Survival of Listeria Strains and Shelf Life Determination of Fresh Blueberries (Vaccinium corymbosum) Treated with Cold Atmospheric Plasma.

Fresh blueberries are delicate, hand-picked, packaged, and refrigerated fruits vulnerable to spoilage and contamination. Cold atmospheric plasma (CAP) is a promising antimicrobial technology; therefore, this study evaluated the CAP treatment effect on acid-tolerant Listeria innocua and Listeria monocytogenes and evaluated changes in the quality of the treated fruit. Samples were spot-inoculated with pH 5.5 and 6.0 acid-adapted Listeria species. Samples were treated with gliding arc CAP for 15, 30, 45, and 60 s and evaluated after 0, 1, 4, 7, and 11 days of storage at 4 °C and 90% humidity for the following quality parameters: total aerobic counts, yeast and molds, texture, color, soluble solids, pH, and titratable acidity. CAP treatments of 30 s and over demonstrated significant reductions in pathogens under both the resistant strain and pH conditions. Sixty-second CAP achieved a 0.54 Log CFU g-1 reduction in L. monocytogenes (pH 5.5) and 0.28 Log CFU g-1 for L. monocytogenes (pH 6.0). Yeast and mold counts on day 0 showed statistically significant reductions after 30, 45, and 60 s CAP with an average 2.34 Log CFU g-1 reduction when compared to non-CAP treated samples. Quality parameters did not show major significant differences among CAP treatments during shelf life. CAP is an effective antimicrobial treatment that does not significantly affect fruit quality.

Delivery of a sebum modulator by an engineered skin microbe in mice.

Microorganisms can be equipped with synthetic genetic programs for the production of targeted therapeutic molecules. Cutibacterium acnes is the most abundant commensal of the human skin, making it an attractive chassis to create skin-delivered therapeutics. Here, we report the engineering of this bacterium to produce and secrete the therapeutic molecule neutrophil gelatinase-associated lipocalin, in vivo, for the modulation of cutaneous sebum production.

New insights into the role of Cutibacterium acnes-derived extracellular vesicles in inflammatory skin disorders.

Cutibacterium acnes (C. acnes) is one of the most prevalent bacteria that forms the human skin microbiota. Specific phylotypes of C. acnes have been associated with the development of acne vulgaris, while other phylotypes have been linked to healthy skin. In this scenario, bacterial extracellular vesicles (EVs) play a role in the interkingdom communication role with the human host. The purpose of this study was to examine the impact of EVs generated by various phylotypes of C. acnes on inflammation and sebum production using different in vitro skin cell types. The main findings of this study reveal that the proteomic profile of the cargo embodied in the EVs reflects distinct characteristics of the different C. acnes phylotypes in terms of life cycle, survival, and virulence. The in vitro skin cell types showed an extended pro-inflammatory modulation of SLST A1 EVs consistently triggering the activation of the inflammation-related factors IL-8, IL-6, TNFα and GM-CSF, in comparison to SLST H1 and SLST H2. Additionally, an acne-prone skin model utilizing PCi-SEB and arachidonic acid as a sebum inducer, was employed to investigate the impact of C. acnes EVs on sebum regulation. Our findings indicated that all three types of EVs significantly inhibited sebum production after a 24-h treatment period, with SLST H1 EVs exhibiting the most pronounced inhibitory effect when compared to the positive control. The results of this study highlight the protective nature of C. acnes SLST H1 EVs and their potential use as a natural treatment option for alleviating symptoms associated with inflammation and oily skin.

Establishing a Cell-Free Transcription-Translation Platform for Cutibacterium acnes to Prototype Engineered Metabolic and Synthetic Biology.

In the past few years, new bacterial-cell-free transcription-translation systems have emerged as potent and quick platforms for protein production as well as for prototyping of DNA regulatory elements, genetic circuits, and metabolic pathways. The Gram-positive commensal Cutibacterium acnes is one of the most abundant bacteria present in the human skin microbiome. However, it has recently been reported that some C. acnes phylotypes can be associated with common inflammatory skin conditions, such as acne vulgaris, whereas others seem to play a protective role, acting as possible "skin probiotics". This fact has made C. acnes become a bacterial model of interest for the cosmetic industry. In the present study we report for the first time the development and optimization of a C. acnes-based cell-free system (CFS) that is able to produce 85 µg/mL firefly luciferase. We highlight the importance of harvesting the bacterial pellet in mid log phase and maintaining CFS reactions at 30 °C and physiological pH to obtain the optimal yield. Additionally, a C. acnes promoter library was engineered to compare coupled in vitro TX-TL activities, and a temperature biosensor was tested, demonstrating the wide range of applications of this toolkit in the synthetic biology field.

Outer Membrane Vesicles from the Probiotic Escherichia coli Nissle 1917 and the Commensal ECOR12 Enter Intestinal Epithelial Cells via Clathrin-Dependent Endocytosis and Elicit Differential Effects on DNA Damage.

Interactions between intestinal microbiota and the human host are complex. The gut mucosal surface is covered by a mucin layer that prevents bacteria from accessing the epithelial cells. Thus, the crosstalk between microbiota and the host mainly rely on secreted factors that can go through the mucus layer and reach the epithelium. In this context, vesicles released by commensal strains are seen as key players in signaling processes in the intestinal mucosa. Studies with Gram-negative pathogens showed that outer membrane vesicles (OMVs) are internalized into the host cell by endocytosis, but the entry mechanism for microbiota-derived vesicles is unknown. Escherichia coli strains are found as part of normal human gut microbiota. In this work, we elucidate the pathway that mediate internalization of OMVs from the probiotic E.coli Nissle 1917 (EcN) and the commensal ECOR12 strains in several human intestinal epithelial cell lines. Time course measurement of fluorescence and microscopy analysis performed with rhodamine B-R18-labeled OMVs in the presence of endocytosis inhibitors showed that OMVs from these strains enter epithelial cells via clathrin-mediated endocytosis. Vesicles use the same endocytosis pathway in polarized epithelial monolayers. Internalized OMVs are sorted to lysosomal compartments as shown by their colocalization with clathrin and specific markers of endosomes and lysosomes. OMVs from both strains did not affect cell viability, but reduce proliferation of HT-29 cells. Labeling of 8-oxo-dG adducts in DNA revealed that neither OMVs from EcN nor from ECOR12 promoted oxidative DNA damage. In contrast, flow cytometry analysis of phosphorylated γH2AX evidenced that OMVs from the probiotic EcN significantly produced more double strand breaks in DNA than ECOR12 OMVs. The EcN genotoxic effects have been attributed to the synthesis of colibactin. However, it is not known how colibactin is exported and delivered into host cells. Whether colibactin is secreted via OMVs is an open question that needs further study.

The secreted autotransporter toxin (Sat) does not act as a virulence factor in the probiotic Escherichia coli strain Nissle 1917.

BACKGROUND: Escherichia coli Nissle 1917 (EcN) is a probiotic used in the treatment of intestinal diseases. Although it is considered safe, EcN is closely related to the uropathogenic E. coli strain CFT073 and contains many of its predicted virulence elements. Thus, it is relevant to assess whether virulence-associated genes are functional in EcN. One of these genes encodes the secreted autotransporter toxin (Sat), a member of the serine protease autotransporters of Enterobacteriaceae (SPATEs) that are secreted following the type V autotransporter pathway. Sat is highly prevalent in certain E. coli pathogenic groups responsible for urinary and intestinal infections. In these pathogens Sat promotes cytotoxic effects in several lines of undifferentiated epithelial cells, but not in differentiated Caco-2 cells. RESULTS: Here we provide evidence that sat is expressed by EcN during the colonization of mouse intestine. The EcN protein is secreted as an active serine protease, with its 107 kDa-passenger domain released into the medium as a soluble protein. Expression of recombinant EcN Sat protein in strain HB101 increases paracellular permeability to mannitol in polarized Caco-2 monolayers. This effect, also reported for the Sat protein of diffusely adherent E. coli, is not observed when this protein is expressed in the EcN background. In addition, we show that EcN supernatants confer protection against Sat-mediated effects on paracellular permeability, thus indicating that other secreted EcN factors are able to prevent barrier disruption caused by pathogen-related factors. Sat is not required for intestinal colonization, but the EcNsat::cat mutant outcompetes wild-type EcN in the streptomycin-treated mouse model. Analysis of the presence of sat in 29 strains of the ECOR collection isolated from stools of healthy humans shows 34.8 % positives, with high prevalence of strains of the phylogenetic groups D and B2, related with extra-intestinal infections. CONCLUSIONS: Sat does not act as a virulence factor in EcN. The role of Sat in intestinal pathogenesis relies on other genetic determinants responsible for the bacterial pathotype.

Proteomic analysis of outer membrane vesicles from the probiotic strain Escherichia coli Nissle 1917.

Escherichia coli Nissle 1917 (EcN) is a probiotic used for the treatment of intestinal disorders. EcN improves gastrointestinal homeostasis and microbiota balance; however, little is known about how this probiotic delivers effector molecules to the host. Outer membrane vesicles (OMVs) are constitutively produced by Gram-negative bacteria and have a relevant role in bacteria-host interactions. Using 1D SDS-PAGE and highly sensitive LC-MS/MS analysis we identified in this study 192 EcN vesicular proteins with high confidence in three independent biological replicates. Of these proteins, 18 were encoded by strain-linked genes and 57 were common to pathogen-derived OMVs. These proteins may contribute to the ability of this probiotic to colonize the human gut as they fulfil functions related to adhesion, immune modulation or bacterial survival in host niches. This study describes the first global OMV proteome of a probiotic strain and provides evidence that probiotic-derived OMVs contain proteins that can target these vesicles to the host and mediate their beneficial effects on intestinal function. All MS data have been deposited in the ProteomeXchange with identifier PXD000367 (http://proteomecentral.proteomexchange.org/dataset/PXD000367).

Characterization of the gene cluster involved in allantoate catabolism and its transcriptional regulation by the RpiR-type repressor HpxUin Klebsiella pneumoniae

Bacteria, fungi, and plants have metabolic pathways for the utilization of nitrogen present in purine bases. In Klebsiella pneumoniae, the genes responsible for the assimilation of purine ring nitrogen are distributed in three separated clusters. We characterized the gene cluster involved in the metabolism of allantoate (genes KPN_01761 to KPN_01771). The functional assignments of HpxK, as an allantoate amidohydrolase, and of HpxU, as a regulator involved in the control of allantoate metabolism, were assessed experimentally. Gene hpxU encodes a repressor of the RpiR family that mediates the regulation of this system by allantoate. In this study, the binding of HpxU to the hpxF promoter and to the hpxU-hpxW intergenic region containing the divergent promoter for these genes was evidenced by electrophoretic mobility shift assays. Allantoate released the HpxU repressor from its target operators whereas other purine intermediate metabolites, such as allantoin and oxamate, failed to induce complex dissociation. Sequence alignment of the four HpxU identified operators identified TGAA-N8-TTCA as the consensus motif recognized by the HpxU repressor (AU)

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Characterization of the gene cluster involved in allantoate catabolism and its transcriptional regulation by the RpiR-type repressor HpxU in Klebsiella pneumoniae.

Bacteria, fungi, and plants have metabolic pathways for the utilization of nitrogen present in purine bases. In Klebsiella pneumoniae, the genes responsible for the assimilation of purine ring nitrogen are distributed in three separated clusters. We characterized the gene cluster involved in the metabolism of allantoate (genes KPN_01761 to KPN_01771). The functional assignments of HpxK, as an allantoate amidohydrolase, and of HpxU, as a regulator involved in the control of allantoate metabolism, were assessed experimentally. Gene hpxU encodes a repressor of the RpiR family that mediates the regulation of this system by allantoate. In this study, the binding of HpxU to the hpxF promoter and to the hpxU-hpxW intergenic region containing the divergent promoter for these genes was evidenced by electrophoretic mobility shift assays. Allantoate released the HpxU repressor from its target operators whereas other purine intermediate metabolites, such as allantoin and oxamate, failed to induce complex dissociation. Sequence alignment of the four HpxU identified operators identified TGAA-N8-TTCA as the consensus motif recognized by the HpxU repressor.

Expresión de ICAM-1 en el endotelio de arterias humanas mediante inmunohistoquímica / ICAM-1 Expression in endothelium of human arteries by immunohistochemistry

Las enfermedades cardiovasculares son la principal causa de muerte a nivel mundial. Entre ellas tienen gran relevancia las de tipo isquémicas, en donde el desarrollo de placas ateroscleróticas es el proceso fisiopatológico central. El estudio de la aterosclerosis es fundamental para comprender como se inicia este proceso patológico y los factores que influyen en su desarrollo. Distintas metodologías de laboratorio, entre otras la inmunohistoquímica, permiten reconocer las células y moléculas que participan en el proceso ateromatoso y que van interactuando según la progresión de la lesión. Un marcador de disfunción endotelial es la mayor expresión de la molécula de adhesión intercelular ICAM-1. En este trabajo se realizó la estandarización de inmunohistoquímica para la molécula de adhesión ICAM-1, y se estudió su expresión en arterias humanas sanas y con placa ateromatosa. En las muestras de arterias humanas con patología aterosclerótica, la expresión de ICAM-1 se observó aumentada, pero fue de difícil reconocimiento. Esto principalmente porque el tejido empleado como control en la estandarización fue una amígdala con hiperplasia y proceso inflamatorio que aumenta notablemente la expresión de ICAM-1. La implementación del método de inmunohistoquímica para ICAM-1 en arterias humanas permitirá conocer estados de disfunción endotelial y el desarrollo futuro del diseño e implementación de métodos de diagnóstico en aquellos procesos ateroclerótico en estado incipiente.

Cardiovascular diseases (CVD) are the leading cause of death in the world. Among them the ischemic type are of great importance, where the development of atherosclerotic plaques is the central pathophysiological process. The study of atherosclerosis is critical to understand how this disease process begins and factors influencing its development. Various laboratory methods, including immunohistochemistry, allow the recognition of cells and molecules involved in the atheromatous process that are interacting according to the progression of the lesion. A marker of endothelial dysfunction is the increased expression of intercellular adhesion molecule ICAM-1. In this paper, an immunohistochemistry method was standardized for the adhesion molecule ICAM-1, and its expression was studied in healthy human arteries with atheromatous plaque. In samples of human arteries with atherosclerotic disease, the expression of ICAM-1 was observed to be increased, but was hardly recognizable. This mainly because the tissue used as a control for standardization was a tonsil with an inflammatory process and hyperplasia, which significantly increases the expression of ICAM-1. The implementation of the immunohistochemistry method for ICAM-1 in human arteries will reveal endothelial dysfunction states that will enable a future design and implementation of methods of diagnosis in atherosclerotic processes in the early stages.

Un nuevo caso clínico de rinosporidiosis en Chile / A new case of rhinosporidiosis in Chile

Antecedentes. La rinosporidiosis es una afección no contagiosa, granulomatosa crónica con desarrollo de pólipos, fundamentalmente nasales, altamente vascularizados que sangran con facilidad. Objetivos. La exposición del caso de un joven de 14 años de edad que presentaba obstrucción y lesión en la fosa nasal derecha de forma polipoidea y de aspecto aframbuesado. Métodos. Se realizó una resección quirúrgica amplia de la base de la lesión y posteriormente se efectuó el procesamiento histopatológico estándar y el análisis microscópico con tinción de hematoxilina-eosina y Grocott. Resultados y conclusiones. El informe histopatológico indicó que el pólipo inflamatorio crónico era compatible con rinosporidiosis(AU)

Background. Rhinosporidiosis is a chronic, granulomatous, and non-contagious infection, in which highly vascularized polyps (mainly present in the nasal cavity) appear. These polyps usually bleed easily. Aims. To present the case of a 14 year-old male suffering from an obstruction and injury of the right nostril due to a polypoid shaped-lesion with a raspberry-like appearance. Methods. A wide surgery resection of the base of the lesion was performed, as well as a standard histopathology procedure, including microscopic analysis with haematoxylin-eosin and Grocott staining. Results and conclusions. The histopathology report indicated that the chronic inflammatory polyp was compatible with rhinosporidiosis(AU)

[Evolution of the prevalence the enteroparasitoses in Talca-Chile]. / Evolución de la prevalencia de enteroparasitosis en la ciudad de Talca, Región del Maule, Chile.

The prevalence of intestinal parasites in preschool and school children in the city of Talca and rural areas belonging to the Maule Region, was assessed annually by means of the serial parasitological studies in stool which were performed in the Parasitology Laboratory of the "Universidad de Talca". For consecutive periods since 1980 until 2008, an estimated prevalence of parasitism of 76.2% in the population studied was found. These results show a marked decrease from 9.8% to 2.5% in pathogenic enteroparasites like: Giardia lamblia, Entamoeba histolytica, Trichocephalos trichiuris, Ascaris lumbricoides, Hymenolepis nana and Taenia sp. Commensal parasites as Entamoeba coli, lodamoeba butschlii, Endolimax nana and Chilomastix mesnili experimented a diminished recovery too. However commensal parasites globally showed an increase in time, given the significant increase of Blastocystis hominis (from 7.6 to 72.9%). A change was also observed in the carriage ofpolyparasitosis (from 64.5% to 9.6%) and monoparasitosis (from 10.0 to 35.5%).

[A new case of rhinosporidiosis in Chile]. / Un nuevo caso clínico de rinosporidiosis en Chile.

BACKGROUND: Rhinosporidiosis is a chronic, granulomatous, and non-contagious infection, in which highly vascularized polyps (mainly present in the nasal cavity) appear. These polyps usually bleed easily. AIMS: To present the case of a 14 year-old male suffering from an obstruction and injury of the right nostril due to a polypoid shaped-lesion with a raspberry-like appearance. METHODS: A wide surgery resection of the base of the lesion was performed, as well as a standard histopathology procedure, including microscopic analysis with haematoxylin-eosin and Grocott staining. RESULTS AND CONCLUSIONS: The histopathology report indicated that the chronic inflammatory polyp was compatible with rhinosporidiosis.