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News and Trends
http://www.biotechnologyforbiofuels.com/content/pdf/1754-6834-3-4.pdf Enzymatic hydrolysis (sometimes called "enzymatic saccharification) is a pretreatment method for breaking-down (i.e., "hydrolyzing") the cellulose molecules in cellulosic-biomass feedstocks, into their component simple sugars (glucose). The glucose is subsequently fermented to biofuel-grade "cellulose-ethanol". A class of enzymes, called "cellulases", is applied to achieve enzymatic hydrolysis. The effectiveness of cellulases is usually limited by the inaccessibility of a large portion of cellulose molecules that lie "buried within the highly ordered and tightly packed fibrillar architecture of the cellulose microfibrils". The enzymes cannot attack these inaccessible portions. The initial stage in the enzymatic hydrolysis of cellulose is called "amorphogenesis", and it is usually characterized by "fiber swelling and fragmentation of cellulose aggregations into short fibers". Amorphogenesis is desirable for increasing the accessibility of cellulose to enzymatic attack. Certain types of proteins have been found to be good "amorphogenesis-inducing agents"; they disrupt the tight cellulose packing in a non-hydrolytic manner and enhance cellulose accessibility. Scientists from the Faculty of Forestry, University of British Columbia (Canada), recently published a review paper on amorphogenesis. They briefly outlined the the structural arrangement of cellulose in the fibrillar architecture, and an overview of "amorphogenesis-inducing agents and their interactions with cellulose". The paper appears in the open access journal, Biotechnology for Biofuels (URL above)..
http://springerlink.com/content/55v5686233623q10/fulltext.pdf A collaborative group of scientists from Michigan State University, York University, Ohio State University and the American Museum of Natural History (United States) report the comparison of beneficial insect populations in three types of biofuel crops: corn, switchgrass and mixed native prairie (native grasses and wildflowers). They tested the hypothesis that "biofuel crops comprising more diverse plant communities would support increased levels of beneficial insects". Among the highlights of the study are: (1) bees were more abundant in switchgrass and prairie than in corn, (2) during the July sampling period, switchgrass and prairie had a higher "richness in bee species", compared to corn, (3) "beneficial insects generally responded positively to the increased vegetational diversity of prairie and switchgrass sites; however, when managed as a dedicated biofuel crop, plant and arthropod diversity may decrease. The report is published in the BioEnergy Research journal (URL above). Energy Crops and Feedstocks for Biofuels Production
http://www.tees.ac.uk/sections/news/pressreleases_story.cfm?story_id=3311&this_issue_title=February%202010&this_issue=201 Since 2004, Teesside University scientists (United Kingdom) under the BioReGen (Biomass, Remediation, re-Generation) project, have been researching on plants which can be suitably cultivated in brownfield sites (abandoned land areas which have been previously used for industrial purposes, most often contaminated by hazardous wastes). They have recently reported that reed canary grass was suitable, "because it grows well on poor soils and contaminated industrial sites". It could also be used as "an excellent fuel for biomass power stations and, on a smaller scale, boilers in buildings like schools". The grass, which can be processed into fuel pellets or fuel bricks, reportedly burns well, and does not add to greenhouse gases. More importantly, "reed canary grass produces a good, clean fuel without picking-up contamination from the soil", according to Dr. Richard Lord, leader in Environmental Geochemistry and Sustainability. The other test plants included willow trees, miscanthus, and switchgrass.. http://www3.interscience.wiley.com/cgi-bin/fulltext/123294315/PDFSTART A recent paper by Alessandro Waclawosky from the Departamento de Bioquímica, Instituto de Química (Brazil) and co-scientists from the Hawaii Agriculture Research Center (United States) reviewed some studies of "sugarcane genes associated with sucrose content, biomass and cell wall metabolism and the preliminary physiological characterization of cultivars that contrast for sugar and biomass yield". In many countries, sugarcane has been eyed as a potential feedstock for biofuel ethanol. It possesses many attributes of a good biofuel feedstock among which are: good yields, low agricultural inputs, and good carbon, as well as energy balance. The lignocellulosic residues (stalks, leaves) after harvest are also potential raw materials for cellulose-ethanol (a "second generation" biofuel ethanol). The review covers the theoretical yield potential of sugarcane, breeding of sugarcane, molecular resources for sugarcane improvement, physiology/regulation of sucrose accumulation, molecular biology studies targeting the sugarcane cell wall, and future prospects. The paper is published in the Plant Biotechnology Journal (URL above).. Biofuels Processing
http://pubs.acs.org/doi/abs/10.1021/ef9013373 Scientists from the Department of Chemistry and the Bioenergy Research Group at the University of California Davis (United States) have developed a biodiesel production process which maximizes the use of the whole oilseed for biodiesel production. Conventional biodiesel production usually involves the (mechanical or chemical) extraction of the oil (the "lipid" component) from the seed, and then converting the oil into biodiesel by a process called, "transesterification". The carbohydrate (cellulosic) residue of the oilseed (after oil extraction) is often discarded. The patented process developed by Mark Mascal and Edward B. Nikitin utilizes both the oil and residue of the seeds by reacting them with aqueous hydrochloric acid and 1,2-dichloroethane in a biphasic reactor, and heating the mixture to 80°C for 3 hours. The seed oil is released intact, while the cellulosic portion of the seed is converted into a compound called 5-(chloromethyl) furfural (CMF). The oil-CMF mixture can then be subjected to another process called, "ethanolysis" to give a "hybrid biodiesel cocktail" of ethyl levulinate (a levulinic acid ethyl ester) and biodiesel ethyl ester . "Levulinate esters are short-chain oxygenates, which can be blended with diesel fuel and may improve its cold-performance properties". The results of the research are published in the Energy and Fuels journal..
http://www3.interscience.wiley.com/journal/123239181/abstract Scientists from the University of Central Florida (United States) report the use of plant-derived enzyme cocktails for the bioconversion of lignocellulosic biomass to ethanol-fermentable sugars. Enzymes are usually used to degrade various polymers in plant biomass, and the use of "cocktails" enables a more broad-spectrum versatility for the degradation of a wide variety of plant-biomass feedstocks. For example, waste orange peels would need more of the pectinase enzyme, and wood would require more of the xylanase enzyme. The interesting point about the research is that enzyme production is "plant-based" (i.e., genes for the production of the enzymes are expressed in a cultivated plant). Traditionally, microorganisms have been used as workhorses for enzyme production. The research team, headed by Henry Daniell, cloned genes from wood-rotting fungi or bacteria and produced enzymes in tobacco plants. Tobacco was used as the model plant for the following reasons: (1) is it not a food crop, (2) it produces large amounts of energy per hectare, and (3) it provides an alternative use for the tobacco plant (i.e., smoking). Internationally renowned crop and soil scientist, Professor Mariam Sticklen says that "Dr. Henry Daniell's team's success in producing a combination of several cell wall degrading enzymes in plants using chloroplast transgenesis is a great achievement". The results of the research are published in the Plant Biotechnology Journal (URL above).. |
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