SBIR Phase I: One-step Production of Lactic Acid from Lignocellulosic Biomass by Recombinant Cellulolytic Bacillus subtilis

这个小型企业创新研究第一阶段项目将开发一个新的超低成本平台，通过使用一种新型的重组纤维素分解枯草芽孢杆菌菌株，直接从经过预处理的木质纤维生物质中一步生产乳酸。乳酸是环境友好的可生物降解塑料聚乳酸的前体。目前，乳酸的商业生产是以玉米淀粉或蔗糖为基础的细菌发酵，这些玉米淀粉或蔗糖是食品和动物饲料。纤维素生物质是最丰富的天然可再生资源，在生产具有短期和长期可持续性的有价值的生物商品方面具有巨大的潜力。然而，将非食用木质纤维原料转化为乳酸的方法还不可行，这是因为纤维素酶的成本很高，而且还需要使用挑剔的培养液。本项目通过系统工程和代谢工程，将枯草芽孢杆菌转化为高效利用木质纤维的枯草芽孢杆菌，并高产高效生产乳酸，适合工业化发酵。本项目更广泛的影响/商业潜力在于，所提出的重组纤维素分解枯草杆菌将是一种超低成本的非食用生物质生产乳酸的平台，与其他正在开发中的CBP微生物相比具有明显的优势。此外，这一努力将作为一个模式系统，将其他工业上重要的微生物转化为纤维素利用率，并导致使用可再生和更便宜的基质来生产有价值的产品。乳酸被美国能源部确定为由生物质制成的30种最具附加值和潜在建筑材料的化学品之一。乳酸有许多潜在的衍生物，其中一些是新的化学产品，另一些是目前从石油中生产的化学品的生物基替代品。鉴于对环保包装的需求不断上升，乳酸用于制造可生物降解的聚乳酸的使用量正在迅速增长。与生产石油塑料相比，生产解放军释放的有毒物质更少，消耗的能源更少，排放的温室气体估计少三分之二。聚乳酸可以堆肥、焚烧或回收利用。毫无疑问，乳酸衍生的可生物降解塑料产品的消费将减少日益严重的环境污染，并吸引更多的消费者对使用绿色产品的兴趣。

This Small Business Innovation Research Phase I project will develop a new ultra-low-cost platform for the production of lactic acid directly from pretreated lignocellulosic biomass in a single step by using a novel recombinant cellulolytic Bacillus subtilis strain. Lactic acid is the precursor of polylactic acid (PLA), an environmentally friendly biodegradable plastic. Currently, lactic acid is commercially produced through bacterial fermentation based on corn starch or cane sugar, which are food and animal feed. Cellulosic biomass is the most abundant natural renewable resource, which has great potential in the production of valuable biocommodities for both short- and long-term sustainability. However, the process for converting non-food lignocellulosic material into lactic acid is not feasible yet due to the high cost of cellulase involved in cellulose hydrolysis and also to the use of fastidious culture media. Through the systematic genetic engineering and metabolic engineering, this project will convert noncellulose- utilizing B. subtilis to an efficient lignocellulose utilizer and to produce lactic acid at high yield and titer, suitable for industrial fermentation.The broader impact/commercial potential of this project is that the proposed recombinant cellulolytic B. subtilis would be an ultra-low-cost platform for producing lactic acid from non-food biomass, with obvious advantages over other developing CBP microorganisms. Also, this effort would serve as a model system to convert other industrially important microorganisms into cellulose utilizers and result in use of renewable and less expensive substrates for the production of valuable products. Lactic acid was identified by the U.S. DOE as one of the top 30 value-added and potential buildingblock chemicals made from biomass. There are many potential derivatives of lactic acid, some of which are new chemical products and others represent biobased alternatives to chemicals currently produced from petroleum. The use of lactic acid for making biodegradable PLA is growing rapidly, given the rising demand for environmentally friendly packaging. The production of PLA releases fewer toxic substances than making petroleum plastic, consumes less energy, and releases an estimated two-thirds less greenhouse gas. PLA can be composted, incinerated or recycled. There is no doubt that the consumption of the biodegradable plastic products derived from lactic acid would decrease the growing environmental pollution and attract greater consumer interest towards the use of green products.