عنوان
پدید آورنده
موضوع
رده
کتابخانه
محل استقرار
شماره کتابشناسی ملی
شماره
TLpq304282295
زبان اثر
زبان متن نوشتاري يا گفتاري و مانند آن
انگلیسی
عنوان و نام پديدآور
عنوان اصلي
Isolation and characterization of an acetyl xylan esterase and its role in biomass conversion
نام عام مواد
[Thesis]
نام نخستين پديدآور
S. R. Decker
وضعیت نشر و پخش و غیره
نام ناشر، پخش کننده و غيره
Colorado State University
تاریخ نشرو بخش و غیره
1996
مشخصات ظاهری
نام خاص و کميت اثر
128
یادداشتهای مربوط به پایان نامه ها
جزئيات پايان نامه و نوع درجه آن
Ph.D.
کسي که مدرک را اعطا کرده
Colorado State University
امتياز متن
1996
یادداشتهای مربوط به خلاصه یا چکیده
متن يادداشت
Cellulose and xylan are the two major polysaccharides found in plant fiber and represent a vast feedstock source for microbial ethanol production. To render the cellulose amenable to bioconversion, xylan is removed by a dilute sulfuric acid pretreatment, and at present, not utilized. However, the recent development of a recombinant Zymomonas moblis capable of co-fermenting glucose and xylose has renewed interest in fermentation of xylan to ethanol. For fermentation, the xylan must first be converted to xylose; enzymatic hydrolysis is a promising approach. Since xylan is a highly branched polymer, it is degraded by multiple debranching and depolymerizing enzymes. Acetyl xylan esterase (AXE), which cleaves acetyl esters from the xylan backbone, is required early in this process. Chapter One describes the purification and biochemical properties of an AXE from Aspergillus niger. The protein has a molecular weight of 32.1 kDa, an isoelectric point of 3.5, and is 10.4% glycosylated. The pH and temperature optima are 6.0 and 55C respectively. The Kusd\rm\sb{m}usd values for AXE are 0.298 g/L acetylated xylan and 0.023 Mp-nitrophenyl acetate; the Vusd\rm\sb{max}usd values are 3692 and 46,603 units/mg protein using acetylated xylan and p-nitrophenyl acetate respectively. N-terminal sequencing showed a single sequence homology, an AXE from A. niger DS16813. In addition to the AXE work, which has long-term potential to improve biomass conversion, studies focused on more immediate advances were undertaken. Dilute sulfuric acid pretreatment is corrosive and produces waste CaSO4. However, dilute phosphoric acid is less corrosive and can be neutralized with ammonia, generating ammonium phosphate, a fermentation nutrient. Chapter Two describes a pretreatment using dilute phosphoric acid in both aqueous and organosolv (70% methanol or ethanol) solutions. Fermentation of corn stover following pretreatment with either phosphoric or sulfuric acid resulted in similar ethanol yields. In addition, fermentation of switchgrass pretreated with phosphoric acid in 70% ethanol produced similar ethanol yields in comparison to dilute sulfuric acid pretreated switchgrass. Hence, phosphoric acid pretreatment is as effective as sulfuric acid pretreatment, but is less corrosive and yields a beneficial neutralization product.
موضوع (اسم عام یاعبارت اسمی عام)
موضوع مستند نشده
Aspergillus niger
موضوع مستند نشده
Biological sciences
موضوع مستند نشده
ethanol
موضوع مستند نشده
hemicellulose
موضوع مستند نشده
Microbiology
موضوع مستند نشده
Pure sciences
نام شخص به منزله سر شناسه - (مسئولیت معنوی درجه اول )
مستند نام اشخاص تاييد نشده
S. R. Decker
دسترسی و محل الکترونیکی
نام الکترونيکي
مطالعه متن کتاب وضعیت انتشار
فرمت انتشار
p
اطلاعات رکورد کتابشناسی
نوع ماده
[Thesis]
کد کاربرگه
276903
اطلاعات دسترسی رکورد
سطح دسترسي
a
تكميل شده
Y
