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1.
Monitoring batch fermentations with an electronic tongue 总被引:5,自引:0,他引:5
An electronic tongue comprising 21 potentiometric chemical sensors with pattern recognition tools was used for the rapid off-line monitoring of batch Escherichia coli fermentations. The electronic tongue was capable of monitoring the changes in the media composition as the fermentation progressed, and could correlate this with an increase in biomass. The electronic tongue was also able to monitor the increase in organic acids, especially acetic acid, throughout the fermentation. This technique clearly shows promise as a rapid tool for fermentation monitoring. 相似文献
2.
An on‐line approach of non‐invasive monitoring of the physiological changes in fermentation processes is presented. In yeast batch and bacterial fed‐batch fermentations it is shown that metabolic state changes can be revealed using an electronic nose. The transient responses of the gas sensors to the changes in the composition of the volatiles emitted from the cell cultures during fermentation are used to retrieve a semi‐quantitative representation of the physiological state of the cultures. With the sensor responses of the electronic nose it is shown that physiological variables such as rates of growth, substrate uptake and product formation can be depicted. The non‐invasive method thus seems as a pertinent alternative to conventional bioreactor monitoring methods. 相似文献
3.
Two electronic tongues based on different measurement techniques were applied to the discrimination of four molds and one yeast. Chosen microorganisms were different species of Aspergillus and yeast specie Zygosaccharomyces bailii, which are known as food contaminants. The electronic tongue developed in Link?ping University was based on voltammetry. Four working electrodes made of noble metals were used in a standard three-electrode configuration in this case. The St. Petersburg electronic tongue consisted of 27 potentiometric chemical sensors with enhanced cross-sensitivity. Sensors with chalcogenide glass and plasticized PVC membranes were used. Two sets of samples were measured using both electronic tongues. Firstly, broths were measured in which either one of the molds or the yeast grew until late logarithmic phase or border of the stationary phase. Broths inoculated by either one of molds or the yeast was measured at five different times during microorganism growth. Data were evaluated using principal component analysis (PCA), partial least square regression (PLS) and linear discriminant analysis (LDA). It was found that both measurement techniques could differentiate between fungi species. Merged data from both electronic tongues improved differentiation of the samples in selected cases. 相似文献
4.
Monitoring haemodialysis using electronic nose and chemometrics 总被引:1,自引:0,他引:1
An ever-increasing number of patients have to undergo regular renal dialysis to compensate for acute or chronic renal failure. The adequacy of the treatment has a profound effect on patients’ morbidity and mortality. Therefore, it is necessary to assess the delivered dialysis dose. For the quantification of the dialysis dose, two parameters are most commonly used, namely the Kt/V value (normalised dose of dialysis) and the urea reduction rate, yet the prescribed dialysis dose often differs from the actual delivered dialysis dose. Currently, no interactive process is available to ensure optimal treatment. The aim of this study was to investigate the potential for an “electronic nose” as a novel monitoring tool for haemodialysis. Blood samples were analysed using an electronic nose, comprising an array of 14 conducting polymer sensors, and compared to traditional biochemistry. Principal component analysis and hierarchical cluster analysis were applied to evaluate the data, and demonstrated the ability to distinguish between pre-dialysis blood from post-dialysis blood independent of the method used. It is concluded that the electronic nose is capable of discriminating pre-dialysis from post-dialysis blood and hence, together with an appropriate classification model, suitable for on-line monitoring. 相似文献
5.
Monitoring the aroma production during wine-must fermentation with an electronic nose. 总被引:3,自引:0,他引:3
Carmen Pinheiro Carla M. Rodrigues Thomas Schfer Joo G. Crespo 《Biotechnology and bioengineering》2002,77(6):632-640
This work discusses the feasibility of using the electronic nose for the on-line and real-time monitoring of the production of a complex aroma profile during a bioconversion process. As a case study, the formation of the muscatel aroma during the wine-must fermentation was selected. During wine-must fermentation, aroma compounds responsible for the organoleptic character are produced in the ppm range, while simultaneously one of the main metabolic products, ethanol, is produced in much higher quantities (up to 10% wt). Because the sensors of the electronic nose array are cross-selective to different volatile compounds, it was investigated in detail how far the electronic nose was able to evaluate the aroma profile along the fermentation. This article discusses and evaluates subsequently the integration of a membrane separation process-organophilic pervaporation-for selectively enriching aroma compounds relative to ethanol, to improve sample discrimination. 相似文献
6.
A rapid and effective identification of fungal species is essential for numerous applications, and electronic nose systems are being proposed as suitable alternatives to currently available fungi identification techniques. Hence, the present review aims to unveil all published information concerning fungi identification by electronic nose systems.A systematic review of the literature was conducted according to the PRISMA guidelines. A total of 16 articles met the inclusion criteria and were included in the analysis. The results of the reviewed studies demonstrated that effective detection of fungi was possible through sensor-based electronic nose systems, which may actually function as a mycotoxin screening tool for several applications.The obtained results suggest that the sensor-based electronic nose systems may not only screen different fungi genera, but also identify the associated species. This technology has already been experimented in several fields, from food industry to clinical practice.By summarizing these results, the present review may accelerate the standardization of electronic noses in fungi detection and discrimination, allowing a faster and more efficient screening of samples. 相似文献
7.
Food intake is the primary method for obtaining energy and component materials in the human being. Humans evaluate the quality of food by combining various facets of information, such as an item of food's appearance, smell, taste, and texture in the mouth. Recently, bioelectronic noses and tongues have been reported that use human olfactory and taste receptors as primary recognition elements, and nanoelectronics as secondary signal transducers. Bioelectronic sensors that mimic human olfaction and gustation have sensitively and selectively detected odor and taste molecules from various food samples, and have been applied to food quality assessment. The portable and multiplexed bioelectronic nose and tongue are expected to be used as next-generation analytical tools for rapid on-site monitoring of food quality. In this review, we summarize recent progress in the bioelectronic nose and tongue using olfactory and taste receptors, and discuss the potential applications and future perspectives in the food industry. 相似文献
8.
Significant effort has been made in the development of an artificial nose system for various applications. Advances in sensor technology have facilitated the development of high-performance electronic and bioelectronic noses. Numerous articles describe the advantages of artificial nose systems for biomedical applications. Recent advances in the development of electronic and bioelectronic noses and their biomedical applications are reviewed in this article. 相似文献
9.
Background
Electronic noses, E-Noses, are instruments designed to reproduce the performance of animal noses or antennae but generally they cannot match the discriminating power of the biological original and have, therefore, been of limited utility. The manner in which odorant space is sampled is a critical factor in the performance of all noses but so far it has been described in detail only for the fly antenna.Methodology
Here we describe how a set of metal oxide (MOx) E-Nose sensors, which is the most commonly used type, samples odorant space and compare it with what is known about fly odorant receptors (ORs).Principal Findings
Compared with a fly''s odorant receptors, MOx sensors from an electronic nose are on average more narrowly tuned but much more highly correlated with each other. A set of insect ORs can therefore sample broader regions of odorant space independently and redundantly than an equivalent number of MOx sensors. The comparison also highlights some important questions about the molecular nature of fly ORs.Conclusions
The comparative approach generates practical learnings that may be taken up by solid-state physicists or engineers in designing new solid-state electronic nose sensors. It also potentially deepens our understanding of the performance of the biological system. 相似文献10.
L. J. W. van den Wollenberg 《Biodiversity and Conservation》2011,20(2):277-286
For many botanic gardens worldwide, seed lists have provided a cost-effective means to replace plant losses in their collections
for many decades, if not centuries. In seed lists, seeds are offered on the basis of what each garden can manage to collect
and considers ‘of interest’ to other botanic gardens, some offering relatively few, while others offer many, or only wild
collected seeds. Seed lists have always been printed on paper. With the use of printed seed lists, the amount of information
per accession has always been quite limited to keep printing costs low. Over the past few years, electronic seed lists have
been rapidly replacing printed seed lists. Since distribution is electronic, there is no longer a direct link between the
amount of information provided and the cost per seed list sent out. This now offers new opportunities to share information
that is linked to the plant material that botanic gardens exchange. Information is not limited to text, as images can also
be included. This situation is beneficial if seed-raised plants are to be used for in situ conservation. Electronic seed lists
have other advantages, but there are also some disadvantages. e.g., electronic information offered via websites is quite ephemeral
in nature. Some suggestions are made to overcome the several drawbacks. 相似文献
11.
Rapid developments in sensor technology have facilitated the production of devices--known as electronic noses--that can detect and discriminate the production profiles of volatile compounds from microbial infections in situ. Such qualitative and semi-quantitative approaches could have a significant role in the early diagnosis and detection of microbial diseases. Using artificial intelligence and web-based knowledge systems, electronic noses might also have a valuable role in monitoring disease epidemiology. 相似文献
12.
Pullulan: biosynthesis,production, and applications 总被引:1,自引:0,他引:1
Pullulan is a linear glucosic polysaccharide produced by the polymorphic fungus Aureobasidium pullulans, which has long been applied for various applications from food additives to environmental remediation agents. This review
article presents an overview of pullulan’s chemistry, biosynthesis, applications, state-of-the-art advances in the enhancement
of pullulan production through the investigations of enzyme regulations, molecular properties, cultivation parameters, and
bioreactor design. The enzyme regulations are intended to illustrate the influences of metabolic pathway on pullulan production
and its structural composition. Molecular properties, such as molecular weight distribution and pure pullulan content, of
pullulan are crucial for pullulan applications and vary with different fermentation parameters. Studies on the effects of
environmental parameters and new bioreactor design for enhancing pullulan production are getting attention. Finally, the potential
applications of pullulan through chemical modification as a novel biologically active derivative are also discussed. 相似文献
13.
Francesca Dini Rosamaria Capuano Tillan Strand Anna-Christina Ek Margareta Lindgren Roberto Paolesse Corrado Di Natale Ingemar Lundstr?m 《PloS one》2013,8(7)
Since almost every fifth patient treated in hospital care develops pressure ulcers, early identification of risk is important. A non-invasive method for the elucidation of endogenous biomarkers related to pressure ulcers could be an excellent tool for this purpose. We therefore found it of interest to determine if there is a difference in the emissions of volatiles from compressed and uncompressed tissue. The ultimate goal is to find a non-invasive method to obtain an early warning for the risk of developing pressure ulcers for bed-ridden persons. Chemical analysis of the emissions, collected in compresses, was made with gas-chromatography – mass spectrometry and with a chemical sensor array, the so called electronic nose. It was found that the emissions from healthy and hospitalized persons differed significantly irrespective of the site. Within each group there was a clear difference between the compressed and uncompressed site. Peaks that could be certainly deemed as markers of the compression were, however, not identified. Nonetheless, different compounds connected to the application of local mechanical pressure were found. The results obtained with GC-MS reveal the complexity of VOC composition, thus an array of non-selective chemical sensors seems to be a suitable choice for the analysis of skin emission from compressed tissues; it may represent a practical instrument for bed side diagnostics. Results show that the adopted electronic noses are likely sensitive to the total amount of the emission rather than to its composition. The development of a gas sensor-based device requires then the design of sensor receptors adequate to detect the VOCs bouquet typical of pressure. This preliminary experiment evidences the necessity of studies where each given person is followed for a long time in a ward in order to detect the insurgence of specific VOCs pattern changes signalling the occurrence of ulcers. 相似文献
14.
Summary. No influence of isotopic substitution in deuterium-substituted tryptophan on the florescence excitation spectrum has previously
been found out. Here, the isotopic effects of electronic excitation of deuterium-substituted tryptophan were experimentally
and theoretically analyzed for first time. It was shown a short-wave shift of the UV-absorption maximum at 220 nm corresponding
to the 360 cal/mol and short-wave shift for fluorescence spectrum corresponding to the 210 cal/mol. To account for this effect,
the quantum chemical calculations of the geometric and electron structure, frequencies of normal vibrations and transition
energies have been performed. The isotopic effects originate from the zero-point energies of ground and excited states. It
was found that isotopic shifts depend on the position of isotope in the molecule and kind of transition. So, it can be utilized
in the analysis of proteins structure and complexation. 相似文献
15.
John F. Oates 《International journal of primatology》1984,5(1):51-61
Some new field observations on West African pottos are presented and compared with previously published information on substrate
use and diet. This evidence suggests that the predominant means by which pottos find food is by carefully searching branches
in the forest canopy with their noses and that gums and slow-moving invertebrates found on branch surfaces are major components
of their diet. When fruits are scarce, gums may be the potto’s chief source of energy. It is argued that the potto’s deliberate
locomotion and some of its anatomical peculiarities are related primarily to this diet and foraging behavior, rather than
to concealment from predators or the capture of birds, two factors previously suggested to have been important in the evolution
of the potto’s locomotor technique. The potto’s niche is compared to that of other lorisid primates and is found to resemble
closely that of Galago crassicaudatusin several respects. 相似文献
16.
Jennie Brandgård Ingvar Sundh Åke Nordberg Anna Schnürer Carl-Fredrik Mandenius Berit Mathisen 《Biotechnology letters》2001,23(4):241-248
Growth of the methanogenic archaea, Methanobacterium formicicum, in pure culture was monitored by analysing samples from the gas phase with an array of chemical gas sensors (an `electronic nose'). Analyses of the methane and protein formation rates were used as independent parameters of growth, and the data obtained from the electronic nose were evaluated using principal component analysis (PCA). We found that different growth phases can be distinguished with the electronic nose followed by PCA evaluation. The fast response of the sensors in combination with the high correlations with other parameters measuring growth show that the electronic nose can be a useful tool to rapidly determine methanogenic growth. 相似文献
17.
Helena Morais Cristina Ramos Esther Forgcs Tibor Cserhti Jos Oliviera 《Journal of biochemical and biophysical methods》2002,50(2-3):99-109
The activity of manganese-dependent and manganese-independent peroxidases produced by Pleurotus ostreatus in culture media composed of agro-residues was measured by visible spectrophotometry. The overall enzyme activity and its selectivity were separated by using spectral mapping technique followed by nonlinear mapping. The relationships between the parameters of enzyme production and the composition of culture media and fermentation time was assessed by stepwise regression analysis. Calculations proved that the addition of extract of straw to the culture media significantly decreased the overall production of both enzymes, whereas the selectivity of enzyme production was influenced by amount of potato extract and the concentration of total sugar in the culture media. Enzyme activity depended quadratically on the fermentation time. 相似文献
18.
The concept of coevolution was first developed by Darwin, who used it to explain how pollinators and food-rewarding flowers
involved in specialized mutualisms could, over time, develop long tongues and deep tubes, respectively. He famously predicted
that Angraecum sesquipedale, a long-spurred Malagasy orchid, must be pollinated by a hawkmoth with an exceptionally long tongue. Darwin’s idea of a coevolutionary
“race” was championed by contemporary naturalists, including Alfred Wallace, and a hawkmoth fitting the expected tongue-length
profile was eventually discovered in Madagascar during the early twentieth century. However, strong empirical support for
the mechanism behind Darwin’s coevolutionary model has been forthcoming only in the past two decades. It is now established
that selection often strongly favors plants with floral tubes that exceed the length of their pollinator’s tongues. There
is also evidence that pollinators gain an energetic benefit from having tongues that enable them to consume most or all of
the nectar in deep tubular flowers. Alternative explanations for the evolution of long pollinator tongues, such as evasion
of predators that use flowers as ambush sites, are considered much less compelling and lack quantitative support. Another
important advance in coevolution research has been the development of approaches that explicitly predict a geographical mosaic
of coevolution. The expectation that coevolution can lead to geographical diversification and trait covariation among strongly
interacting organisms is strongly supported by studies of long-proboscid fly and oil-bee pollination systems in South Africa.
Macro- and microevolutionary studies of pollination systems suggest that coevolution can operate alongside other one-sided
evolutionary processes, such as shifts, in shaping plant and pollinator traits. 相似文献
19.
Sesquiterpenes, one of the most important classes of biogenic volatile organic compounds, are potentially significant precursors
to secondary organic aerosols (SOAs) in nature. The electronic structure of sesquiterpenes and their reactivity in the ozonolysis
reaction were investigated by density functional theory. Results from the CIS calculations combined with an analysis of transition
intensities show that the first peaks in the ultraviolet (UV) spectra for saturated and unsaturated isomers are σ–σ* and π–π*
transitions, respectively. The UV absorption wavelength and absorbency are dictated by the electronic structures of these
compounds. An increase in the number of double bonds and formation of a conjugated system expand the range of absorption in
the UV region. An isomer with an endocyclic C = C bond presents weaker UV transition intensity than its corresponding exocyclic
isomer. Results from conceptual DFT chemical reactivity indices of isomers suggest that no quantitative linear relationships
between the structural changes and their reactivity, such as different degrees of unsaturated C = C double bonds, or the number
of substituents attached to the C = C bond were discovered. In the ozonolysis reaction of sesquiterpenes, isomers with larger
steric hindrance of substituents or endocyclic C = C bond possess higher chemical reactivity compared to isomers with smaller
steric hindrandce or with an exocyclic C = C bond. These results are imperative to a better understanding of SOAs production
mechanisms in the troposphere. 相似文献
20.
Summary The applicability of clinical multilayer test strips based on dry reagent chemistries for the quantitative analysis of fermentation media constituents was evaluated. For glucose and amylase determinations a significant correlation to conventional wet chemical methods was obtained. Bacterial biomass in the range of 0.5–5 g/l has no interfering effect. It is a rapid and cost-effective method for fermentation process monitoring and control. 相似文献