权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Evaluation of consolidated bioprocessing as a strategy for production of fuels and chemicals from lignocellulose

综合生物加工作为木质纤维素生产燃料和化学品策略的评估

基本信息

批准号：
BB/I00534X/2
负责人：
David Jonathan Leak
金额：
$ 41.17万
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FI00534X%2F2
关键词：
Evaluation consolidated bioprocessing strategy production

项目摘要

There are a number of reasons why it is imperative to look at alternatives to fossil fuels as sources of energy and chemicals. Of immediate concern is the major contribution that the burning of fossil fuels is making to greenhouse gas accumulation. While power stations might address this through carbon capture, this is not feasible for distributed systems such as transport and chemicals. Therefore, there is a strong drive to find renewable sources of liquid fuels and chemicals. Currently, this is being addressed using glucose obtained from maize or wheat starch, which is having a negative impact on the price of starch for food. We urgently need to find ways to use the more abundant carbohydrates found in woody material and grasses (lignocellulose), either purpose grown or as wastes. However, this is currently uneconomic due mainly to the cost of releasing the useful carbohydrate from woods and grasses (pre-treatment). This project will address the economics of pre-treatment by exploring the benefits of an approach called 'Consolidated Bioprocessing' (CBP). Current methods rely on acids or alkalis to break down either the lignin and/or some of the long chains (polymers) of carbohydrates found in woody material, followed by treatment with enzyme cocktails, generally referred to as cellulases, but typically containing a complex mixture of enzyme activities, to produce monomeric carbohydrates. These cellulases are typically bought from one of the two major enzyme producers and add a significant cost and greenhouse gas contribution to the process. The concept of CBP envisages that the micro-organism that produces the desired end-product also produces some/all of the enzymes necessary to break down the carbohydrate polymers, so reducing these additional costs. In order to be able to investigate the benefits and disadvantages of CBP within the timescale of the programme we intend to work with a group of bacteria known as Geobacillus spp which grow best in the 50-70oC temperature range and already have the ability to use some of the intermediates produced from polymer degradation. In this way we should only have to engineer in a limited array of novel activities, and we already have the genetic tools and organisms containing the relevant additional enzymatic activities that we require. The project will focus on using miscanthus, a high-yielding grass under consideration in the USA and Europe as a purpose-grown lignocellulosic feedstock. This will be pre-treated by two established methods that leave the polymeric carbohydrates largely intact but disrupt the lignin. Having constructed suitable bacterial strains for CBP the intention is to generate information that allows us to judge the practically and economics of the process when operated at a large scale. This will be done largely by generating models, based on information gathered from small scale operations, and applying appropriate scaling-up criteria. Factors such as the consequence of including significant amounts of solids in the fermentation process and the 'cost' to the organism of producing extra enzymes will be examined. Because CBP is still largely a concept, there are a number of areas of process development which may impact overall practicality and economics which will need to be addressed during the project. By doing this we intend to produce the first genuine assessment of the practicalities of CBP and guidelines on areas that may need further improvement.

有许多理由表明，有必要将化石燃料的替代品视为能源和化学品的来源。眼下令人关切的是，化石燃料的燃烧对温室气体积累的主要贡献。虽然发电站可以通过碳捕获来解决这个问题，但对于运输和化学品等分布式系统来说，这是不可行的。因此，人们强烈要求寻找可再生的液体燃料和化学品来源。目前，正在使用从玉米或小麦淀粉中获得的葡萄糖来解决这一问题，这对食品淀粉的价格产生了负面影响。我们迫切需要找到方法来利用在木质材料和草本植物(木质纤维素)中发现的更丰富的碳水化合物，无论是专门种植的还是作为废物使用。然而，目前这是不经济的，主要是因为从木材和草中释放有用的碳水化合物的成本(前处理)。这个项目将通过探索一种名为“联合生物处理”(CBP)的方法的好处来解决前处理的经济学问题。目前的方法依赖于酸或碱来分解木质材料中的木质素和/或碳水化合物的一些长链(聚合物)，然后用酶鸡尾酒处理，通常称为纤维素酶，但通常包含复杂的酶活性混合物，以产生单体碳水化合物。这些纤维素酶通常从两大酶生产商中的一家购买，并为这一过程增加了显著的成本和温室气体贡献。CBP的概念设想，产生所需最终产品的微生物也会产生分解碳水化合物聚合物所需的部分/全部酶，从而降低这些额外成本。为了能够在计划的时间范围内调查CBP的优点和缺点，我们打算与一组被称为地杆菌的细菌合作，这些细菌在50-70oC的温度范围内生长得最好，并且已经有能力使用从聚合物降解产生的一些中间体。通过这种方式，我们应该只需要设计一系列有限的新活性，我们已经拥有了包含我们所需的相关额外酶活性的基因工具和生物体。该项目将重点使用芒草，一种在美国和欧洲正在考虑的高产牧草，作为一种专门种植的木质纤维原料。这将通过两种既定的方法进行预处理，这两种方法使聚合碳水化合物基本保持不变，但会破坏木质素。在为CBP构建了合适的细菌菌株后，目的是产生信息，使我们能够判断该过程在大规模运行时的实用性和经济性。这在很大程度上将通过根据从小规模业务收集的信息生成模型并应用适当的放大标准来完成。这些因素包括在发酵过程中加入大量固体物质的后果，以及生产额外酶对生物体的“成本”。由于CBP在很大程度上仍是一个概念，有许多工艺开发领域可能会影响总体实用性和经济性，因此需要在项目期间加以解决。通过这样做，我们打算对CBP的实用性进行第一次真正的评估，并就可能需要进一步改进的领域制定指导方针。