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Recently, researchers from the U.S. Department of Energy and the Institute of Bioenergy Research have for the first time produced Escherichia coli bacteria capable of digesting switchgrass biomass through genetic engineering, converting the sugars into alternatives to gasoline, diesel and aviation fuel. Three advanced bioenergy sources for transportation fuels, and no need to add any enzymes. Related papers were published in the Proceedings of the National Academy of Sciences.
Normal Escherichia coli could not grow on switchgrass, but the researchers engineered the bacteria so that it can express a variety of enzymes that can digest cellulose or hemicellulose to survive. Escherichia coli that breaks down cellulose and hemicellulose can also be co-cultured on switchgrass and further designed into three metabolic pathways that allow them to produce fuel substitutes or prophase molecules suitable for gasoline, diesel, and aero engines. This is the first demonstration that Escherichia can produce these three forms of transportation fuel.
In addition, since cellulose and hemicellulose in plants are difficult to extract, the researchers used an ionic liquid (melted salt) to pretreat the biomass to dissolve it, and then Escherichia coli digested the dissolved biomass. Produce hydrocarbons with petroleum fuel properties.
Lead author of the paper and Gregory Borkinski, a postdoctoral fellow at the Joint BioEnergy Institute, explained that pretreatment of switchgrass with ionic liquids is indispensable. They are a combination of ionic liquid pretreatment and transgenic Escherichia coli. .
Advanced fuels processed from non-food crops and agricultural waste cellulose are considered to be the best renewable liquid transport fuels available for current engines and infrastructure, but the biggest hurdle is the high cost and difficulty in competing with other fuels. “We can reduce the cost of the largest part of the process – adding enzymes to depolymerize cellulose and hemicellulose into fermentable sugars, and combining the two steps into one can reduce fuel production costs and produce advanced materials for lignocellulosic materials. Biofuels opens the door," said Jay Keslin, CEO of the Joint BioEnergy Institute, which is responsible for the study.
The research team is also further studying how to increase the output of synthetic fuels. Boginsky said: "We already have a fuel product route and can get higher yields than we have demonstrated so far. We also need to find an enzyme that can be secreted by Escherichia coli, while also digesting more The ionic liquid-treated biomass, or the modified ionic liquid pretreatment step, makes it easier to digest."
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(1) are generally made of carbonized carbon steel (accounting for 99% of total production). It can also be made of stainless steel or non-ferrous metals.
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(3) The product surface hardness is high, the core toughness is good. That is, "soft inside strong outside". This is a major feature of tapping Screw performance requirements. If the surface hardness is low, it can not be screwed into the matrix; If the core toughness is poor, a twist will break, can not be used. So "inside soft outside steel" is self-tapping screw to meet the use of performance, very important requirements.
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