Sweet Sorghum Juice and Bagasse as Feedstocks for the Production of Optically Pure Lactic Acid by Native and Engineered <em>Bacillus coagulans</em> Strains [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 662.7 Coke and charcoal
• Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Energy Efficiency and Renewable Energy ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2015
• Mô tả vật lý: Size: p. 123-131 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 263627
• Chủ đề: 1. 09 biomass fuels; 2. Bacillus coagulans; 3. Fermentation; 4. Lactic acid; 5. Sorghumbicolor

Tóm tắt

 Sweet sorghum is a bioenergy crop that produces large amounts of soluble sugars in its stems (3-7 Mg. ha-1) and generates significant amounts of bagasse (15-20 Mg .ha-1) as a lignocellulosic feedstock. These sugars can be fermented to biofuels, but also to bio-based chemicals. The market potential of the latter may be higher given the current prices of petroleum and natural gas. The yield and rate of production of optically pure D-(-)- and L-(+)-lactic acid as precursors for the bio-degradable plastic polylactide was optimized for two thermotolerant Bacillus coagulans strains. Strain 36D1 fermented the sugars in unsterilized sweet sorghum juice -1 -1 -1 at 50�C to L-(+)-lactic acid (~150 g .L
  productivity, 7.2 g .L .h ). B. coagulans strain QZ19- 2 was used to ferment sorghum juice to D-(-)-lactic acid (~125 g .L Carbohydrates in the sorghum bagasse were also fermented after pretreatment with 0.5% phosphoric acid at 190�C for 5 min. Simultaneous saccharification and co-fermentation of all the sugars (SScF) by B. coagulans resulted in a conversion of 80% of available carbohydrates to optically pure lactic acid depending on the B. coagulans strain used as the microbial biocatalyst. Liquefaction of pre-treated bagasse with cellulases before SScF (L+SScF) increased the productivity of lactic acid. These results show that B. coagulans is an effective biocatalyst for fermentation of all the sugars present in sweet sorghum juice and bagasse to optically pure lactic acid at high titer and productivity as feedstock for bio-based plastics.