Parameter identification of the fermentative production of fructo-oligosaccharides by Aureobasidium pullulans

In this study, a mathematical model for the production of Fructo-oligosaccharides (FOS) by Aureobasidium pullulans is developed. This model contains a relatively large set of unknown parameters, and the identification problem is analyzed using simulation data, as well as experimental data. Batch experiments were not sufficiently informative to uniquely estimate all the unknown parameters, thus, additional experiments have to be achieved in fed-batch mode to supplement the missing information. © 2015 IEEE.funded by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office. The authors thank the financial support from the F.R.S.-FNRS, the Belgium National Fund for the Scientific Research (Research Project 24643.08). C. Nobre thanks the Fundação para a Ciência e Tecnologia for the strategic funding of UID/BIO/04469/2013 uni

Microbial treatment approaches for high-purity fructo-oligosaccharides production

The production of high-purity fructooligosaccharides (FOS), known as prebiotics, by sucrose fermentation using whole microbial cells has been recently explored. At the end of the fermentation process, FOS are present in mixture with small saccharides that are known to have an inhibitory effect of transfructosylating enzymes and to decrease the prebiotic activity of the mixture. This issue can be overcome by reducing the small saccharides present in FOS broth, which can be done using a combined microbial treatment, among others, improving as well the further purification of FOS by Simulated Moving Bed (SMB) chromatography. The main goal of this work was the use of combined microbial treatment approaches to improve FOS production and enhance a high purity FOS content. Aureobasidium pullulans and Saccharomyces cerevisiae were used combined to produce FOS and reduce the small sugars in the culture, respectively. FOS-producing microorganism was used free, immobilized to a non-conventional carrier or encapsulated in Ca-alginate beads, in mixture with the non-oligosaccharides consuming microorganism, free or encapsulated in Ca-alginate beads. A factorial design, considering three different variables, was performed, to select the microbial treatment approach through which increased FOS levels and yields can be obtained. The 38 assays were performed in shaken-flasks and the most suitable one was scaled-up to a 3L bioreactor. The inoculation time of S. cerevisiae showed to be the most relevant variable for FOS production, and the use of immobilized A. pullulans, mixed with encapsulated S. cerevisiae inoculated after 20h of fermentation, was the best combination, with statistical relevance (p<0.01), to obtain enhanced FOS concentration, percentage in the medium, yield and productivity. Results in bioreactor showed a higher fermentation time (20 to 25h) needed to obtain an increased maximal production of FOS (around 132 g.L-1) and yielded 0.70 ± 0.05 g of FOS per gram of initial sucrose. Also, the approach selected improved the percentage of FOS in the medium throughout the fermentation time, providing a pre-purified broth, with lower levels of mono-saccharides for further purification by SMB

Fructo-oligosaccharides separation and purification by simulated moving bed chromatography

The interest on oligosaccharides such as fructo-oligosaccharides (FOS) has strongly increased in recent years for food and pharmaceutical applications, mainly due to their improved technological and functional properties. FOS can be produced by fermentative processes from sucrose, and can be found in mixture with other mono- and di-saccharides and salts, at the end of the process [1]. Unlike FOS, the small saccharides (SGF), namely fructose, glucose and sucrose in the mixture, are known to be cariogenic, caloric and do not present prebiotic activity. The purification of FOS from the other sugars can represent and important increment on the economic value of the final product, which can be further used in diabetic and dietetic food [2]. Different strategies have been developed for this purpose, including microbial treatment [3], ultra and nano-filtration, activated charcoal systems [4], or ion-exchange chromatography [5]. Ion exchange resins may be then used in batch or continuous chromatographic processes, as Simulated Moving Bed (SMB) chromatography, to purify sugars. A screening of different commercial resins was previously done in order to select the most suitable to separate the oligosaccharides [5]. The resin Diaion 535Ca showed an increased recovery yield and purity of FOS (92 and 90%, respectively). In the present work, the separation process was implemented in the SMB, using the selected resin, namely. Equilibrium adsorption isotherms were determined by the Retention Time Method (RTM), for each single sugar. The resin was afterwards packed in eight SMB columns, and tested in the pilot plant. Different operation parameters, including switching time, extra time, internal flow-rates and operating pump flow-rates for feed, raffinate, desorbent, eluent and recycling streams, were tested in the plant. The separation of fructose from glucose and FOS from the SGF was evaluated. Firstly, the separation of a binary sugar mixture of fructose/sucrose (~ 50/50%) was performed followed by the separation of FOS from a fermentative broth. Fructose was purified from 53 to 76% and sucrose from 47 to 77%. FOS and SGF were purified from 50 to 67%. The implementation of UV detectors between the SMB columns allowed following the sugar concentration profile online during the separation process. The accurate selection of the operating parameters was made using the concentration signal obtained and showed to be a crucial step for an improved separation

Air quality impacts of European wildfire emissions in a changing climate

Wildfires are not only a threat to human property and a vital element of many ecosystems, but also an important source of air pollution. In this study, we first review the available evidence for a past or possible future climate-driven increase in wildfire emissions in Europe. We then introduce an ensemble of model simulations with a coupled wildfire–dynamic-ecosystem model, which we combine with published spatial maps of both wildfire and anthropogenic emissions of several major air pollutants to arrive at air pollutant emission projections for several time slices during the 21st century. The results indicate moderate wildfire-driven emission increases until 2050, but there is a possibility of large increases until the last decades of this century at high levels of climate change. We identify southern and north-eastern Europe as potential areas where wildfires may surpass anthropogenic pollution sources during the summer months. Under a scenario of high levels of climate change (Representative Concentration Pathway, RCP, 8.5), emissions from wildfires in central and northern Portugal and possibly southern Italy and along the west coast of the Balkan peninsula are projected to reach levels that could affect annual mean particulate matter concentrations enough to be relevant for meeting WHO air quality targets

An overview of ADSL Homed Nepenthes Honeypots In Western Australia

This paper outlines initial analysis from research in progress into ADSL homed Nepenthes honeypots. One of the Nepenthes honeypots prime objective in this research was the collection of malware for analysis and dissection. A further objective is the analysis of risks that are circulating within ISP networks in Western Australian. What differentiates Nepenthes from many traditional honeypot designs it that is has been engineered from a distributed network philosophy. The program allows distribution of results across a network of sensors and subsequent aggregation of malware statistics readily within a large network environment

The Fire Modeling Intercomparison Project (FireMIP), phase 1: experimental and analytical protocols

The important role of fire in regulating vegetation community composition and contributions to emissions of greenhouse gases and aerosols make it a critical component of dynamic global vegetation models and Earth system models. Over two decades of development, a wide variety of model structures and mechanisms have been designed and incorporated into global fire models, which have been linked to different vegetation models. However, there has not yet been a systematic examination of how these different strategies contribute to model performance. Here we describe the structure of the first phase of the Fire Model Intercomparison Project (FireMIP), which for the first time seeks to systematically compare a number of models. By combining a standardized set of input data and model experiments with a rigorous comparison of model outputs to each other and to observations, we will improve the understanding of what drives vegetation fire, how it can best be simulated, and what new or improved observational data could allow better constraints on model behavior. Here we introduce the fire models used in the first phase of FireMIP, the simulation protocols applied, and the benchmarking system used to evaluate the models

Sensitivity analysis and reduction of a dynamic model of a bioproduction of fructo-oligosaccharides

Starting from a relatively detailed model of a bioprocess producing fructo-oligosaccharides, a set of experimental data collected in batch and fed-batch experiments is exploited to estimate the unknown model parameters. The original model includes the growth of the fungus Aureobasidium pullulans which produces the enzymes responsible for the hydrolysis and transfructosylation reactions, and as such contains 25 kinetic parameters and 16 pseudo-stoichiometric coefficients, which are not uniquely identifiable with the data at hand. The aim of this study is, therefore, to show how sensitivity analysis and quantitative indicators based on the Fisher information matrix can be used to reduce the detailed model to a practically identifiable model. Parametric sensitivity analysis can indeed be used to progressively simplify the model to a representation involving 15 kinetic parameters and 8 pseudo-stoichiometric coefficients. The reduced model provides satisfactory prediction and can be convincingly cross validated.The authors thank the financial support from the F.R.S.-FNRS, the Belgium National Fund for the Scientific Research (Research Project 24643.08). C. Nobre thanks the Fundação para a Ciência e Tecnologia for the strategic funding of UID/BIO/04469 /2013 unit.info:eu-repo/semantics/publishedVersio

California wildfire spread derived using VIIRS satellite observations and an object-based tracking system

Changing wildfire regimes in the western US and other fire-prone regions pose considerable risks to human health and ecosystem function. However, our understanding of wildfire behavior is still limited by a lack of data products that systematically quantify fire spread, behavior and impacts. Here we develop a novel object-based system for tracking the progression of individual fires using 375 m Visible Infrared Imaging Radiometer Suite active fire detections. At each half-daily time step, fire pixels are clustered according to their spatial proximity, and are either appended to an existing active fire object or are assigned to a new object. This automatic system allows us to update the attributes of each fire event, delineate the fire perimeter, and identify the active fire front shortly after satellite data acquisition. Using this system, we mapped the history of California fires during 2012–2020. Our approach and data stream may be useful for calibration and evaluation of fire spread models, estimation of near-real-time wildfire emissions, and as means for prescribing initial conditions in fire forecast models

Deviation of eyes and head in acute cerebral stroke

BACKGROUND: It is a well-known phenomenon that some patients with acute left or right hemisphere stroke show a deviation of the eyes (Prévost's sign) and head to one side. Here we investigated whether both right- and left-sided brain lesions may cause this deviation. Moreover, we studied the relationship between this phenomenon and spatial neglect. In contrast to previous studies, we determined not only the discrete presence or absence of eye deviation with the naked eye through clinical inspection, but actually measured the extent of horizontal eye-in-head and head-on-trunk deviation. In further contrast, measurements were performed early after stroke onset (1.5 days on average). METHODS: Eye-in-head and head-on-trunk positions were measured at the bedside in 33 patients with acute unilateral left or right cerebral stroke consecutively admitted to our stroke unit. RESULTS: Each single patient with spatial neglect and right hemisphere lesion showed a marked deviation of the eyes and the head to the ipsilesional, right side. The average spontaneous gaze position in this group was 46° right, while it was close to the saggital body midline (0°) in the groups with acute left- or right-sided stroke but no spatial neglect as well as in healthy subjects. CONCLUSION: A marked horizontal eye and head deviation observed ~1.5 days post-stroke is not a symptom associated with acute cerebral lesions per se, nor is a general symptom of right hemisphere lesions, but rather is specific for stroke patients with spatial neglect. The evaluation of the patient's horizontal eye and head position thus could serve as a brief and easy way helping to diagnose spatial neglect, in addition to the traditional paper-and-pencil tests