Escherichia coli binary culture engineered for direct fermentation of hemicellulose to a biofuel.
نویسندگان
چکیده
Metabolic engineering has created several Escherichia coli biocatalysts for production of biofuels and other useful molecules. However, the inability of these biocatalysts to directly use polymeric substrates necessitates costly pretreatment and enzymatic hydrolysis prior to fermentation. Consolidated bioprocessing has the potential to simplify the process by combining enzyme production, hydrolysis, and fermentation into a single step but requires a fermenting organism to multitask by producing both necessary enzymes and target molecules. We demonstrate here a binary strategy for consolidated bioprocessing of xylan, a complex substrate requiring six hemicellulases for complete hydrolysis. An integrated modular approach was used to design the two strains to function cooperatively in the process of transforming xylan into ethanol. The first strain was engineered to coexpress two hemicellulases. Recombinant enzymes were secreted to the growth medium by a method of lpp deletion with over 90% efficiency. Secreted enzymes hydrolyzed xylan into xylooligosaccharides, which were taken in by the second strain, designed to use the xylooligosaccharides for ethanol production. Cocultivation of the two strains converted xylan hemicellulose to ethanol with a yield about 55% of the theoretical value. Inclusion of other three hemicellulases improved the ethanol yield to 70%. Analysis of the culture broth showed that xylooligosaccharides with four or more xylose units were not utilized, suggesting that improving the use of higher xyloogligomers should be the focus in future efforts. This is the first demonstration of an engineered binary culture for consolidated bioprocessing of xylan. The modular design should allow the strategy to be adopted for a broad range of biofuel and biorefinery products.
منابع مشابه
Synthesis of three advanced biofuels from ionic liquid-pretreated switchgrass using engineered Escherichia coli.
One approach to reducing the costs of advanced biofuel production from cellulosic biomass is to engineer a single microorganism to both digest plant biomass and produce hydrocarbons that have the properties of petrochemical fuels. Such an organism would require pathways for hydrocarbon production and the capacity to secrete sufficient enzymes to efficiently hydrolyze cellulose and hemicellulose...
متن کاملMicrobial production of sabinene—a new terpene-based precursor of advanced biofuel
BACKGROUND Sabinene, one kind of monoterpene, accumulated limitedly in natural organisms, is being explored as a potential component for the next generation of aircraft fuels. And demand for advanced fuels impels us to develop biosynthetic routes for the production of sabinene from renewable sugar. RESULTS In this study, sabinene was significantly produced by assembling a biosynthetic pathway...
متن کاملFermentation of lactose to ethanol in cheese whey permeate and concentrated permeate by engineered Escherichia coli
BACKGROUND Whey permeate is a lactose-rich effluent remaining after protein extraction from milk-resulting cheese whey, an abundant dairy waste. The lactose to ethanol fermentation can complete whey valorization chain by decreasing dairy waste polluting potential, due to its nutritional load, and producing a biofuel from renewable source at the same time. Wild type and engineered microorganisms...
متن کاملProduction of isoprene, one of the high-density fuel precursors, from peanut hull using the high-efficient lignin-removal pretreatment method
Background Isoprene as the feedstock can be used to produce renewable energy fuels, providing an alternative to replace the rapidly depleting fossil fuels. However, traditional method for isoprene production could not meet the demands for low-energy consumption and environment-friendliness. Moreover, most of the previous studies focused on biofuel production out of lignocellulosic materials suc...
متن کاملIsoprenoids Production from Lipid-Extracted Microalgal Biomass Residues Using Engineered E. coli.
Microalgae are recognized as a third generation feedstock for biofuel production due to their rapid growth rates and lignin-free characteristics. In this study, a lipid extracted microalgal biomass residues was used as the raw material to produce isoprene, α-pinene and β-pinene with an engineered E. coli strain. We adopted an optimal sulfuric acid hydrolysis method (1:7 ratio of solid to acid s...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Applied and environmental microbiology
دوره 76 24 شماره
صفحات -
تاریخ انتشار 2010