Publications by authors named "Roger Ibbett"

Background: Understanding how fungi degrade lignocellulose is a cornerstone of improving renewables-based biotechnology, in particular for the production of hydrolytic enzymes. Considerable progress has been made in investigating fungal degradation during time-points where CAZyme expression peaks. However, a robust understanding of the fungal survival strategies over its life time on lignocellulose is thereby missed.

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Sugar beet pectin is rich in rhamnogalacturonan-I (RG-I) region, which is a potential source of prebiotics. RG-I pectin cannot be extracted the same way as commercial homogalacturan-rich pectin using hot acid. Therefore, this study has explored several alternative methods, including microwave-assisted extraction (MAE) and conventional-solvent extraction (CSE) at atmospheric pressure using different solvents, and microwave-assisted hydrothermal extraction (MAHE) under pressure using water.

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In 2015/2016, the total municipal solid waste (MSW) collected by local authority in the U.K. was 26 million tonnes and over 57% is still put into landfill or incinerated.

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The aim of this study was 1) to investigate the influence of polymeric additives such as carboxyl methyl cellulose (CMC) and locust bean gum (LBG) added before and after homogenisation on the moisture uptake of microfibrillar cellulose (MFC) in the dry and semi-wet state; and 2) to further understand the thermally induced structural transitions of low moisture MFC in the presence of the polymeric additives. A higher moisture content in the highly dense MFC network maintains the fibrillated network structure, which is lost during the drying process resulting in MFC aggregates. The addition of polymeric additives results in the regaining of the structure upon redispersion of the dry material with CMC being more effective than LBG).

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An innovative procedure for plant chloroplasts isolation has been proposed, which consists of juice extraction by physical fractionation from plant material and recovery of its chloroplast-rich fraction (CRF) by centrifugation. This simple method has been applied to pea vine haulm subjected to different post-harvest treatments: blanching, storage at different relative humidity values and fermentation. Additionally, freeze storage of the extracted juice was carried out.

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Article Synopsis
  • Fungi can degrade lignocellulose, which is important for producing biofuels and high-value compounds; understanding their responses to treated substrates could help lower production costs of biofuel cocktails.
  • Research investigated the effects of untreated, ionic liquid, and hydrothermally pretreated wheat straw on fungal gene expression using RNA-seq and proteomics, finding that ionic liquid pretreatment preserved more hemicellulosic sugars and altered gene activity compared to hydrothermal methods.
  • The study revealed that both pretreatments significantly affected gene expression related to carbohydrate-active enzymes, with implications for optimizing enzyme production and efficiency in lignocellulosic biomass processing.
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Background: Saprobic fungi are the predominant industrial sources of Carbohydrate Active enZymes (CAZymes) used for the saccharification of lignocellulose during the production of second generation biofuels. The production of more effective enzyme cocktails is a key objective for efficient biofuel production. To achieve this objective, it is crucial to understand the response of fungi to lignocellulose substrates.

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Background: Saprobic fungi are the predominant industrial sources of Carbohydrate Active enZymes (CAZymes) used for the saccharification of lignocellulose during the production of second generation biofuels. The production of more effective enzyme cocktails is a key objective for efficient biofuel production. To achieve this objective, it is crucial to understand the response of fungi to lignocellulose substrates.

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Background: The use of a microwave synthesis reactor has allowed kinetic data for the hydrothermal reactions of straw biomass to be established from short times, avoiding corrections required for slow heating in conventional reactors, or two-step heating. Access to realistic kinetic data is important for predictions of optimal reaction conditions for the pretreatment of biomass for bioethanol processes, which is required to minimise production of inhibitory compounds and to maximise sugar and ethanol yields.

Results: The gravimetric loss through solubilisation of straw provided a global measure of the extent of hydrothermal deconstruction.

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Background: The investigation of structural organisation in lignocellulose materials is important to understand changes in cellulase accessibility and reactivity resulting from hydrothermal deconstruction, to allow development of strategies to maximise bioethanol process efficiencies. To achieve progress, wheat straw lignocellulose and comparative model wood cellulose were characterised following increasing severity of hydrothermal treatment. Powder and fibre wide-angle X-ray diffraction techniques were employed (WAXD), complemented by enzyme kinetic measurements up to high conversion.

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A key challenge in the production of second generation biofuels is the conversion of lignocellulosic substrates into fermentable sugars. Enzymes, particularly those from fungi, are a central part of this process, and many have been isolated and characterised. However, relatively little is known of how fungi respond to lignocellulose and produce the enzymes necessary for dis-assembly of plant biomass.

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Differential Scanning Calorimetry, Dynamic Mechanical Thermal Analysis, gravimetric and chemical techniques have been used to study hydrothermal reactions of straw biomass. Exothermic degradation initiates above 195 °C, due to breakdown of the xylose ring from hemicellulose, which may be similar to reactions occurring during the early stage pyrolysis of dry biomass, though activated at lower temperature through water mediation. The temperature and magnitude of the exotherm reduce with increasing acid concentration, suggesting a reduction in activation energy and a change in the balance of reaction pathways.

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The disruption of starch granular structure during dissolution in varying concentrations of N-methyl morpholine N-oxide (NMMO) has been studied using three maize starches with varying ratios of amylose and amylopectin. Behavior in NMMO has been characterized by differential scanning calorimetry (DSC), microscopy, rapid viscosity analysis (RVA), and rheometry. Exothermic transitions were observed for the three starches in both 78 and 70% NMMO; the transition changed to an endotherm at 60 and 50% NMMO.

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The molecular and crystal deformations of a range of lyocell cellulose fibres, produced using different drawing conditions, are reported. The fibres are spun using increasing draw ratios to both increase the molecular and crystal orientation and, consequently, mechanical stiffness. Raman spectroscopy and X-ray diffraction are used to follow molecular and crystal deformation, respectively.

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The determination of the crystal orientation of regenerated cellulose fibers produced under different drawing regimes is presented. Orientation is determined by using wide-angle X-ray diffraction from a synchrotron source and by measuring the azimuthal width of equatorial reflections. The orientation parameter theta is then determined to compare fiber samples.

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