chao Yuan
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China
| | - Ce Zhu
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China.,Department of Preventive Dentistry, Shanghai Jiao Tong University School of Dentistry, Shanghai Ninth People's Hospital, Shanghai, People's Republic of China
| | - Qian Zhang
- Central Laboratory, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China
| | - Junkang Quan
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China
| | - Xiangyu Sun
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China.
| | - Shuguo Zheng
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing, People's Republic of China.
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13
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Seherler S, Bozdogan A, Ozal Ildeniz TA, Kok FN, Anac Sakir I. Detection of cholera toxin with surface plasmon field-enhanced fluorescent spectroscopy. Biotechnol Appl Biochem 2021; 69:1557-1566. [PMID: 34297408 DOI: 10.1002/bab.2227] [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: 01/18/2021] [Accepted: 07/20/2021] [Indexed: 11/10/2022]
Abstract
In this work, a biosensor based on surface plasmon field-enhanced florescence spectroscopy (SPFS) method was successfully constructed to detect the truncated form of cholera toxin, that is, its beta subunit (CTX-B). CTX-B is a relatively small molecule (12 kDa) and it was chosen as model analyte for the detection of protein toxins originated from waterborne pathogens. Recognition layer was prepared on gold-coated LaSFN9 glasses modified with 11-mercaptoundecanoic acid (11-MUA). Biotin-conjugated anti-CTX-B polyclonal antibody (B-Ab) was immobilized on streptavidin (SA) layer constructed on the 11-MUA-modified surface. CTX-B amount was determined with direct assay using B-Ab in surface plasmon resonance (SPR) mode and with sandwich assay in SPFS mode using Cy5-conjugated anti-CTX-B polyclonal antibody. Minimum detected CTX-B concentrations were 10 and 0.01 μg/ml with SPR and SPFS, respectively, showing the sensitivity of the SPFS system over the conventional one. The detection was done in 2-6 h, which was faster than both culture and polymerase chain reaction (PCR)-based methods. Stability tests were performed with SA-coated sensors (excluding B-Ab). In this form, the layer was stable after 30 days of storage in phosphate-buffered saline (PBS; 0.01 M, pH = 7.4) at +4°C. B-Ab layer was formed immediately on them before each measurement.
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Affiliation(s)
- Sebnem Seherler
- Molecular Biology-Genetics and Biotechnology Programme, Istanbul Technical University, Istanbul, Turkey
| | - Anil Bozdogan
- Department of Material Science and Engineering, Gebze Technical University, Kocaeli, Turkey.,Center for Electrochemical Surface Technology (CEST), Austrian Institute of Technology, Tulln, Austria
| | - Tugba Arzu Ozal Ildeniz
- Department of Medical Engineering, Faculty of Engineering, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Fatma Nese Kok
- Molecular Biology-Genetics and Biotechnology Programme, Istanbul Technical University, Istanbul, Turkey
| | - Ilke Anac Sakir
- Department of Material Science and Engineering, Gebze Technical University, Kocaeli, Turkey.,Institute of Biotechnology, Gebze Technical University, Kocaeli, Turkey
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14
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How to Evaluate Non-Growing Cells-Current Strategies for Determining Antimicrobial Resistance of VBNC Bacteria. Antibiotics (Basel) 2021; 10:antibiotics10020115. [PMID: 33530321 PMCID: PMC7912045 DOI: 10.3390/antibiotics10020115] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 12/17/2022] Open
Abstract
Thanks to the achievements in sanitation, hygiene practices, and antibiotics, we have considerably improved in our ongoing battle against pathogenic bacteria. However, with our increasing knowledge about the complex bacterial lifestyles and cycles and their plethora of defense mechanisms, it is clear that the fight is far from over. One of these resistance mechanisms that has received increasing attention is the ability to enter a dormancy state termed viable but non-culturable (VBNC). Bacteria that enter the VBNC state, either through unfavorable environmental conditions or through potentially lethal stress, lose their ability to grow on standard enrichment media, but show a drastically increased tolerance against antimicrobials including antibiotics. The inability to utilize traditional culture-based methods represents a considerable experimental hurdle to investigate their increased antimicrobial resistance and impedes the development and evaluation of effective treatments or interventions against bacteria in the VBNC state. Although experimental approaches were developed to detect and quantify VBNCs, only a few have been utilized for antimicrobial resistance screening and this review aims to provide an overview of possible methodological approaches.
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15
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Devane ML, Moriarty E, Weaver L, Cookson A, Gilpin B. Fecal indicator bacteria from environmental sources; strategies for identification to improve water quality monitoring. WATER RESEARCH 2020; 185:116204. [PMID: 32745743 DOI: 10.1016/j.watres.2020.116204] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 07/13/2020] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
In tropical to temperate environments, fecal indicator bacteria (FIB), such as enterococci and Escherichia coli, can persist and potentially multiply, far removed from their natural reservoir of the animal gut. FIB isolated from environmental reservoirs such as stream sediments, beach sand and vegetation have been termed "naturalized" FIB. In addition, recent research suggests that the intestines of poikilothermic animals such as fish may be colonized by enterococci and E. coli, and therefore, these animals may contribute to FIB concentrations in the aquatic environment. Naturalized FIB that are derived from fecal inputs into the environment, and subsequently adapted to maintain their population within the non-host environment are termed "naturalized enteric FIB". In contrast, an additional theory suggests that some "naturalized" FIB diverged from enteric FIB many millions of years ago and are now normal inhabitants of the environment where they are referred to as "naturalized non-enteric FIB". In the case of the Escherichia genus, the naturalized non-enteric members are identified as E. coli during routine water quality monitoring. An over-estimation of the health risk could result when these naturalized, non-enteric FIB, (that is, not derived from avian or mammalian fecal contamination), contribute to water quality monitoring results. It has been postulated that these environmental FIB belonging to the genera Escherichia and Enterococcus can be differentiated from enteric FIB by genetic methods because they lack some of the genes required for colonization of the host intestine, and have acquired genes that aid survival in the environment. Advances in molecular tools such as next generation sequencing will aid the identification of genes peculiar or "enriched" in particular habitats to discriminate between enteric and environmental FIB. In this appraisal, we have reviewed the research studying "naturalized" FIB, and discussed the techniques for their differentiation from enteric FIB. This differentiation includes the important distinction between enteric FIB derived from fresh and non-recent fecal inputs, and those truly non-enteric environmental microbes, which are currently identified as FIB during routine water quality monitoring. The inclusion of tools for the identification of naturalized FIB (enteric or environmental) would be a valuable resource for future studies assessing water quality.
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Affiliation(s)
- Megan L Devane
- Institute of Environmental Science and Research Ltd., 27 Creyke Rd, Ilam, Christchurch, New Zealand.
| | - Elaine Moriarty
- Institute of Environmental Science and Research Ltd., 27 Creyke Rd, Ilam, Christchurch, New Zealand
| | - Louise Weaver
- Institute of Environmental Science and Research Ltd., 27 Creyke Rd, Ilam, Christchurch, New Zealand
| | - Adrian Cookson
- AgResearch Ltd., Hopkirk Research Institute, Massey University, Palmerston North, New Zealand; mEpiLab, School of Veterinary Sciences, Massey University, Palmerston North, New Zealand
| | - Brent Gilpin
- Institute of Environmental Science and Research Ltd., 27 Creyke Rd, Ilam, Christchurch, New Zealand
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16
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Liu Y, Kumblathan T, Uppal GK, Zhou A, Moe B, Hrudey SE, Li XF. A hidden risk: Survival and resuscitation of Escherichia coli O157:H7 in the viable but nonculturable state after boiling or microwaving. WATER RESEARCH 2020; 183:116102. [PMID: 32745672 DOI: 10.1016/j.watres.2020.116102] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 06/04/2020] [Accepted: 06/21/2020] [Indexed: 06/11/2023]
Abstract
We report the existence and resuscitation of viable but nonculturable (VBNC) Escherichia coli O157:H7 cells in drinking water induced by the common point-of-use disinfection treatments of boiling or microwaving. Tap water and saline samples containing E. coli O157:H7 culturable cells from a bovine isolate or two clinical isolates were boiled (1, 10, or 15 min) on a hot plate or microwaved (1.5 min) to reach boiling. No culturable E. coli O157:H7 cells were observed in the treated samples using conventional plating methods. In samples boiled for 1 or 10 min, two viability assays separately detected that 2-5.5% of the cells retained an intact membrane, while 28 to 87 cells out of the initial 108 cells retained both measurable intracellular esterase activity and membrane integrity. In samples boiled for 15 min, no viable cells were detected. The microwaved samples contained 6-10% of cells with an intact membrane, while 21 to 108 cells out of the initial 108 cells retained both membrane integrity and esterase activity. The number of viable cells retaining both metabolic activity and membrane integrity were consistent in all samples, supporting the survival of a small number of E. coli O157:H7 cells in the VBNC state after boiling for 1 or 10 min or microwaving. Furthermore, the VBNC E. coli O157:H7 cells regained growth at 37 °C in culture media containing autoinducers produced by common non-pathogenic E. coli, commonly present in the human intestine, and norepinephrine. The resuscitated cells were culturable on conventional plates and expressed mRNA encoding the E. coli O157 lipopolysaccharide gene (rfbE) and the H7 flagellin gene (fliC). This study highlights potential concerns for public health risk management of VBNC E. coli O157:H7 in drinking water disinfected by heat treatment at point-of-use. The public health significance of these concerns warrants further investigation.
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Affiliation(s)
- Yanming Liu
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada
| | - Teresa Kumblathan
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada
| | - Gursharan K Uppal
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada
| | - Angela Zhou
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada
| | - Birget Moe
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada; Alberta Centre for Toxicology, Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Steve E Hrudey
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada
| | - Xing-Fang Li
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, T6G 2G3, Canada.
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17
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Fu Y, Ye Z, Jia Y, Fan J, Hashmi MZ, Shen C. An Optimized Method to Assess Viable Escherichia coli O157:H7 in Agricultural Soil Using Combined Propidium Monoazide Staining and Quantitative PCR. Front Microbiol 2020; 11:1809. [PMID: 32849416 PMCID: PMC7411311 DOI: 10.3389/fmicb.2020.01809] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/09/2020] [Indexed: 11/29/2022] Open
Abstract
Agricultural soil contaminated by manure is becoming an important source for the transmission of foodborne pathogens. There is an urgent need for a rapid and accurate method for viable pathogen detection in agricultural soil samples. Propidium monoazide (PMA) is a DNA-binding dye that can inhibit the amplification of DNA from dead cells through subsequent quantitative polymerase chain reaction (qPCR), thus allowing for viable cells detection and quantification. The objective of this study was to detect viable Escherichia coli O157:H7 in the agricultural soils by PMA-qPCR. In this study, cell extraction and gradient density centrifugation were incorporated before PMA-qPCR to reduce the interference of soil particle including turbidity and a high ratio of dead cells. The optimized treatment conditions were determined as follows, the maximum removal of DNA from dead cells was achieved by 1.067 g/mL Percoll of centrifugation and 50 μM PMA treatment. Under these conditions, the turbidity of paddy soil suspensions decreased from 3500 to 28.4 nephelometric turbidity units (NTU), and the ratio of viable cells to dead cells increased from 0.001 to 1.025%. For typical agricultural soils collected in China, as low as 102colony-forming units (CFU)/g of viable cells could be accurately detected in the presence of a large number of dead cells (107 CFU/g) by the optimized PMA-qPCR. Significantly, with comparable accuracy, the optimized PMA-qPCR assay was more sensitive, accessible and rapid than conventional culture methods. In addition, the viable but non-culturable (VBNC) state of E. coli O157:H7 cells in paddy soils, which often escaped the detection by conventional culture methods, could be quantitatively characterized by the optimized PMA-qPCR method. Potentially, the optimized PMA-qPCR can be further applied for viable pathogens detection and give insight into the prevalence of VBNC E. coli O157:H7 in agricultural soil.
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Affiliation(s)
- Yulong Fu
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Zhe Ye
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Yangyang Jia
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Jiahui Fan
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | | | - Chaofeng Shen
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
- Zhejiang Provincial Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, China
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18
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Chhetri VS, Han Y, Janes ME, Adhikari A. Evaluation of viability of E. coli O157: H7 on chlorine and lactic acid treated spinach leaves using combined propidium monoazide staining and real-time PCR. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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19
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Miotto M, Barretta C, Ossai SO, da Silva HS, Kist A, Vieira CRW, Parveen S. Optimization of a propidium monoazide-qPCR method for Escherichia coli quantification in raw seafood. Int J Food Microbiol 2020; 318:108467. [PMID: 31835094 DOI: 10.1016/j.ijfoodmicro.2019.108467] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 11/13/2019] [Accepted: 11/30/2019] [Indexed: 11/15/2022]
Abstract
The present study compared different concentrations of propidium monoazide (PMA), time of exposure to light and different light intensities to determine the optimal conditions for the quantification of viable Escherichia coli in cell suspension and in food matrix. The influence of cell density and the effectiveness of PMA in viable but non-culturable (VBNC) E. coli cells were evaluated and also applied in food matrix. For that purpose, different concentrations of PMA (20 μM, 40 μM, 50 μM, 60 μM and 80 μM) under different times of exposure (5 min, 10 min, 15 min, 20 min and 30 min) to lights of different intensities (500 W and 650 W) were evaluated. After determining the optimal conditions, the PMA-qPCR methods were applied to different compositions of live and heat-killed E. coli suspensions (v:v; 0:1; 1:0; 1:1) in concentrations ranging from 3 Log to 7 Log CFU/mL. The same dilutions were prepared with E. coli in VBNC state and applied in food matrix. The results obtained from qPCR, PMA-qPCR and plate counts were compared. The results suggested that a PMA treatment of 50 μM PMA for 15 min under 650 W light intensity was optimal under our conditions. For E. coli cell suspensions, the amplification of heat-killed cells was inhibited greatly by PMA when concentrations were ≤ 5 Log CFU/mL. For the samples of oyster inoculated with heat-killed cells, E. coli was not detected by PMA-qPCR in concentrations ≤4 Log CFU/g. Regarding the results with VBNC state, we considered the PMA-qPCR method to be applicable for enumerating E. coli VBNC cells in oyster samples. Based on our findings, we further recommend the use of PMA-qPCR with the aim of reducing the amplification of dead cells for improving its performance, since false-positives could still occur depending on the level of E. coli in the sample. The application of the PMA-qPCR for quantification of bacteria, compared to the use of culture-dependent methods, is quite promising. However, further studies are recommended, especially using different food matrices.
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Affiliation(s)
- Marilia Miotto
- Department of Food Science and Technology, Federal University of Santa Catarina, 1346 Admar Gonzaga, 88034-001 Florianopolis, Santa Catarina, Brazil.
| | - Clarissa Barretta
- Department of Food Science and Technology, Federal University of Santa Catarina, 1346 Admar Gonzaga, 88034-001 Florianopolis, Santa Catarina, Brazil
| | - Sylvia O Ossai
- Food Science and Technology Program, University of Maryland Eastern Shore, 2116 Backbone Road, 21853 Princess Anne, MD, United States
| | - Helen Silvestre da Silva
- Department of Food Science and Technology, Federal University of Santa Catarina, 1346 Admar Gonzaga, 88034-001 Florianopolis, Santa Catarina, Brazil
| | - Airton Kist
- Laboratory of Computational and Applied Statistics, Department of Mathematics and Statistics, State University of Ponta Grossa, 4748 Gen. Carlos Cavalcanti, 84030-900 Ponta Grossa, Parana, Brazil
| | - Cleide Rosana Werneck Vieira
- Department of Food Science and Technology, Federal University of Santa Catarina, 1346 Admar Gonzaga, 88034-001 Florianopolis, Santa Catarina, Brazil
| | - Salina Parveen
- Food Science and Technology Program, University of Maryland Eastern Shore, 2116 Backbone Road, 21853 Princess Anne, MD, United States
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20
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Ling N, Shen J, Guo J, Zeng D, Ren J, Sun L, Jiang Y, Xue F, Dai J, Li B. Rapid and accurate detection of viable Vibrio parahaemolyticus by sodium deoxycholate-propidium monoazide-qPCR in shrimp. Food Control 2020. [DOI: 10.1016/j.foodcont.2019.106883] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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21
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Gorski L, Rivadeneira P, Cooley MB. New strategies for the enumeration of enteric pathogens in water. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:765-776. [PMID: 31342654 DOI: 10.1111/1758-2229.12786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/15/2019] [Accepted: 07/21/2019] [Indexed: 06/10/2023]
Abstract
Water quality standards for drinking water and recreational waters have long been based on the enumeration of faecal coliforms in the various water supplies, with 0 CFU Escherichia coli/100 ml for drinking water and <126 CFU generic E. coli/100 ml for recreational waters. Irrigation water will soon undergo the same scrutiny in the United States. For over 50 years the most probable number method has been used by laboratories to estimate the level of viable bacteria in a sample, but this method is labour intensive and slow, especially if large numbers of samples need to be tested. In this review, we describe some recent innovations in methods to enumerate enteric pathogens in water. These methods are based on different reasoning schemes that can be categorized as biosensors and nucleic acid-based methods. All the methods described here used natural water sources. Several were also used to survey the bacterial levels in naturally contaminated samples. The different methods vary in their limits of detection, ease of use, and potential portability. Some combine very good limits of detection with the ability to overcome technical challenges; however, there is considerable room for improvement, as none of the methods are without shortcomings.
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Affiliation(s)
- Lisa Gorski
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, USA
| | - Paula Rivadeneira
- Department of Soil, Water, and Environmental Science, The University of Arizona, Yuma, AZ, USA
| | - Michael B Cooley
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA, USA
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22
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Tilton L, Das G, Yang X, Wisuthiphaet N, Kennedy IM, Nitin N. Nanophotonic Device in Combination with Bacteriophages for Enhancing Detection Sensitivity of Escherichia coli in Simulated Wash Water. ANAL LETT 2019. [DOI: 10.1080/00032719.2019.1604726] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Lianna Tilton
- Department of Food Science and Technology, University of California Davis, Davis, CA, USA
| | - Gautom Das
- Department of Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
| | - Xu Yang
- Department of Food Science and Technology, University of California Davis, Davis, CA, USA
| | - Nicharee Wisuthiphaet
- Department of Food Science and Technology, University of California Davis, Davis, CA, USA
| | - Ian M. Kennedy
- Department of Mechanical and Aerospace Engineering, University of California Davis, Davis, CA, USA
| | - Nitin Nitin
- Department of Food Science and Technology, University of California Davis, Davis, CA, USA
- Department of Biological and Agricultural Engineering, University of California Davis, Davis, CA, USA
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