Fatty acid secretion by the white rot fungus, Trametes versicolor

Fungi can acquire and store nutrients through decomposing and converting organic matter into fatty acids. This research demonstrates for the first time that the white-rot fungus Trametes versicolor has the ability to secrete extracellular droplets which can contain a high concentration of long chain fatty acids and unsaturated fatty acids as well as monosaccharides and polysaccharides. The concentration and composition of the fatty acids varied according to the age of the droplet and the feedstock used for growth of the fungi. The results raise the possibility that these droplets could be harvested offering a new approach for the microbial generation of oil from waste

Reappraisal of putative glyoxalase 1-deficient mouse and dicarbonyl stress on embryonic stem cells in vitro

Glyoxalase 1 (Glo1) is a cytoplasmic enzyme with a cytoprotective function linked to metabolism of the cytotoxic side product of glycolysis, methylglyoxal (MG). It prevents dicarbonyl stress — the abnormal accumulation of reactive dicarbonyl metabolites, increasing protein and DNA damage. Increased Glo1 expression delays ageing and suppresses carcinogenesis, insulin resistance, cardiovascular disease and vascular complications of diabetes and renal failure. Surprisingly, gene trapping by the International Mouse Knockout Consortium (IMKC) to generate putative Glo1 knockout mice produced a mouse line with the phenotype characterised as normal and healthy. Here, we show that gene trapping mutation was successful, but the presence of Glo1 gene duplication, probably in the embryonic stem cells (ESCs) before gene trapping, maintained wild-type levels of Glo1 expression and activity and sustained the healthy phenotype. In further investigation of the consequences of dicarbonyl stress in ESCs, we found that prolonged exposure of mouse ESCs in culture to high concentrations of MG and/or hypoxia led to low-level increase in Glo1 copy number. In clinical translation, we found a high prevalence of low-level GLO1 copy number increase in renal failure where there is severe dicarbonyl stress. In conclusion, the IMKC Glo1 mutant mouse is not deficient in Glo1 expression through duplication of the Glo1 wild-type allele. Dicarbonyl stress and/or hypoxia induces low-level copy number alternation in ESCs. Similar processes may drive rare GLO1 duplication in health and disease

Biodegradation as natural fibre pre-treatment in composite manufacturing

Bacterial and fungal degradation of wheat straw has become intensively scrutinised in recent years because of the growing interest in procuring useful feedstocks and chemicals from lignocellulosic sources. Typically, after the extraction of valuable sugars and phenolics, significant quantities of solid biomass remain as waste. In this work, it has been shown that the leftover fermented wheat straw can be successfully used to reinforce epoxy resins, providing better strength properties compared to non-degraded straw. A 12% and a 22% increase in Young’s modulus and ultimate tensile strength respectively were observed for degraded wheat straw/epoxy composites compared to composites containing non-degraded straw. The improvement in mechanical strength is explained in terms of the structural and morphological transformations that occurred in the fibres during the fermentation process. The opportunity to use degraded natural fibres in the manufacturing of composites, in addition to the production of chemicals from lignocellulosic feedstocks, looks promising for improving biorefinery economics further

Mask estimation based on sound localisation for missing data speech recognition

ABSTRACT This paper describes a perceptually motivated computational auditory scene analysis (CASA) system that combines sound separation according to spatial location with 'missing data' techniques for robust speech recognition in noise. Missing data time-frequency masks are produced using cross-correlation to estimate interaural time differenre (ITD) and hence spatial azimuth; this is used to determine which regions of the signal constitute reliable evidence of the target speech signal. Three experiments are performed that compare the effects of different reverberation surfaces, localisation methods and azimuth separations on recognition accuracy, together with the effects of two post-processing techniques (morphological operations and supervised learning) for improving mask estimation. Both post-processing techniques greatly improve performance; the best performance occurs using a learnt mapping

A comparison of ergosterol and PLFA methods for monitoring the growth of ligninolytic fungi during wheat straw solid state cultivation

Ergosterol, total phospholipid fatty acid (PLFA) and linoleic acid (18:2n-6) have all been used to determine fungal growth. This paper compares these methods to assess the growth of four different saprotrophic fungal species during solid state cultivation using a wheat straw substrate that have not been compared or measured previously. Ergosterol production appeared to track the mycelia growth well but its production differed considerably between fungi. This means that a specific conversion factor needs to be determined and applied for any given fungus. In comparison, measurements of total PLFA and linoleic acid only showed promise for determining the growth of Postia placenta due to the positive correlation with ergosterol measurements. In contrast, the other fungi tested (Phanerochaete chrysosporium, Serpula lacrymans and Schizophyllum commune) showed either no correlation or in some cases a negative correlation using this assay. The novel findings highlight the variation in fungal fatty acid between species, culture conditions and durations of incubation; suggesting that measurement of linoleic acid is only usable in specific cases. These findings provide important consideration for the study of fungi growing in solid substrates and suggest that the use of PLFA might bias diversity indices

Extraction of vanillin following bioconversion of rice straw and its optimization by response surface methodology

Value-added chemicals, including phenolic compounds, can be generated through lignocellulosic biomass conversion via either biological or chemical pretreatment. Currently vanillin is one of the most valuable of these products that has been shown to be extractable on an industrial scale. This study demonstrates the potential of using rice straw inoculated with Serpula lacrymans, which produced a mixture of high value bio-based compounds including vanillin. Key extraction conditions were identified to be the volume of solvent used and extraction time, which were optimized using response surface methodology (RSM). The vanillin compounds extracted from rice straw solid state fermentation (SSF) was confirmed through LC-ESI MS/MS in selective ion mode. The optimum concentration and yield differed depending on the solvent, which was predicted using 60 mL ethyl acetate for 160 min were 0.408% and 3.957 μg g−1 respectively. In comparison, when ethanol was used, the highest concentration and yields of vanillin were 0.165% and 2.596 μg g−1. These were achieved using 40 mL of solvent, and extraction time increased to 248 min. The results confirm that fungal conversion of rice straw to vanillin could consequently offer a cost-effect alternative to other modes of production

Genetic regulation of glucoraphanin accumulation in Beneforté® broccoli

Diets rich in broccoli (Brassica oleracea var italica) have been associated with maintenance of cardiovascular health and reduction in risk of cancer. These health benefits have been attributed to glucoraphanin that specifically accumulates in broccoli. The development of broccoli with enhanced concentrations of glucoraphanin may deliver greater health benefits. Three high-glucoraphanin F1 broccoli hybrids were developed in independent programmes through genome introgression from the wild species Brassica villosa. Glucoraphanin and other metabolites were quantified in experimental field trials. Global SNP analyses quantified the differential extent of B. villosa introgression The high-glucoraphanin broccoli hybrids contained 2.5–3 times the glucoraphanin content of standard hybrids due to enhanced sulphate assimilation and modifications in sulphur partitioning between sulphur-containing metabolites. All of the high-glucoraphanin hybrids possessed an introgressed B. villosa segment which contained a B. villosa Myb28 allele. Myb28 expression was increased in all of the high-glucoraphanin hybrids. Two high-glucoraphanin hybrids have been commercialised as Beneforte broccoli. The study illustrates the translation of research on glucosinolate genetics from Arabidopsis to broccoli, the use of wild Brassica species to develop cultivars with potential consumer benefits, and the development of cultivars with contrasting concentrations of glucoraphanin for use in blinded human intervention studie

The white-rot fungus, Phanerochaete chrysosporium, under combinatorial stress produces variable oil profiles following analysis of secondary metabolites

Aims: The effects of combinatorial stress on lipid production in Phanerochaete chrysosporium remains understudied. This species of white‐rot fungi was cultivated on solid‐state media whilst under variable levels of known abiotic and biotic stressors to establish the effect upon fungal oil profiles. Methods and Results: Environmental stressors induced upon the fungus included: temperature; nutrient limitation; and interspecies competition to assess impact upon oil profiles. Fatty acid type and concentration was determined using analytical methods of Gas Chromatography and Mass Spectrometry. Growth rate under stress was established using High Performance Liquid Chromatography with ergosterol as the biomarker. Fungi grown on solid‐state agar were able to simultaneously produce short and long‐chain fatty acids which appeared to be influenced by nutritional composition as well as temperature. Addition of nitrogen supplements increased the growth rate, but lipid dynamics remained unchanged. Introducing competition‐induced stress had significantly altered the production of certain fatty acids beyond that of the monoculture whilst under nutrient‐limiting conditions. Linoleic acid concentrations, for example, increased from an average of 885 ng/μl at monoculture towards 13820 ng/μl at co‐culture, following 7 days of incubation. Conclusions: Interspecies competition produced the most notable impact on lipid production for solid‐state media cultivated fungi whilst the addition of nitrogen supplementation presented growth and lipid accumulation to be uncorrelated. Combinatorial stress therefore influences the yield of overall lipid production as well as the number of intermediate fatty acids produced, deriving similar oil profiles to the composition of vegetable and fish oils. Significance and Impact of Study: Fungal secondary metabolism remains highly sensitive following combinatorial stress. The outcome impacts the research towards optimising fungal oil profiles for biomass and nutrition. Future investigations on fungal stress tolerance mechanisms need to address these environmental factors throughout the experimental design

Biochemical characterization of Serpula lacrymans iron-reductase enzymes in lignocellulose breakdown

Putative iron-reductase (IR) genes from Serpula lacrymans with similarity to the conserved iron-binding domains of cellobiose dehydrogenase (CDH) enzymes have been identified. These genes were cloned and expressed to functionally characterize their activity and role in the decomposition of lignocellulose. The results show that IR1 and IR2 recombinant enzymes have the ability to depolymerize both lignin and cellulose, are capable of the reduction of ferric iron to the ferrous form, and are capable of the degradation of nitrated lignin. Expression of these genes during wheat straw solid-state fermentation was shown to correlate with the release of compounds associated with lignin decomposition. The results suggest that both IR enzymes mediate a non-enzymatic depolymerisation of lignocellulose and highlight the potential of chelator-mediated Fenton systems in the industrial pre-treatment of biomass