Rhodobacter johrii sp. nov., an endospore-producing cryptic species isolated from semi-arid tropical soils

An oval to rod shaped phototrophic purple nonsulfur bacterium, strain JA192T was isolated from an enrichment culture of a pasteurized rhizosphere soil sample of jowar crop collected from Godumakunta village, near Hyderabad, India. Strain JA192T is Gram-negative, motile and produces endospores. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that the strain JA192T is closely related to Rhodobacter sphaeroides DSM 158T (99.9% sequence similarity), Rhodobacter megalophilus JA194T (99.8%) and Rhodobacter azotoformans JCM 9340T (98.1%) and clusters with other species of the genus Rhodobacter of the family Rhodobacteraceae. However, DNA-DNA hybridization with Rba. sphaeroides DSM 158T, Rba. megalophilus JA194T and Rba. azotoformans JCM 9320T showed a relatedness of only 38-57% with respect to JA192T. On the basis of 16S rRNA gene sequence analysis, DNA-DNA hybridization data, morphological, physiological and chemotaxanomic characters, strain JA192T represents a novel species of the genus Rhodobacter, for which the name Rhodobacter johrii sp. nov. is proposed. The type strain is JA192T (= DSM 18678T = JCM 14543T = MTCC 8172T)

Cloning and Characterization of Genes Involved in Nostoxanthin Biosynthesis of Sphingomonas elodea ATCC 31461

Most Sphingomonas species synthesize the yellow carotenoid nostoxanthin. However, the carotenoid biosynthetic pathway of these species remains unclear. In this study, we cloned and characterized a carotenoid biosynthesis gene cluster containing four carotenogenic genes (crtG, crtY, crtI and crtB) and a β-carotene hydroxylase gene (crtZ) located outside the cluster, from the gellan-gum producing bacterium Sphingomonas elodea ATCC 31461. Each of these genes was inactivated, and the biochemical function of each gene was confirmed based on chromatographic and spectroscopic analysis of the intermediates accumulated in the knockout mutants. Moreover, the crtG gene encoding the 2,2′-β-hydroxylase and the crtZ gene encoding the β-carotene hydroxylase, both responsible for hydroxylation of β-carotene, were confirmed by complementation studies using Escherichia coli producing different carotenoids. Expression of crtG in zeaxanthin and β-carotene accumulating E. coli cells resulted in the formation of nostoxanthin and 2,2′-dihydroxy-β-carotene, respectively. Based on these results, a biochemical pathway for synthesis of nostoxanthin in S. elodea ATCC 31461 is proposed

Use of liquefied cold temperature dimethyl ether for extraction of pigments from fresh vegetable tissues

Dimethyl ether (DME) is known as a useful precursor to other organic compounds and is a promising alternative fuel without issues of toxicity, production, infrastructure, and transportation as is the case with various other fuels. Recently, DME has attracted the attention of scientists and engineers since it behaves as a subcritical solvent or a low-temperature solvent applicable for the extraction of organic molecules from bio-materials. This paper presents the extraction of chlorophylls and carotenoids from green peel and yellow cortex of Japanese squash, spinach leaves and carrot roots using low-temperature liquefied DME. Spectroscopic and fluorescence analyses of the extracted pigments revealed that chlorophylls were successfully extracted by liquefied DME from green materials (squash peel and spinach leaves). HPLC analysis further confirmed that chlorophylls extracted include both chlorophylls a and b. By using liquefied DME, carotenoids were extracted from all vegetable samples examined. The performance of DME as a novel pigment extracting agent is confirmed in this work and its use as a “green” solvent, as opposed to conventional solvents, for the preparation and extraction of various plant pigments is highly encouraged from an environmental point of view

New nonlinear-laser effects in crystalline fine-grained ceramics based on cubic Sc2O3 and Lu2O3 oxides: second and third harmonic generation, and cascaded self-sum-frequency mixing in UV spectral region

We report on the first observation of the nonlinear cascading chi((3)) chi((3)) effects in UV spectral range and second harmonic generation stipulated by the "defect" nonlinearity under one-micron pumping in crystalline ceramics based on cubic oxides Sc2O3 and Lu2O3. Broadband their multi-wavelength Stokes and anti-Stokes combs with the extension of 10475 cm(-1) (for Sc2O3) and 8232 cm(-1) (for Lu2O3) were recorded as well

Mechanical and optical properties of Lu2O3 host-ceramics for Ln(3+) lasants

Micro-hardness and fracture toughness, as well as linear optical properties (full transmission spectrum and refractive index dispersion) of fine-grained Lu2O3 ceramics fabricated by VSN method are presented

Antioxidant Activity of Hawaiian Marine Algae

Marine algae are known to contain a wide variety of bioactive compounds, many of which have commercial applications in pharmaceutical, medical, cosmetic, nutraceutical, food and agricultural industries. Natural antioxidants, found in many algae, are important bioactive compounds that play an important role against various diseases and ageing processes through protection of cells from oxidative damage. In this respect, relatively little is known about the bioactivity of Hawaiian algae that could be a potential natural source of such antioxidants. The total antioxidant activity of organic extracts of 37 algal samples, comprising of 30 species of Hawaiian algae from 27 different genera was determined. The activity was determined by employing the FRAP (Ferric Reducing Antioxidant Power) assays. Of the algae tested, the extract of Turbinaria ornata was found to be the most active. Bioassay-guided fractionation of this extract led to the isolation of a variety of different carotenoids as the active principles. The major bioactive antioxidant compound was identified as the carotenoid fucoxanthin. These results show, for the first time, that numerous Hawaiian algae exhibit significant antioxidant activity, a property that could lead to their application in one of many useful healthcare or related products as well as in chemoprevention of a variety of diseases including cancer

Regression Analysis of PEM Fuel Cell Transient Response

To develop operating strategies in polymer electrolyte membrane (PEM) fuel cell-powered applications, precise computationally efficient models of the fuel cell stack voltage are required. Models are needed for all operating conditions, including transients. In this work, transient evolutions of voltage, in response to load changes, are modeled with a sum of three exponential decay functions. Amplitude factors are correlated to steady-state operating data (temperature, humidity, average current, resistance, and voltage). The obtained time constants reflect known processes of the membrane heat/water transport. These model parameters can form the basis for the prediction of voltage overshoot/undershoot used in computational-based control systems, used in real-time simulation. Furthermore, the results provide an empirical basis for the estimation of the magnitude of temporary voltage loss to be expected with sudden load changes, as well as a systematic method for the analysis of experimental data. Its applicability is currently limited to thin membranes with low to moderate humidity gases, and with adequately high reactant-gas stoichiometry

Phylogenetic and Evolutionary Patterns in Microbial Carotenoid Biosynthesis Are Revealed by Comparative Genomics

BACKGROUND: Carotenoids are multifunctional, taxonomically widespread and biotechnologically important pigments. Their biosynthesis serves as a model system for understanding the evolution of secondary metabolism. Microbial carotenoid diversity and evolution has hitherto been analyzed primarily from structural and biosynthetic perspectives, with the few phylogenetic analyses of microbial carotenoid biosynthetic proteins using either used limited datasets or lacking methodological rigor. Given the recent accumulation of microbial genome sequences, a reappraisal of microbial carotenoid biosynthetic diversity and evolution from the perspective of comparative genomics is warranted to validate and complement models of microbial carotenoid diversity and evolution based upon structural and biosynthetic data. METHODOLOGY/PRINCIPAL FINDINGS: Comparative genomics were used to identify and analyze in silico microbial carotenoid biosynthetic pathways. Four major phylogenetic lineages of carotenoid biosynthesis are suggested composed of: (i) Proteobacteria; (ii) Firmicutes; (iii) Chlorobi, Cyanobacteria and photosynthetic eukaryotes; and (iv) Archaea, Bacteroidetes and two separate sub-lineages of Actinobacteria. Using this phylogenetic framework, specific evolutionary mechanisms are proposed for carotenoid desaturase CrtI-family enzymes and carotenoid cyclases. Several phylogenetic lineage-specific evolutionary mechanisms are also suggested, including: (i) horizontal gene transfer; (ii) gene acquisition followed by differential gene loss; (iii) co-evolution with other biochemical structures such as proteorhodopsins; and (iv) positive selection. CONCLUSIONS/SIGNIFICANCE: Comparative genomics analyses of microbial carotenoid biosynthetic proteins indicate a much greater taxonomic diversity then that identified based on structural and biosynthetic data, and divides microbial carotenoid biosynthesis into several, well-supported phylogenetic lineages not evident previously. This phylogenetic framework is applicable to understanding the evolution of specific carotenoid biosynthetic proteins or the unique characteristics of carotenoid biosynthetic evolution in a specific phylogenetic lineage. Together, these analyses suggest a "bramble" model for microbial carotenoid biosynthesis whereby later biosynthetic steps exhibit greater evolutionary plasticity and reticulation compared to those closer to the biosynthetic "root". Structural diversification may be constrained ("trimmed") where selection is strong, but less so where selection is weaker. These analyses also highlight likely productive avenues for future research and bioprospecting by identifying both gaps in current knowledge and taxa which may particularly facilitate carotenoid diversification

De Novo Transcriptomic Analysis of an Oleaginous Microalga: Pathway Description and Gene Discovery for Production of Next-Generation Biofuels

Background: Eustigmatos cf. polyphem is a yellow-green unicellular soil microalga belonging to the eustimatophyte with high biomass and considerable production of triacylglycerols (TAGs) for biofuels, which is thus referred to as an oleaginous microalga. The paucity of microalgae genome sequences, however, limits development of gene-based biofuel feedstock optimization studies. Here we describe the sequencing and de novo transcriptome assembly for a non-model microalgae species, E. cf. polyphem, and identify pathways and genes of importance related to biofuel production. Results: We performed the de novo assembly of E. cf. polyphem transcriptome using Illumina paired-end sequencing technology. In a single run, we produced 29,199,432 sequencing reads corresponding to 2.33 Gb total nucleotides. These reads were assembled into 75,632 unigenes with a mean size of 503 bp and an N50 of 663 bp, ranging from 100 bp to.3,000 bp. Assembled unigenes were subjected to BLAST similarity searches and annotated with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology identifiers. These analyses identified the majority of carbohydrate, fatty acids, TAG and carotenoids biosynthesis and catabolism pathways in E. cf. polyphem. Conclusions: Our data provides the construction of metabolic pathways involved in the biosynthesis and catabolism of carbohydrate, fatty acids, TAG and carotenoids in E. cf. polyphem and provides a foundation for the molecular genetics and functional genomics required to direct metabolic engineering efforts that seek to enhance the quantity and character o