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Cellulolytic Activity (cellulolytic + activity)
Selected AbstractsEvaluation of Minimal Trichoderma reesei Cellulase Mixtures on Differently Pretreated Barley Straw SubstratesBIOTECHNOLOGY PROGRESS, Issue 6 2007Lisa Rosgaard The commercial cellulase product Celluclast 1.5, derived from Trichoderma reesei (Novozymes A/S, Bagsværd, Denmark), is widely employed for hydrolysis of lignocellulosic biomass feedstocks. This enzyme preparation contains a broad spectrum of cellulolytic enzyme activities, most notably cellobiohydrolases (CBHs) and endo-1,4-,-glucanases (EGs). Since the original T. reesei strain was isolated from decaying canvas, the T. reesei CBH and EG activities might be present in suboptimal ratios for hydrolysis of pretreated lignocellulosic substrates. We employed statistically designed combinations of the four main activities of Celluclast 1.5, CBHI, CBHII, EGI, and EGII, to identify the optimal glucose-releasing combination of these four enzymes to degrade barley straw substrates subjected to three different pretreatments. The data signified that EGII activity is not required for efficient lignocellulose hydrolysis when addition of this activity occurs at the expense of the remaining three activities. The optimal ratios of the remaining three enzymes were similar for the two pretreated barley samples that had been subjeced to different hot water pretreatments, but the relative levels of EGI and CBHII activities required in the enzyme mixture for optimal hydrolysis of the acid-impregnated, steam-exploded barley straw substrate were somewhat different from those required for the other two substrates. The optimal ratios of the cellulolytic activities in all cases differed from that of the cellulases secreted by T. reesei. Hence, the data indicate the feasibility of designing minimal enzyme mixtures for pretreated lignocellulosic biomass by careful combination of monocomponent enzymes. This strategy can promote both a more efficient enzymatic hydrolysis of (ligno)cellulose and a more rational utilization of enzymes. [source] The effect of hydration time and ethanol concentration on the rate of hydrolysis of extracted vanilla beans by commercial cellulase preparationsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2005Sandy L. Ovando Summary The rate of producing reducing sugars from extracted vanilla beans by using cellulolytic enzymes was studied. The hydration of cellulose improved the efficiency of hydrolysis. The treatment using Crystalzyme PML-MX at a concentration of 2.64 International Filter Paper Units (IFPU) g,1 of bean was the most successful and the enzyme stable for up to 5:100 (weight:volume) of ethanol. After 48 h of prehydration and 26 h of enzymatic hydrolysis with this enzyme preparation, 196.6 mg g,1 reducing sugars containing 15.9 mg g,1 glucose were liberated. Less active enzyme products, Zymafilt L-300 and Novozym, had greater cellulolytic activity when 10 or 15:100 (weight:volume) of ethanol were added respectively. Because of their stability with ethanol, the enzyme products could be used in the pretreatment of botanical material that are rich in flavour compounds and in this manner improve the final extraction of valuable flavours. [source] Hydrolysis and microbial community analyses in two-stage anaerobic digestion of energy cropsJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2007D.G. Cirne Abstract Aims:, The roles of the diverse populations of micro-organisms responsible for biodegradation of organic matter to form methane and carbon dioxide are rudimentarily understood. To expand the knowledge on links between microbial communities and the rate limiting, hydrolytic stage of two-stage biogas production from energy crops, this study was performed. Methods and Results:, The process performance and microbial communities (as determined by fluorescence in situ hybridization) in two separate two-stage batch digestions of sugar beets and grass/clover were studied. The microbial populations developed in the hydrolytic stage of anaerobic digestion of beets and grass/clover showed very few similarities, despite that the hydrolysis dynamics were similar. In both substrates, the solubilization of organic material was rapid for the first 10 days and accompanied by a build-up of volatile fatty acids (VFAs) and lactate. Between days 10 and 15, VFA and lactate concentrations decreased, as did the solubilization rates. For both substrates, Archaea started to appear in the hydrolytic stage between days 10 and 15, and the fraction of Bacteria decreased. The major bacterial group detected in the leachate fraction for beets was Alphaproteobacteria, whereas for grass/clover it was Firmicutes. The number of cells that bound to probes specifically targeting bacteria with cellulolytic activity was higher in the digestion of grass than in the digestion of beet. Conclusions:, This study allowed the identification of the general bacterial groups involved, and the identification of a clear shift in the microbial population when hydrolysis rate became limiting for each of the substrates investigated. Significance and Impact of the Study:, The findings from this study could be considered as a first step towards the development of strategies to stimulate hydrolysis further and ultimately increasing the methane production rates and yields from reactor-based digestion of these substrates. [source] Effect of D-mannitol on feed digestion and cecotrophic system in rabbitsANIMAL SCIENCE JOURNAL, Issue 2 2009Hamza HANIEH ABSTRACT This study aimed to evaluate the effect of sugar alcohol as an energy source for cecal microbes on digestibility, cecotrophy (i.e. reingestion of microbial products of cecum, cecotrophs) and performance in rabbits. Thus, we fed rabbits an experimental diet that included 5% of D-mannitol, and collected hard feces and cecotrophs to be analyzed for crude protein (CP), acid detergent fiber (ADF), ether extract (EE), crude ash (CA) and dry matter (DM). Cecotrophic behavior of the rabbits was also observed. Feeding D-mannitol increased (P < 0.01) digestibility of ADF, resulting in a decrease (P < 0.05) in the concentration in hard feces. The increase (P < 0.05) in CP concentration was attributed to lower (P < 0.05) digestibility. D-mannitol had a similar modulatory effect on CP and ADF concentrations in hard feces and cecotrophs. Accordingly, estimations of the proportion of nutrients recycled by cecotrophy to dietary intake (PR), obtained by the two calculation methods, showed an increase (P < 0.01) in PR of CP and a decrease (P < 0.05) in that of ADF. Daily weight gain and feed efficiency increased (P < 0.05) for D-mannitol-fed rabbits, while daily feed intake decreased (P < 0.05). These results suggest the possibility of using D-mannitol as a stimulator of cecal microbial growth and cellulolytic activity, and therefore, improved rabbits performance. [source] Purification, crystallization and preliminary crystallographic analysis of the catalytic domain of the extracellular cellulase CBHI from Trichoderma harzianumACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2010Francieli Colussi The filamentous fungus Trichoderma harzianum has a considerable cellulolytic activity that is mediated by a complex of enzymes which are essential for the hydrolysis of microcrystalline cellulose. These enzymes were produced by the induction of T. harzianum with microcrystalline cellulose (Avicel) under submerged fermentation in a bioreactor. The catalytic core domain (CCD) of cellobiohydrolase I (CBHI) was purified from the extracellular extracts and submitted to robotic crystallization. Diffraction-quality CBHI CCD crystals were grown and an X-ray diffraction data set was collected under cryogenic conditions using a synchrotron-radiation source. [source] | |||||||||||||