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Yadav M, Dhyani S, Joshi P, Awasthi S, Tanwar S, Gupta V, Rathore DK, Chaudhuri S. Formic acid, an organic acid food preservative, induces viable-but-non-culturable state, and triggers new Antimicrobial Resistance traits in Acinetobacter baumannii and Klebsiella pneumoniae. Front Microbiol 2022; 13:966207. [PMID: 36504816 PMCID: PMC9730046 DOI: 10.3389/fmicb.2022.966207] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/14/2022] [Indexed: 11/25/2022] Open
Abstract
Numerous human pathogens, especially Gram-negative bacteria, are able to enter the viable-but-non-culturable (VBNC) state when they are exposed to environmental stressors and pose the risk of being resuscitated and causing infection after the removal of the trigger. Widely used food preservatives like weak organic acids are potential VBNC inducers in food processing and packaging facilities but have only been reported for food-borne pathogens. In the present study, it is demonstrated for the first time that one such agent, formic acid (FA), can induce a VBNC state at food processing, storage, and distribution temperatures (4, 25, and 37°C) with a varied time of treatment (days 4-10) in pathogenic Gram-negative bacteria Acinetobacter baumannii and Klebsiella pneumoniae. The use of hospital-associated pathogens is critical based on the earlier reports that demonstrated the presence of these bacteria in hospital kitchens and commonly consumed foods. VBNC induction was validated by multiple parameters, e.g., non-culturability, metabolic activity as energy production, respiratory markers, and membrane integrity. Furthermore, it was demonstrated that the removal of FA was able to resuscitate VBNC with an increased expression of multiple virulence and Antimicrobial Resistance (AMR) genes in both pathogens. Since food additives/preservatives are significantly used in most food manufacturing facilities supplying to hospitals, contamination of these packaged foods with pathogenic bacteria and the consequence of exposure to food additives emerge as pertinent issues for infection control, and control of antimicrobial resistance in the hospital setting.
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Affiliation(s)
| | | | | | | | | | | | | | - Susmita Chaudhuri
- Department of Multidisciplinary Clinical and Translational Research, Translational Health Science and Technology Institute, Faridabad, Haryana, India
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Tortosa G, Fernández-González AJ, Lasa AV, Aranda E, Torralbo F, González-Murua C, Fernández-López M, Benítez E, Bedmar EJ. Involvement of the metabolically active bacteria in the organic matter degradation during olive mill waste composting. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 789:147975. [PMID: 34082203 DOI: 10.1016/j.scitotenv.2021.147975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/05/2021] [Accepted: 05/19/2021] [Indexed: 06/12/2023]
Abstract
RNA-based high-throughput sequencing is a valuable tool in the discernment of the implication of metabolically active bacteria during composting. In this study, "alperujo" composting was used as microbial model for the elucidation of structure-function relationships with physicochemical transformation of the organic matter. DNA and RNA, subsequently retrotranscribed into cDNA, were isolated at the mesophilic, thermophilic and maturation phases. 16S rRNA gene was amplified by quantitative PCR (qPCR) and Illumina MiSeq platform to assess bacterial abundance and diversity, respectively. The results showed that the abundance of active bacteria assessed by qPCR was maximum at thermophilic phase, which confirm it as the most active stage of the process. Concerning diversity, Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the main phyla presented in composts. Concomitantly, three different behaviours were observed for bacterial dynamics: some genera decreased during the whole process meanwhile others proliferated only at thermophilic or maturation phase. Statistical correlation between physicochemical transformations of the organic matter and bacterial diversity revealed bacterial specialisation. This result indicated that specific groups of bacteria were only involved in the organic matter degradation during bio-oxidative phase or humification at maturation. Metabolic functions predictions confirmed that active bacteria were mainly involved in carbon (C) and nitrogen (N) cycles transformations, and pathogen reduction.
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Affiliation(s)
- Germán Tortosa
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), Agencia Estatal CSIC, c/ Profesor Albareda, 1, 18008 Granada, Spain.
| | - Antonio J Fernández-González
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), Agencia Estatal CSIC, c/ Profesor Albareda, 1, 18008 Granada, Spain
| | - Ana V Lasa
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), Agencia Estatal CSIC, c/ Profesor Albareda, 1, 18008 Granada, Spain
| | - Elisabet Aranda
- Institute of Water Research, University of Granada, Edificio Fray Luis, c/ Ramón y Cajal, 4, 18071 Granada, Spain; Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus de Cartuja, s/n, 18071 Granada, Spain
| | - Fernando Torralbo
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena, s/n, 48940 Leioa, Bizkaia, Spain
| | - Carmen González-Murua
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena, s/n, 48940 Leioa, Bizkaia, Spain
| | - Manuel Fernández-López
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), Agencia Estatal CSIC, c/ Profesor Albareda, 1, 18008 Granada, Spain
| | - Emilio Benítez
- Department of Environmental Protection, Estación Experimental del Zaidín (EEZ), Agencia Estatal CSIC, c/ Profesor Albareda, 1, 18008 Granada, Spain
| | - Eulogio J Bedmar
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ), Agencia Estatal CSIC, c/ Profesor Albareda, 1, 18008 Granada, Spain
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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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Guo L, Ye C, Cui L, Wan K, Chen S, Zhang S, Yu X. Population and single cell metabolic activity of UV-induced VBNC bacteria determined by CTC-FCM and D 2O-labeled Raman spectroscopy. ENVIRONMENT INTERNATIONAL 2019; 130:104883. [PMID: 31229870 DOI: 10.1016/j.envint.2019.05.077] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 05/19/2019] [Accepted: 05/30/2019] [Indexed: 06/09/2023]
Abstract
The occurrence of viable but non-culturable (VBNC) bacteria will result in significant underestimation of viable bacterial counts in drinking water. Whereas, much is unknown in characterizing their viability. In this study, two environmental isolates (Aeromonas sp. and Pseudomonas sp.) and two model strains (E. coli and S. aureus) were induced into VBNC state by UV irradiation. Then, their metabolic activity was determined by 5-cyano-2,3-ditolyl tetrazolium chloride combination flow cytometry (CTC-FCM) and D2O-labeled Raman spectroscopy, respectively, at both population and single cell levels. The results showed that almost all strains could enter VBNC state irradiated by ≥ 5 mJ/cm2 UV. When determined by CTC-FCM, the population metabolic activity for each strain did not vary significantly (p > 0.05) unless the UV dose reached 200 mJ/cm2. Their single cell activity spectrum narrowed slightly, as indicated by changes in the standard deviation of the logarithmic normal distribution (σ) of 0.015-0.033. This minute difference suggested the CTC-FCM method was suitable for assessing the essential viability of VBNC bacteria. With respect to Raman method, an obvious dose-response effect was recorded. With the UV dosages increased from 10 to 200 mJ/cm2, the CD/(CD + CH) for the four strains were reduced to between 95.7% and 47.9% of unirradiated controls, depending on strain and UV dose. Meanwhile, the single cellular Raman spectrum showed much more heterogeneously metabolic activity distribution, with some cells even entering metabolic "silence". Considering the ubiquitous participation of water in biochemical processes, the Raman method was more appropriate in assessing the overall metabolic activity. The above findings can not only be a reference for VBNC mechanism studies, but also have the potential in optimizing disinfection and other bacterial removal processes.
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Affiliation(s)
- Lizheng Guo
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Chengsong Ye
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Li Cui
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Kun Wan
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Sheng Chen
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Shenghua Zhang
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
| | - Xin Yu
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
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