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"da Silva, Teresa"
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Organizational innovation in the multinational enterprise
This article engages in a methodological experiment by using historical evidence to challenge a common misperception about internalization theory. The theory has often been criticized for maintaining that it assumes a hierarchically organized MNE based on knowledge flowing from the home country. This is not an accurate description of how global firms operate in recent decades, but this article shows it has never been true historically. Using longitudinal data on individual firms from the nineteenth century onwards, it reveals evidence of how entrepreneurs and firms with multinational activity faced with market imperfections changed the design of their headquarters and their organizational structures.
Journal Article
Red yeasts and carotenoid production: outlining a future for non-conventional yeasts of biotechnological interest
Carotenoids are one of the most common classes of pigments that occur in nature. Due to their biological properties, they are widely used in phytomedicine and in the chemical, pharmaceutical, cosmetic, food and feed industries. Accordingly, their global market is continuously growing, and it is expected to reach about US$1.4 billion in 2018. Carotenoids can be easily produced by chemical synthesis, although their biotechnological production is rapidly becoming an appealing alternative to the chemical route, partly due to consumer concerns against synthetic pigments. Among the yeasts, and apart from the pigmented species Phaffia rhodozyma (and its teleomorph Xanthophyllomyces dendrorhous), a handful of species of the genera Rhodosporidium, Rhodotorula, Sporobolomyces and Sporidiobolus are well known carotenoid producers. These are known as ‘red yeasts’, and their ability to synthesize mixtures of carotenoids from low-cost carbon sources has been broadly studied recently. Here, in agreement with the renewed interest in microbial carotenoids, the recent literature is reviewed regarding the taxonomy of the genera Rhodosporidium, Rhodotorula, Sporobolomyces and Sporidiobolus, the stress factors that influence their carotenogenesis, and the most advanced analytical tools for evaluation of carotenoid production. Moreover, a synopsis of the molecular and “-omic” tools available for elucidation of the metabolic pathways of the microbial carotenoids is reported.
Journal Article
Integrated microbial processes for biofuels and high value-added products: the way to improve the cost effectiveness of biofuel production
The production of microbial biofuels is currently under investigation, as they are alternative sources to fossil fuels, which are diminishing and their use has a negative impact on the environment. However, so far, biofuels derived from microbes are not economically competitive. One way to overcome this bottleneck is the use of microorganisms to transform substrates into biofuels and high value-added products, and simultaneously taking advantage of the various microbial biomass components to produce other products of interest, as an integrated process. In this way, it is possible to maximize the economic value of the whole process, with the desired reduction of the waste streams produced. It is expected that this integrated system makes the biofuel production economically sustainable and competitive in the near future. This review describes the investigation on integrated microbial processes (based on bacteria, yeast, and microalgal cultivations) that have been experimentally developed, highlighting the importance of this approach as a way to optimize microbial biofuel production process.
Journal Article
Pathogenicity assessment of Shiga toxin‐producing Escherichia coli (STEC) and the public health risk posed by contamination of food with STEC
The provisional molecular approach, proposed by EFSA in 2013, for the pathogenicity assessment of Shiga toxin‐producing Escherichia coli (STEC) has been reviewed. Analysis of the confirmed reported human STEC infections in the EU/EEA (2012–2017) demonstrated that isolates positive for any of the reported Shiga toxin (Stx) subtypes (and encoding stx gene subtypes) may be associated with severe illness (defined as bloody diarrhoea (BD), haemolytic uraemic syndrome (HUS) and/or hospitalisation). Although strains positive for stx2a gene showed the highest rates, strains with all other stx subtypes, or combinations thereof, were also associated with at least one human case with a severe clinical outcome. Serogroup cannot be used as a predictor of clinical outcome and the presence of the intimin gene (eae) is not essential for severe illness. These findings are supported by the published literature, a review of which suggested there was no single or combination of virulence markers associated exclusively with severe illness. Based on available evidence, it was concluded that all STEC strains are pathogenic in humans, capable of causing at least diarrhoea and that all STEC subtypes may be associated with severe illness. Source attribution analysis, based on ‘strong evidence’ outbreak data in the EU/EEA (2012–2017), suggests that ‘bovine meat and products thereof’, ‘milk and dairy products’, ‘tap water including well water’ and ‘vegetables, fruit and products thereof’ are the main sources of STEC infections in the EU/EEA, but a ranking between these categories cannot be made as the data are insufficient. Other food commodities are also potentially associated with STEC infections but rank lower. Data gaps are identified, and are primarily caused by the lack of harmonisation in sampling strategies, sampling methods, detection and characterisation methods, data collation and reporting within the EU.
Journal Article
Evaluating low-cost substrates for Crypthecodinium cohnii lipids and DHA production, by flow cytometry
Crypthecodinium cohnii growth was studied on pure carbon sources (glucose, acetate, glycerol) and low-cost complex carbon sources (sugarcane molasses, crude glycerol and vinegar effluent) for lipid and DHA production. Among the pure substrates, glucose induced the highest lipid content (14.75% w/w DCW) and DHA content (7.14 mg g−1 DCW). Among the low-cost substrates, the highest lipid and DHA content were observed for the crude glycerol assay (14.7% w/w DCW and 6.56 mg g−1, respectively). Molasses induced the highest proportion of DHA of total fatty acids (49.58% w/w TFA) among all the substrates studied. Flow cytometric analysis revealed that the vinegar effluent induced the highest proportion of C. cohnii cells with injured membrane (92.8%). These results foresee the possibility of using these low-cost substrates at a larger scale for C. cohnii DHA and biodiesel production, aiming at zero wastes and process costs reduction.
Journal Article
The Role of Heterotrophic Microalgae in Waste Conversion to Biofuels and Bioproducts
In the last few decades, microalgae have attracted attention from the scientific community worldwide, being considered a promising feedstock for renewable energy production, as well as for a wide range of high value-added products such as pigments and poly-unsaturated fatty acids for pharmaceutical, nutraceutical, food, and cosmetic markets. Despite the investments in microalgae biotechnology to date, the major obstacle to its wide commercialization is the high cost of microalgal biomass production and expensive product extraction steps. One way to reduce the microalgae production costs is the use of low-cost feedstock for microalgae production. Some wastes contain organic and inorganic components that may serve as nutrients for algal growth, decreasing the culture media cost and, thus, the overall process costs. Most of the research studies on microalgae waste treatment use autotrophic and mixotrophic microalgae growth. Research on heterotrophic microalgae to treat wastes is still scarce, although this cultivation mode shows several benefits over the others, such as higher organic carbon load tolerance, intracellular products production, and stability in production all year round, regardless of the location and climate. In this review article, the use of heterotrophic microalgae to simultaneously treat wastes and produce high value-added bioproducts and biofuels will be discussed, critically analyzing the most recent research done in this area so far and envisioning the use of this approach to a commercial scale in the near future.
Journal Article
Effects of high intensity interval training on neuro-cardiovascular dynamic changes and mitochondrial dysfunction induced by high-fat diet in rats
Mitochondrial swelling is involved in the pathogenesis of many human diseases associated with oxidative stress including obesity. One of the strategies for prevention of deleterious effects related to obesity and overweight is engaging in regular physical activity, of which high intensity interval training (HIIT) is efficient in promoting biogenesis and improving the function of mitochondria. Therefore, our aims were to investigate the effects of HIIT on metabolic and neuro-cardiovascular dynamic control and mitochondrial swelling induced by high-fat diet (HFD). Twenty-three male Wistar rats (60 - 80g) were divided into 4 subgroups: control (C), HIIT, HFD and HFD+HIIT. The whole experimentation period lasted for 22 weeks and HIIT sessions were performed 5 days a week during the last 4 weeks. At the end of the experiments, fasting glucose and insulin tolerance tests were performed. Cerebral microcirculation was analyzed using cortical intravital microscopy for capillary diameter and functional density. Cardiac function and ergoespirometric parameters were also investigated. Mitochondrial swelling was evaluated on brain and heart extracts. HFD promoted an increase on body adiposity (p<0.001), fasting glucose levels (p<0.001), insulin resistance index (p<0.05), cardiac hypertrophy index (p<0.05) and diastolic blood pressure (p<0.05), along with worsened cardiac function (p<0.05), reduced functional cerebral capillary density (p<0.05) and its diameter (p<0.01), and heart and brain mitochondrial function (p<0.001). HFD did not affect any ergoespirometric parameter. After 4 weeks of training, HIIT was able to improve cardiac hypertrophy index, diastolic blood pressure, cerebral functional capillary density (p<0.01) and heart and brain mitochondrial swelling (p<0.001). In animals subjected to HFD, HIIT ameliorated both cerebral mitochondrial swelling and functional capillary density, but it did not improve cardiovascular function suggesting that the cardiovascular dysfunction elicited by HFD was not due to heart mitochondrial swelling.
Journal Article
The Dark Side of Microalgae Biotechnology: A Heterotrophic Biorefinery Platform Directed to ω-3 Rich Lipid Production
Microbial oils have been considered a renewable feedstock for bioenergy not competing with food crops for arable land, freshwater and biodiverse natural landscapes. Microalgal oils may also have other purposes (niche markets) besides biofuels production such as pharmaceutical, nutraceutical, cosmetic and food industries. The polyunsaturated fatty acids (PUFAs) obtained from oleaginous microalgae show benefits over other PUFAs sources such as fish oils, being odorless, and non-dependent on fish stocks. Heterotrophic microalgae can use low-cost substrates such as organic wastes/residues containing carbon, simultaneously producing PUFAs together with other lipids that can be further converted into bioenergy, for combined heat and power (CHP), or liquid biofuels, to be integrated in the transportation system. This review analyses the different strategies that have been recently used to cultivate and further process heterotrophic microalgae for lipids, with emphasis on omega-3 rich compounds. It also highlights the importance of studying an integrated process approach based on the use of low-cost substrates associated to the microalgal biomass biorefinery, identifying the best sustainability methodology to be applied to the whole integrated system.
Journal Article
Whole genome sequencing and metagenomics for outbreak investigation, source attribution and risk assessment of food‐borne microorganisms
This Opinion considers the application of whole genome sequencing (WGS) and metagenomics for outbreak investigation, source attribution and risk assessment of food‐borne pathogens. WGS offers the highest level of bacterial strain discrimination for food‐borne outbreak investigation and source‐attribution as well as potential for more precise hazard identification, thereby facilitating more targeted risk assessment and risk management. WGS improves linking of sporadic cases associated with different food products and geographical regions to a point source outbreak and can facilitate epidemiological investigations, allowing also the use of previously sequenced genomes. Source attribution may be favoured by improved identification of transmission pathways, through the integration of spatial‐temporal factors and the detection of multidirectional transmission and pathogen–host interactions. Metagenomics has potential, especially in relation to the detection and characterisation of non‐culturable, difficult‐to‐culture or slow‐growing microorganisms, for tracking of hazard‐related genetic determinants and the dynamic evaluation of the composition and functionality of complex microbial communities. A SWOT analysis is provided on the use of WGS and metagenomics for Salmonella and Shigatoxin‐producing Escherichia coli (STEC) serotyping and the identification of antimicrobial resistance determinants in bacteria. Close agreement between phenotypic and WGS‐based genotyping data has been observed. WGS provides additional information on the nature and localisation of antimicrobial resistance determinants and on their dissemination potential by horizontal gene transfer, as well as on genes relating to virulence and biological fitness. Interoperable data will play a major role in the future use of WGS and metagenomic data. Capacity building based on harmonised, quality controlled operational systems within European laboratories and worldwide is essential for the investigation of cross‐border outbreaks and for the development of international standardised risk assessments of food‐borne microorganisms.
Journal Article