High levels of variation in Salix lignocellulose genes revealed using poplar genomic resources

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Background:
Little is known about the levels of variation in lignin or other wood related genes in Salix, a genus that is being increasingly used for biomass and biofuel production. The lignin biosynthesis pathway is well characterized in a number of species, including the model tree Populus. We aimed to transfer the genomic resources already available in Populus to its sister genus Salix to assess levels of variation within genes involved in wood formation.
Results:
Amplification trials for 27 gene regions were undertaken in 40 Salix taxa. Twelve of these regions were sequenced. Alignment searches of the resulting sequences against reference databases, combined with phylogenetic analyses, showed the close similarity of these Salix sequences to Populus, confirming homology of the primer regions and indicating a high level of conservation within the wood formation genes. However, all sequences were found to vary considerably among Salix species, mainly as SNPs with a smaller number of insertions-deletions. Between 25 and 176 SNPs per kbp per gene region (in predicted exons) were discovered within Salix.
Conclusions:
The variation found is sizeable but not unexpected as it is based on interspecific and not intraspecific comparison; it is comparable to interspecific variation in Populus. The characterisation of genetic variation is a key process in pre-breeding and for the conservation and exploitation of genetic resources in Salix. This study characterises the variation in several lignocellulose gene markers for such purposes.Source:
http://www.biotechnologyforbiofuels.com/content/6/1/114

The synergistic action of accessory enzymes enhances the hydrolytic potential of a ¿cellulase mixture¿ but is highly substrate specific

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Background:
Currently, the amount of protein/enzyme required to achieve effective cellulose hydrolysis is still too high. One way to reduce the amount of protein/enzyme required is to formulate a more efficient enzyme cocktail by adding so-called accessory enzymes such as xylanase, lytic polysaccharide monooxygenase (AA9, formerly known as GH61), etc., to the cellulase mixture. Previous work has shown the strong synergism that can occur between cellulase and xylanase mixtures during the hydrolysis of steam pretreated corn stover, requiring lower protein loading to achieve effective hydrolysis. However, relatively high loadings of xylanases were required. When family 10 and 11 endo-xylanases and family 5 xyloglucanase were supplemented to a commercial cellulase mixture varying degrees of improved hydrolysis over a range of pretreated, lignocellulosic substrates were observed.
Results:
The potential synergistic interactions between cellulase monocomponents and hemicellulases from family 10 and 11 endo-xylanases (GH10 EX and GH11 EX) and family 5 xyloglucanase (GH5 XG), during hydrolysis of various steam pretreated lignocellulosic substrates, were assessed. It was apparent that the hydrolytic activity of cellulase monocomponents was enhanced by the addition of accessory enzymes although the “boosting” effect was highly substrate specific. The GH10 EX and GH5 XG both exhibited broad substrate specificity and showed strong synergistic interaction with the cellulases when added individually. The GH10 EX was more effective on steam pretreated agriculture residues and hardwood substrates whereas GH5 XG addition was more effective on softwood substrates. The synergistic interaction between GH10 EX and GH5 XG when added together further enhanced the hydrolytic activity of the cellulase enzymes over a range of pretreated lignocellulosic substrates. GH10 EX addition could also stimulate further cellulose hydrolysis when added to the hydrolysis reactions when the rate of hydrolysis had levelled off.
Conclusions:
Endo-xylanases and xyloglucanases interacted synergistically with cellulases to improve the hydrolysis of a range of pretreated lignocellulosic substrates. However, the extent of improved hydrolysis was highly substrate dependent. It appears that those accessory enzymes, such as GH10 EX and GH5 XG, with broader substrate specificities promoted the greatest improvements in the hydrolytic performance of the cellulase mixture on all of the pretreated biomass substrates.Source:
http://www.biotechnologyforbiofuels.com/content/6/1/112

Journal of Petroleum

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Journal of Petroleum Environmental Biotechnology OMICS Publishing Group
This video is by OMICS Publishing Group of Applied mechanics which is a branch of the physical sciences dealing with the practical application of mechanics. ...

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Journal of Petroleum

The synergistic action of accessory enzymes enhances the hydrolytic potential of a "cellulase mixture" but is highly substrate specific

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Background:
Currently, the amount of protein/enzyme required to achieve effective cellulose hydrolysis is still too high. One way to reduce the amount of protein/enzyme required is to formulate a more efficient enzyme cocktail by adding so-called accessory enzymes such as xylanase, lytic polysaccharide monooxygenase (AA9, formerly known as GH61), etc., to the cellulase mixture. Previous work has shown the strong synergism that can occur between cellulase and xylanase mixtures during the hydrolysis of steam pretreated corn stover, requiring lower protein loading to achieve effective hydrolysis. However, relatively high loadings of xylanases were required. When family 10 and 11 endo-xylanases and family 5 xyloglucanase were supplemented to a commercial cellulase mixture varying degrees of improved hydrolysis over a range of pretreated, lignocellulosic substrates were observed.
Results:
The potential synergistic interactions between cellulase monocomponents and hemicellulases from family 10 and 11 endo-xylanases (GH10 EX and GH11 EX) and family 5 xyloglucanase (GH5 XG), during hydrolysis of various steam pretreated lignocellulosic substrates, were assessed. It was apparent that the hydrolytic activity of cellulase monocomponents was enhanced by the addition of accessory enzymes although the "boosting" effect was highly substrate specific. The GH10 EX and GH5 XG both exhibited broad substrate specificity and showed strong synergistic interaction with the cellulases when added individually. The GH10 EX was more effective on steam pretreated agriculture residues and hardwood substrates whereas GH5 XG addition was more effective on softwood substrates. The synergistic interaction between GH10 EX and GH5 XG when added together further enhanced the hydrolytic activity of the cellulase enzymes over a range of pretreated lignocellulosic substrates. GH10 EX addition could also stimulate further cellulose hydrolysis when added to the hydrolysis reactions when the rate of hydrolysis had levelled off.
Conclusions:
Endo-xylanases and xyloglucanases interacted synergistically with cellulases to improve the hydrolysis of a range of pretreated lignocellulosic substrates. However, the extent of improved hydrolysis was highly substrate dependent. It appears that those accessory enzymes, such as GH10 EX and GH5 XG, with broader substrate specificities promoted the greatest improvements in the hydrolytic performance of the cellulase mixture on all of the pretreated biomass substrates.Source:
http://www.biotechnologyforbiofuels.com/content/6/1/112

Phenotypic selection of a wild Saccharomyces cerevisiae strain for simultaneous saccharification and co-fermentation of AFEX¿ pretreated corn stover

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Background:
Simultaneous saccharification and co-fermentation (SSCF) process involves enzymatic hydrolysis of pretreated lignocellulosic biomass and fermentation of glucose and xylose in one bioreactor. The optimal temperatures for enzymatic hydrolysis are higher than the standard fermentation temperature of ethanologenic Saccharomyces cerevisiae. Moreover, degradation products resulting from biomass pretreatment impair fermentation of sugars, especially xylose, and can synergize with high temperature stress. One approach to resolve both concerns is to utilize a strain background with innate tolerance to both elevated temperatures and degradation products.
Results:
In this study, we screened a panel of 108 wild and domesticated Saccharomyces cerevisiae strains isolated from a wide range of environmental niches. One wild strain was selected based on its growth tolerance to simultaneous elevated temperature and AFEX™ (Ammonia Fiber Expansion) degradation products. After engineering the strain with two copies of the Scheffersomyces stipitis xylose reductase, xylitol dehydrogenase and xylulokinase genes, we compared the ability of this engineered strain to the benchmark 424A(LNH-ST) strain in ethanol production and xylose fermentation in standard lab medium and AFEX pretreated corn stover (ACS) hydrolysates, as well as in SSCF of ACS at different temperatures. In SSCF of 9% (w/w) glucan loading ACS at 35°C, the engineered strain showed higher cell viabilities and produced a similar amount of ethanol (51.3 g/L) compared to the benchmark 424A(LNH-ST) strain.
Conclusion:
These results validate our approach in the selection of wild Saccharomyces cerevisiae strains with thermo-tolerance and degradation products tolerance properties for lignocellulosic biofuel production. The wild and domesticated yeast strains phenotyped in this work are publically available for others to use as genetic backgrounds for fermentation of their pretreated biomass at elevated temperatures.Source:
http://www.biotechnologyforbiofuels.com/content/6/1/108

The fate of lignin during hydrothermal pretreatment

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Background:
Effective enzymatic hydrolysis of lignocellulosic biomass benefits from lignin removal, relocation, and/or modification during hydrothermal pretreatment. Phase transition, depolymerization/repolymerization, and solubility effects may all influence these lignin changes. To better understand how lignin is altered, Populus trichocarpa x P. deltoides wood samples and cellulolytic enzyme lignin (CEL) isolated from P. trichocarpa x P. deltoides were subjected to batch and flowthrough pretreatments. The residual solids and liquid hydrolysate were characterized by gel permeation chromatography, heteronuclear single quantum coherence NMR, compositional analysis, and gas chromatography--mass spectrometry.
Results:
Changes in the structure of the solids recovered after the pretreatment of CEL and the production of aromatic monomers point strongly to depolymerization and condensation being primary mechanisms for lignin extraction and redeposition. The differences in lignin removal and phenolic compound production from native P. trichocarpa x P. deltoides and CEL suggested that lignin-carbohydrate interactions increased lignin extraction and the extractability of syringyl groups relative to guaiacyl groups.
Conclusions:
These insights into delignification during hydrothermal pretreatment point to desirable pretreatment strategies and plant modifications. Because depolymerization followed by repolymerization appears to be the dominant mode of lignin modification, limiting the residence time of depolymerized lignin moieties in the bulk liquid phase should reduce lignin content in pretreated biomass. In addition, the increase in lignin removal in the presence of polysaccharides suggests that increasing lignin-carbohydrate cross-links in biomass would increase delignification during pretreatment.Source:
http://www.biotechnologyforbiofuels.com/content/6/1/110

The production and characterization of a new active lipase from Acremonium alcalophilum using a plant bioreactor

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Background:
Microorganisms are the most proficient decomposers in nature, using secreted enzymes in the hydrolysis of lignocellulose. As such, they present the most abundant source for discovery of new enzymes. Acremonium alcalophilum is the only known cellulolytic fungus that thrives in alkaline conditions and can be cultured readily in the laboratory. Its optimal conditions for growth are 30[degree sign]C and pH 9.0-9.2. The genome sequence of Acremonium alcalophilum, has revealed a large number of genes encoding biomass-degrading enzymes. Among these enzymes, lipases are interesting because of several industrial applications including biofuels, detergent, food processing and textile industries.
Results:
We identified a lipA gene in the genome sequence of Acremonium alcalophilum, encoding a protein with a predicted lipase domain with weak sequence identity to characterized enzymes. Unusually, the predicted lipase displays [almost equal to] 30% amino acid sequence identity to both characterized feruloyl esterase and lipase of Aspergillus niger. The protein LipA, when transiently produced in Nicotiana benthamiana, accumulated to over 9% of total soluble protein. Plant-produced recombinant LipA is active towards p-nitrophenol esters of various carbon chain lengths with peak activity on medium-chain fatty acid (C8). The enzyme is also highly active on xylose tetra-acetate and oat spelt xylan. These results suggests that LipA is a novel lipolytic enzyme that possesses both lipase and acetylxylan esterase activity. We determined that LipA is a glycoprotein with pH and temperature optima at 8.0 and 40[degree sign]C, respectively.
Conclusion:
Besides being the first heterologous expression and characterization of a gene coding for a lipase from A. alcalophilum, this report shows that LipA is very versatile exhibiting both acetylxylan esterase and lipase activities potentially useful for diverse industry sectors, and that tobacco is a suitable bioreactor for producing fungal proteins.Source:
http://www.biotechnologyforbiofuels.com/content/6/1/111

Andrew Jack introduces the 2013 FT Global Pharmaceutical and Biotechnology Conference – Video

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Andrew Jack introduces the 2013 FT Global Pharmaceutical and Biotechnology Conference
https://www.ft-live.com/pharmabio The FT Global Pharmaceutical and Biotechnology Conference is Europe #39;s pre-eminent industry event attended by leading execut...

By: FTGlobalConferences

Link:
Andrew Jack introduces the 2013 FT Global Pharmaceutical and Biotechnology Conference - Video