1
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Golovko O, Ahrens L, Schelin J, Sörengård M, Bergstrand KJ, Asp H, Hultberg M, Wiberg K. Organic micropollutants, heavy metals and pathogens in anaerobic digestate based on food waste. J Environ Manage 2022; 313:114997. [PMID: 35395528 DOI: 10.1016/j.jenvman.2022.114997] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/07/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
Anaerobic digestate based on food waste is increasingly used as fertilizer in food production. This study examined the characteristics of anaerobic digestate based on food waste from three biogas plants in Sweden. The characterization included measurements of heavy metals (n = 7), chemicals of emerging concern (CECs), such as currently used drugs and pesticides (n = 133), and an extended range of food-borne pathogens, including two notable sporeformers and some widespread antibiotic-resistant bacteria. The amounts of Escherichia coli, enterococci, and Salmonella and the concentrations of the target heavy metals were all below the maximum accepted levels at all three locations studied. However, the spore-forming Bacillus cereus was found to be present at high levels in samples from all three biogas plants. Among the 133 CECs investigated, 48 were detected at least once, and the highest concentrations were found for pyroxidine, nicotine, caffeine, theobromine, and nicotine. The biofertilizers from the different biogas plants had similar CEC profiles, which indicate similarities in household waste composition and thorough mixing in the biogas plants. If this profile is found to be spatially and temporally consistent, it can help regulators to establish priority lists of CECs of top concern. Assuming increasing use of biofertilizers for food production in the future, it would be beneficial to have concentration limits for CECs Risk estimation based on risk quotients (RQs) indicated generally low environmental risks associated with application of biofertilizer to soils for food crop production. However, the toxicity of CEC mixtures needs to be considered when estimating the risks from application of biofertilizers on agricultural land or in other production systems.
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Affiliation(s)
- Oksana Golovko
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), SE-75007, Uppsala, Sweden.
| | - Lutz Ahrens
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), SE-75007, Uppsala, Sweden
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, SE-221 00, Lund, Sweden
| | - Mattias Sörengård
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), SE-75007, Uppsala, Sweden
| | - Karl-Johan Bergstrand
- Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Box 190, SE-234 22, Lomma, Sweden
| | - Håkan Asp
- Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Box 190, SE-234 22, Lomma, Sweden
| | - Malin Hultberg
- Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Box 190, SE-234 22, Lomma, Sweden
| | - Karin Wiberg
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), SE-75007, Uppsala, Sweden
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2
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Bozzola T, Scalise M, Larsson CU, Newton-Vesty MC, Rovegno C, Mitra A, Cramer J, Wahlgren WY, Radhakrishnan Santhakumari P, Johnsson RE, Schwardt O, Ernst B, Friemann R, Dobson RCJ, Indiveri C, Schelin J, Nilsson UJ, Ellervik U. Sialic Acid Derivatives Inhibit SiaT Transporters and Delay Bacterial Growth. ACS Chem Biol 2022; 17:1890-1900. [PMID: 35675124 PMCID: PMC9295122 DOI: 10.1021/acschembio.2c00321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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Antibiotic resistance
is a major worldwide concern, and new drugs
with mechanistically novel modes of action are urgently needed. Here,
we report the structure-based drug design, synthesis, and evaluation
in vitro and in cellular systems of sialic acid derivatives able to
inhibit the bacterial sialic acid symporter SiaT. We designed and
synthesized 21 sialic acid derivatives and screened their affinity
for SiaT by a thermal shift assay and elucidated the inhibitory mechanism
through binding thermodynamics, computational methods, and inhibitory
kinetic studies. The most potent compounds, which have a 180-fold
higher affinity compared to the natural substrate, were tested in
bacterial growth assays and indicate bacterial growth delay in methicillin-resistant Staphylococcus aureus. This study represents the
first example and a promising lead in developing sialic acid uptake
inhibitors as novel antibacterial agents.
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Affiliation(s)
- Tiago Bozzola
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.,Molecular Pharmacy Group, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, 87036 Arcavacata di Rende, Italy
| | - Christer U Larsson
- Division of Applied Microbiology, Department of Chemistry, Lund University, 22100 Lund, Sweden
| | - Michael C Newton-Vesty
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, 8140 Christchurch, New Zealand
| | - Caterina Rovegno
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Ankita Mitra
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Jonathan Cramer
- Molecular Pharmacy Group, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.,Institute for Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University of Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Weixiao Yuan Wahlgren
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, S-40530 Gothenburg, Sweden
| | - Partha Radhakrishnan Santhakumari
- Institute for Stem Cell Science and Regenerative Medicine, Bengaluru, Karnataka 560065, India.,Manipal Academy of Higher Education, Tiger Circle Road, Manipal, Karnataka 576104, India
| | | | - Oliver Schwardt
- Molecular Pharmacy Group, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Beat Ernst
- Molecular Pharmacy Group, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Rosmarie Friemann
- Department of Clinical Microbiology, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, 40530 Gothenburg, Sweden
| | - Renwick C J Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, 8140 Christchurch, New Zealand.,Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, 87036 Arcavacata di Rende, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), National Research Council-CNR, Via Amendola 122/O, 70126 Bari, Italy
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, 22100 Lund, Sweden
| | - Ulf J Nilsson
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Ulf Ellervik
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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3
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Marklinder I, Eskhult G, Ahlgren R, Blücher A, Börjesson SME, Moazzami M, Schelin J, Danielsson-Tham ML. A Structural Equation Model Demonstrating the Relationship between Food Safety Background, Knowledge, Attitudes and Behaviour among Swedish Students. Foods 2022; 11:foods11111595. [PMID: 35681344 PMCID: PMC9180796 DOI: 10.3390/foods11111595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/25/2022] [Accepted: 05/26/2022] [Indexed: 02/04/2023] Open
Abstract
Traditionally, food safety knowledge has been seen as a factor in improving food safety behaviour. However, the relationship between knowledge and behavior is complex. The aim of the present study was to investigate self-reported data from 408 university students regarding food safety background, knowledge, attitudes, and behaviour using Structural Equation Model (SEM) to examine the influence of different factors on food safety behaviour. The SEM was applied to four factors derived from the data: Background, Knowledge, Attitude and Behaviour. The novelty of this current investigation is the inclusion of the Background factor (genus; experience of cooking and handling different food items; experience of a food safety education course; the foremost sources of food safety knowledge). The factors were constructed from variables with sufficient factor loadings and set up in a predetermined structure confirmed to be valid in previous studies. The results, demonstrated as regression coefficients between factors, confirm that the Background factor strongly influenced Knowledge (0.842). The Knowledge factor, in turn, strongly affected Attitude (0.605), while it did not directly affect Behaviour (0.301) in the same way as Attitude. Attitude had a stronger influence on Behaviour (0.438) than Knowledge. Thus, the Attitude factor seemed to play a mediating role between Knowledge and Behaviour. This indicates that students´ attitudes towards the importance of food safety may have an impact on their food safety behavior, which should have implications for the development of food safety education. This warrants further investigation and practical development.
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Affiliation(s)
- Ingela Marklinder
- Department of Food Studies, Nutrition and Dietetics, Uppsala University, 751 22 Uppsala, Sweden
- Correspondence:
| | - Gustav Eskhult
- Department of Statistics, Uppsala University, 751 20 Uppsala, Sweden;
| | - Roger Ahlgren
- Department of Food, Nutrition and Culinary Science, Umeå University, 901 87 Umeå, Sweden;
| | - Anna Blücher
- Faculty of Health and Life Sciences, Linnaeus University, 430 38 Kalmar, Sweden;
| | | | - Madeleine Moazzami
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden;
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, 221 00 Lund, Sweden;
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4
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Mata Forsberg M, Arasa C, van Zwol W, Uzunçayir S, Schönbichler A, Regenthal P, Schelin J, Lindkvist-Petersson K, Björkander S, Sverremark-Ekström E. Activation of human γδ T cells and NK cells by Staphylococcal enterotoxins requires both monocytes and conventional T cells. J Leukoc Biol 2021; 111:597-609. [PMID: 34114693 DOI: 10.1002/jlb.3a1020-630rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Staphylococcal enterotoxins (SE) pose a great threat to human health due to their ability to bypass antigen presentation and activate large amounts of conventional T cells resulting in a cytokine storm potentially leading to toxic shock syndrome. Unconventional T- and NK cells are also activated by SE but the mechanisms remain poorly understood. In this study, the authors aimed to explore the underlying mechanism behind SE-mediated activation of MAIT-, γδ T-, and NK cells in vitro. CBMC or PBMC were stimulated with the toxins SEA, SEH, and TSST-1, and cytokine and cytotoxic responses were analyzed with ELISA and flow cytometry. All toxins induced a broad range of cytokines, perforin and granzyme B, although SEH was not as potent as SEA and TSST-1. SE-induced IFN-γ expression in MAIT-, γδ T-, and NK cells was clearly reduced by neutralization of IL-12, while cytotoxic compounds were not affected at all. Kinetic assays showed that unconventional T cell and NK cell-responses are secondary to the response in conventional T cells. Furthermore, co-cultures of isolated cell populations revealed that the ability of SEA to activate γδ T- and NK cells was fully dependent on the presence of both monocytes and αβ T cells. Lastly, it was found that SE provoked a reduced and delayed cytokine response in infants, particularly within the unconventional T and NK cell populations. This study provides novel insights regarding the activation of unconventional T- and NK cells by SE, which contribute to understanding the vulnerability of young children towards Staphylococcus aureus infections.
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Affiliation(s)
- Manuel Mata Forsberg
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Claudia Arasa
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Willemien van Zwol
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Sibel Uzunçayir
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Anna Schönbichler
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Paulina Regenthal
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden
| | | | - Sophia Björkander
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Eva Sverremark-Ekström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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5
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Etter D, Schelin J, Schuppler M, Johler S. Staphylococcal Enterotoxin C-An Update on SEC Variants, Their Structure and Properties, and Their Role in Foodborne Intoxications. Toxins (Basel) 2020; 12:E584. [PMID: 32927913 PMCID: PMC7551944 DOI: 10.3390/toxins12090584] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 12/20/2022] Open
Abstract
Staphylococcal enterotoxins are the most common cause of foodborne intoxications (staphylococcal food poisoning) and cause a wide range of diseases. With at least six variants staphylococcal enterotoxin C (SEC) stands out as particularly diverse amongst the 25 known staphylococcal enterotoxins. Some variants present unique and even host-specific features. Here, we review the role of SEC in human and animal health with a particular focus on its role as a causative agent for foodborne intoxications. We highlight structural features unique to SEC and its variants, particularly, the emetic and superantigen activity, as well as the roles of SEC in mastitis and in dairy products. Information about the genetic organization as well as regulatory mechanisms including the accessory gene regulator and food-related stressors are provided.
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Affiliation(s)
- Danai Etter
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zürich, 8057 Zürich, Switzerland;
- Laboratory of Food Microbiology, Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland;
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, 22100 Lund, Sweden;
| | - Markus Schuppler
- Laboratory of Food Microbiology, Institute of Food, Nutrition and Health, ETH Zürich, 8092 Zürich, Switzerland;
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zürich, 8057 Zürich, Switzerland;
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6
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Schelin J, Cohn MT, Frisk B, Frees D. A Functional ClpXP Protease is Required for Induction of the Accessory Toxin Genes, tst, sed, and sec. Toxins (Basel) 2020; 12:E553. [PMID: 32872362 PMCID: PMC7551677 DOI: 10.3390/toxins12090553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/21/2020] [Accepted: 08/26/2020] [Indexed: 01/09/2023] Open
Abstract
Staphylococcal toxic shock syndrome is a potentially lethal illness attributed to superantigens produced by Staphylococcus aureus, in particular toxic shock syndrome toxin 1 (TSST-1), but staphylococcal enterotoxins (SEs) are also implicated. The genes encoding these important toxins are carried on mobile genetic elements, and the regulatory networks controlling expression of these toxins remain relatively unexplored. We show here that the highly conserved ClpXP protease stimulates transcription of tst (TSST-1), sec (SEC), and sed (SED) genes in the prototypical strains, SA564 and RN4282. In the wild-type cells, the post-exponential upregulation of toxin gene transcription was proposed to occur via RNAIII-mediated downregulation of the Rot repressor. Contradictive to this model, we showed that the post-exponential induction of tst, sed, and sec transcription did not occur in cells devoid of ClpXP activity, despite the Rot level being diminished. To identify transcriptional regulators with a changed expression in cells devoid of ClpXP activity, RNA sequencing was performed. The RNAseq analysis revealed a number of global virulence regulators that might act downstream of ClpXP, to control expression of tst and other virulence genes. Collectively, the results extend our understanding of the complex transcriptional regulation of the tst, sed, and sec genes.
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Affiliation(s)
- Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden; (J.S.); (B.F.)
| | - Marianne Thorup Cohn
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederikberg C, Denmark;
| | - Barbro Frisk
- Division of Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden; (J.S.); (B.F.)
| | - Dorte Frees
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederikberg C, Denmark;
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7
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Marklinder I, Ahlgren R, Blücher A, Ehn Börjesson SM, Hellkvist F, Moazzami M, Schelin J, Zetterström E, Eskhult G, Danielsson-Tham ML. Food safety knowledge, sources thereof and self-reported behaviour among university students in Sweden. Food Control 2020. [DOI: 10.1016/j.foodcont.2020.107130] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Zeaki N, Johler S, Skandamis PN, Schelin J. The Role of Regulatory Mechanisms and Environmental Parameters in Staphylococcal Food Poisoning and Resulting Challenges to Risk Assessment. Front Microbiol 2019; 10:1307. [PMID: 31244814 PMCID: PMC6581702 DOI: 10.3389/fmicb.2019.01307] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 05/27/2019] [Indexed: 11/29/2022] Open
Abstract
Prevention, prediction, control, and handling of bacterial foodborne diseases - an ongoing, serious, and costly concern worldwide - are continually facing a wide array of difficulties. Not the least due to that food matrices, highly variable and complex, can impact virulence expression in diverse and unpredictable ways. This review aims to present a comprehensive overview of challenges related to the presence of enterotoxigenic Staphylococcus aureus in the food production chain. It focuses on characteristics, expression, and regulation of the highly stable staphylococcal enterotoxins and in particular staphylococcal enterotoxin A (SEA). Together with the robustness of the pathogen under diverse environmental conditions and the range of possible entry routes into the food chain, this poses some of the biggest challenges in the control of SFP. Furthermore, the emergence of new enterotoxins, found to be connected with SFP, brings new questions around their regulatory mechanisms and expression in different food environments. The appearance of increasing amounts of antibiotic resistant strains found in food is also highlighted. Finally, potentials and limitations of implementing existing risk assessment models are discussed. Various quantitative microbial risk assessment approaches have attempted to quantify the growth of the bacterium and production of disease causing levels of toxin under various food chain and domestic food handling scenarios. This requires employment of predictive modeling tools, quantifying the spatiotemporal population dynamics of S. aureus in response to intrinsic and extrinsic food properties. In this context, the armory of predictive modeling employs both kinetic and probabilistic models to estimate the levels that potentiate toxin production, the time needed to reach that levels, and overall, the likelihood of toxin production. Following risk assessment, the main challenge to mitigate the risk of S. aureus intoxication is first to prevent growth of the organism and then to hamper the production of enterotoxins, or at least prevent the accumulation of high levels (e.g., >10-20 ng) in food. The necessity for continued studies indeed becomes apparent based on the challenges to understand, control, and predict enterotoxin production in relation to the food environment. Different types of food, preservatives, processing, and packaging conditions; regulatory networks; and different staphylococcal enterotoxin-producing S. aureus strains need to be further explored to obtain more complete knowledge about the virulence of this intriguing pathogen.
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Affiliation(s)
- Nikoleta Zeaki
- Division of Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden
| | - Sophia Johler
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Panagiotis N. Skandamis
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden
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9
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Artursson K, Schelin J, Thisted Lambertz S, Hansson I, Olsson Engvall E. Foodborne pathogens in unpasteurized milk in Sweden. Int J Food Microbiol 2018; 284:120-127. [PMID: 29887505 DOI: 10.1016/j.ijfoodmicro.2018.05.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 05/11/2018] [Accepted: 05/17/2018] [Indexed: 11/15/2022]
Abstract
Raw milk may be a risk for public health if it is contaminated with zoonotic pathogens. To study the prevalence in unpasteurized milk from Swedish farms, bovine and small ruminant dairy farms were sampled. Since the sampling method and transport conditions may influence the outcome of analyses, efforts were made to optimize the methodology. Culturing of bacteria was done from in-line milk filters collected from the milk pipe at the point where it enters the milk bulk tank at the farms and this way of sampling was compared to sampling bulk tank milk (BTM) directly. Analysing milk filters were found to be superior to analysing BTM directly. Conditions for transport of milk filter samples were further improved by the addition of Cary Blair transport medium, which significantly increased the number of positive samples for pathogenic bacteria. The isolation of several foodborne pathogens from milk filters was demonstrated. The prevalence of samples with Staphylococcus aureus was 71% and 64%, and Listeria spp. 21% and 29% from dairy cow and goat/sheep farms, respectively. Campylobacter jejuni, Yersinia enterocolitica and verotoxigenic Escherichia coli (VTEC) O157 were detected in 9%, 2% and 2% of samples from bovine milk, respectively. We conclude that the choice of sampling method and sample handling influence the results of bacterial culturing. From the results of this study, we strongly recommend to sample in-line milk filters instead of BTM directly and to use Cary Blair medium during transport, especially if the samples are to be analysed for Campylobacter spp. and/or Listeria spp. The findings also show that unpasteurized milk from Swedish farms occasionally contain bacteria with zoonotic potential.
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Affiliation(s)
- Karin Artursson
- National Veterinary Institute, Uppsala, Sweden; Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Sweden.
| | - Jenny Schelin
- Applied Microbiology, Faculty of Engineering, Lund University, Lund, Sweden
| | - Susanne Thisted Lambertz
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Sweden; National Food Agency, Uppsala, Sweden
| | - Ingrid Hansson
- National Veterinary Institute, Uppsala, Sweden; Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Sweden
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10
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Schelin J, Susilo YB, Johler S. Expression of Staphylococcal Enterotoxins under Stress Encountered during Food Production and Preservation. Toxins (Basel) 2017; 9:E401. [PMID: 29244757 PMCID: PMC5744121 DOI: 10.3390/toxins9120401] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/12/2017] [Accepted: 12/14/2017] [Indexed: 12/24/2022] Open
Abstract
Staphylococcal food poisoning (SFP) is the most prevalent cause of food-borne intoxications worldwide. Consumption of enterotoxins preformed in food causes violent vomiting and can be fatal in children and the elderly. While being repressed by competing bacteria in most matrices, Staphylococcus aureus benefits from crucial competitive advantages in foods with high osmolarity or low pH. During recent years, the long-standing belief in the feasibility of assessing SFP risk based on colony-forming units of S. aureus present in food products has been disproven. Instead, researchers and food business operators are acutely aware of the imminent threat arising from unforeseeable enterotoxin production under stress conditions. This paradigm shift led to a variety of new publications enabling an improved understanding of enterotoxin expression under stress conditions encountered in food. The wealth of data provided by these studies is extremely diverse, as it is based on different methodological approaches, staphylococcal strains, stressors, and enterotoxins. Therefore, in this review, we aggregated and critically evaluated the complex findings of these studies, to provide readers with a current overview of the state of research in the field.
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Affiliation(s)
- Jenny Schelin
- Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden.
| | - Yusak Budi Susilo
- Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden.
| | - Sophia Johler
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
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11
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Susilo YB, Sihto HM, Rådström P, Stephan R, Johler S, Schelin J. Reduced Enterotoxin D Formation on Boiled Ham in Staphylococcus Aureus Δagr Mutant. Toxins (Basel) 2017; 9:E263. [PMID: 28841182 PMCID: PMC5618196 DOI: 10.3390/toxins9090263] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 08/21/2017] [Accepted: 08/24/2017] [Indexed: 11/16/2022] Open
Abstract
Staphylococcal food poisoning (SFP) is a common cause of foodborne illness worldwide, and enterotoxin D (SED) is one of the most frequent Staphylococcus aureus enterotoxins associated with it. It has been reported that the expression and formation of SED in S. aureus is regulated by the quorum sensing Agr system. In this study, the effect of agr deletion on sed expression in S. aureus grown on boiled ham was investigated. Growth, sed mRNA and SED protein levels in an S. aureus wild type strain and its isogenic Δagr mutant were monitored for 14 days at 22 °C. The results showed that although deletion of the agr gene did not affect the growth rate or maximum cell density of S. aureus on boiled ham, it had a pronounced effect on SED formation during the first 5 days of incubation. The SED concentration was not reflected in the amount of preceding sed transcripts, suggesting that sed transcription levels may not always reflect SED formation. The expression of RNAIII transcript, the regulatory signal of the Agr system, was also monitored. Similar transcription patterns were observed for RNAIII and sed. Surprisingly, in the Δagr mutant, sed expression was comparable to that in the wild type strain, and was thus unaffected by deletion of the Agr system. These results demonstrate that the Agr system appears to only partially affect SED formation, even in a real food environment.
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Affiliation(s)
- Yusak Budi Susilo
- Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden.
| | - Henna-Maria Sihto
- Institute for Food Safety and Hygiene, University of Zurich, CH-8057 Zurich, Switzerland.
| | - Peter Rådström
- Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden.
| | - Roger Stephan
- Institute for Food Safety and Hygiene, University of Zurich, CH-8057 Zurich, Switzerland.
| | - Sophia Johler
- Institute for Food Safety and Hygiene, University of Zurich, CH-8057 Zurich, Switzerland.
| | - Jenny Schelin
- Applied Microbiology, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden.
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Narayanan V, Schelin J, Gorwa-Grauslund M, van Niel EWJ, Carlquist M. Increased lignocellulosic inhibitor tolerance of Saccharomyces cerevisiae cell populations in early stationary phase. Biotechnol Biofuels 2017; 10:114. [PMID: 28484514 PMCID: PMC5418707 DOI: 10.1186/s13068-017-0794-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 04/18/2017] [Indexed: 05/23/2023]
Abstract
BACKGROUND Production of second-generation bioethanol and other bulk chemicals by yeast fermentation requires cells that tolerate inhibitory lignocellulosic compounds at low pH. Saccharomyces cerevisiae displays high plasticity with regard to inhibitor tolerance, and adaptation of cell populations to process conditions is essential for reaching efficient and robust fermentations. RESULTS In this study, we assessed responses of isogenic yeast cell populations in different physiological states to combinations of acetic acid, vanillin and furfural at low pH. We found that cells in early stationary phase (ESP) exhibited significantly increased tolerance compared to cells in logarithmic phase, and had a similar ability to initiate growth in the presence of inhibitors as pre-adapted cells. The ESP cultures consisted of subpopulations with different buoyant cell densities which were isolated with flotation and analysed separately. These so-called quiescent (Q) and non-quiescent (NQ) cells were found to possess similar abilities to initiate growth in the presence of lignocellulosic inhibitors at pH 3.7, and had similar viabilities under static conditions. Therefore, differentiation into Q-cells was not the cause for increased tolerance of ESP cultures. Flow cytometry analysis of cell viability, intracellular pH and reactive oxygen species levels revealed that tolerant cell populations had a characteristic response upon inhibitor perturbations. Growth in the presence of a combination of inhibitors at low pH correlated with pre-cultures having a high frequency of cells with low pHi and low ROS levels. Furthermore, only a subpopulation of ESP cultures was able to tolerate lignocellulosic inhibitors at low pH, while pre-adapted cell populations displayed an almost uniform high tolerance to the adverse condition. This was in stark contrast to cell populations growing exponentially in non-inhibitory medium that were uniformly sensitive to the inhibitors at low pH. CONCLUSIONS ESP cultures of S. cerevisiae were found to have high tolerance to lignocellulosic inhibitors at low pH, and were able to initiate growth to the same degree as cells that were pre-adapted to inhibitors at a slightly acidic pH. Carbon starvation may thus be a potential strategy to prepare cell populations for adjacent stressful environments which may be beneficial from a process perspective for fermentation of non-detoxified lignocellulosic substrates at low pH. Furthermore, flow cytometry analysis of pHi and ROS level distributions in ESP cultures revealed responses that were characteristic for populations with high tolerance to lignocellulosic inhibitors. Measurement of population distribution responses as described herein may be applied to predict the outcome of environmental perturbations and thus can function as feedback for process control of yeast fitness during lignocellulosic fermentation.
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Affiliation(s)
- Venkatachalam Narayanan
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Jenny Schelin
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Marie Gorwa-Grauslund
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Ed WJ van Niel
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
| | - Magnus Carlquist
- Division of Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, SE 221 00 Lund, Sweden
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Artursson K, Söderlund R, Liu L, Monecke S, Schelin J. Genotyping of Staphylococcus aureus in bovine mastitis and correlation to phenotypic characteristics. Vet Microbiol 2016; 193:156-61. [DOI: 10.1016/j.vetmic.2016.08.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 08/12/2016] [Accepted: 08/16/2016] [Indexed: 01/01/2023]
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14
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Zeaki N, Rådström P, Schelin J. Evaluation of Potential Effects of NaCl and Sorbic Acid on Staphylococcal Enterotoxin A Formation. Microorganisms 2015; 3:551-66. [PMID: 27682105 PMCID: PMC5023250 DOI: 10.3390/microorganisms3030551] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 08/03/2015] [Accepted: 09/01/2015] [Indexed: 12/24/2022] Open
Abstract
The prophage-encoded staphylococcal enterotoxin A (SEA) is recognized as the main cause of staphylococcal food poisoning (SFP), a common foodborne intoxication disease, caused by Staphylococcus aureus. Studies on the production of SEA suggest that activation of the SOS response and subsequent prophage induction affect the regulation of the sea gene and the SEA produced, increasing the risk for SFP. The present study aims to evaluate the effect of NaCl and sorbic acid, in concentrations relevant to food production, on SOS response activation, prophage induction and SEA production. The impact of stress was initially evaluated on steady state cells for a homogenous cell response. NaCl 2% was found to activate the SOS response, i.e., recA expression, and trigger prophage induction, in a similar way as the phage-inducer mitomycin C. In contrast, sorbic acid decreased the pH of the culture to a level where prophage induction was probably suppressed, even when combined with NaCl stress. The impact of previous physiological state of the bacteria was also addressed on cells pre-exposed to NaCl, and was found to potentially affect cell response upon exposure to further stress. The results obtained highlight the possible SFP-related risks arising from the use of preservatives during food processing.
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Affiliation(s)
- Nikoleta Zeaki
- Applied Microbiology, Department of Chemistry, Lund University, Lund 22100, Sweden.
| | - Peter Rådström
- Applied Microbiology, Department of Chemistry, Lund University, Lund 22100, Sweden.
| | - Jenny Schelin
- Applied Microbiology, Department of Chemistry, Lund University, Lund 22100, Sweden.
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15
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Schelin J, Andersson G, Vigre H, Norling B, Häggblom P, Hoorfar J, Rådström P, Löfström C. Evaluation of pre-PCR processing approaches for enumeration of Salmonella enterica
in naturally contaminated animal feed. J Appl Microbiol 2013; 116:167-78. [DOI: 10.1111/jam.12337] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 08/09/2013] [Accepted: 08/27/2013] [Indexed: 11/29/2022]
Affiliation(s)
- J. Schelin
- Applied Microbiology; Department of Chemistry; Lund University; Lund Sweden
| | - G. Andersson
- Department of Chemistry; Environment and Feed hygiene; National Veterinary Institute (SVA); Uppsala Sweden
| | - H. Vigre
- National Food Institute; Technical University of Denmark; Søborg Denmark
| | - B. Norling
- Quintessence Research AB (QRAB); Alunda Sweden
| | - P. Häggblom
- Department of Chemistry; Environment and Feed hygiene; National Veterinary Institute (SVA); Uppsala Sweden
| | - J. Hoorfar
- National Food Institute; Technical University of Denmark; Søborg Denmark
| | - P. Rådström
- Applied Microbiology; Department of Chemistry; Lund University; Lund Sweden
| | - C. Löfström
- National Food Institute; Technical University of Denmark; Søborg Denmark
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16
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Schelin J, Wallin-Carlquist N, Cohn MT, Lindqvist R, Barker GC, Rådström P. The formation of Staphylococcus aureus enterotoxin in food environments and advances in risk assessment. Virulence 2011; 2:580-92. [PMID: 22030860 PMCID: PMC3260550 DOI: 10.4161/viru.2.6.18122] [Citation(s) in RCA: 208] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/15/2011] [Accepted: 09/16/2011] [Indexed: 01/02/2023] Open
Abstract
The recent finding that the formation of staphylococcal enterotoxins in food is very different from that in cultures of pure Staphylococcus aureus sheds new light on, and brings into question, traditional microbial risk assessment methods based on planktonic liquid cultures. In fact, most bacteria in food appear to be associated with surfaces or tissues in various ways, and interaction with other bacteria through molecular signaling is prevalent. Nowadays it is well established that there are significant differences in the behavior of bacteria in the planktonic state and immobilized bacteria found in multicellular communities. Thus, in order to improve the production of high-quality, microbiologically safe food for human consumption, in situ data on enterotoxin formation in food environments are required to complement existing knowledge on the growth and survivability of S. aureus. This review focuses on enterotoxigenic S. aureus and describes recent findings related to enterotoxin formation in food environments, and ways in which risk assessment can take into account virulence behavior. An improved understanding of how environmental factors affect the expression of enterotoxins in foods will enable us to formulate new strategies for improved food safety.
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Affiliation(s)
- Jenny Schelin
- Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden.
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17
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Aprodu I, Walcher G, Schelin J, Hein I, Norling B, Rådström P, Nicolau A, Wagner M. Advanced sample preparation for the molecular quantification of Staphylococcus aureus in artificially and naturally contaminated milk. Int J Food Microbiol 2011; 145 Suppl 1:S61-5. [DOI: 10.1016/j.ijfoodmicro.2010.09.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 08/06/2010] [Accepted: 09/20/2010] [Indexed: 10/19/2022]
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18
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Márta D, Wallin-Carlquist N, Schelin J, Borch E, Rådström P. Extended staphylococcal enterotoxin D expression in ham products. Food Microbiol 2010; 28:617-20. [PMID: 21356473 DOI: 10.1016/j.fm.2010.11.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 10/29/2010] [Accepted: 11/18/2010] [Indexed: 11/24/2022]
Abstract
Staphylococcal enterotoxin D (SED) is one of the most frequently recovered enterotoxins in staphylococcal food poisoning (SFP) outbreaks. The expression and production of SED were investigated in three ham products, i.e. boiled ham, smoked ham and dry-cured Serrano ham incubated at room temperature for seven days. Staphylococcus aureus was also, as a reference, grown in cultivation broth during optimal growth conditions for seven days. In boiled and smoked ham, continuous sed expression was observed throughout the incubation period with a second increase in sed expression found after five days of incubation. In smoked ham, nine times less SED per colony-forming unit of S. aureus was detected than in boiled ham. In boiled ham, the SED levels unpredictably decreased after three days of incubation. In the Serrano ham, SED was detected after five days of incubation although S. aureus growth was poor and sed expression was too low to determine. After five days of incubation, all three products contained enough SED to cause SFP. These results show that the specific production levels of SED vary in the different ham products, and that toxin production was in part uncoupled from bacterial growth.
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Affiliation(s)
- Dóra Márta
- Applied Microbiology, Lund Institute of Technology, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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19
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Parachin NS, Schelin J, Norling B, Rådström P, Gorwa-Grauslund MF. Flotation as a tool for indirect DNA extraction from soil. Appl Microbiol Biotechnol 2010; 87:1927-33. [DOI: 10.1007/s00253-010-2691-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 10/19/2022]
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20
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Artin I, Mason DR, Pin C, Schelin J, Peck MW, Holst E, Rådström P, Carter AT. Effects of carbon dioxide on growth of proteolytic Clostridium botulinum, its ability to produce neurotoxin, and its transcriptome. Appl Environ Microbiol 2010; 76:1168-72. [PMID: 20038699 PMCID: PMC2820955 DOI: 10.1128/aem.02247-09] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 12/14/2009] [Indexed: 01/02/2023] Open
Abstract
The antimicrobial gas carbon dioxide is frequently used in modified atmosphere packaging. In the present study, the effects of CO2 (10 to 70%, vol/vol) on gene expression (measured using quantitative reverse transcription-PCR and a whole-genome DNA microarray) and neurotoxin formation (measured using an enzyme-linked immunosorbent assay [ELISA]) by proteolytic Clostridium botulinum type A1 strain ATCC 3502 were studied during the growth cycle. Interestingly, in marked contrast to the situation with nonproteolytic C. botulinum types B and E, CO2 had little effect on any of these parameters. At all CO2 concentrations, relative expression of neurotoxin cluster genes peaked in the transition between exponential and stationary phases, with evidence of a second rise in expression in late stationary phase. Microarray analysis enabled identification of coding sequences whose expression profiles matched those of the neurotoxin cluster. Further research is needed to determine whether these are connected to neurotoxin formation or are merely growth phase associated.
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Affiliation(s)
- Ingrid Artin
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - David R. Mason
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Carmen Pin
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Jenny Schelin
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Michael W. Peck
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Elisabet Holst
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Peter Rådström
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Andrew T. Carter
- Institute of Food Research, Norwich, United Kingdom, Applied Microbiology, Lund Institute of Technology, Lund University, Lund, Sweden, Division of Medical Microbiology, Department of Laboratory Medicine, Lund University, Lund, Sweden
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21
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Andersson FI, Tryggvesson A, Sharon M, Diemand AV, Classen M, Best C, Schmidt R, Schelin J, Stanne TM, Bukau B, Robinson CV, Witt S, Mogk A, Clarke AK. Structure and function of a novel type of ATP-dependent Clp protease. J Biol Chem 2009; 284:13519-13532. [PMID: 19237538 DOI: 10.1074/jbc.m809588200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Clp protease is conserved among eubacteria and most eukaryotes, and uses ATP to drive protein substrate unfolding and translocation into a chamber of sequestered proteolytic active sites. The main constitutive Clp protease in photosynthetic organisms has evolved into a functionally essential and structurally intricate enzyme. The model Clp protease from the cyanobacterium Synechococcus consists of the HSP100 molecular chaperone ClpC and a mixed proteolytic core comprised of two distinct subunits, ClpP3 and ClpR. We have purified the ClpP3/R complex, the first for a Clp proteolytic core comprised of heterologous subunits. The ClpP3/R complex has unique functional and structural features, consisting of twin heptameric rings each with an identical ClpP3(3)ClpR(4) configuration. As predicted by its lack of an obvious catalytic triad, the ClpR subunit is shown to be proteolytically inactive. Interestingly, extensive modification to ClpR to restore proteolytic activity to this subunit showed that its presence in the core complex is not rate-limiting for the overall proteolytic activity of the ClpCP3/R protease. Altogether, the ClpP3/R complex shows remarkable similarities to the 20 S core of the proteasome, revealing a far greater degree of convergent evolution than previously thought between the development of the Clp protease in photosynthetic organisms and that of the eukaryotic 26 S proteasome.
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Affiliation(s)
- Fredrik I Andersson
- Department of Plant and Environmental Sciences, University of Gothenburg, Box 461, S-405 30 Göteborg, Sweden
| | - Anders Tryggvesson
- Department of Plant and Environmental Sciences, University of Gothenburg, Box 461, S-405 30 Göteborg, Sweden
| | - Michal Sharon
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Alexander V Diemand
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany
| | - Mirjam Classen
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Christoph Best
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Ronny Schmidt
- Zentrum fur Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
| | - Jenny Schelin
- Department of Applied Microbiology, Lund Institute of Technology, Lund University, Box 124, S-221 00 Lund, Sweden
| | - Tara M Stanne
- Department of Plant and Environmental Sciences, University of Gothenburg, Box 461, S-405 30 Göteborg, Sweden
| | - Bernd Bukau
- Zentrum fur Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
| | - Carol V Robinson
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Susanne Witt
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Axel Mogk
- Zentrum fur Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
| | - Adrian K Clarke
- Department of Plant and Environmental Sciences, University of Gothenburg, Box 461, S-405 30 Göteborg, Sweden.
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22
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Selstam E, Schelin J, Williams WP, Brain APR. Structural organisation of prolamellar bodies (PLB) isolated from Zea mays. Parallel TEM, SAXS and absorption spectra measurements on samples subjected to freeze-thaw, reduced pH and high-salt perturbation. Biochim Biophys Acta 2007; 1768:2235-45. [PMID: 17559801 DOI: 10.1016/j.bbamem.2007.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 04/26/2007] [Accepted: 05/03/2007] [Indexed: 11/24/2022]
Abstract
Well-organised PLB gives rise to a X-ray diffraction pattern overlaid by a scattering pattern arising from individual tubules within less well-organised regions of the lattice. TEM and SAXS measurements were used to characterise the structural changes in PLB subjected to perturbation by freeze-thaw, exposure to pH 6.5, or resuspension in high-salt media. Comparison of SAXS patterns measured, before and after structural perturbation allows the separation of the contributions from ordered and disordered PLB. The diffraction pattern is shown to be based on a diamond cubic (Fd3m) lattice of unit cell a=78 nm. Freeze-thaw and high-salt disruption lead to the breakdown of ordered PLB into disordered tubules of similar dimensions to those making up the original PLB lattice. Their scattering patterns suggest that they are approximately 26 nm in diameter with a central lumen about 16 nm in diameter. The tubules formed at pH 6.5 are appreciably narrower, probably reflecting changes in the pattern of ionisation of charged groups at the membrane surface. Absorption spectra of PLB in media containing different concentrations of salts indicated that the structural and spectral changes are related. NADPH, have a significant role in the protection of POR-PChlide(650) but to have only a relatively small effect on the preservation of PLB organisation indicating that the retention of POR-PChlide(650) in isolated PLB preparations is a poor guide to their structural integrity.
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Affiliation(s)
- Eva Selstam
- Umeå Plant Science Center, Plant Physiology Department, University of Umeå, Umeå S-901 87, Sweden.
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23
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Lindahl AL, Olsson ME, Mercke P, Tollbom O, Schelin J, Brodelius M, Brodelius PE. Production of the artemisinin precursor amorpha-4,11-diene by engineered Saccharomyces cerevisiae. Biotechnol Lett 2006; 28:571-80. [PMID: 16614895 DOI: 10.1007/s10529-006-0015-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Accepted: 01/18/2006] [Indexed: 11/26/2022]
Abstract
The gene encoding for amorpha-4,11-diene synthase from Artemisia annua was transformed into yeast Saccharomyces cerevisiae in two fundamentally different ways. First, the gene was subcloned into the galactose-inducible, high-copy number yeast expression vector pYeDP60 and used to transform the Saccharomyces cerevisiae strain CEN.PK113-5D. Secondly, amorpha-4,11-diene synthase gene, regulated by the same promoter, was introduced into the yeast genome by homologous recombination. In protein extracts from galactose-induced yeast cells, a higher activity was observed for yeast expressing the enzyme from the plasmid. The genome-transformed yeast grows at the same rate as wild-type yeast while plasmid-carrying yeast grows somewhat slower than the wild-type yeast. The plasmid and genome-transformed yeasts produced 600 and 100 microg/l of the artemisinin precursor amorpha-4,11-diene, respectively, during 16-days' batch cultivation.
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Affiliation(s)
- Ann-Louise Lindahl
- Department of Chemistry and Biomedical Science, University of Kalmar, SE-39182, Kalmar, Sweden
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24
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Barker-Aström K, Schelin J, Gustafsson P, Clarke AK, Campbell DA. Chlorosis during nitrogen starvation is altered by carbon dioxide and temperature status and is mediated by the ClpP1 protease in Synechococcus elongatus. Arch Microbiol 2004; 183:66-9. [PMID: 15549267 DOI: 10.1007/s00203-004-0741-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 09/30/2004] [Accepted: 10/05/2004] [Indexed: 11/25/2022]
Abstract
The interactive effects of inorganic carbon status, temperature and light on chlorosis induced by nitrogen deficiency, and the roles of Clp proteases in this process were investigated. In wild-type cultures grown in high or ambient CO(2), following transfer to media lacking combined nitrogen, phycocyanin per cell dropped primarily through dilution of the pigment through cell division, and also suffered variable degrees of net degradation. When grown at high CO(2) (5%), chlorophyll (Chl) suffered net degradation to a greater extent than phycocyanin. In marked contrast, growth at ambient CO(2) resulted in Chl per cell dropping through dilution. Conditions that drove net Chl degradation in the wild-type resulted in little or no net Chl degradation in a clpPI inactivation mutant, with Chl content dropping largely through growth dilution in the mutant. The chlorotic response of a clpPII inactivation strain was nearly the same as that of wild-type, although phycocyanin degradation may have been slightly accelerated in the former.
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Affiliation(s)
- Kara Barker-Aström
- Umeå Plant Sciences Centre, Department of Plant Physiology, Umeå University, 90187 Umeå, Sweden
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25
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Schelin J, Lindmark F, Clarke AK. The clpP multigene family for the ATP-dependent Clp protease in the cyanobacterium Synechococcus. Microbiology (Reading) 2002; 148:2255-2265. [PMID: 12101312 DOI: 10.1099/00221287-148-7-2255] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In the cyanobacterium Synechococcus sp. strain PCC 7942 a multigene family of three different isozymes encodes the proteolytic subunit ClpP of the ATP-dependent Clp protease. In contrast to the monocistronic clpPI gene, clpPII and clpPIII are part of two bicistronic operons with clpX and clpR, respectively. Unlike most bacterial Clp proteins, the Synechococcus ClpP2, ClpP3, ClpR and ClpX proteins were not highly inducible by high temperatures, or by other stresses such as cold, high light or oxidation, although slower gradual rises occurred for all four proteins during high light, and for ClpP3, ClpR and ClpX at low temperature. Attempts to inactivate the clpPII, clpIII, clpR or clpX genes were only successful for clpPII, suggesting the others are essential for Synechococcus cell viability. The DeltaclpPII mutant exhibited no significant phenotypic changes from the wild-type, including no change in ClpX content. Despite the apparent bicistronic arrangement of both clpPII-clpX and clpR-clpPIII, all four genes primarily produce monocistronic transcripts, although polycistronic transcripts were detected. Mapping of 5' ends for the clpX and clpPIII monocistronic transcripts revealed promoters situated within the 3' region of clpPII and clpR, respectively. Transcriptional and translational studies further showed differences in the expression and regulation between the clpP-clpR-clpX genes. Inactivation of clpPI caused a significant decrease in ClpP2 protein concomitant to small increases in both ClpP3 and ClpR. Inactivation of clpPII resulted in a large rise in clpPI transcripts but to a lesser extent in ClpP1 protein. Similar small increases in ClpP3, ClpR and ClpX proteins also occurred in DeltaclpPII. These results highlight the regulatory complexity of these multiple clp genes and their functional importance in cyanobacteria.
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Affiliation(s)
- Jenny Schelin
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden1
| | - Fredrik Lindmark
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden1
| | - Adrian K Clarke
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden1
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26
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Selstam E, Schelin J, Brain T, Williams WP. The effects of low pH on the properties of protochlorophyllide oxidoreductase and the organization of prolamellar bodies of maize (Zea mays). Eur J Biochem 2002; 269:2336-46. [PMID: 11985616 DOI: 10.1046/j.1432-1033.2002.02897.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Prolamellar bodies (PLB) contain two photochemically active forms of the enzyme protochlorophyllide oxidoreductase POR-PChlide640 and POR-PChlide650 (the spectral forms of POR-Chlide complexes with absorption maxima at the indicated wavelengths). Resuspension of maize PLB in media with a pH below 6.8 leads to a rapid conversion of POR-PChlide650 to POR-PChlide640 and a dramatic re-organization of the PLB membrane system. In the absence of excess NADPH, the absorption maximum of the POR complex undergoes a further shift to about 635 nm. This latter shift is reversible on the re-addition of NADPH with a half-saturation value of about 0.25 mm NADPH for POR-PChlide640 reformation. The disappearance of POR-PChlide650 and the reorganization of the PLB, however, are irreversible. Restoration of low-pH treated PLB to pH 7.5 leads to a further breakdown down of the PLB membrane and no reformation of POR-PChlide650. Related spectral changes are seen in PLB aged at room temperature at pH 7.5 in NADPH-free assay medium. The reformation of POR-PChlide650 in this system is readily reversible on re-addition of NADPH with a half-saturation value about 1.0 microm. Comparison of the two sets of changes suggest a close link between the stability of the POR-PChlide650, membrane organization and NADPH binding. The low-pH driven spectral changes seen in maize PLB are shown to be accelerated by adenosine AMP, ADP and ATP. The significance of this is discussed in terms of current suggestions of the possible involvement of phosphorylation (or adenylation) in changes in the aggregational state of the POR complex.
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Affiliation(s)
- Eva Selstam
- Umeå Plant Science Center, Department of Plant Physiology, University of Umeå, Sweden
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Abstract
Synechococcus sp. strain PCC 7942 has a second clpB gene that encodes a 97-kDa protein with novel features. ClpBII is the first ClpB not induced by heat shock or other stresses; it is instead an essential, constitutive protein. ClpBII is unable to complement ClpBI function for acquired thermotolerance. No truncated ClpBII version is normally produced, unlike other bacterial forms, while ectopic synthesis of a putative truncated ClpBII dramatically decreased cell viability.
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Affiliation(s)
- M J Eriksson
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S-901 87 Umeå, Sweden
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28
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Porankiewicz J, Schelin J, Clarke AK. The ATP-dependent Clp protease is essential for acclimation to UV-B and low temperature in the cyanobacterium Synechococcus. Mol Microbiol 1998; 29:275-83. [PMID: 9701820 DOI: 10.1046/j.1365-2958.1998.00928.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ClpP is the proteolytic subunit of the ATP-dependent Clp protease in eubacteria, mammals and plant chloroplasts. Cyanobacterial ClpP protein is encoded by a multigene family, producing up to four distinct isozymes. We have examined the importance of the first ClpP protein (ClpP1) isolated from the cyanobacterium Synechococcus sp. PCC 7942 for acclimation to ecologically relevant UV-B and low-temperature regimens. When the growth light of 50 mumol photons m-2 s-1 was supplemented with 0.5 W m-2 UV-B for 8 h, the constitutive level of ClpP1 rose eightfold after an initial lag of 1 h. Wild-type cells readily acclimated to this UV-B level, recovering after the initial stress to almost the same growth rate as that before UV-B exposure. Growth of a clpP1 null mutant (delta clpP1), however, was severely inhibited by UV-B, being eight times slower than the wild type after 8 h. In comparison, ClpP1 content increased 15-fold in wild-type cultures shifted from 37 degree C to 25 degree C for 24 h. Wild-type cultures readily acclimated to 25 degree C after 24 h, whereas the delta clpP1 strain did not and eventually lost viability with prolonged cold treatment. During acclimation to either UV-B or cold, photosynthesis in the wild type was initially inhibited upon the shift but then recovered. Photosynthesis in delta clpP1 cultures, however, was more severely inhibited by the stress treatment and failed to recover. Acclimation was also monitored by examining the exchange of photosystem II reaction centre D1 proteins that occurs in wild-type Synechococcus during conditions of excitation stress. During both cold and UV-B shifts, wild-type cultures replaced the acclimative form of D1 (D1:1) with the alternative D1 form 2 (D1:2) within the first hours. Once acclimated to either 25 degree C or 0.5 W m-2 UV-B, D1:2 was exchanged back for D1:1. In delta clpP1 cultures, this second exchange between D1 forms did not occur, with D1:2 remaining the predominant D1 form. Our results demonstrate that the ATP-dependent Clp protease is an essential component of the cold and UV-B acclimation processes of Synechococcus.
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Affiliation(s)
- J Porankiewicz
- Department of Plant Physiology, University of Umeå, Sweden
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Clarke AK, Schelin J, Porankiewicz J. Inactivation of the clpP1 gene for the proteolytic subunit of the ATP-dependent Clp protease in the cyanobacterium Synechococcus limits growth and light acclimation. Plant Mol Biol 1998; 37:791-801. [PMID: 9678574 DOI: 10.1023/a:1006016302074] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
ClpP functions as the proteolytic subunit of the ATP-dependent Clp protease in eubacteria, mammals and plant chloroplasts. We have cloned a clpP gene, designated clpP1, from the cyanobacterium Synechococcus sp. PCC 7942. The monocistronic 591 bp gene codes for a protein 80% similar to one of four putative ClpP proteins in another cyanobacterium, Synechocystis sp. PCC 6803. The constitutive ClpP1 content in Synechococcus cultures was not inducible by high temperatures, but it did rise fivefold with increasing growth light from 50 to 175 micromol photons m(-2) s(-1). A clpP1 inactivation strain (delta clpP1) exhibited slower growth rates, especially at the higher irradiances, and changes in the proportion of the photosynthetic pigments, chlorophyll a and phycocyanin. Many mutant cells (ca. 35%) were also severely elongated, up to 20 times longer than the wild type. The stress phenotype of delta clpP1 when grown at high light was confirmed by the induction of known stress proteins, such as the heat shock protein GroEL and the alternate form of PSII reaction center D1 protein, D1 form 2. ClpP1 content also rose significantly during short-term photoinhibition, but its loss in delta clpP1 did not exacerbate the extent of inactivation of photosynthesis, nor affect the inducible D1 exchange mechanism, indicating ClpP1 is not directly involved in D1 protein turnover.
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Affiliation(s)
- A K Clarke
- Department of Plant Physiology, University of Umeå, Sweden
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