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

该小型企业创新研究第一阶段项目将开发一种新的超低成本平台，通过使用新型重组纤维素分解枯草芽孢杆菌菌株，一步直接从预处理的木质纤维素生物质中生产乳酸。乳酸是聚乳酸（PLA）的前体，聚乳酸是一种环境友好的可生物降解塑料。目前，商业上通过基于玉米淀粉或蔗糖的细菌发酵来生产乳酸，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自然可再生资源，在生产短期和长期可持续的有价值的生物商品方面具有巨大潜力。然而，将非食品木质纤维素材料转化为乳酸的方法还不可行，这是由于纤维素水解中涉及的纤维素酶的高成本以及苛刻培养基的使用。本项目将通过系统的基因工程和代谢工程，将非纤维素利用型B转化为非纤维素利用型.枯草芽孢杆菌转化为高效的木质纤维素利用菌，并以高产率和效价生产乳酸，适合于工业发酵。枯草芽孢杆菌将是一个超低成本的平台，从非食品生物质生产乳酸，具有明显的优势，比其他开发CBP微生物。此外，这一努力将作为一个模型系统，将其他工业上重要的微生物转化为纤维素利用者，并导致使用可再生和较便宜的底物生产有价值的产品。乳酸被美国能源部确定为由生物质制成的前30大增值和潜在的建筑砌块化学品之一。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生产的化学品的生物基替代品。由于对环保包装的需求不断增长，乳酸用于制造可生物降解的PLA的使用正在迅速增长。与生产石油塑料相比，生产PLA释放的有毒物质更少，消耗的能源更少，释放的温室气体估计少三分之二。PLA可以堆肥，焚烧或回收。毫无疑问，消费由乳酸衍生的可生物降解塑料产品将减少日益严重的环境污染，并吸引消费者对使用绿色产品的更大兴趣。

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.