Coronavirus, transmisión alimentaria y cuidados en el confinamiento / No disponible

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Motility and Survival of Salmonella Enterica Subspecies Enterica Serovar Enteritidis in Tomato Plants (Solanum lycopersicum L)

The presence of enteropathogens such as Salmonella affects the quality and safety of vegetables that are consumed in a minimally processed state. Worldwide, tomatoes are one of the main vegetables whose raw consumption has caused health alerts. As such, the aim of this study was to determine the motility and survival of Salmonella enterica subspecies enterica serovar Enteritidis on greenhouse-grown tomato plants. A completely randomized experimental design was used, and bacteria were inoculated into the substrate at the time of transplanting as well as by puncturing the plant stem, petiole, and peduncle during the vegetative, flowering, and fruiting stages. Survival was monitored throughout the production cycle; motility was evaluated separately in plant organs separated from the point of inoculation. Salmonella enteritidis survived the 120 days of the experiment both at the point of inoculation and in other organs of the tomato plant. For all treatments, there was a significant difference (P < 0.05) between bacterial counts in the root (12.45 ± 2.52 to 160 ± 4.01 CFU/g), stem (16.10 ± 2.31 to 90.55 ± 3.62 CFU/g), flower (7.0 ± 2.15 to 51.10 ± 3.80 CFU/g), and fruit (8.75 ± 2.38 to 28.2 ± 3.29 CFU/g). The results of the study indicate that Salmonella enteritidis in contact with tomato plants is a latent danger because its ability to enter, survive, and move within tomato plants until reaching the fruit, limits the effectiveness of commonly used disinfection methods, it would potentiate the risk to human health

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Rescue of Escherichia coli cells from UV-induced death and filamentation by caspase-3 inhibitor

Escherichia coli cells have been observed earlier to display caspase-3-like protease activity (CLP) and undergo programmed cell death (PCD) when exposed to gamma rays. The presence of an irreversible caspase-3 inhibitor (Ac-DEVD-CMK) during irradiation was observed to increase cell survival. Since radiation is known to induce SOS response, the effect of a caspase-3 inhibitor on SOS response was studied in E. coli. UV, a well-known SOS inducer, was used in the current study. Cell filamentation in E. coli upon UV exposure was found to be inhibited by ninefold in the presence of a caspase-3 inhibitor. CLP activity was found to increase twofold in UV-exposed cells than in control (non-treated) cells. Further, bright fluorescing filaments were observed in UV-exposed E. coli cells treated with FITC-DEVD-FMK, a fluorescent dye tagged with an irreversible caspase-3 inhibitor (DEVD-FMK), indicating the presence of active CLP in these cells. Unlike caspase-3 inhibitor, a serine protease inhibitor, phenylmethanesulfonyl fluoride (PMSF), was not found to improve cell survival after UV treatment. Additionally, a SOS reporter system known as SIVET (selectable in vivo expression technology) assay was performed to reconfirm the inhibition of SOS induction in the presence of caspase-3 inhibitor. SIVET assay is used to quantify cells in which the SOS response has been induced leading to a scorable permanent selectable change in the cell. The SIVET induction frequency (calculated as the ratio of SIVET-induced cells to total viable cells) increased around tenfold in UV-exposed cultures. The induction frequency was found to decrease significantly to 51 from 80% in the cells pre-incubated with caspase-3 inhibitor. On the contrary, caspase-3 inhibitor failed to improve cell survival of E. coli ΔrecA and E. coli DM49 (SOS non-inducible) cells post UV treatment. Summing together, the results indicated a possible linkage of SOS response and the PCD process in E. coli. The findings also indicated that functional SOS pathway is required for CLP-like activity; however, the exact mechanism remains to be elucidated

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Recomendaciones GEMICOMED/GEIRAS-SEIMC para el manejo de las infecciones y colonizaciones por Candida auris / GEMICOMED/GEIRAS-SEIMC recommendations for the management of Candida auris infection and colonization

Candida auris es una nueva especie de Candida responsable de diversos brotes nosocomiales en varios países del mundo, incluida España; es resistente al fluconazol y se han descrito cepas multi y panresistentes. Presenta una elevada transmisibilidad y extensa supervivencia en el entorno hospitalario, lo que es causa de brotes de larga duración difíciles de detectar en fases tempranas y dificulta su control e intento de erradicación. C.auris constituye actualmente una amenaza emergente para la salud global. Para limitar el impacto y facilitar el control de la infección por C.auris, el presente documento ofrece un conjunto de recomendaciones basadas en las experiencias obtenidas en los brotes de España y del Reino Unido, elaboradas por un equipo multidisciplinar. La puesta en marcha de medidas de vigilancia y control es esencial para evitar la propagación del brote, que puede prolongarse en el tiempo y representar así un riesgo importante para los pacientes quirúrgicos complejos, críticos e inmunocomprometidos. La notificación inmediata del aislamiento de C.auris a los equipos clínicos y de control de infecciones, así como a las autoridades e instituciones sanitarias, es esencial para implementar las medidas de control de infecciones a todos los niveles y escalas de manera oportuna, para evitar la transmisión interna e intercentros, y para garantizar la vigilancia y la prevención del desarrollo de infecciones en pacientes que ya se encuentran colonizados

Candida auris is a new species of Candida that causes nosocomial outbreaks in several countries around the world, including Spain. C.auris is resistant to fluconazole and multi- and pan-resistant strains have been described. It is highly transmissible and can survive long term in the hospital environment, causing long-lasting outbreaks that are difficult to detect in early stages, and making it difficult to control and eradicate. It is currently an emerging threat to global health. This document provides a set of guidelines, developed by a multidisciplinary team, to limit the impact and facilitate the control of C.auris infection based on the experiences gathered in the Spanish and English outbreaks. The implementation of early and strict surveillance and control measures is essential to prevent the spread of the outbreak, which can spread over time, posing a significant risk to complex, critical and immunocompromised surgical patients. Immediate notification of C.auris isolation to clinical and infection control teams, as well as to health authorities and institutions, is essential to implement infection control measures at all levels in a timely manner, to prevent internal and inter-centre transmission, and to ensure a proper surveillance and prevention to patients who are already colonized and can develop an infection

Safety, functional properties and technological performance in whey-based media of probiotic candidates from human breast milk

We aimed at isolating and characterising microorganisms present in human breast milk with probiotic potential. In an 8-week postpartum sampling period, two strains of bifidobacteria (Bifidobacterium longum LM7a and Bifidobacterium dentium LM8a') and four strains of lactobacilli were isolated, all during the first 4-week postpartum. B. longum LM7a and B. dentium LM8a', together with four strains previously isolated from breast milk (Bifidobacterium lactis INL1, INL2, INL4 and INL5), were considered for further studies. Susceptibility of the strains to tetracycline, erythromycin, clindamycin, streptomycin, vancomycin and chloramphenicol was evaluated and the isolates exhibited, in general, the same properties as previously reported for bifidobacteria. All isolates showed low hydrophobicity and B. lactis and B. longum strains had satisfactory resistance to gastric digestion and bile shock, but not to pancreatin. B. lactis INL1, B. longum LM7a and B. dentium LM8a' were selected for some comparative technological studies. In particular, B. lactis INL1 displayed technological potential, with satisfactory growth in cheese whey-based media in biofermentor and resistance to freeze-drying, accelerated storage conditions and simulated gastric digestion

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Simvastatin and other inhibitors of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase of Ustilago maydis (Um-Hmgr) affect the viability of the fungus, its synthesis of sterols and mating / La simvastatina y otros inhibidores de la enzima 3-hidroxi-3-metilglutaril-coenzima A-reductasa de Ustilago maydis (Um-Hmgr) afectan a la viabilidad del hongo, la síntesis de esteroles y el mating

Background: The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (Hmgr) catalyzes the synthesis of mevalonate, a key compound for the synthesis of cholesterol in humans and ergosterol in fungi. Since the Hmgr enzymes of Saccharomyces cerevisiae, Schizosaccharomyces pombe and Candida glabrata are similar to the Hmgr enzymes of mammals, fungal Hmgr enzymes have been proposed as a model for studying antifungal agents. Aims: To examine the correlation between inhibiting Um-Hmgr enzyme and the viability, sterols synthesis and mating in Ustilago maydis. Methods: Using in silico analysis, the ORF codifying for Um-Hmgr was identified and the protein characteristics were deduced. The effect of the competitive inhibitors of Um-Hmgr on the viability of this basidiomycota, the synthesis of its sterols, and its mating were evaluated. Results: The Umhmgr gene (XP_011389590.1) identified putatively codifies a protein of 1443 aa (ca. MW = 145.5 kDa) that has a possible binding domain in the endoplasmic reticulum (ER) and high identity with the Hmgr catalytic domain of humans and other yeasts. The inhibition of Um-Hmgr caused a decrease of viability and synthesis of sterols, and also the inhibition of mating. The activity of Um-Hmgr is mainly located in the membrane fraction of the fungus. Conclusions: Given our results we believe U. maydis is a valid model for studying synthetic inhibitors with lipid-lowering or antifungal activity. Additionally, we propose the Hmgr enzyme as an alternative molecular target to develop compounds for treating both phytopathogenic and pathogenic human fungi

Antecedentes: La enzima 3-hidroxi-3-metilglutaril-coenzima A-reductasa (Hmgr) cataliza la síntesis de mevalonato, compuesto clave precursor en la biosíntesis del colesterol en el ser humano y en la del ergosterol en los hongos. Las enzimas Hmgr de Saccharomyces cerevisiae, Schizosaccharomyces pombe y Candida glabrata presentan similitud con la Hmgr de los mamíferos, motivo por el cual se han propuesto como modelo para el estudio de antifúngicos. Objetivos: Estudiar la correlación que existe entre la inhibición de la enzima Um-Hmgr y la viabilidad, la síntesis de esteroles y el mating en Ustilago maydis. Métodos: Por medio de un análisis in silico se identificó el ORF de la Um-Hmgr, y se dedujeron las características de la proteína. Se evaluó el efecto de los inhibidores competitivos de la enzima Um-Hmgr en la viabilidad, la síntesis de esteroles y el mating. Resultados: El gen Umhmgr (XP_011389590.1) codifica una proteína putativa de 1.443 aa (MW = 145,5 kDa), con un posible dominio de unión al retículo endoplásmico (RE) y una identidad alta con el dominio catalítico de la Hmgr humana y de otras levaduras. La inhibición de la Um-Hmgr ocasionó una disminución en la viabilidad y síntesis de esteroles del hongo, así como la inhibición del mating. La actividad de la Um-Hmgr está localizada principalmente en la fracción membranal del hongo. Conclusiones: La enzima Um-Hmgr está anclada probablemente al RE y presenta una elevada homología con el dominio catalítico de otras Hmgr de eucariotas. La Um-Hmgr participa en la síntesis de esteroles de este basidiomiceto, y su inhibición provoca la pérdida de la viabilidad, la reducción de los niveles de esteroles y del mating del hongo

In vitro evaluation of the prebiotic effect of red and white grape polyphenolic extracts

Nowadays, the strong relationship between diet and health is well known. Although the primary role of diet is to provide nutrients to fulfill metabolic requirements, the use of foods to improve health and the state of well-being is an idea increasingly accepted by society in the last three decades. During the last years, an important number of scientific advances have been achieved in this field and, although in some situations, it is difficult to establish a distinction between "harmful" and "good" bacteria, experts agree in classifying the genera Bifidobacterium and Lactobacillus as beneficial bacteria. Thus, several strategies can be used to stimulate the proliferation of these beneficial intestinal bacteria, being one of them the consumption of prebiotics. The development of new prebiotics, with added functionality, is one of the most serious challenges shared not only by the scientific community but also by the food industry. The objective of this work was to evaluate the potential prebiotic effect of red and white grape residues, both obtained during the winemaking process. For such purpose, an in vitro study with pure cultures of Lactobacillus and Bifidobacterium was first conducted. Secondly, a study with mixed cultures using human fecal inocula was carried out in a simulator of the distal part of the colon. The obtained results showed an increase in the Lactobacillus and Bifidobacterium population, indicating that these ingredients are serious candidates to be considered as prebiotics

Survival of Pochonia chlamydosporia on the soil surface after different exposure intervals at ambient conditions / Supervivencia de Pochonia chlamydosporia en la superficie del suelo después de diferentes intervalos de exposición a condiciones ambientales

Background. Exposure of the nematophagous fungus Pochonia chlamydosporia to solar radiation and elevated temperatures before being incorporated into the soil can reduce its survival and efficiency as biocontrol agent. Aims. A field experiment was carried out to assess the effect of the exposure period on the viability of P. chlamydosporia applied on the soil surface. Methods. A commercial bionematicide based on P. chlamydosporia was sprayed on soil, and soil samples were collected before and at 0, 30, 60, 90, 120, and 150 min after fungal application. Relative humidity (RH), the irradiance (IR), air temperature (AT), and soil temperature (ST) were recorded. The number of P. chlamydosporia colony forming units (CFUs) was evaluated after 20 days of incubation. Results. P. chlamydosporia survival decreased over the time of exposure on the soil surface. Overall, the number of CFUs decreased by more than 90% at 150min after application. Exposure to RH ≥61%, ST and AT between 25-35°C and 19-29°C, and IR between 1172 and 2126μmol of photons m−2s−1 induced a negative exponential effect on the survival of the fungus over the time. Conclusions. Exposure to climatic conditions on the soil surface reduces P. chlamydosporia viability (AU)

Antecedentes. La exposición del hongo nematófago Pochonia chlamydosporia a la radiación solar y la temperatura elevada antes de ser incorporado al suelo puede reducir su supervivencia y eficiencia como agente de biocontrol. Objetivos. Se realizó un experimento de campo para evaluar el efecto del período de exposición a condiciones ambientales sobre la viabilidad de P. chlamydosporia en la superficie del suelo. Métodos. Se pulverizó sobre el suelo un bionematicida comercial hecho a base de P. chlamydosporia y se recogieron muestras de suelo antes y después de 0, 30, 60, 90, 120 y 150min tras la aplicación del hongo. Se registraron la humedad relativa (HR), la irradiación (IR), la temperatura del aire (TA) y la temperatura del suelo (TS). Se evaluó el número de unidades formadoras de colonias (UFC) de P. chlamydosporia después de 20 días de incubación. Resultados. La supervivencia de P. chlamydosporia disminuyó durante el tiempo de exposición en la superficie del suelo. En general, el número de UFC disminuyó en más de un 90% a los 150min después de la aplicación. La exposición a HR≥61%, TS y TA entre 25-35°C y 19-29°C, e IR entre 1.172 y 2.126μmol de fotones m−2 s−1 indujo un efecto exponencial negativo en la supervivencia del hongo. Conclusiones. La exposición a las condiciones climáticas en la superficie del suelo reduce la viabilidad de P. chlamydosporia (AU)

Functional ecology of soil microbial communities along a glacier forefield in Tierra del Fuego (Chile)

A previously established chronosequence from Pia Glacier forefield in Tierra del Fuego (Chile) containing soils of different ages (from bare soils to forest ones) is analyzed. We used this chronosequence as framework to postulate that microbial successional development would be accompanied by changes in functionality. To test this, the GeoChip functional microarray was used to identify diversity of genes involved in microbial carbon and nitrogen metabolism, as well as other genes related to microbial stress response and biotic interactions. Changes in putative functionality generally reflected succession-related taxonomic composition of soil microbiota. Major shifts in carbon fixation and catabolism were observed, as well as major changes in nitrogen metabolism. At initial microbial dominated succession stages, microorganisms could be mainly involved in pathways that help to increase nutrient availability, while more complex microbial transformations such as denitrification and methanogenesis, and later degradation of complex organic substrates, could be more prevalent at vegetated successional states. Shifts in virus populations broadly reflected changes in microbial diversity. Conversely, stress response pathways appeared relatively well conserved for communities along the entire chronosequence. We conclude that nutrient utilization is likely the major driver of microbial succession in these soils (AU)

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Evaluación de contaminantes microbianos en muestras de cannabis incautadas en Costa Rica / Evaluation of microbial contamination in samples of cannabis seized in Costa Rica

Diferentes literaturas sugieren que el consumo de cannabis es un importante problema para la salud pública. El cannabis, por su naturaleza ilegal, llega a sus usuarios sin cumplimiento de normas adecuadas de cultivo, almacenamiento, procesamiento y tráfico; lo que puede generar diversos contaminantes, que pueden ser químicos, físicos o microbianos. La presencia de contaminantes microbianos es un riesgo para la salud de los usuarios, sobre todo en pacientes con el sistema inmune comprometido. Costa Rica no cuenta con estudios sobre la presencia de contaminantes microbianos en el cannabis comercializado, por lo que este estudio pretendía establecer si los hay en las muestras incautadas en seis regiones del territorio costarricense y relacionar este hecho con riesgos para la salud de sus consumidores. En dichas muestras se realizaron pruebas de conteo total de bacterias aeróbicas, levaduras y hongos según los procedimientos establecidos por la Farmacopea de los Estados Unidos de América (USP). Para la identificación de microorganismos potencialmente patógenos, se realizaron los procedimientos descritos por la USP, el uso del sistema API y metodología de identificación morfológica de hongos. Los conteos totales de bacterias, de levaduras y hongos superan los límites establecidos por USP en la mayoría de las muestras. Se hallaron cuatro tipos de hongos: Aspergillus sp., Scopulariopsis sp, Fusarium sp y Penicillum sp y cinco especies bacterianas: Staphylococcus aureus, S. xylosus, S. lentus, Enterobacter cloacae y E. sakazakki. La contaminación hallada requiere de un debate para el establecimiento de una verdadera política de regulación, tanto para fin terapéutico como para fines recreativos

Different literature suggests that cannabis use is a major problem for public health. Cannabis, through its illegal nature, reaches its users without complying with any suitable standards of growth, storage, processing and transport, which may generate diverse pollutants, which can be chemical, physical or microbial. The presence of microbial pollutants is a risk for the user’s health, especially in patients whose immune system is compromised. In Costa Rica there are no studies on the presence of microbial pollutants in commercialized cannabis, which is why the aim of this study was to establish the presence of the aforementioned pollutants in cannabis samples seized in six regions of Costa Rican territory and to relate this fact to risks for the health of its consumers. These samples were tested for their total count in aerobic bacteria, yeast and fungi according to procedures established by the Pharmacopoeia of the United States (USP). Identification of potentially pathogenic microorganisms was performed using methods described by USP; using the API system and methodology for morphological identification of fungi. The total counts of bacteria, yeast and fungus exceed limits set by USP on most of the seized samples. Four types of fungus were found: Aspergillus sp, Scopulariopsis sp, Fusarium sp and Penicillium sp, and five bacterial species: Staphylococcus aureus, S. xylosus, S. lentus, Enterobacter cloacae and E. sakazakki. The contamination found requires a debate for establishing a genuine policy of cannabis regulation, both for therapeutic or recreational purposes

Long-term survival of Cryptococcus neoformans and Cryptococcus gattii in stored environmental samples from Colombia / / Supervivencia a largo plazo de las especies Cryptococcus neoformans y Cryptococcus gattii en muestras ambientales almacenadas procedentes de Colombia

Background. Both Cryptococcus neoformans and Cryptococcus gattii have been isolated from a variety of environmental sources in Colombia. Aim. To determine the viability of C. neoformans/C. gattii isolates in stored soil samples, filtrates and bird droppings from which these yeasts were previously recovered. Methods. A total of 964 samples collected between 2003 and 2009, and kept at room temperature were processed. From them, 653 samples were from trees decaying wood, 274 from soil filtrates and 37 from bird droppings. When C. neoformans or C. gattii were recovered, the molecular type of each isolate was established by PCR fingerprinting using the single primer (GTG)5. Results. Among the processed samples, 161 isolates were recovered. From those, 81 (50.3%) corresponded to C. gattii recovered from decaying wood of Eucalyptus spp., Corymbia ficifolia, Terminalia catappa and Ficus spp. trees, and 80 (49.7%) corresponded to C. neoformans recovered from Ficus spp. and eucalyptus trees, as well as from bird droppings. The most prevalent molecular type among the C. gattii and C. neoformans isolates was VGII and VNI, respectively. Conclusions . The re-isolation of C. neoformans/C. gattii from 10-year stored samples suggests that these yeasts are able to keep viable in naturally colonized samples (AU)

Antecedentes. Cryptococcus neoformans y Cryptococcus gattii han sido aislados de diversas fuentes ambientales en Colombia. Objetivos. Determinar la viabilidad de C. neoformans/C. gattii en muestras de suelo, filtrados y excrementos de aves en las que se habían aislado las levaduras previamente. Métodos. Se procesaron 964 muestras recogidas entre los años 2003 y 2009, y almacenadas a temperatura ambiente. De estas, 653 muestras provenían de detritos, 274 de filtrados de suelo y 37 de excrementos de aves. Una vez recuperados C. neoformans y C. gattii, se determinó el patrón molecular mediante la técnica de PCR huella digital con el iniciador (GTG)5. Resultados. Entre las muestras procesadas, se recuperaron 161 aislamientos. De estos, 81 (50,3%) fueron C. gattii recuperados de detritos de Eucalyptus spp., Corymbia ficifolia, Terminalia catappa y Ficus spp., y 80 (49,7%) eran C. neoformans recuperados de Ficus spp. y eucaliptos, así como de excrementos de aves. El patrón molecular más prevalente entre C. gattii y C. neoformans fue VGII y VNI, respectivamente. Conclusiones. El reaislamiento de C. neoformans/C. gattii de muestras almacenadas durante 10 años evidencia que estas levaduras son capaces de mantenerse viables en muestras colonizadas naturalmente (AU)

Efecto bactericida del cobre medido por la supervivencia de Escherichia coliy ABRIM* en superficies de acero inoxidable y aleación de cobre / No disponible

FUNDAMENTO: Determinar el tiempo de supervivencia de una cepa de Escherichia coli (E. coli) y otra de Acinetobacter baumanii imipenem-resistente (ABRIM) sobre un tipo de superficie de tirador de puerta de acero inoxidable y otro de aleación del 63,71% de cobre de uso en hospitales. Los autores se proponen estudiar la eficacia antibacteriana del cobre a nivel de superficies. Método: Se procedió a contaminar un dispositivo de acero inoxidable y otro de aleación de cobre con una cepa de E. coli, y otra de ABRIM aislada en un brote epidémico de nuestro hospital. Posteriormente se tomaron muestras de los dispositivos en varias etapas: con E. coli en los primeros 7 minutos, luego cada 10 minutos en la primera hora y a las 6,12 y 24 horas. Con ABRIM, sólo los primeros 7 minutos. Resultados: El crecimiento de E. coli fue casi nulo en el dispositivo de cobre con sólo un cultivo positivo en el minuto 4, y persistió en el acero inoxidable hasta la hora. En cuanto al ABRIM no creció en la aleación de cobre al 7º minuto, con un decrecimiento de 6 logaritmos, persistiendo en todos los cultivos realizados en el acero inoxidable. Conclusiones: La supervivencia fue significativamente inferior en el ispositivo con aleación de cobre estudiado. Parece confirmarse la alta eficacia antibacteriana en los tiradores de puertas de cobre instalados en boxes de una Unidad de Cuidados Intensivos

INTRODUCTION: To determine the survival time of a strain of Escherichia coli (E. coli) and Imipenem-resistant Acinetobacter baumannii (Abrim) on a surface type door handle stainless steel and other alloy of 63.71% copper use in hospitals. The authors aim to study the antibacterial efficacy of copper surfaces level. MATERIAL AND METHODS: We proceeded to contaminate a stainless steel device and a copper alloy with a strain of E. coli, and a Abrim isolated in an outbreak in our hospital. Later devices were sampled in several stages with E. coli in the first 7 minutes, then every 10 minutes during the first hour and 6, 12 and 24 hours. With Abrim only the first 7 minutes. RESULTS: The growth of E. coli was almost no copper in the device with only a positive culture in minute No. 4, and persisted in stainless steel to time. As for Abrim not grow in the copper alloy to 7th minute, a decrease of 6 logarithms, persisting in the crops grown on stainless steel. DISCUSSION: Survival was significantly lower in the device with copper alloy studied. Seems to confirm the high antibacterial efficacy in copper door handles installed in ICU

Inactivation and recovery of Listeria monocytogenes, Salmonella enterica and Staphylococcus aureus after high hydrostatic pressure treatments up to 900 MPa

High hydrostatic pressure (HP) processing is used in the food industry to enhance the safety and extend the shelf-life of food. Although a drastic decrease in microbial viability is achieved immediately after the application of HP treatments, under favorable conditions the injured bacteria can recover. The present study evaluated the inactivation and recovery of five strains of Listeria monocytogenes, Salmonella enterica and Staphylococcus aureus subjected to pressures of 400, 600, and 900 MPa under stressing and non-stressing conditions in a complex medium. Treatments at 400 and 600 MPa were found to greatly affect the viability of L. monocytogenes and S. enterica, but only a treatment of 5 min at 900 MPa decreased the levels of the three pathogens to below the detection limit (8-9 log units reduction). After HP treatment, not only the baroresistant S. aureus but also several replicates of L. monocytogenes and S. enterica strains recovered during subsequent incubation under favorable conditions. However, when HP was combined with low pH and nitrite but not with NaCl or lactate, the viability of pressurized S. aureus cells progressively decreased. As pathogenic bacteria can recover even after the application of very high pressure levels, the combination of HP with other hurdles for microbial growth, either intrinsically present in the food product or extrinsically applied, may be needed to guarantee the efficacy of technologies aimed at pathogen reduction and shelf-life extension (AU)

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Effect of a heterotrimeric G protein α subunit on conidia germination, stress response, and roquefortine C production in Penicillium roqueforti

Heterotrimeric G protein signaling regulates many processes in fungi, such as development, pathogenicity, and secondary metabolite biosynthesis. For example, the Galpha subunit Pga1 from Penicillium chrysogenum regulates conidiation and secondary metabolite production in this fungus. The dominant activating allele, pga1G42R, encoding a constitutively active Pga1 Galpha subunit, was introduced in Penicillium roqueforti by transformation, resulting in a phenotype characterized by low sporulation and slow growth. In this work, the effect of the constitutively active Pga1G42R Galpha subunit on conidial germination, stress tolerance, and roquefortine C production of P. roqueforti was studied. Pga1G42R triggered germination in the absence of a carbon source, in addition to negatively regulating thermal and osmotic stress tolerance. The presence of the Pga1G42R Galpha subunit also had an important effect on roquefortine C biosynthesis, increasing production and maintaining high levels of the mycotoxin throughout a culture period of 30 days. Together, the results suggest that G protein-mediated signaling participates in the regulation of these three processes in P. roqueforti (AU)

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