دانلود ترجمه مقاله ساخت تخمیری اسید استیک توسط کلستریدیوم – نشریه اسپرینگر

فهرست مطالب:

 چکیده
مقدمه
مواد و روش ها
آزمایشات تخمیر
آماده سازی بیوپلیمر های فراوری شده
براورد ها
نتایج
تخمیر مواد سلولزی خالص مختلف
تخمیر مواد کشاورزی تیمار شده
تخمیر مواد کشاورزی کشاورزی خام
تخمیر با غلظت های بالای بقایای کشاورزی چوب زدایی شده
بحث

بخشی از ترجمه:

توانایی C. lentocellum برای رشد و تجزیه سلولز خالص و مواد کشاورزی تحت تیمار قلیا به طور کارامد بیانگر حضور یک سلولز واقعی (Duong et al.1983; Beguin & Aubert 1994) و سیستم همی سلولز است(Gilbert & Hazel wood 1993) (جدول ۱ و ۳). رشد روی نمک سدیم کربوکسی متیل سلولز نشان می دهد که جایگزینی واحد های سلولز با گروه های کربوکسی متیل منجر به استفاده ضعیف شد. فریر و همکاران ۱۹۸۸ در C. thermocellumJW20 و رامسن و همکاران ۱۹۸۸ در Ruminococcus ¯avifaciensFD1 مشاهده کرد که رشد ارگانیسم بستکی به میزان جا به جایی دارد و هر چه جایگزینی بیشتر باشد رشد کم تر خواهد بود. سای رام و همکاران ۱۹۹۱ کاهش تولید اتانول و اسید استیک را در C. thermocellumSS8 و GS1 در کربوکسی متیل سلولز در مقایسه با دیکر سوبستراهای سلولزی خالص گزارش کردند.
رشد ضعیف سویه SG6 روی بیوپلیمر های خام می تواند ناشی از وجود مهار کننده های حلالی باشد که بعد از تیمار آب داغ خارج شده و موجب رشد محسوس و تجزیه سوبسترا شده است( جدول۲).. تیمار قلیا موجب افزایش چوب زدایی سوبسترا شده و باعث شد تا آن ها در برابر تجزیه بیشتر آسیب پذیر شوند(جدول ۳-Doneferet al.1969; Datta 1981; Kunduet al. 1983; Sai Ram & Seenayya 1991). نسبت استات به اتانول تخمیر با C. lentocellumSG6 در جخت تبدیل بیوماس به اتانول به عنوان سوبسترا در مقایسه با سوبستراهای سلولزی خالص است (جداول ۱-۳). این از خصوصیات برجسته C. lentocellumSG6 برخلاف ارکانیسم های اتانولژنیک است که از اتانول شیفت کرده و تمایل به استاتی نشان می دهند که روی مواد بیوماس کار می کند(Sai Ram & Seenayya 1991).
تخمیر سلولزی خالص و مواد کشاورزی تیمار شده و تولید اسید استیک توسط C. lentocellumSG6 کارامد تر از دیگر سویه های باکتر یایی، سلولوتیک و تک کشت می باشد(Fondet al. 1983; Khanet al.1984; Ruyetet al.1984; Sai Ram & Seenayya 1991).فوند و همکاران ۱۹۸۳ تولید کم اسید استیک را توسط Clostridiumsp. H10 در ۶ گرم Solka Floc با ۶۵ درصد تجزیه سوبسترا نشان دادند.

بخشی از مقاله انگلیسی:

Introduction Acetic acid is widely used in the food, pharmaceutical and textile industries and is also an important component in the synthesis of many chemicals, such as vinyl acetate, cellulose acetate, acetic acid esters, terepthalic acid etc. (Ghose & Bhadra 1985; Cheryan et al. 1997). The microbial conversion of abundant and renewable cellulosic biomass to organic acids and ethanol o€ers an attractive alternative to fuels and basic chemical feed stocks derived from petroleum (Ghose & Bhadra 1985; Lowe et al. 1993; Beguin & Aubert 1994; Lee 1997). Cellulosic biomass is available in enormous quantities as waste of agricultural, industrial, and forestry residues, municipal solids waste etc. The microbial conversion of these wastes to generate value-added products can also alleviate pollution problems. The direct conversion of cellulosic biomass to acetic acid by single step fermentation can be economical over the expensive multi-step process in which fungal cellulases, yeasts and acetogenic bacteria are used. (Lynd 1989; Parisi 1989; Ebner et al. 1996). Moreover, 3 M of acetic acid are produced by anaerobic fermentations from 1 M of glucose equivalents fermented, whereas in aerobic breakdown only 2 M of acetic acid are produced (Ghose & Bhadra 1985; Sugaya et al. 1986; Cheryan et al. 1997). In this direction, we have reported the direct conversion of biomass to acetic acid by various cellulolytic, mesophilic and anaerobic Clostridium spp. (Ravinder et al. 1998). One of these strains, identi®ed as C. lentocellum SG6, produced high amounts of acetic acid, 0.63 g g)1 of cellulose (Whatman No. 1 ®lter paper). An agrarian country such as India generates about 388 million tonnes of biomass per annum, which includes paddy straw, cotton straw, sorghum stover, grass etc. (Anonymous 1991). In order to develop a practical process for acetic acid production, it is necessary to evaluate the ability of the strain to degrade natural cellulosic substrates. In the present study, the ability of C. lentocellum SG6 to ferment high concentrations of various pure cellulosic materials and pre-treated agricultural materials such as paddy straw, cotton straw, sorghum stover, grass etc., to produce acetic acid is reported. Materials and Methods Fermentation experiments Clostridium lentocellum SG6 was grown in 120 ml serum vials with 20 ml of pre-reduced CMS medium (Sai Ram World Journal of Microbiology & Biotechnology 16: 507±۵۱۲, ۲۰۰۰٫ ۵۰۷ Ó ۲۰۰۰ Kluwer Academic Publishers. Printed in the Netherlands. & Seenayya 1991) containing (g l)1 ); KH2PO4, 1.5; K2HPO4, 2.0; urea, 2.0; MgSO4, 0.8; CaCl2, 0.15; sodium citrate, 3.5; cysteine HCl, 0.15; yeast extract, 5.0; resazurin, 0.002; cellulose, 8.0; in N2 atmosphere. The medium was sterilized by autoclaving at 121 °C for 30 min. The pH of the fermentation medium was adjusted to 7.2 before inoculation. A 5% (v/v) inoculum, grown on 4 g cellulose l)1 , was added and incubations were carried out at 37 ‹ ۲ °C without shaking. The presence of growth was assessed by visual observation and substrate degradation. The medium was bu€ered with 0.5, 1.24, 2.5, 3.74, 5.0 and 6.24% CaCO3 at 10, 25, 50, 75, 100 and 125 g cellulosic substrate l)1 , respectively. Triple strength CMS medium was used when the substrate concentration was above 10 g l)1 . The carbon sources used were cellulose (Whatman No. 1 ®lter paper), tissue paper, Avicel, Solka Floc, native cotton, carboxymethylcellulose sodium salt (low viscosity, Sigma) and the agricultural materials, cotton straw, paddy straw, grass, ground nut shells, sorghum stover, corn cobs and castor straw. Preparation of the treated biopolymers The agricultural materials were cut into pieces of approximately 1 cm, ground with a mortar and pestle and extracted by boiling with distilled water for 30 min. Alkali-extracted fractions were prepared by autoclaving the agricultural materials at 121 °C for 15 min with 1% (w/v) NaOH, followed by neutralization with H2SO4. These fractions were thoroughly washed with distilled water and dried at 60 °C for 48 h (Sai Ram & Seenayya 1991). Estimations Undegraded cellulose was estimated gravimetrically by the method of Weimer & Zeikus (1977). Cultures were centrifuged at 25,000 ´ g for 15 min and the supernatant was drawn o€ gently with a Pasteur pipette. The pellet was resuspended in 8% formic acid to lyse the cells. The process was repeated to eliminate residual CaCO3 if any. This solution was then passed through preweighed 0.45 l Millipore ®lters. The ®lters were dried at 60 °C to constant weight and the residual cellulose was determined by di€erence. Residual carboxymethylcellulose sodium salt (NaCMC) in fermented broth was determined after acid hydrolysis by the DNS method. 50 ll of 5 M H2SO4 solution was added to 0.5 ml of fermented broth samples. These samples were placed in a steam bath for 3 h and then neutralized by the addition of 35 ll of 10 N NaOH solution. The reducing sugars released were determined by the DNS method. The amount of undegraded NaCMC was estimated by ®nding reducing sugar values from the calibration curve of standard 1% NaCMC solution, which was treated by the same procedure as described above.