Formation of Lutein, ß-Carotene and Astaxanthin in a Coelastrella sp. Isolate.

In this study, the effect of media composition, N/P ratio and cultivation strategy on the formation of carotenoids in a Coelastrella sp. isolate was investigated. A two-stage process utilizing different media in the vegetative stage, with subsequent re-suspension in medium without nitrate, was employed to enhance the formation of carotenoids. The optimal growth and carotenoid content (ß-carotene and lutein) in the vegetative phase were obtained by cultivation in M-8 and BG11 media. Use of a N/P ratio of 37.5 and low light intensity of 40 µmol m-2 s-1 (control conditions) led to optimal biomass production of up to 1.31 g L-1. Low concentrations of astaxanthin (maximum of 0.31 wt. %) were accumulated under stress conditions (nitrogen-deficient medium containing 1.5 % of NaCl and light intensity of 500 µmol m-2 s-1), while ß-carotene and lutein (combined maximum of 2.12 wt. %) were produced under non-stress conditions. Lipid analysis revealed that palmitic (C16:0) and oleic (C18:1) constituted the main algal fatty acid chains (50.2 ± 2.1% of the total fatty acids), while esterifiable lipids constituted 17.2 ± 0.5% of the biomass by weight. These results suggest that Coelastrella sp. could also be a promising feedstock for biodiesel production.

A Genetic Algorithmic Approach to Determine the Structure of Li-Al Layered Double Hydroxides.

Layered double hydroxides (LDH) demonstrate significant potential across a range of applications, including as catalysts, delivery vehicles for pharmaceuticals, environmental remediation, and supercapacitors. Explaining the mechanism of LDH action at the atomic scale in these and other applications is challenging, however, due to the difficulty in precisely defining the bulk and surface structure and chemical compositions. Here, we focus on the determination of the structure of lithium-aluminum (Li-Al) LDH, which has shown promise in the catalytic depolymerization of lignin, both directly as the catalyst and as a support for gold nanoparticles. While the relative positions of the Li and Al metals are generally well resolved by X-ray crystallography, it is the structures of the anionic layers, consisting of water and carbonate, that are less well established. Combinatorial analyses of all possible positions and rotations of the water and carbonate in the three-layered Li-AL LDH polytope reveals that the phase space is much too large to examine in any reasonable time frame in a one-by-one structure exploration. To overcome this limitation, we develop and deploy a genetic algorithm (GA) wherein fitness is determined by matching a calculated X-ray diffraction (XRD) pattern for a given structure to the known experimental XRD pattern. The GA approach results in structures of high fitness that portend the bulk Li-Al LDH structure. Importantly, the GA approach offers the potential to determine the structures of other LDH, and more generally layered materials, which are generally difficult to describe given the large chemical and structural space to be explored.

Selective molecular separation of lignin model compounds by reduced graphene oxide membranes from solvent-water mixture.

Selective separation of lignin depolymerization products is key to fractionating and isolating high-value aromatic compounds from the depolymerization process. The primary aim of this study was to synthesis graphene oxide (GO) membranes for selective separations of lignin oligomeric units from polar organic solvent-water media. GO membranes were synthesized on a polymeric substrate by a shear assisted casting of aqueous GO dispersion using a wire-wound rod. Deposited GO was then reduced to different extents by controlled thermal incubation, and the impact on membrane performance was investigated. The extent of reduction of GO was established by extensive characterization with FTIR, XPS, Raman Spectroscopy, XRD, and contact angle measurements. Impressive performance with the rejection of over 70% for the model compound trimer BMP (2,6-bis[(2-hydroxy-5-methyl phenyl) methyl]-4-methylphenol) was achieved compared to only 20% rejection for the dimer GGE (guaiacylglycerol-ß-guaiacylether) with isopropanol-water (90-10% by volume) as a solvent. This corresponds to an encouraging selective separation with selective permeation of dimer (GGE) 3.5 times higher compared to trimer (BMP). rGO membranes exhibited a stable performance over 84 h of operation at a shear rate of 1.1 Pa in a cross-flow mode of operation. Selective separation of GO can be effectively modulated by controlling the O/C ratio by the extent of reduction of GO; indeed, the retention of trimeric compounds increased with increasing GO reduction. The remarkable performance of GO membranes could enable energy-efficient fractionation of lignin oligomeric compounds from polar organic solvents.

Selective cleavage of the C(α)-C(ß) linkage in lignin model compounds via Baeyer-Villiger oxidation.

Lignin is an amorphous aromatic polymer derived from plants and is a potential source of fuels and bulk chemicals. Herein, we present a survey of reagents for selective stepwise oxidation of lignin model compounds. Specifically, we have targeted the oxidative cleavage of Cα-Cß bonds as a means to depolymerize lignin and obtain useful aromatic compounds. In this work, we prepared several lignin model compounds that possess structures, characteristic reactivity, and linkages closely related to the parent lignin polymer. We observed that selective oxidation of benzylic hydroxyl groups, followed by Baeyer-Villiger oxidation of the resulting ketones, successfully cleaves the Cα-Cß linkage in these model compounds.

Global bioenergy potential from high-lignin agricultural residue.

Almost one-quarter of the world's population has basic energy needs that are not being met. Efforts to increase renewable energy resources in developing countries where per capita energy availability is low are needed. Herein, we examine integrated dual use farming for sustained food security and agro-bioenergy development. Many nonedible crop residues are used for animal feed or reincorporated into the soil to maintain fertility. By contrast, drupe endocarp biomass represents a high-lignin feedstock that is a waste stream from food crops, such as coconut (Cocos nucifera) shell, which is nonedible, not of use for livestock feed, and not reintegrated into soil in an agricultural setting. Because of high-lignin content, endocarp biomass has optimal energy-to-weight returns, applicable to small-scale gasification for bioelectricity. Using spatial datasets for 12 principal drupe commodity groups that have notable endocarp byproduct, we examine both their potential energy contribution by decentralized gasification and relationship to regions of energy poverty. Globally, between 24 million and 31 million tons of drupe endocarp biomass is available per year, primarily driven by coconut production. Endocarp biomass used in small-scale decentralized gasification systems (15-40% efficiency) could contribute to the total energy requirement of several countries, the highest being Sri Lanka (8-30%) followed by Philippines (7-25%), Indonesia (4-13%), and India (1-3%). While representing a modest gain in global energy resources, mitigating energy poverty via decentralized renewable energy sources is proposed for rural communities in developing countries, where the greatest disparity between societal allowances exist.

Effects of Treatment Conditions on Pd Speciation in CHA and Beta Zeolites for Passive NO x Adsorption.

The structure and evolution of Pd species in Pd-exchanged zeolite materials intended for use as passive NO x adsorbers were examined under various pretreatment conditions. Using in situ CO-diffuse reflectance infrared spectroscopy, Pd structures were characterized after 500 °C pretreatments in inert (Ar), water (1-2% H2O in Ar), oxidizing (air), and reducing (H2, CO) atmospheres. Two zeolites of similar Si/Al ratios but different framework topologies (Beta, CHA) were found to show different distributions of Pd species, depending on the reducing agent used. Reduction in H2 (500 °C; 10% H2 in Ar) followed by re-oxidation (500 °C; air) led to higher amounts of single-site Pd ions on Pd-CHA than Pd-Beta, whereas high-temperature reduction in CO (500 °C; 1000 ppm CO in Ar) followed by re-oxidation (500 °C; air) led to significant loss of ionic Pd on both Pd-CHA and Pd-Beta, albeit H2 temperature-programmed reduction and XPS experiments suggest that this phenomena may be limited to surface Pd. High-temperature treatments with water (500 °C; 1-2% H2O in Ar) are shown to form either Pd metal or PdO particles, with Pd-Beta being more susceptible to these effects than Pd-CHA. This work suggests that the effects of CO are especially problematic with respect to the durability of these materials in passive NO x adsorption applications, especially in the case of Beta zeolite.

Simultaneous promotion of photosynthesis and astaxanthin accumulation during two stages of Haematococcus pluvialis with ammonium ferric citrate.

To simultaneously promote biomass yield and astaxanthin content of Haematococcus pluvialis, ammonium ferric citrate (AFC) was employed to stimulate light harvest in photosynthesis during the green stage and oxidation induction in astaxanthin accumulation during the red stage. AFC not only improved chlorophyll synthesis by 22.5% to provide more electrochemical potential energy in the green stage, but also alleviated photosystem II damage to maintain a high level of effective quantum yield by enhancing carotenoid production. The citrate derived from AFC stimulated acetyl-CoA and NADPH production through citric acid cycle and transaminase cycle during the red stage, resulting in an increased lipid content by 1.77-fold. The astaxanthin content in H. pluvialis cells cultivated with 5 µM AFC was 12.5% higher than that without AFC, which was attributed to severe oxidative stress caused by AFC through Haber-Weiss reaction. These results provided a new approach to reduce emission of greenhouse gasses with producing high-value products.

Beneficial re-use of industrial CO2 emissions using microalgae: Demonstration assessment and biomass characterization.

A novel cyclic flow photobioreactor, designed for the capture and recycle of CO2 using microalgae, was deployed at a coal-fired power plant. Scenedesmus acutus was cultured continuously for a four-month period, during which a biomass productivity of 0.1-0.2 g L-1 day-1 was observed. Samples taken for DNA sequencing showed a strong correlation between the composition of the culture and environmental conditions. Dry and liquid biomass samples and the industrial fertilizers used for preparation of the nutrient medium were analyzed to determine the presence of heavy metals (As, Cd, Hg, Se) and results were compared with standardized and/or regulated maximum contaminant levels (MCLs) for metals in several possible algae derived products. Concentrations of the metals in dry algae biomass were consistent with the incorporation of metals from the supplied nutrients.

Gold-catalyzed conversion of lignin to low molecular weight aromatics.

A heterogeneous catalyst system, employing Au nanoparticles (NPs) and Li-Al (1 : 2) layered double hydroxide (LDH) as support, showed excellent activity in aerobic oxidation of the benzylic alcohol group in ß-O-4 linked lignin model dimers to the corresponding carbonyl products using molecular oxygen under atmospheric pressure. The synergistic effect between Au NPs and the basic Li-Al LDH support induces further reaction of the oxidized model compounds, facilitating facile cleavage of the ß-O-4 linkage. Extension to oxidation of γ-valerolactone (GVL) extracted lignin and kraft lignin using Au/Li-Al LDH under similar conditions produced a range of aromatic monomers in high yield. Hydrolysis of the Au/Li-Al LDH oxidized lignin was found to increase the degree of lignin depolymerization, with monomer yields reaching 40% for GVL extracted lignin. Based on these results, the Au/Li-Al LDH + O2 catalyst system shows potential to be an environmentally friendly means of depolymerizing lignin to low molecular weight aromatics under mild conditions.

A new locus for split hand/foot malformation with long bone deficiency (SHFLD) at 2q14.2 identified from a chromosome translocation.

Split hand/foot malformation (SHFM) with long bone deficiency (SHFLD) is a distinct entity in the spectrum of ectrodactylous limb malformations characterised by associated tibial a/hypoplasia. Pedigrees with multiple individuals affected by SHFLD often include non-penetrant intermediate relatives, making genetic mapping difficult. Here we report a sporadic patient with SHFLD who carries a de novo chromosomal translocation t(2;18)(q14.2;p11.2). Characterisation of the breakpoints revealed that neither disrupts any known gene; however, the chromosome 2 breakpoint lies between GLI2 and INHBB, two genes known to be involved in limb development. To investigate whether mutation of a gene in proximity to the chromosome 2 breakpoint underlies the SHFLD, we sought independent evidence of mutations in GLI2, INHBB and two other genes (RALB and FLJ14816) in 44 unrelated patients with SHFM, SHFLD or isolated long bone deficiency. No convincing pathogenic mutations were found, raising the possibility that a long-range cis acting regulatory element may be disrupted by this translocation. The previous description of a translocation with a 2q14.2 breakpoint associated with ectrodactyly, and the mapping of the ectrodactylous Dominant hemimelia mouse mutation to a region of homologous synteny, suggests that 2q14.2 represents a novel locus for SHFLD.

Reducing biomass recalcitrance by heterologous expression of a bacterial peroxidase in tobacco (Nicotiana benthamiana).

Commercial scale production of biofuels from lignocellulosic feed stocks has been hampered by the resistance of plant cell walls to enzymatic conversion, primarily owing to lignin. This study investigated whether DypB, the lignin-degrading peroxidase from Rodococcus jostii, depolymerizes lignin and reduces recalcitrance in transgenic tobacco (Nicotiana benthamiana). The protein was targeted to the cytosol or the ER using ER-targeting and retention signal peptides. For each construct, five independent transgenic lines were characterized phenotypically and genotypically. Our findings reveal that expression of DypB in the cytosol and ER does not affect plant development. ER-targeting increased protein accumulation, and extracts from transgenic leaves showed higher activity on classic peroxidase substrates than the control. Intriguingly, in situ DypB activation and subsequent saccharification released nearly 200% more fermentable sugars from transgenic lines than controls, which were not explained by variation in initial structural and non-structural carbohydrates and lignin content. Pyrolysis-GC-MS analysis showed more reduction in the level of lignin associated pyrolysates in the transgenic lines than the control primarily when the enzyme is activated prior to pyrolysis, consistent with increased lignin degradation and improved saccharification. The findings reveal for the first time that accumulation and in situ activation of a peroxidase improves biomass digestibility.

Mutagenesis breeding for increased 3-deoxyanthocyanidin accumulation in leaves of Sorghum bicolor (L.) Moench: a source of natural food pigment.

Natural food colorants with functional properties are of increasing interest. Prior papers indicate the chemical suitability of sorghum leaf 3-deoxyanthocyanidins as natural food colorants. Via mutagenesis-assisted breeding, a sorghum variety that greatly overaccumulates 3-deoxyanthocyanidins of leaf tissue, named REDforGREEN (RG), has been isolated and characterized. Interestingly, RG not only caused increased 3-deoxyanthocyanidins but also caused increased tannins, chlorogenic acid, and total phenolics in the leaf tissue. Chemical composition of pigments was established through high-performance liquid chromatography (HPLC) that identified luteolinidin (LUT) and apigeninidin (APG) as the main 3-deoxyanthocianidin species. Specifically, 3-deoxyanthocianidin levels were 1768 µg g⁻¹ LUT and 421 µg g⁻¹ APG in RG leaves compared with trace amounts in wild type, representing 1000-fold greater levels in the mutant leaves. Thus, RG represents a useful sorghum mutagenesis variant to develop as a functionalized food colorant.

Sorghum mutant RG displays antithetic leaf shoot lignin accumulation resulting in improved stem saccharification properties.

BACKGROUND: Improving saccharification efficiency in bioenergy crop species remains an important challenge. Here, we report the characterization of a Sorghum (Sorghum bicolor L.) mutant, named REDforGREEN (RG), as a bioenergy feedstock. RESULTS: It was found that RG displayed increased accumulation of lignin in leaves and depletion in the stems, antithetic to the trend observed in wild type. Consistent with these measurements, the RG leaf tissue displayed reduced saccharification efficiency whereas the stem saccharification efficiency increased relative to wild type. Reduced lignin was linked to improved saccharification in RG stems, but a chemical shift to greater S:G ratios in RG stem lignin was also observed. Similarities in cellulose content and structure by XRD-analysis support the correlation between increased saccharification properties and reduced lignin instead of changes in the cellulose composition and/or structure. CONCLUSION: Antithetic lignin accumulation was observed in the RG mutant leaf-and stem-tissue, which resulted in greater saccharification efficiency in the RG stem and differential thermochemical product yield in high lignin leaves. Thus, the red leaf coloration of the RG mutant represents a potential marker for improved conversion of stem cellulose to fermentable sugars in the C4 grass Sorghum.

Identification and thermochemical analysis of high-lignin feedstocks for biofuel and biochemical production.

BACKGROUND: Lignin is a highly abundant biopolymer synthesized by plants as a complex component of plant secondary cell walls. Efforts to utilize lignin-based bioproducts are needed. RESULTS: Herein we identify and characterize the composition and pyrolytic deconstruction characteristics of high-lignin feedstocks. Feedstocks displaying the highest levels of lignin were identified as drupe endocarp biomass arising as agricultural waste from horticultural crops. By performing pyrolysis coupled to gas chromatography-mass spectrometry, we characterized lignin-derived deconstruction products from endocarp biomass and compared these with switchgrass. By comparing individual pyrolytic products, we document higher amounts of acetic acid, 1-hydroxy-2-propanone, acetone and furfural in switchgrass compared to endocarp tissue, which is consistent with high holocellulose relative to lignin. By contrast, greater yields of lignin-based pyrolytic products such as phenol, 2-methoxyphenol, 2-methylphenol, 2-methoxy-4-methylphenol and 4-ethyl-2-methoxyphenol arising from drupe endocarp tissue are documented. CONCLUSIONS: Differences in product yield, thermal decomposition rates and molecular species distribution among the feedstocks illustrate the potential of high-lignin endocarp feedstocks to generate valuable chemicals by thermochemical deconstruction.

Fragile XE: an important differential diagnosis.

Fragile X is a common cause of mental retardation in boys that can also affect girls. We present the case of a 21-year-old woman with Fragile X E (FRAXE) with learning difficulty, behavioural problems and epilepsy. Her diagnosis was made after investigations spanning several years, highlighting the importance of considering FRAXE and the benefits of reviewing genetic test results in the light of advancing technology.

A chromosome 21-derived minute marker in a mosaic trisomy 21 background: implications for risk assessments in marker chromosome cases.

We report a prenatal case of a chromosome 21-derived minute supernumerary marker, found as a mosaic along with a trisomy 21 cell line at amniocentesis. Follow-up analysis of other fetal tissues confirmed the mosaicism and also disclosed a normal cell line. It is likely that the marker reflects a mutation event that resulted in trisomy rescue early in embryonic development. Had the trisomy 21 cell line not been found at amniocentesis, a low risk of an abnormal phenotype (approximately 5%) would have been assigned. We suggest that the risk associated with minute non-euchromatic marker chromosomes should be revised to account for the possibility of mosaicism with potentially aneuploid populations and/or uniparental disomy (UPD). The finding of any marker chromosome should prompt a thorough investigation for aneuploid cell lines. In the case of small markers with no euchromatin, the given risk of adverse phenotypic effects is not likely to be associated with the marker per se but with the possible presence of a cryptic aneuploid cell line from which the marker may have arisen.