| 1. |
- Bozzola, Tiago, et al.
(author)
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Sialic Acid Derivatives Inhibit SiaT Transporters and Delay Bacterial Growth
- 2022
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In: Acs Chemical Biology. - : American Chemical Society (ACS). - 1554-8929 .- 1554-8937. ; 17:7, s. 1890-1900
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Journal article (peer-reviewed)abstract
- 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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| 2. |
- Etter, Danai, et al.
(author)
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Staphylococcal Enterotoxin C—An Update on SEC Variants, Their Structure and Properties, and Their Role in Foodborne Intoxications
- 2020
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In: Toxins. - : MDPI AG. - 2072-6651. ; 12:9
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Research review (peer-reviewed)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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| 3. |
- Golovko, Oksana, et al.
(author)
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Organic micropollutants, heavy metals and pathogens in anaerobic digestate based on food waste
- 2022
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In: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 313
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Journal article (peer-reviewed)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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| 4. |
- Marklinder, Ingela, 1959-, et al.
(author)
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A Structural Equation Model Demonstrating the Relationship between Food Safety Background, Knowledge, Attitudes and Behaviour among Swedish Students
- 2022
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In: Foods. - : MDPI. - 2304-8158. ; 11:11
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Journal article (peer-reviewed)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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| 5. |
- Marklinder, Ingela, et al.
(author)
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Attitudes Related to Food Safety Behavior Among Students in Sweden
- 2021
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In: IAFP:s European Symposium on food safety. Virtual meeting 27-28 April 2021.. ; , s. 65-
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Conference paper (peer-reviewed)abstract
- Introduction: It has earlir been shown through an online questionnaire performed on 606 students from 24 different Swedish universities that the foremost sources of food safety knowledge were family and friends. However, more than a third of the students had experienced food safety education which was shown to provide knowledge and promoted more optimal food safety behavior.Purpose: Self-reported food safety attitudes, knowledge and behaviour among university students in Sweden were investigated through multivariate path analysis in order to identify factors' influence on behavior.Methods: A nationwide web-based questionnaire targeting university students in Sweden was distributed through social media, email and various university contacts. A structural equation model was applied on statistics from the questionnaire. Four factors: Background, Knowledge, Attitude and Behavior were derived from the data. The factors, built up from variables with sufficient factor loadings were set up in a predetermined structure. The structure was based on whether background affects knowledge and whether knowledge affects behavior and attitude, and whether attitude affects behavior. The structure has been confirmed valid in previous studies done.Results: The factor loadings were ranging from -1 to 1 where the closer to 1 indicates a stronger loading. Background affected knowledge (0.841). Attitude has a stronger influence on the Behavior (0.457) than Knowledge (0.278). However, Knowledge has directly a strong effect on Attitude (0.606). Out of 606 respiondents, 408 answers were deemed usable for the analysis. More than half of the variables have sufficient loadings to their respective factors to be included. The goodness-of-fit indices, indicated that the model had a good fit to the data, and this including hypothesis testing with a significance of < 0.005.Significance: It can be confirmed that background such as attending a food safety education strongly influenced knowledge. Knowledge in turns strongly affects attitudes but it does not directly affect bahavior. Thus, attitudes seemed to have a mediating role between food safety knowledge and behavior.
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| 6. |
- Marklinder, Ingela, et al.
(author)
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Food safety knowledge, sources thereof and self-reported behaviour among university students in Sweden
- 2020
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In: Food Control. - : Elsevier. - 0956-7135 .- 1873-7129. ; 113
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Journal article (peer-reviewed)abstract
- International studies have noted shortcomings in food safety knowledge and behaviour among university students. In general students do not constitute a pronounced risk group but there are wider implications. In a foreseeable future some of them will become pregnant and a majority will be responsible for vulnerable groups in their near environment. A crucial question exists, therefore, about their food safety knowledge and safe food handling practices. The aim of this study is to investigate food safety knowledge, sources thereof and self-reported food safety behavior among university students in Sweden. A quantitative study design using a web-based questionnaire was chosen as the data collection method. The questionnaire was distributed through social media and e-mail. Among the 606 respondents from 24 Swedish universities 80% were 18-30 years and 78% were women. The average number of correct answers on the knowledge questions was 7.61 out of 12 (63.4%). The foremost source of food safety knowledge was "Family and friends" (45%). Just 21.1% reported Food safety education as a source, although 35.6% had experience of a course in food hygiene/safety and/or microbiology. Respondents who reported "Family and friends" to be the foremost food safety source of knowledge also got a significantly lower rate of correct answers. Students who estimated their food safety knowledge to be good also had more correct answers. Experience of food safety education at secondary school/university/working place/polytechnic school significantly correlated with more correct answers on the knowledge questions and indicated a safer self-reported behaviour. Those with fewer correct answers also reported more unfavourable behaviours. The present study indicates that education promotes more optimal behaviors. The authors would suggest a more systematic food safety education at younger ages.
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| 7. |
- Marklinder, Ingela, 1959-, et al.
(author)
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Food safety knowledge, sources thereof and self-reported behaviour among university students in Sweden
- 2020
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In: Food Control. - : Elsevier. - 0956-7135 .- 1873-7129. ; 113
-
Journal article (peer-reviewed)abstract
- International studies have noted shortcomings in food safety knowledge and behaviour among university students. In general students do not constitute a pronounced risk group but there are wider implications. In a foreseeable future some of them will become pregnant and a majority will be responsible for vulnerable groups in their near environment. A crucial question exists, therefore, about their food safety knowledge and safe food handling practices.The aim of this study is to investigate food safety knowledge, sources thereof and self-reported food safety behavior among university students in Sweden.A quantitative study design using a web-based questionnaire was chosen as the data collection method. The questionnaire was distributed through social media and e-mail.Among the 606 respondents from 24 Swedish universities 80% were 18-30 years and 78% were women. The average number of correct answers on the knowledge questions was 7.61 out of 12 (63.4%). The foremost source of food safety knowledge was "Family and friends" (45%). Just 21.1% reported Food safety education as a source, although 35.6% had experience of a course in food hygiene/safety and/or microbiology. Respondents who reported "Family and friends" to be the foremost food safety source of knowledge also got a significantly lower rate of correct answers. Students who estimated their food safety knowledge to be good also had more correct answers. Experience of food safety education at secondary school/university/working place/polytechnic school significantly correlated with more correct answers on the knowledge questions and indicated a safer self-reported behaviour. Those with fewer correct answers also reported more unfavourable behaviours. The present study indicates that education promotes more optimal behaviors. The authors would suggest a more systematic food safety education at younger ages.
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| 8. |
- Mata Forsberg, Manuel, et al.
(author)
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Activation of human γδ T cells and NK cells by Staphylococcal enterotoxins requires both monocytes and conventional T cells
- 2022
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In: Journal of Leukocyte Biology. - 0741-5400 .- 1938-3673. ; 111:3, s. 597-609
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Journal article (peer-reviewed)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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| 9. |
- Schelin, Jenny, et al.
(author)
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A Functional ClpXP Protease is Required for Induction of the Accessory Toxin Genes, tst, sed, and sec
- 2020
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In: Toxins. - : MDPI AG. - 2072-6651. ; 12:9
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Journal article (peer-reviewed)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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| 10. |
- Södergren, Julia, et al.
(author)
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Food waste to new food : Risk assessment and microbial community analysis of anaerobic digestate as a nutrient source in hydroponic production of vegetables
- 2022
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 333
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Journal article (peer-reviewed)abstract
- In this study, the microbiological food safety of using anaerobic digestate as a fertilizer in hydroponic production of vegetables was evaluated. The used anaerobic digestate was a liquid residue obtained from the digestion of food waste in the production of biogas. Replacing the customary inorganic fertilizer used in hydroponic production with this recycled fertilizer (biofertilizer) could allow for sustainable urban food production close to retailers and consumers. However, in striving for circular food production, it is vital that the food safety of utilizing recycled resources is ensured. Especially in the application of hydroponic farming, where the nutrient loop is shorter than on arable land, a microbiological food safety risk assessment is crucial when adopting new and recycled fertilizers. The biofertilizer based on anaerobic digestate was therefore studied with regard to its microbial community (16S rRNA gene amplicon sequencing) during production of vegetables in a hydroponic system. The biofertilizer was also challenge tested with food borne pathogens (Salmonella enterica, Listeria monocytogenes and Bacillus cereus). Furthermore, the microbial activity of the biofertilizer was studied using isothermal calorimetry. The results showed that the microbial community of the biofertilizer changed distinctly through a necessary initial nitrification process, and that the most abundant genus was Mycobacterium. Deliberate contaminations with 5 log10 CFU mL−1 of either S. enterica or L. monocytogenes in the nitrified biofertilizer were no longer detectable with selective plating after 48 h of incubation at 20 °C. Selective plating for B. cereus revealed that the biofertilizer contained low levels (∼10 CFU mL−1) of the bacterium, and an inoculation of 5 log10 CFU mL−1 B. cereus decreased to these levels within 24 h of incubation at 20 °C. Analysis of the microbial activity of the biofertilizer indicated that the biofertilizer does not seem to support microbial activity without the addition of an external nutrient source that contains an accessible carbon source and trace elements. The type of biofertilizer investigated in this study is thus regarded as microbiologically safe for use in hydroponic cultivation. The constant presence of viable B. cereus, however, emphasizes the fundamental importance of continuous risk assessment in case of any modifications or supplementations of the biofertilizer, since it clearly can act as a reservoir for bacterial endospores.
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