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The environmental strain Aeromonas salmonicida subsp. pectinolytica 34melT produces abundant melanin through the homogentisate pathway in several culture media, but unexpectedly not when grown in a medium containing glycerol. Using this observation as a starting point, this study investigated the underlying causes of the inhibition of melanin synthesis by glycerol, to shed light on factors that affect melanin production in this microorganism. The effect of different carbon sources on melanin formation was related to the degree of oxidation of their C atoms, as the more reduced substrates delayed melanization more than the more oxidized ones, although only glycerol completely abolished melanin production. Glyphosate, an inhibitor of aromatic amino acid synthesis, did not affect melanization, while bicyclopyrone, an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (Hpd), the enzyme responsible for the synthesis of homogentisate, prevented melanin synthesis. These results showed that melanin production in 34melT depends on the degradation of aromatic amino acids from the growth medium and not on de novo aromatic amino acid synthesis. The presence of glycerol changed the secreted protein profile, but none of the proteins affected could be directly connected with melanin synthesis or transport. Transcription analysis of hpd, encoding the key enzyme for melanin synthesis, showed a clear inhibition caused by glycerol. The results obtained in this work indicate that a significant decrease in the transcription of hpd, together with a more reduced intracellular state, would lead to the abolishment of melanin synthesis observed. The effect of glycerol on melanization can thus be attributed to a combination of metabolic and regulatory effects. [ABSTRACT FROM AUTHOR]

This paper presents a new global burned area (BA) product, generated from the MODIS red (R) and near infrared (NIR) reflectances and thermal anomalies data, thus providing the highest spatial resolution (approx. 250m) among the existing global BA datasets. The product includes the full times series (2001-2016) of the MODIS archive. The BA detection 20 algorithm was based on temporal composites of daily images, using temporal and spatial distance to active fires. The algorithm has two steps, the first one aiming to reduce commission errors by selecting the most clearly burned pixels (seeds), and the second one aiming to reduce omission errors by applying contextual analysis around the seed pixels. The product was developed within the European Space Agency's (ESA) Climate Change Initiative programme, under the Fire Disturbance project (Fire_cci). The final output includes two types of BA products: monthly full-resolution continental tiles (http://doi.org/cpk7) and biweekly global grid files at a degraded resolution of 0.25 degrees (http://doi.org/gcx9gf). Each one includes several auxiliary variables that were defined by the climate users to facilitate the ingestion of the product into global dynamic vegetation and emission models. The validation was based on a stratified random sample of 1200 pairs of Landsat images, covering the whole globe from 2003 to 2014. The estimated commission and omission error rates of the pixel product was 0.512 (0.020) and 0.708 (0.030), respectively, lower 30 than previous ESA products but higher than the latest NASA MCD64A1 BA dataset. Examples of potential applications of this product to fire modelling based on burned patches analysis are included in this paper. They show greater sensitivity of our product to small burn patch detection than existing BA products. [ABSTRACT FROM AUTHOR]

This study presents the methods for the generation of the first global fuel data set, containing all the parameters required to be input in the Fuel Characteristic Classification System (FCCS). The data set was developed from different spatial variables, both based on satellite Earth observation products and fuel databases, and is comprised by a global fuelbed map and a database that includes the parameters of each fuelbed that affect fire behavior and effects. A total of 274 fuelbeds were created and parameterized, and can be input into FCCS to obtain fire potentials, surface fire behavior and carbon biomass for each fuelbed. We present a first assessment of the fuel data set by comparing the carbon biomass obtained from our FCCS fuelbeds with the average biome values of four other regional or global biomass products. The results showed a good agreement both in terms of geographical distribution and biomass loads when compared to other biomass data, with the best results found for tropical and boreal forests (Spearman's coefficient of 0.79 and 0.77). This global fuel data set may be used for a varied range of applications, including fire danger assessment, fire behavior estimations, fuel consumption calculations and emissions inventories. [ABSTRACT FROM AUTHOR]

This study presents the methods for the generation of the first global fuel dataset, containing all the parameters required to be input in the Fuel Characteristic Classification System (FCCS). The dataset was developed from different spatial variables, both based on satellite Earth observation products and fuel databases, and is comprised by a global fuelbed map and a database that includes the parameters of each fuelbed that affect fire behavior and effects. A total of 274 fuelbeds were created and parameterized, and can be input into FCCS to obtain fire potentials, surface fire behavior and carbon biomass for each fuelbed. To assess the results, FCCS was used to calculate the carbon biomass of each fuelbed, and the results were compared to the values obtained for four other regional or global biomass products. The results showed reasonable agreement both in terms of geographical distribution and biomass loads when compared to other biomass data, with the best results found for Tropical and Boreal forests (Spearman's coefficient of 0.79 and 0.77). This global fuel dataset could be used for a varied range of applications, including fire danger assessment, fire behavior estimations, fuel consumption calculations and emissions inventories. [ABSTRACT FROM AUTHOR]

Phasins are a group of proteins associated to granules of polyhydroxyalkanoates (PHAs). Apart from their structural role as part of the PHA granule cover, different structural and regulatory functions have been found associated to many of them, and several biotechnological applications have been developed using phasin protein fusions. Despite their remarkable functional diversity, the structure of these proteins has not been analyzed except in very few studies. PhaP from Azotobacter sp. FA8 (PhaPAz) is a representative of the prevailing type in the multifunctional phasin protein family. Previous work performed in our laboratory using this protein have demonstrated that it has some very peculiar characteristics, such as its stress protecting effects in recombinant Escherichia coli, both in the presence and absence of PHA. The aim of the present work was to perform a structural characterization of this protein, to shed light on its properties. Its aminoacid composition revealed that it lacks clear hydrophobic domains, a characteristic that appears to be common to most phasins, despite their lipid granule binding capacity. The secondary structure of this protein, consisting of α-helices and disordered regions, has a remarkable capacity to change according to its environment. Several experimental data support that it is a tetramer, probably due to interactions between coiled-coil regions. These structural features have also been detected in other phasins, and may be related to their functional diversity. [ABSTRACT FROM AUTHOR]

Escherichia coli and other facultative anaerobes can adapt their metabolism according to oxygen availability by means of aerobic and anaerobic respiration and fermentation. ArcAB is a two-component signal transduction system that controls, at the transcriptional level, the choice of energy generation pathway according to the intracellular redox state. High throughput studies on different redox regulator mutants, involving transcriptome analysis, RT-PCR and phenotypic arrays enabled the elucidation of a repertoire of operons coordinated by ArcA which extended beyond respiration control including, among others, those which code for survival, chromosome replication and degradation of fatty acids. Flux analysis by 13C labeling provided new clues to the understanding of the distribution of metabolites mediated by ArcAB. The genetic manipulation of this regulator proved to be useful for the generation of reduced products of commercial value. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Pseudomonas sp. 14-3 accumulates polyhydroxybutyrate (PHB) from octanoate, but not from glucose. To elucidate this unusual phenotype, genes responsible for the synthesis of PHB were cloned and analyzed. A PHB polymerase gene ( phaC) was found downstream from genes coding for a β-ketothiolase ( phaA), an acetoacetyl-coenzyme A reductase ( phaB) and a putative transcriptional regulator ( phaR). All genes were similar to pha genes from several related species, but differences were observed in the distal region of phaA. Complementation with heterologous β-ketothiolase genes from Azotobacter sp. FA8 or Pseudomonas putida GPp104 restored the capability of Pseudomonas sp. 14-3 to synthesize PHB from glucose, demonstrating that its β-ketothiolase was nonfunctional. Analysis of the genome sequences of other Pseudomonas species has revealed the existence of putative β-ketothiolase genes. The functionality of one of these thiolase genes, belonging to P. putida GPp104, was experimentally demonstrated. Pseudomonas sp. 14-3 is the first natural phaA mutant described, that despite this mutation accumulates high amounts of PHB when growing on fatty acids. [ABSTRACT FROM AUTHOR]

A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor concentrations as well as ionic strength (based on phosphate buffer concentration) as the three main independent components of the culture medium that significantly (p < 0.05) influenced biomass and poly(3-hydroxybutyrate) (PHB) production in recombinant cells of Escherichia coli. This strain carries a plasmid encoding phb genes from a natural isolate of Azotobacter sp. Response surface methodology, using a central composite rotatable design, demonstrated that the optimal concentrations of the three components, defined as those yielding maximal biomass and PHB production in shaken flasks, were 37.96 g deproteinated milk whey powder/l, 29.39 g corn steep liquor/l, and 23.76 g phosphates/l (r² = 0.957). The model was validated by culturing the recombinant cells in medium containing these optimal concentrations, which yielded 9.41 g biomass/l and 6.12 g PHB/l in the culture broth. Similar amounts of PHB were obtained following batch fermentations in a bioreactor. These results show that PHB can be produced efficiently by culturing the recombinant strain in medium containing cheap carbon and nitrogen sources. [ABSTRACT FROM AUTHOR]

Insertion of factor MudJ in the intergenic region between divergent genes yrfF and yrfE, at centisome 76 in the genome of Salmonella enterica serovar Typhimurium LT2, confers the characteristics recently described for mucM mutants, i.e. mucoidy and resistance to mecillinam. Cloning of the intergenic region plus either the yrfF or the yrfE gene in a multicopy plasmid showed that only the plasmid carrying the yrfF gene complemented mucM mutants, thus suggesting that mucM mutations are in fact yrfF mutations. A null yrfF mutation obtained by insertion of a kanamycin cassette into the yrfF open reading frame (yrfF28::Kan) produced abortive colonies when transduced to a wild-type strain but was normally accepted by rcsB, rcsC or yojN strains. Neither mutations preventing synthesis of the capsular exopolysaccharide colanic acid (cps, galE) nor rcsA mutations, which reduce expression of cps genes, conferred tolerance to the lethal yrfF28::Kan mutation. Spontaneous suppressor mutations arose very frequently in abortive yrfF28::Kan colonies, and all of them affected either rcsC, yojN, or rcsB genes. Thus, the lethal effect caused by inactivation of gene yrfF appears to be mediated by a function that is dependent on the rcsC-yojN-rcsB phosphorelay system but does not involve synthesis of colanic acid. [Copyright &y& Elsevier]