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/1
负责人：
David Jonathan Leak
金额：
$ 68.78万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FI00534X%2F1
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.

有很多原因为什么必须将化石燃料的替代品作为能源和化学物质的来源。直接关注的是化石燃料对温室气体积聚做出的主要贡献。尽管电站可能通过碳捕获来解决这一问题，但对于分布式系统（例如运输和化学物质），这是不可行的。因此，有很强的动力可以找到可再生的液体燃料和化学物质来源。目前，正在使用从玉米或小麦淀粉获得的葡萄糖来解决这，这对食物的淀粉价格产生了负面影响。我们迫切需要找到方法来使用在木质材料和草（木质纤维素）中发现的更丰富的碳水化合物，无论是生长的目的还是废物。但是，目前这是不经济的，这主要是由于从树林和草中释放有用的碳水化合物的成本（预处理）。该项目将通过探索称为“合并生物处理”（CBP）的方法的好处来解决预处理的经济学。当前的方法依靠酸或碱分解木质素和/或某些在木质材料中发现的碳水化合物的长链（聚合物），然后用酶鸡尾酒处理，通常称为纤维素酶，通常称为纤维素酶，但通常含有复杂的酶活性混合物，以产生单体级别的碳水化合物。这些纤维素酶通常是从两个主要酶生产商之一中购买的，并为该过程增加了巨大的成本和温室气体的贡献。 CBP的概念设想，产生所需的最终产品的微生物还产生了分解碳水化合物聚合物所需的一些/所有酶，从而降低了这些额外的成本。为了能够在该程序的时间尺度内研究CBP的益处和缺点，我们打算与一组称为Geobacillus SPP的细菌配合使用，这些细菌在50-70oC温度范围内生长最佳，并且已经具有使用来自聚合物降解的一些中间体。通过这种方式，我们只需要在有限的新型活动中进行设计，并且我们已经拥有包含我们需要的相关其他酶促活动的遗传工具和生物。该项目将着重于使用Miscanthus，这是美国和欧洲正在考虑的高产草作为目的木质纤维素原料。这将通过两种已建立的方法预先处理，这些方法将聚合物碳水化合物在很大程度上完好无损，但会破坏木质素。为CBP构建合适的细菌菌株后，目的是生成信息，使我们在大规模运行时可以判断该过程的实际和经济学。这将在很大程度上通过基于从小规模操作收集的信息以及应用适当扩大标准的信息来完成。将检查诸如在发酵过程中包括大量固体以及产生额外酶的“成本”之类的因素。由于CBP仍然很大程度上是一个概念，因此有许多过程开发领域可能会影响整体实用性和经济学，需要在项目期间解决。通过这样做，我们打算对CBP的实用性进行首次真正的评估，并就需要进一步改进的领域进行准则。