Home About us Contact
|
Home About us Contact | ||
|
|
||
Starch Hydrolysis (starch + hydrolysis)
Selected AbstractsFermentation of glucose and starch particles using an inexpensive mediumJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2010Nancy Bawa Abstract BACKGROUND: In North America, compared with sugar, starch is a more economical raw material to produce ethanol. Recently low temperature processing of starch granules directly to ethanol has been commercialized. With a view to minimizing process costs while maintaining a satisfactory ethanol yield, an inexpensive medium that does not require the addition of commercial ,-amylase has been developed for low temperature, direct fermentation of starch particles. RESULTS: Compared with an expensive medium that contained both yeast extract and ,-amylase, the inexpensive medium resulted in identical and 10% higher ethanol yields using glucose and starch granules as the raw substrates, respectively, but required longer processing times. Based on the different ingredient prices for expensive and inexpensive media, the operating cost to produce 10 million litres per year of ethanol utilizing simultaneous raw starch hydrolysis and fermentation is reduced over $ 2 million (Cdn) per year when using inexpensive medium. CONCLUSION: The new inexpensive medium and simultaneous raw starch hydrolysis and fermentation is considered the best strategy to produce ethanol directly from starch particles in North America. Copyright © 2009 Society of Chemical Industry [source] Carbon Metabolism Alterations in Sunflower Plants Infected with the Sunflower Chlorotic Mottle VirusJOURNAL OF PHYTOPATHOLOGY, Issue 5 2003M. C. Arias Abstract Sunflower chlorotic mottle virus (SuCMoV) causes chlorotic mottling symptoms and important growth reductions and yield losses in sunflower (Helianthus annuus L., cv. Contiflor 7). This paper describes the effects of SuCMoV on some aspects of carbon metabolism of sunflower plants. After symptoms became evident, CO2 fixation rates decreased, nevertheless, soluble sugars and starch increased in infected leaves. High H2O2 accumulation, lipid peroxidation and chlorophyll degradation were, like the other changes, observed only after symptom expression. Increased soluble carbohydrate accumulation was not related to changes in , -amylase (EC 3.2.1.1) activity, nor in the activities of enzymes associated with sugar import and hydrolysis such as invertase (EC 3.2.1.26) and sucrose synthase (EC 2.4.1.13), suggesting it did not derive from starch hydrolysis nor increased sugar import. Rather, it may derive from recycling of cell components associated with the development of oxidative damage. The physiological alterations caused by this virus share many common features with the development of senescence. [source] New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L.PLANT CELL & ENVIRONMENT, Issue 8 2004S. SALLEO ABSTRACT Xylem recovery from embolism was studied in Laurus nobilis L. stems that were induced to cavitate by combining negative xylem pressure potentials (PX = ,1.1 MPa) with positive air pressures (PC) applied using a pressure collar. Xylem refilling was measured by recording the percentage loss of hydraulic conductance (PLC) with respect to the maximum 2 min, 20 min and 15 h after pressure release. Sodium orthovanadate (an inhibitor of many ATP-ases) strongly inhibited xylem refilling while fusicoccin (a stimulator of the plasma membrane H+ -ATPase) promoted complete embolism reversal. So, the refilling process was interpreted to result from energy-dependent mechanisms. Stem girdling induced progressively larger inhibition to refilling the nearer to the embolized stem segment phloem was removed. The starch content of wood parenchyma was estimated as percentages of ray and vasicentric cells with high starch content with respect to the total, before and after stem embolism was induced. A closely linear positive relationship was found to exist between recovery from PLC and starch hydrolysis. This, was especially evident in vasicentric cells. A mechanism for xylem refilling based upon starch to sugar conversion and transport into embolized conduits, assisted by phloem pressure-driven radial mass flow is proposed. [source] The importance of starch and sucrose digestion in nutritive biology of synanthropic acaridid mites: ,-Amylases and ,-glucosidases are suitable targets for inhibitor-based strategies of mite control,ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 3 2009Tomas Erban Abstract The adaptation of nine species of mites that infest stored products for starch utilization was tested by (1) enzymatic analysis using feces and whole mite extracts, (2) biotests, and (3) inhibition experiments. Acarus siro, Aleuroglyphus ovatus, and Tyroborus lini were associated with the starch-type substrates and maltose, with higher enzymatic activities observed in whole mite extracts. Lepidoglyphus destructor was associated with the same substrates but had higher activities in feces. Dermatophagoides farinae, Chortoglyphus arcuatus, and Caloglyphus redickorzevi were associated with sucrose. Tyrophagus putrescentiae and Carpoglyphus lactis had low or intermediate enzymatic activity on the tested substrates. Biotests on starch additive diets showed accelerated growth of species associated with the starch-type substrates. The inhibitor acarbose suppressed starch hydrolysis and growth of the mites. We suggest that the species with higher starch hydrolytic activity in feces were more tolerant to acarbose, and ,-amylase and ,-glucosidase of synanthropic mites are suitable targets for inhibitor-based strategies of mite control. © 2009 Wiley Periodicals, Inc. [source] Structure and enzyme properties of Zabrotes subfasciatus ,-amylaseARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 2 2006Patrícia B. Pelegrini Abstract Digestive ,-amylases play an essential role in insect carbohydrate metabolism. These enzymes belong to an endo-type group. They catalyse starch hydrolysis, and are involved in energy production. Larvae of Zabrotes subfasciatus, the Mexican bean weevil, are able to infest stored common beans Phaseolus vulgaris, causing severe crop losses in Latin America and Africa. Their ,-amylase (ZSA) is a well-studied but not completely understood enzyme, having specific characteristics when compared to other insect ,-amylases. This report provides more knowledge about its chemical nature, including a description of its optimum pH (6.0 to 7.0) and temperature (20,30°C). Furthermore, ion effects on ZSA activity were also determined, showing that three divalent ions (Mn2+, Ca2+, and Ba2+) were able to enhance starch hydrolysis. Fe2+ appeared to decrease ,-amylase activity by half. ZSA kinetic parameters were also determined and compared to other insect ,-amylases. A three-dimensional model is proposed in order to indicate probable residues involved in catalysis (Asp204, Glu240, and Asp305) as well other important residues related to starch binding (His118, Ala206, Lys207, and His304). Arch. Insect Biochem. Physiol. 61:77,86, 2006. © 2006 Wiley-Liss, Inc. [source] Engineering of the ,-amylase from Geobacillus stearothermophilus US100 for detergent incorporationBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2009Bassem Khemakhem Abstract AmyUS100,IG is a variant of the most thermoactive and thermostable maltohexaose forming ,-amylase produced by Geobacillus stearothermophilus sp.US100. This enzyme which was designed to improve the thermostability of the wild-type enzyme has acquired a very high resistance to chelator agents. According to modeling structural studies and with the aim of enhancing its resistance towards chemical oxidation, a mutant (AmyUS100,IG/M197A) was created by substituting methionine 197 to alanine. The catalytic proprieties of the resulting mutant show alterations in the specific activity and the profile of starch hydrolysis. Interestingly, AmyUS100,IG/M197A displayed the highest resistance to oxidation compared to the AmyUS100,IG and to Termamyl300®, the well-known commercial amylase used in detergent. Further, performance of the engineered ,-amylase was estimated in the presence of commonly used detergent compounds and a wide range of commercial detergent (liquid and solid). These studies indicated a high compatibility and performance of AmyUS100,IG/M197A, suggesting its potential application in detergent industry. Biotechnol. Bioeng. 2009;102: 380,389. © 2008 Wiley Periodicals, Inc. [source] Immobilization of a thermostable ,-amylase by covalent binding to an alginate matrix increases high temperature usabilityBIOTECHNOLOGY PROGRESS, Issue 2 2009Boon L. Tee Abstract Thermostable ,-amylase was covalently bound to calcium alginate matrix to be used for starch hydrolysis at liquefaction temperature of 95°C. 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride (EDAC) was used as crosslinker. EDAC reacts with the carboxylate groups on the calcium alginate matrix and the amine groups of the enzyme. Ethylenediamine tetraacetic acid (EDTA) treatment was applied to increase the number of available carboxylate groups on the calcium alginate matrix for EDAC binding. After the immobilization was completed, the beads were treated with 0.1 M calcium chloride solution to reinstate the bead mechanical strength. Enzyme loading efficiency, activity, and reusability of the immobilized ,-amylase were investigated. Covalently bound thermostable ,-amylase to calcium alginate produced a total of 53 g of starch degradation/mg of bound protein after seven consecutive starch hydrolysis cycles of 10 min each at 95°C in a stirred batch reactor. The free and covalently bound ,-amylase had maximum activity at pH 5.5 and 6.0, respectively. The Michaelis-Menten constant (Km) of the immobilized enzyme (0.98 mg/mL) was 2.5 times greater than that of the free enzyme (0.40 mg/mL). The maximum reaction rate (Vmax) of immobilized and free enzyme were determined to be 10.4-mg starch degraded/mL min mg bound protein and 25.7-mg starch degraded/mL min mg protein, respectively. The high cumulative activity and seven successive reuses obtained at liquefaction temperature make the covalently bound thermostable ,-amylase to calcium alginate matrix, a promising candidate for use in industrial starch hydrolysis process. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Use of Co-Immobilized ,-Amylase and Pullulanase in Reduction of Saccharification Time of Starch and Increase in Maltose YieldBIOTECHNOLOGY PROGRESS, Issue 3 2003K. S. Atia ,-Amylase and pullulanase were co-immobilized to poly(acrylamide-acrylic acid) resin [P(AAm-AAc)] using 1-ethyl-3,(3-dimethylaminopropyl) carbodimide hydrochloride (EDC). The combined ,-amylase and pullulanase activity was 32% relative to the nonimmobilized ,-amylase. Co-immobilization of ,-amylase and pullulanase increased the maltose yield compared to thart of the immobilized ,-amylase alone and reduced the saccharification time to about 50 h. The results showed that there is a significant increase in the thermal stability, pH stability, and stability toward , irradiation. The results also suggest that the co-immobilization of ,-amylase and pullulanase is a potentially useful approach for commercial starch hydrolysis. [source] | |||||||||||||