Assimilation Of Sources Research Articles

Production of Invertases by Anamorphic (<i>Aspergillus nidulans</i>) and Teleomorphic (<i>Emericela nidulans</i>) Fungi under Submerged Fermentation Using Rye Flour as Carbon Source

The production of invertases by anamorph (A. nidulans) and teleomorph (E. nidulans) was investigated. The best level of extracellular enzymatic production for anomorph was obtained in Khanna medium containing sucrose as carbon source, whereas for teleomorph the best production was archived using M5 medium containing inulin as carbon source. Despite this, rye flour was selected as carbon source. The extracellular enzyme production was higher for teleomorph than that observed for anomorph for all carbon sources used. The enzyme production was inhibited by the addition of fructose and glucose in the medium containing rye flour as carbon source. The best conditions to recover the higher enzymatic activity were temperature of 54℃ - 62℃ and pH of 4.8 5.6 for both enzymes determined by experimental design (CCRD). The stability of the temperatures at 40℃ and 50℃were similar for both enzymes. The invertases from the anomorph and teleomorph were activated by Mn2+, but the response of each one towards the presence of this cation was different with best activation observed for the anomorph enzyme (+80%). The extracellular enzymes were able to hydrolyze inulin, sucrose and raffinose. However, the affinity was higher for sucrose than inulin. In conclusion, the carbon source assimilation and the invertase production, as well as the enzymes properties, were different for the anomorph and teleomorph mycelia.

The improvement of riboflavin production in Ashbya gossypii via disparity mutagenesis and DNA microarray analysis

We generated a high riboflavin-producing mutant strain of Ashbya gossypii by disparity mutagenesis using mutation of DNA polymerase δ in the lagging strand, resulting in loss of DNA repair function by the polymerase. Among 1,353 colonies generated in the first screen, 26 mutants produced more than 3 g/L of riboflavin. By the second screen and single-colony isolation, nine strains that produced more than 5.2 g/L of riboflavin were selected as high riboflavin-producing strains. These mutants were resistant to oxalic acid and hydrogen peroxide as antimetabolites. One strain (W122032) produced 13.7 g/L of riboflavin in a 3-L fermentor using an optimized medium. This represents a ninefold improvement on the production of the wild-type strain. Proteomic analysis revealed that ADE1, RIB1, and RIB5 proteins were expressed at twofold higher levels in this strain than in the wild type. DNA microarray analysis showed that purine and riboflavin biosynthetic pathways were upregulated, while pathways related to carbon source assimilation, energy generation, and glycolysis were downregulated. Genes in the riboflavin biosynthetic pathway were significantly overexpressed during both riboflavin production and stationary phases, for example, RIB1 and RIB3 were expressed at greater than sixfold higher levels in this strain compared to the wild type. These results indicate that the improved riboflavin production in this strain is related to a shift in carbon flux from β-oxidation to the riboflavin biosynthetic pathway.

The mineralogy of late stage lunar volcanism as observed by the Moon Mineralogy Mapper on Chandrayaan-1

[1] The last major phases of lunar volcanism produced spectrally unique high-titanium basalts on the western nearside of the Moon. The Moon Mineralogy Mapper (M3) on Chandrayaan-1 has provided detailed measurements of these basalts at spatial and spectral resolutions necessary for mineralogical interpretation and mapping of distinct compositional units. The M3 imaging spectrometer acquired data in 85 spectral bands from ∼430 to 3000 nm at 140 to 280 m/pixel in its global mapping mode during the first half of 2009. Reflectance data of several key sites in the western maria were also acquired at higher spatial and spectral resolutions using M3's target mode, prior to the end of the Chandrayaan-1 mission. These new observations confirm that both fresh craters and mare soils within the western high-Ti basalts display strong 1 μm and weak 2 μm absorptions consistent with olivine-rich basaltic compositions. The inferred abundance of olivine is observed to correlate with stratigraphic sequence across different mare regions and absolute ages. The apparent stratigraphic evolution and Fe-rich compositions of these basalts as a whole suggest an origin from evolved residual melts rather than through the assimilation of more primitive olivine-rich sources. Mare deposits with spectral properties similar to these late stage high-Ti basalts appear to be very limited outside the Procellarum-Imbrium region of the Moon and, where present, appear to occur as small areas of late stage regional volcanism. Detailed analyses of these new data and supporting measurements are in progress to provide further constraints on the mineralogy, olivine abundance, and compositions of these final products of lunar volcanism and the nature and evolution of their source regions.

Mastitis bovina por Prototheca zopfii: primer aislamiento en Chile

SUMMARY The genus Prototheca includes unicellular achlorophyllous microalgae widely distributed in the environment, some of which could be pathogenic for human and animals. However, there is no previous report regarding these pathogenic microalgae causing infections in man or animals in Chile. Twohundred milk samples collected from 150 dairy cows with clinical mastitis were inoculated onto PIM modified medium. Prototheca spp was isolated on two consecutive occasions from one cow sampled two months apart. Direct microscopic examination of wet smears made from milk samples revealed typical Prototheca cells. Biochemical tests based on carbon source assimilation identified the organism as Prototheca zopfii. This finding represents the first isolation of this environmental alga from bovine mastitis in Chile. This could be of great importance for mastitis control programs in dairy herds as Prototheca is an uncommon mastitis pathogen that does not respond to conventional antibiotic treatment.

Atrazine biodegradation in the lab and in the field: enzymatic activities and gene regulation

SummaryAtrazine is an herbicide of the s‐triazine family that is used primarily as a nitrogen source by degrading microorganisms. While many catabolic pathways for xenobiotics are subjected to catabolic repression by preferential carbon sources, atrazine utilization is repressed in the presence of preferential nitrogen sources. This phenomenon appears to restrict atrazine elimination in nitrogen‐fertilized soils by indigenous organisms or in bioaugmentation approaches. The mechanisms of nitrogen control have been investigated in the model strain Pseudomonas sp. ADP. Expression of atzA, atzB ad atzC, involved in the conversion of atrazine in cyanuric acid, is constitutive. The atzDEF operon, encoding the enzymes responsible for cyanuric acid mineralization, is a target for general nitrogen control. Regulation of atzDEF involves a complex interplay between the global regulatory elements of general nitrogen control and the pathway‐specific LysR‐type regulator AtzR. In addition, indirect evidence suggests that atrazine transport may also be a target for nitrogen regulation in this strain. The knowledge about regulatory mechanisms may allow the design of rational bioremediation strategies such as biostimulation using carbon sources or the use of mutant strains impaired in the assimilation of nitrogen sources for bioaugmentation.

Identification and Characterization of a Psychrophilic Yeast Strain Newly Isolated from the Fermentative Starter (Loog-pang) of a Traditional Drink in Thailand

One psychrophilic yeast strain, that grew well in a cold environment such as in a refrigerator, was isolated from the yeast starter (Loog-pang) of a traditional alcohol drink in Thailand. The isolated strain OPU-FC11 was identified as Cryptococcus diffluens by the assay for 26S ribosomal DNA and the test for carbon source assimilation. OPU-FC11 showed a good amount of growth at 4 degrees 0 at which a commonly found yeast like Saccharomyces cerevisiae did not grow, and produced cold-adapted enzymes that showed a relatively high activity at lower temperatures.

THE ABILITY OF THE PROTOTHECA ZOPFII SPECIES FOR “GAS OIL” AND OTHERS HYDROCARBONS UTILIZATION

P. zopfii (Chlorophyta) is able to degrade “gas oil”, recorded for the first time in contaminated waters in Argentina. P. zopfii (Trebouxiophyceae, Chlorophyta) is a coccoid colorless algae that we isolated from soil, plants, river, contaminated waters, etc. Morphological and physiological (carbon sources assimilation) studies were carried out for its correct identification. The ability of P. zopfii for “gas oil” utilization was evaluated by its growth in culture media containing “gas oil” up to 10%, as unique carbon and energy source.

A Genomic View on Nitrogen Metabolism and Nitrogen Control in Mycobacteria

Knowledge about nitrogen metabolism and control in the genus Mycobacterium is sparse, especially compared to the state of knowledge in related actinomycetes like Streptomyces coelicolor or the close relative Corynebacterium glutamicum. Therefore, we screened the published genome sequences of Mycobacterium smegmatis, Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium avium ssp. paratuberculosis and Mycobacterium leprae for genes encoding proteins for uptake of nitrogen sources, nitrogen assimilation and nitrogen control systems, resulting in a detailed comparative genomic analysis of nitrogen metabolism-related genes for all completely sequenced members of the genus. Transporters for ammonium, nitrate, and urea could be identified, as well as enzymes crucial for assimilation of these nitrogen sources, i.e. glutamine synthetase, glutamate dehydrogenase, glutamate synthase, nitrate reductase, nitrite reductase, and urease proteins. A reduction of genes encoding proteins for nitrogen transport and metabolism was observed for the pathogenic mycobacteria, especially for M. leprae. Signal transduction components identified for the different species include adenylyl- and uridylyltransferase and a P_II-type signal transduction protein. Exclusively for M. smegmatis, two homologs of putative nitrogen regulatory proteins were found, namely GlnR and AmtR, while in other mycobacteria, AmtR was absent and GlnR seems to be the nitrogen transcription regulator protein.

Inactivation of the general transcription factor TnrA in Bacillus subtilis by proteolysis

Under conditions of nitrogen limitation, the general transcription factor TnrA in Bacillus subtilis activates the expression of genes involved in assimilation of various nitrogen sources. Previously, TnrA activity has been shown to be controlled by protein-protein interaction with glutamine synthetase, the key enzyme of ammonia assimilation. Furthermore, depending on ATP and 2-oxoglutarate levels, TnrA can bind to the GlnK-AmtB complex. Here, we report that upon transfer of nitrate-grown cells to combined nitrogen-depleted medium, TnrA is rapidly eliminated from the cells by proteolysis. As long as TnrA is membrane-bound through GlnK-AmtB interaction it seems to be protected from degradation. Upon removal of nitrogen sources, the localization of TnrA becomes cytosolic and degradation occurs. The proteolytic activity against TnrA was detected in the cytosolic fraction but not in the membrane, and its presence does not depend on the nitrogen regime of cell growth. The proteolytic degradation of TnrA as a response to complete nitrogen starvation might represent a novel mechanism of TnrA control in B. subtilis.

Proteomic investigation of the adaptation of Lactococcus lactis to the mouse digestive tract

Lactic acid bacteria are used on an industrial scale for the manufacturing of dairy products. It is now intended to develop novel applications of lactic acid bacteria that could be used as living vehicles for the targeting of antigens or therapeutics to the digestive mucosa. The aim of this study was to analyze the adaptations of Lactococcus lactis, a model lactic acid bacteria to the digestive tract and to identify functions required for colonization of the intestine. For this purpose, we combined gnotobiology with proteomics: axenic mice were colonized with a dairy L. lactis strain and the bacterial proteome was examined by 2-DE. As compared to cultures in broth, the proteome profile of bacteria grown in the intestine indicates the activation of metabolic pathways involved in various carbon sources assimilation and suggests the adoption of a mixed acids fermentative metabolism. We identified the product of the ywcC gene as essential for the colonization of the digestive tract and demonstrated that the corresponding gene product (YwcC) possesses a phosphogluconolactonase activity, suggesting an important role of the pentose phosphate pathway for the development of L. lactis in the digestive environment.

Applying machine learning methods to avalanche forecasting

AbstractAvalanche forecasting is a complex process involving the assimilation of multiple data sources to make predictions over varying spatial and temporal resolutions. Numerically assisted forecasting often uses nearest-neighbour methods (NN), which are known to have limitations when dealing with high-dimensional data. We apply support vector machines (SVMs) to a dataset from Lochaber, Scotland, UK, to assess their applicability in avalanche forecasting. SVMs belong to a family of theoretically based techniques from machine learning and are designed to deal with high-dimensional data. Initial experiments showed that SVMs gave results that were comparable with NN for categorical and probabilistic forecasts. Experiments utilizing the ability of SVMs to deal with high dimensionality in producing a spatial forecast show promise, but require further work.

Isolation and characterization of a Mastigocladus species capable of growth, N(2)-fixation and N-assimilation at elevated temperature.

A Mastigocladus species was isolated from the hot spring of Jakrem (Meghalaya) India. Uptake and utilization of nitrate, nitrite, ammonium and amino acids (glutamine, asparagine, arginine, alanine) were studied in this cyanobacterium grown at different temperatures (25°C, 45°C). There was 2-3 fold increase in the heterocyst formation and nitrogenase activity in N-free medium at higher temperature (45°C). Growth and uptake and assimilation of various nitrogen sources were also 2-3 fold higher at 45°C indicating that it is a thermophile. The extent of induction and repression of nitrate uptake by NO(3) (-) and NH(4) (+), respectively, differed from that of nitrite. It appeared that Mastigocladus had two independent nitrate/nitrite transport systems. Nitrate reductase and nitrite reductase activitiy was not NO(3) (-)-inducible and ammonium or amino acids caused only partial repression. Presence of various amino acids in the media partially repressed glutamine synthetase activity. Ammonium (methylammonium) and amino acid uptake showed a biphasic pattern, was energy-dependent and the induction of uptake required de novo protein synthesis. Ammonium transport was substrate (NH(4) (+))-repressible, while the amino acid uptake was substrate inducible. When grown at 25°C, the cyanobacterium formed maximum akinetes that remained viable upto 5 years under dry conditions.

A Land Data Assimilation System for Soil Moisture and Temperature: An Information Content Study

Abstract A Canadian Land Data Assimilation System (CaLDAS) for the analysis of land surface prognostic variables is designed and implemented at the Meteorological Service of Canada for the initialization of numerical weather prediction and climate models. The assimilation of different data sources for the production of daily soil moisture and temperature analyses is investigated in a set of observing system simulation experiments over North America. A simplified variational technique is adapted to accommodate different observation types at their appropriate time in a 24-h time window. The screen-level observations of temperature and relative humidity, from conventional synoptic surface observations (SYNOP)/aviation routine weather report (METAR)/surface aviation observation (SA) reports, are considered together with presently available satellite observations provided by the Aqua satellite (microwave C-band), Geostationary Operational Environmental Satellite (GOES) [infrared (IR)], and observations available in the future by the Soil Moisture and Ocean Salinity (SMOS) satellite mission (microwave L-band). The aim of these experiments is to assess the information content brought by each observation type in the land surface analysis. The observation systems are simulated according to their spatial coverage, temporal availability, and nominal or expected errors. The results show that the observable with the largest dynamical response to perturbations of the control variable carries the greatest information content into the analysis. The observational error and the observation frequency counterbalance this feature in the analysis. If one considers a single observation both for soil moisture and soil temperature analysis, then satellite measurements (L-band, C-band, and IR in decreasing order of importance) are the primary source of information. When observation availability is considered and the highest temporal frequency of screen-level observations is used (1 h), a large amount of information is extracted from SYNOP-like reports. The screen-level observations are shown to provide valuable soil moisture information mainly during the daytime, while during nighttime these observations (and particularly screen-level temperature) are mostly useful for the soil temperature analysis. The results are presented with perspectives for future operational developments and preliminary assimilation experiments are performed with hourly screen-level observations.

Transcriptome Analysis of Pseudomonas putida in Response to Nitrogen Availability

This work describes a regulatory network of Pseudomonas putida controlled in response to nitrogen availability. We define NtrC as the master nitrogen regulator and suggest that it not only activates pathways for the assimilation of alternative nitrogen sources but also represses carbon catabolism under nitrogen-limited conditions, possibly to prevent excessive carbon and energy flow in the cell.

Lack of Control of Nitrite Assimilation by Ammonium in an Oceanic Picocyanobacterium, Synechococcus sp. Strain WH 8103

In cyanobacteria, the transcriptional activator NtcA is involved in global nitrogen control and, in the absence of ammonium, regulates the expression of genes involved in the assimilation of alternative nitrogen sources. The oceanic picocyanobacterium Synechococcus sp. strain WH 8103 harbors a copy of ntcA, but in the present study, we show that unlike other marine cyanobacteria that have been investigated, this strain is capable of coassimilating nitrite when grown in the presence of ammonium. Transcript levels for the genes encoding the nitrate/nitrite-bispecific permease NrtP and nitrate reductase (NarB) were substantially down-regulated by ammonium, whereas the abundances of nitrite reductase (NirA) transcripts were similar in nitrite- and ammonium-grown cells. The growth of Synechococcus sp. strain WH 8103 in medium containing both ammonium and nitrite resulted in only minor changes in the expression profile in comparison to that of nitrite-grown cells with the exception that the gene encoding the high-affinity ammonium transporter Amt1 was down-regulated to the levels seen in ammonium-grown cells. Whereas the expression of nrtP, narB, and amt1 appears to be NtcA dependent in this marine cyanobacterium, the transcription and expression of nirA appear not to be. The ability to coassimilate nitrite and reduced-nitrogen sources like ammonium may be an adaptive trait that enables oceanic strains like Synechococcus sp. strain WH 8103 to exploit the low nitrite concentrations found in oceanic surface waters that are not available to their principal and more numerous competitor, Prochlorococcus.

Woman with a Fan: Paul Gauguin's Heavenly Vairaumati—a Parable of Immortality

Woman with a Fan (1902) is the culmination of Gauguin's representations of the Tahitian goddess of regeneration. His depiction of Vairaumati frames his intertwined aesthetic and spiritual beliefs. Her fan signals her immortal status and, through its blue, white, and red ornament, Gauguin's revolutionary call to “the right to dare all.” This justifies his assimilation of multiple sources, which, through a process he called transposition, took on new life. Thus, the regeneration epitomized by Vairaumati is implemented in the pictorial dynamic through the mutation of the sources that constitute her identity, tying the permutations of art to the soul's immortality.

Growth Characteristics of Fusants by Protoplast Fusion between the Thermotolerant Yeast, Kluyveromyces marxianus, and the Starch-assimilating Yeast, Schwanniomyces occidentalis

Intergeneric fusants were obtained by protoplast fusion between the thermotolerant yeast, Kluyveromyces marxianus, and the starch-assimilating yeast, Schwanniomyces occidentalis. Two thermotolerant fusants growing at 40 degrees C were screened on the medium containing soluble starch. These fusants showed weak growth in a soluble starch medium and the production of a little amylase. The carbon source assimilation and the chromosome composition of the fusants were similar to those of the K. marxianus parent. However, a chromosomal difference from K. marxianus was recognized in the fusants. These results show the possibility that the fusants are amylase-producing strains rearranged from K. marxianus.

Phenotypic methods and commercial systems for the discrimination between C. albicans and C. dubliniensis

Candida dubliniensis is a recently described Candida species associated with oral candidosis that exhibits a high degree of phenotypic similarity to Candida albicans. However, these species show differences in levels of resistance to antimycotic agents and ability to cause infections. Therefore, accurate clinical identification of C. dubliniensis and C. albicans species is important in order to treat oral candidal infections. Phenotypic identification methods are easy-to-use procedures for routine discrimination of oral isolates in the clinical microbiology laboratory. However, C. dubliniensis may be so far underreported in clinical samples because most currently used identification methods fail to recognize this yeast. Phenotypic methods depend on growth temperature, carbon source assimilation, chlamydospore and hyphal growth production, positive or negative growth on special media and intracellular enzyme production, among others. In this review, some phenotypic methods are presented with a special emphasis on the discrimination of C. dubliniensis and C. albicans.

New drug prescribing by hospital doctors: The nature and meaning of knowledge

In the UK the high cost of new drugs is partly accountable for the growth in spending on prescription drugs. Most prescribing takes place in general practice and the influence of secondary care prescribing on primary care prescribing is well recognized; yet the factors that influence hospital prescribing have been little researched. Drawing on accounts of actual prescribing events from hospital doctors from a range of specialities, we investigated the processes by which new drugs come into practice, from hospital doctors’ awareness of new drugs to the assimilation and interpretation of evidential sources. The determinants of new drug prescribing were interconnected within four forms of knowledge: scientific knowledge, social knowledge, patient knowledge and experiential knowledge. Furthermore, the nature of knowledge could only be understood within its situated context. The revelation of multiple and contingent forms of knowledge highlights the problematic nature of knowledge construction within the approaches of evidence-based medicine.

Burkholderia tropica sp. nov., a novel nitrogen-fixing, plant-associated bacterium

In an ecological survey of nitrogen-fixing bacteria isolated from the rhizosphere and as endophytes of sugarcane, maize and teosinte plants in Brazil, Mexico and South Africa, a new phylogenetically homogeneous group of N(2)-fixing bacteria was identified within the genus Burkholderia. This polyphasic taxonomic study included microscopic and colony morphology, API 20NE tests and growth on different culture media at different pH and temperatures, as well as carbon source assimilation tests and whole-cell protein pattern analysis. Analysis of 16S rRNA gene sequences showed 99.2-99.9 % similarity within the novel species and 97.2 % similarity to the closest related species, Burkholderia sacchari. The novel species was composed of four distinct amplified 16S rDNA restriction analysis groups. The DNA-DNA reassociation values within the novel species were greater than 70 % and less than 42 % for the closest related species, B. sacchari. Based on these results and on many phenotypic characteristics, a novel N(2)-fixing species is proposed for the genus Burkholderia, Burkholderia tropica sp. nov., with the type strain Ppe8(T) (=ATCC BAA-831(T)=LMG 22274(T)=DSM 15359(T)). B. tropica was isolated from plants grown in geographical regions with climates ranging from temperate subhumid to hot humid.