GENPLAT(GLBRC酵素のプラットフォーム)は、バイオマスの分解のための酵素カクテルの発見と最適化のための自動化されたプラットフォームです。それは、複数のコンポーネントが含まれている酵素の複数の原料と混合物に適合させることができます。
The high cost of enzymes for biomass deconstruction is a major impediment to the economic conversion of lignocellulosic feedstocks to liquid transportation fuels such as ethanol. We have developed an integrated high throughput platform, called GENPLAT, for the discovery and development of novel enzymes and enzyme cocktails for the release of sugars from diverse pretreatment/biomass combinations. GENPLAT comprises four elements: individual pure enzymes, statistical design of experiments, robotic pipeting of biomass slurries and enzymes, and automated colorimeteric determination of released Glc and Xyl. Individual enzymes are produced by expression in Pichia pastoris or Trichoderma reesei, or by chromatographic purification from commercial cocktails or from extracts of novel microorganisms. Simplex lattice (fractional factorial) mixture models are designed using commercial Design of Experiment statistical software. Enzyme mixtures of high complexity are constructed using robotic pipeting into a 96-well format. The measurement of released Glc and Xyl is automated using enzyme-linked colorimetric assays. Optimized enzyme mixtures containing as many as 16 components have been tested on a variety of feedstock and pretreatment combinations.
GENPLAT is adaptable to mixtures of pure enzymes, mixtures of commercial products (e.g., Accellerase 1000 and Novozyme 188), extracts of novel microbes, or combinations thereof. To make and test mixtures of ˜10 pure enzymes requires less than 100 μg of each protein and fewer than 100 total reactions, when operated at a final total loading of 15 mg protein/g glucan. We use enzymes from several sources. Enzymes can be purified from natural sources such as fungal cultures (e.g., Aspergillus niger, Cochliobolus carbonum, and Galerina marginata), or they can be made by expression of the encoding genes (obtained from the increasing number of microbial genome sequences) in hosts such as E. coli, Pichia pastoris, or a filamentous fungus such as T. reesei. Proteins can also be purified from commercial enzyme cocktails (e.g., Multifect Xylanase, Novozyme 188). An increasing number of pure enzymes, including glycosyl hydrolases, cell wall-active esterases, proteases, and lyases, are available from commercial sources, e.g., Megazyme, Inc. (www.megazyme.com), NZYTech (www.nzytech.com), and PROZOMIX (www.prozomix.com).
Design-Expert software (Stat-Ease, Inc.) is used to create simplex-lattice designs and to analyze responses (in this case, Glc and Xyl release). Mixtures contain 4-20 components, which can vary in proportion between 0 and 100%. Assay points typically include the extreme vertices with a sufficient number of intervening points to generate a valid model. In the terminology of experimental design, most of our studies are “mixture” experiments, meaning that the sum of all components adds to a total fixed protein loading (expressed as mg/g glucan). The number of mixtures in the simplex-lattice depends on both the number of components in the mixture and the degree of polynomial (quadratic or cubic). For example, a 6-component experiment will entail 63 separate reactions with an augmented special cubic model, which can detect three-way interactions, whereas only 23 individual reactions are necessary with an augmented quadratic model. For mixtures containing more than eight components, a quadratic experimental design is more practical, and in our experience such models are usually statistically valid.
All enzyme loadings are expressed as a percentage of the final total loading (which for our experiments is typically 15 mg protein/g glucan). For “core” enzymes, the lower percentage limit is set to 5%. This limit was derived from our experience in which yields of Glc and/or Xyl were very low if any core enzyme was present at 0%. Poor models result from too many samples showing very low Glc or Xyl yields. Setting a lower limit in turn determines an upper limit. That is, for a six-component experiment, if the lower limit for each single component is set to 5%, then the upper limit of each single component will be 75%. The lower limits of all other enzymes considered as “accessory” are set to 0%. “Core” and “accessory” are somewhat arbitrary designations and will differ depending on the substrate, but in our studies the core enzymes for release of Glc from corn stover comprise the following enzymes from T. reesei: CBH1 (also known as Cel7A), CBH2 (Cel6A), EG1(Cel7B), BG (β-glucosidase), EX3 (endo-β1,4-xylanase, GH10), and BX (β-xylosidase).
これは、広く酵素のコストを削減することが経済的なリグノセルロースエタノール産業の発展にとって重要であることが認識されている。現在入手可能な市販の酵素カクテルは、多くのタンパク質(Nagendranら、2009)の複雑で不完全に定義された混合物であり、これらは主に酸で前処理トウモロコシの茎葉上での使用に適合している。優れた酵素カクテルの開発を加速するためには、いくつかの研究室では、酵素の発見と特性評価のためのハイスループットプラットフォームを開発しました。 。。デッカーらロボットの酵素とバイオマススラリーの調剤、実験の統計的設計、および/またはグルコースの自動測定とXYL(ベルリンら、2007:この地域での取り組みもGENPLATで見つかった次のプロパティの一つ以上を組み込んでいますら、2009;。Kimら、1998;。キングら、2009)。。 GENPLATはに最大で6つのコンポーネントから分析することができる酵素の混合物の複雑さで最も大きく、これらの以前の取り組みを拡張する私たちの最新作で16個以上の初期の研究(バネルジーら、2010C)。穏やかに転倒回転による消化中に混合;とGluとXYLの自動比色定量GENPLATのその他の主要機能は、調剤中に中断された茎葉のスラリーを保つことができるビーズ混合室の使用(パドルの貯水池)です。
The authors have nothing to disclose.
この作品は、エネルギー五大湖バイオエネルギー研究センター(科学BER DE – FC02 – 07ER64494のDOE事務所)と米国エネルギー省、基礎エネルギー科学のオフィスからの助成金DE – FG02 – 91ER200021、部門の米国エネルギー省の一部で賄われていた化学科学、地球科学と生命科学。我々は彼らの材料と概念的な貢献のためにジョンスコットクレイグとメリッサBorruschに感謝。
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