Labile Research Articles

Isolation and partial characterization of a novel bacteriocin from Pseudomonas azotoformans with antimicrobial activity against Pasterella multocida.

In this study, a bacteriocin PA996 isolated from Pseudomonas azotoformans (P. azotoformans) was purified to homogeneity by ammonium sulphate precipitation and SP-Sepharose column chromatography. P. azotoformans began to grow at 6h, reached exponential phase at 12-18h. Bacteriocin PA996 was produced at 18h and reached a maximum level of 2400AU/mL. The molecular mass of purified bacteriocin PA996 was estimated by SDS-PAGE and its molecular mass was approximately 50kDa. By screening in vitro, the bacteriocin PA996 showed an antimicrobial activity against Pasteurella multocida (P. multocida). The bacteriocin PA996 showed antibacterial activity in the range of pH2-10 and it was heat labile. The inhibitory activities were diminished after treatment with proteinase K, trypsin and papain, respectively, while catalase treatment was ineffective. The minimal inhibitory concentration (MIC) and bactericidal kinetics curves showed that the bacteriocin PA996 had a good inhibitory ability against P. multocida. Our data indicate that bacteriocin PA996 could inhibit the growth of P. maltocida and it may have the potential to apply as an alternative therapeutic drug.

Physicochemical properties of muffins prepared with lutein & zeaxanthin-enriched egg yolk powder

Designing functional foods relies not only on incorporating bioactive compounds into a formulation but also on their ability to remain useful within the product. In this study, lutein and zeaxanthin (L&Z)-enriched egg yolk powder (EEYP), sourced from hens fed with Dunaliella tertiolecta mp3, was incorporated as a functional ingredient in muffins. Two formulations were prepared: with butter (EEYP-B) and butter-free (EEYP-BF). The color and texture of the muffins and the thermal stability and bioaccessibility after simulated digestion of the carotenoids were assessed. The results indicated that the physical properties of the muffins were not influenced by the L&Z addition. Moreover, L&Z in EEYP-B were less heat labile than in EEYP-BF and control samples with degradation rates of 10–12%, 15–17%, and >20%, respectively. Surprisingly, the bioaccessibility of L&Z in the EEYP-BF muffins was higher than in the control and butter-containing samples after digestion. As a result, enriching a daily product with L&Z was proved successful at increasing its carotenoid content after baking, evidencing also that the butter-free formulation exhibited the highest bioaccessibility.

Enteropathogen Changes After Rotavirus Vaccine Scale-up.

To inform next steps in pediatric diarrhea burden reduction by understanding the shifting enteropathogen landscape after rotavirus vaccine implementation. We conducted a case-control study of 1788 medically attended children younger than 5 years, with and without gastroenteritis, after universal rotavirus vaccine implementation in Peru. We tested case and control stools for 5 viruses, 19 bacteria, and parasites; calculated coinfection-adjusted attributable fractions (AFs) to determine pathogen-specific burdens; and evaluated pathogen-specific gastroenteritis severity using Clark and Vesikari scales. Six pathogens were independently positively associated with gastroenteritis: norovirus genogroup II (GII) (AF 29.1, 95% confidence interval [CI]: 28.0-32.3), rotavirus (AF 8.9, 95% CI: 6.8-9.7), sapovirus (AF 6.3, 95% CI: 4.3-7.4), astrovirus (AF 2.8, 95% CI: 0.0-4.0); enterotoxigenic Escherichia coli heat stable and/or heat labile and heat stable (AF 2.4, 95% CI: 0.6-3.1), and Shigella spp. (AF 2.0, 95% CI: 0.4-2.2). Among typeable rotavirus cases, we most frequently identified partially heterotypic strain G12P[8] (54 of 81, 67%). Mean severity was significantly higher for norovirus GII-positive cases relative to norovirus GII-negative cases (Vesikari [12.7 vs 11.8; P < .001] and Clark [11.7 vs 11.4; P = .016]), and cases in the 6- to 12-month age range relative to cases in other age groups (Vesikari [12.7 vs 12.0; P = .0002] and Clark [12.0 vs 11.4; P = .0016]). Norovirus is well recognized as the leading cause of pediatric gastroenteritis in settings with universal rotavirus vaccination. However, sapovirus is often overlooked. Both norovirus and sapovirus contribute significantly to the severe pediatric disease burden in this setting. Decision-makers should consider multivalent vaccine acquisition strategies to target multiple caliciviruses in similar countries after successful rotavirus vaccine implementation.

High-throughput low-cost nl-qPCR for enteropathogen detection: A proof-of-concept among hospitalized patients in Bangladesh.

BackgroundDiarrheal disease is a leading cause of morbidity and mortality globally, especially in low- and middle-income countries. High-throughput and low-cost approaches to identify etiologic agents are needed to guide public health mitigation. Nanoliter-qPCR (nl-qPCR) is an attractive alternative to more expensive methods yet is nascent in application and without a proof-of-concept among hospitalized patients.MethodsA census-based study was conducted among diarrheal patients admitted at two government hospitals in rural Bangladesh during a diarrheal outbreak period. DNA was extracted from stool samples and assayed by nl-qPCR for common bacterial, protozoan, and helminth enteropathogens as the primary outcome.ResultsA total of 961 patients were enrolled; stool samples were collected from 827 patients. Enteropathogens were detected in 69% of patient samples; More than one enteropathogen was detected in 32%. Enteropathogens most commonly detected were enteroaggregative Escherichia coli (26.0%), Shiga toxin-producing E.coli (18.3%), enterotoxigenic E. coli (15.5% heat stable toxin positive, 2.2% heat labile toxin positive), Shigella spp. (14.8%), and Vibrio cholerae (9.0%). Geospatial analysis revealed that the median number of pathogens per patient and the proportion of cases presenting with severe dehydration were greatest amongst patients residing closest to the study hospitals.”ConclusionsThis study demonstrates a proof-of-concept for nl-qPCR as a high-throughput low-cost method for enteropathogen detection among hospitalized patients.

Interaction of Soybean Varieties and Heat Treatments and Its Effect on Growth Performance and Nutrient Digestibility in Broiler Chickens

Simple SummarySoybeans are the major source of protein in today´s livestock diets. However, European soybean imports are under criticism because of environmental issues. Therefore, production of European soybeans is expected to grow. To ensure optimal feeding properties, soybeans require a heating process to eliminate intrinsic compounds interfering negatively with the animal’s digestive tract. A heating process might have different effects on different soybean varieties. Therefore, two different soybean varieties were treated at two different heat intensities in the present study—110 °C and 120 °C. The results showed, that while both heat intensities had a sufficient deactivating effect in one variety, the other variety was not treated sufficiently at 110 °C. Insufficient heat treatment was expressed in lower weight gains and lower feed intake. No negative effect of heat treatment at 120 °C was observed for growth performance, but amino acid digestibility was reduced. The present study shows that the optimal processing conditions can vary for different soybean varieties, which has to be considered especially when handling small and heterogeneous soybean batches.As production of European soybeans is expected to grow, optimal processing conditions need to be ensured for small and heterogeneous batches of soybeans. The effect of different soybean varieties, as well as heat treatments, on the growth performance and nutrient digestibility in broiler chickens was investigated. Two varieties, regarded as heat stable and heat labile after preliminary experiments, were partially de-oiled and thermally processed at 110 °C for 20 min and 120 °C for 20 min. The resulting soybean cakes were integrated into a mash diet and subjected to a 36-day long feeding experiment. A total of 336 one-day-old broiler chickens were divided into 24 pens, resulting in 6 replicates per treatment. With application of the 110 °C treatment, analysis of soybean cakes showed that the commonly required reduction in trypsin inhibitor activity (TIA) was only reached with one soybean variety. The higher processing temperature of 120 °C ensured sufficient TIA reductions in both soybean varieties. Elevated TIA concentrations resulted in decreased growth performances (p < 0.05) of the chickens, whereas no negative effect from overheating on growth performance appeared. Total-tract nitrogen retention (p < 0.05) and pre-caecal digestibility of several amino acids (p < 0.10) decreased with higher processing temperatures but had no negative effects on growth performance. In conclusion, the results indicate that processing conditions adjusted to the different varieties are essential to ensure optimal product quality.

A smart magnetically separable MIL-53(Al) MOF-coated nano-adsorbent for antibiotic pollutant removal with rapid and non-contact inductive heat regeneration

Metal-organic framework (MOF), MIL-53(Al), coated magnetic nanoparticles (MNP) were developed in this work for highly efficient adsorption and removal of an antibiotic pollutant oxytetracycline (OTC) from water. The adsorbed OTC molecules, which are heat labile, can be degraded rapidly using inductive heating which also regenerates the nano-adsorbent. Polyethylene glycol (PEG) coated MNP was used as a seed for growing the MIL-53(Al) MOF. The MIL-53(Al) coating was achieved via a facile green synthesis route using deprotonated terephthalic acid in an aqueous alkaline solution. The MIL-53(Al) coating layer on the MNP was found to have low crystallinity compared to that of the pristine MIL-53(Al) possibly due to the mismatch growth on the PEG-coated MNP surface. Nevertheless, the obtained nano-sorbent displays high OTC adsorption capacity of 794 mg/g at optimal pH 8. The adsorbed OTC on the nano-sorbent can be destructed using a rapid non-contact inductive heating of the magnetic core. Adsorption and regeneration were carried out up to 9 cycles in the presence of OTC. FTIR and PXRD shows that OTC adheres strongly to the MIL-53(Al) framework which causes gradual MIL-53(Al) degradation after several cycles of heat regeneration. Nevertheless, the MIL-53(Al) coated MNP without the adsorbed OTC shows strong structural integrity even after 9 regeneration cycles. The work demonstrates the high potential of the developed nano-sorbent for use in pollutant removal, magnetic separation of toxic pollutants as well as rapid regeneration of the nano-sorbents using induction heating.

Temperature and solvent exposure response of three fatty acid peroxygenase enzymes for application in industrial enzyme processes

Free fatty acids (FFAs) are a useful feedstock for a range of industrial chemical synthesis applications. However, efficiently converting FFAs to molecules for biofuel and other high-value chemicals requires more efficient and cost-effective catalysts. Cytochrome P450 fatty acid peroxygenases (CYP152) have a unique chemistry that allows use of the peroxide shunt pathway for biochemical conversion of FFAs. Known CYP152s are heat labile, however, requiring characterization of more thermotolerant versions for use in industrial applications. A fatty acid peroxygenase from Bacillus methanolicus (CYP152K6) was shown here to have a higher optimal reaction temperature than OleT (CYP152L1). CYP152K6 was stable up to 50 °C and showed great stability in 3% acetone and dimethylformamide. Stability in solvents helps the enzyme's substrates remain soluble in solution for more efficient catalysis, and heat stability allows enzymes to remain active longer during industrial processes.

DmLT Adjuvant Enhances Cytokine Responses to T Cell Stimuli, Whole Cell Vaccine Antigens and Lipopolysaccharide in Both Adults and Infants.

Enhancement of mucosal immune responses in children and infants using novel adjuvants such as double mutant heat labile toxin (dmLT) is an important goal in the enteric vaccine field. dmLT has been shown to enhance mucosal IgA responses to the oral inactivated enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX. dmLT can enhance IL-17A production from adult T cells, which may increase the production and secretion of mucosal IgA antibodies. However, the adjuvant mechanism remains to be fully elucidated and might differ between infants and adults due to age-related differences in the development of the immune system. The main objective of this study was to determine how dmLT influences antigen presenting cells and T cells from infants compared to adults, and the role of IL-1β for mediating the adjuvant activity. Peripheral blood mononuclear cells (PBMCs) from Bangladeshi infants (6-11 months) and adults (18-40 years) were stimulated with the mitogen phytohaemagglutinin (PHA), the superantigen Staphylococcal enterotoxin B (SEB), ETVAX whole cell component (WCC) or E. coli lipopolysaccharide (LPS) ± dmLT, and cytokine production was measured using ELISA and electrochemiluminescence assays. The adjuvant dmLT significantly enhanced SEB- and PHA-induced IL-17A, but not IFN-γ responses, in PBMCs from both infants and adults. Blocking experiments using an IL-1 receptor antagonist demonstrated the importance of IL-1 signaling for the adjuvant effect. dmLT, ETVAX WCC and LPS induced dose-dependent IL-1β responses of comparable magnitudes in infant and adult cells. Depletion experiments suggested that IL-1β was mainly produced by monocytes. dmLT enhanced IL-1β responses to low doses of WCC and LPS, and the adjuvant effect appeared over a wider dose-range of WCC in infants. dmLT and WCC also induced IL-6, IL-23 and IL-12p70 production in both age groups and dmLT tended to particularly enhance IL-23 responses to WCC. Our results show that dmLT can induce IL-1β as well as other cytokines, which in turn may enhance IL-17A and potentially modulate other immunological responses in both infants and adults. Thus, dmLT may have an important function in promoting immune responses to the ETVAX vaccine, as well as other whole cell- or LPS-based vaccines in infants in low- and middle-income countries.

Combination of dmLT and MPL-A adjuvants synergistically and differentially activates the canonical inflammasome in DCs and macrophages in the absence of pyroptosis

Abstract The initiation of innate immune responses is critical for the formation of a protective adaptive immune response following vaccination. Innate immune cells, such as dendritic cells (DCs) and macrophages, phagocytose and display antigen, produce immune modulators and migrate to lymphoid tissues, leading to the activation of naïve T cells. These professional antigen-presenting cells are activated in response to pathogen or danger associated molecular patterns, a process that is normally not robust with vaccine antigen alone. Adjuvants are able to increase the immunogenicity of vaccine antigens by influencing the activation status of these innate immune cells. Only a few vaccine adjuvants are currently approved for use in the US and, along with the discovery of novel adjuvants, combination adjuvants are likely to have a major impact on future vaccine development. Here, we investigated the ability of both the double mutant Escherichia coli heat labile toxin (dmLT) and the TLR4 agonist monophosphoryl lipid A (MPL-A) to drive innate and adaptative immune responses independently and in combination. We found that the combination adjuvant induces more robust activation of DCs and macrophages than either adjuvant alone, leading to the formation of the NLRP3 inflammasome complex and GSDMD independent secretion of IL-1b in the absence of pyroptosis. Furthermore, RNA sequencing and ingenuity pathway analysis support that the combination adjuvant may allow these DCs to polarize a multi-faceted Th1/2/17 CD4 T cell response. Because macrophages and DCs have distinct roles in the interface between innate and adaptive immunity, understanding the cellular and molecular actions of adjuvants on these cells is critical when developing new vaccines.

Thermal Inactivation of Myrosinase from White Mustard Seeds

Myrosinases (thioglucosidases) catalyze the hydrolysis of a class of compounds called glucosinolates, of which the aglycones show various biological functions. It is often necessary to minimize the loss of myrosinase activity during thermal processing of cruciferous vegetables. Myrosinase was isolated from a popular spice, white mustard (Sinapis alba), and its thermal inactivation kinetics was investigated. The enzyme was extracted from white mustard seeds and purified by a sequential processes of ammonium sulfate fractionation, Concanavalin A-Sepharose column chromatography, and gel permeation chromatography. At least three isozymes were revealed by Concanavalin A-Sepharose column chromatography. The purity of the major myrosinase was examined by native polyacrylamide gel electrophoresis and on-gel activity staining with methyl red. The molecular weight of the major enzyme was estimated to be 171 kDa. When the consecutive step model was used for the thermal inactivation of the major myrosinase, its inactivation energy was 44.388 kJ/mol for the early stage of destruction and 32.019 kJ/mol for the late stage of destruction. When the distinct two enzymes model was used, the inactivation energy was 77.772 kJ/mol for the labile enzyme and 95.145 kJ/mol for the stable enzyme. The thermal inactivation energies lie within energy range causing nutrient destruction on heating.

Molecular mechanism of Escherichia coli H10407 induced diarrhoea and its control through immunomodulatory action of bioactives from Simarouba amara (Aubl.).

Enterotoxigenic Escherichia coli (ETEC) infection is a major cause of death in children under the age of five in developing countries. ETEC (O78:H11:CFA/I:LT+:ST+) mechanism has been studied in detail with either heat labile (LT) or heat stable (ST) toxins using in vitro and in vivo models. However, there is no adequate information on ETEC pathogenesis producing both the toxins (LT, ST) in BALB/c mice model. In this study, female mice have been employed to understand ETEC H10407 infection induced changes in physiology, biochemical and immunological patterns up to seven days post-infection and the antidiarrhoeal effect of Simarouba amara (Aubl.) bark aqueous extract (SAAE) has also been looked into. The results indicate that BALB/c is sensitive to ETEC infection resulting in altered jejunum and ileum histomorphology. Withal, ETEC influenced cAMP, PGE2, and NO production resulting in fluid accumulation with varied Na+, K+, Cl-, and Ca2+ levels. Meanwhile, ETEC subverted expression of IL-1β, intestine alkaline phosphatase (IAP), and myeloperoxidase (MPO) in jejunum and ileum. Our data also indicate the severity of pathogenesis reduction which might be due to attainment of equilibrium after reaching optimum rate of infection. Nevertheless, degree of pathogenesis was highly significant (p < 0.01) in all the studied parameters. Besides that, SAAE was successful in reducing the infectious diarrhoea by inhibiting ETEC H10407 in intestine (jejunum and ileum), and shedding in feces. SAAE decreased cAMP, PGE2, and fluid accumulation effectively and boosted the functional activity of immune system in jejunum and ileum IAP, MPO, IL-1β, and nitric oxide.

Molecular Basis and Enzymatic Properties of Glucose 6-Phosphate Dehydrogenase Volendam, Leading to Chronic Nonspherocytic Anemia, Granulocyte Dysfunction, and Increased Susceptibility to Infections

AbstractWe have investigated the blood cells from a woman with a low degree of chronic nonspherocytic hemolytic anemia and frequent bacterial infections accompanied by icterus and anemia. The activity of glucose 6-phosphate dehydrogenase (G6PD) in her red blood cells (RBCs) was below detection level, and in her leukocytes less than 3% of normal. In cultured skin fibroblasts, G6PD activity was approximately 15% of normal, with 4- to 5-fold increased Michaelis constant (Km) for NADP and for glucose 6-phosphate. Activated neutrophils showed a decreased respiratory burst. Family studies showed normal G6PD activity in the RBCs from all family members, including both parents and the 2 daughters of the patient. Sequencing of polymerase chain reaction (PCR)-amplified genomic DNA showed a novel, heterozygous 514C→T mutation, predicting a Pro172→Ser replacement. Analysis of G6PD RNA from the patient’s leukocytes and fibroblasts showed only transcripts with the 514C→T mutation. This was explained by the pattern of X-chromosome inactivation, studied by means of the human androgen receptor (HUMARA) assay, which proved to be skewed in the patient, her mother, and one of the patient’s daughters. Thus, the patient has inherited a de novo mutation in G6PD from her father and an X-chromosome inactivation determinant from her mother, causing exclusive expression of the mutated G6PD allele. Purified mutant protein from an Escherichia coli expression system showed strongly decreased specific activity, increased Km for NADP and for glucose 6-phosphate, and increased heat lability, which indicates that the defective phenotype is due to 2 synergistic molecular dysfunctions: decreased catalytic efficiency and protein instability.

Influência das condições de armazenamento de alcoolaturas das sementes de sucupira (Pterodon emarginatus) na presença de seus metabólitos bioativos

O tratamento de afecções inflamatórias empregando fitoterápicos preparados pela maceração de sementes de sucupira em bebidas alcoólicas é uma prática comum. A volatilidade e labilidade dos metabólitos pode promover variações na composição química dos fitoterápicos, conforme as condições de armazenamento. Este trabalho teve como objetivo investigar como o armazenamento afetam o perfil químico de extratos hidroalcóolicos de sementes de sucupira, principalmente em relação a presença e concentração relativa dos metabólitos bioativos. Para tanto, foram preparadas macerações de sementes de sucupira 10% (p/v) em álcool 70 °GL e, em duplicata. O acondicionamento destas foi realizado em frascos transparentes e âmbar que foram armazenados em condições variadas: em contato direto com a irradiação solar, a temperatura ambiente, em refrigerador e em freezer. Após 15, 45, 90 e 155 dias foram retiradas alíquotas de cada amostra e, estas tiveram seus perfis químicos determinados por técnica de cromatografia gasosa acoplada à espectrometria de massas (CG-EM). O armazenamento por períodos de 15, 45 e 90 dias levou a alteração química significativa, apenas das amostras expostas simultaneamente ao calor e luz solar. Aos 115 dias de armazenamento, as amostras armazenadas em frasco âmbar, nas demais condições de armazenamento, não exibiram todos os metabólitos extraídos, mas mantiveram a presença dos compostos que apresentam ação aint-inflamatória. Por tais resultados é possível concluir que as preparações caseiras, armazenadas a temperatura ambiente, sob refrigeração e congeladas, manterão a presença dos metabólitos de ação anti-inflamatória mesmo quando armazenadas por 115 dias, independente se este armazenamento ocorrer em frasco âmbar ou transparente.

White-tailed Deer Fecal Matter Distribution and Nutrient Contribution in Tallgrass Prairie

Herbivores can have nonconsumptive effects on ecosystems, including the redistribution of nutrients in their waste. In tallgrass prairie bison (Bison bison) historically increased soil nitrogen availability via labile waste deposits. White-tailed deer (Odocoileus virginianus) are now the dominant native large herbivore in prairie and have been shown to consume higher nutrient-content plants than those preferred by bison. Deer are also edge-dwelling species that reuse the trails they make as they move and browse throughout the prairie. Therefore, deer may differ from bison in their spatial patterns of nutrient content and redistribution of fecal matter. We examined the nutrient content and spatial distribution of deer pellets by measuring the number of deer pellet piles along deer trails and transects that were systematically placed at the forest border and in open prairie. We also measured the nitrogen content of deer pellets. White-tailed deer pellets had twofold greater nitrogen concentrations (3.43% N and 40.8% C) compared to values reported for bison fecal matter. Deer pellet piles were more concentrated on deer trails compared to the transects, resulting in fourfold greater N inputs on deer trails compared to areas off of trails. As a result, White-tailed deer have the potential to create patches of increased nutrient availability through their clumped distribution of nutrient rich fecal matter, with potential consequences for prairie plant communities.

SYNTHESIS AND STABILITY OF THERMALLY LABILE 1,2-OXAPHOSPHETANE 2-OXIDES AND 1,2-THIAPHOSPHETANE 2-SULFIDES

Synthesis and thermal stability of 1,2-oxaphosphetane 2-oxide and 1,2-thiaphosphetane 2-sulfide derivatives are discussed. This microreview covers the available synthetic methods of thermally labile 1,2-oxaphosphetane 2-oxides and 1,2-thiaphosphetane 2-sulfides and their fragmentation. The synthetic approaches may be classified in four distinct categories: cycloaddition, cyclization, fragmentation, and annulation.

Characterisation of Bacteriocins Produced by Lactobacillus spp. Isolated from the Traditional Pakistani Yoghurt and Their Antimicrobial Activity against Common Foodborne Pathogens.

Lactic acid bacteria (LAB) are widely known for their probiotic activities for centuries. These bacteria synthesise some secretory proteinaceous toxins, bacteriocins, which help destroy similar or interrelated bacterial strains. This study was aimed at characterising bacteriocins extracted from Lactobacillus spp. found in yoghurt and assessing their bactericidal effect on foodborne bacteria. Twelve isolated Lactobacillus spp. were examined to produce bacteriocins by the organic solvent extraction method. Bacteriocins produced by two of these strains, Lactobacillus helveticus (BLh) and Lactobacillus plantarum (BLp), showed the most significant antimicrobial activity, especially against Staphylococcus aureus and Acinetobacter baumannii. Analysis of SDS-PAGE showed that L. plantarum and L. helveticus bacteriocins have a molecular weight of ~10 kDa and ~15 kDa, respectively. L. plantarum (BLp) bacteriocin was heat stable while L. helveticus (BLh) bacteriocin was heat labile. Both bacteriocins have shown activity at acidic pH. Exposure to a UV light enhances the activity of the BLh; however, it had negligible effects on the BLp. Different proteolytic enzymes confirmed the proteinaceous nature of both the bacteriocins. From this study, it was concluded that bacteriocin extracts from L. helveticus (BLh) can be considered a preferable candidate against foodborne pathogens as compared to L. plantarum (BLp). These partially purified bacteriocins should be further processed to attain purified product that could be useful for food spoilage and preservation purposes.

Exploring the pathogen binding potential within the human gut microbiome

The infection process of bacterial gastroenteritis often relies on the initial binding of toxins to carbohydrate receptors on host cells. We screened the human gut microbiota for microorganisms naturally expressing toxin-binding carbohydrate structures. Out of stool samples from four healthy adult donors, we isolated bacterial strains specifically binding the cholera toxin and the heat labile toxin. These results suggest a new mechanism by which the microbiome may shape people’s individual sensitivity to gastrointestinal infections. This study may also pave the way for the development of non-antibiotic microbiome based strategies to treat and prevent gastrointestinal infections.

Food Processing Does Not Abolish the Allergenicity of the Carrot Allergen Dau c 1: Influence of pH, Temperature, and the Food Matrix.

The major carrot allergen Dau c 1 belongs to the group of pathogenesis related class 10 (PR-10) proteins and is homologous to the birch pollen allergen Betv1. In contrast to most other PR-10 allergens, Dau c 1 can elicit Bet v 1 independent sensitization. Although Dau c 1 is considered heat labile, allergic reactions against cooked carrots are possible. The pH and temperature stability as well as the allergenic potential before and after treatment of purified natural (n) Dau c 1 and different recombinant (r) isoallergens is investigated: rDau c 1.0104, rDau c 1.0105, rDau c 1.0201, rDau c 1.0301. All proteins except rDau c 1.0201 are able to refold at physiological pH. pH conditions around the pI (4.4-5.5) or the presence of the carrot matrix reduce the refolding capacity. Below the pI, most isoallergens are heat resistant and still able to cause mediator release, indicating allergenicity. Moreover, cooked carrot extract is still able to provoke mediator release due to remaining soluble Dau c 1. Patients allergic to carrots should avoid processed carrot containing foodstuff because heating or pH treatment do not completely abolish the allergenicity of Dau c 1.

Thawing permafrost: an overlooked source of seeds for Arctic cloud formation

As the Arctic warms at twice the global rate, radiative feedbacks from clouds will lead to compounding impacts on the surface energy budget that affect both regional and global weather, and climate. In a future warmer world, the Arctic is projected to become cloudier. However, the formation and evolution of Arctic clouds remain highly uncertain in part due to a limited understanding of current and future sources of ice nucleating particles (INPs). In particular, the sources and abundance of biologically-derived INPs are poorly characterized, yet they may be pivotal for cloud ice formation, especially at temperatures in which Arctic mixed-phase clouds (AMPCs) persist (i.e. >−15 °C). Here, we show for the first time that permafrost is a remarkably rich source of biologically-derived INPs, both heat labile (probably proteinaceous) and other organic INPs of biomolecular origin (41%–100% and 99%–100% of the total INPs, respectively). INP concentrations in 1000 to 30 000 year old permafrost were comparable to the most active of other Arctic and midlatitude soil sources (up to 1010 INPs per gram of soil). Thawing of permafrost—which promotes metabolic activity in microbes—and subsequent mobilization of those soils directly into the atmosphere or into lakes, rivers, and the ocean, suggests the intriguing possibility that increasing emissions of INPs from this hitherto overlooked reservoir could be widespread, and, in time, greatly impact Arctic cloud cloud glaciation and radiative properties. This discovery is timely given the rapidly-thawing permafrost in Alaska and across Earth’s high latitudes. Since permafrost covers 15% of Northern Hemisphere land, this novel and prevalent INP source may become central to predictions of aerosol-cloud-precipitation interactions in AMPCs.

Use of a multiplex PCR system for the simultaneous detection of heat labile toxin I and heat stable toxin II Escherichia coli cells in environmental waters near Taichung City

Use of a multiplex PCR system for the simultaneous detection of heat labile toxin I and heat stable toxin II Escherichia coli cells in environmental waters near Taichung City