共查询到20条相似文献,搜索用时 10 毫秒
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Tamires Carvalho dos Santos Devson Paulo Palma Gomes Renata Cristina Ferreira Bonomo Marcelo Franco 《Food chemistry》2012
This paper analyses the effects of water content, temperature and time on the kinetic activity of cellulolytic enzymes produced during the solid state fermentation of potato peel, using Aspergillus niger. Three main analytical steps – analysis of variance, regression analysis and plotting of response surface – were performed to obtain an optimum condition for enzymatic activity. The statistical results indicated that the best activity time for enzyme CMCase (carboxymethylcellulase) is 82.88 h, with water content of 51.48% and temperature of 29.46 °C; for FPase (filter paperase), the best activity time is 80.62 h, water content of 50.19% and temperature at 30.00 °C; for xylanase, time is 81.92 h, water content is 50.72% and temperature is 28.85 °C. Pareto charts have shown that all variables were significant in enzymatic activity for CMCase and xylanase. On the other hand, FPase shows that time and temperature have significant effect for this response variable. 相似文献
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Zhang J Qu Y Xiao P Wang X Wang T He F 《Journal of Bioscience and Bioengineering》2012,113(6):697-703
The Trametes sp. AH28-2 laccase gene lacA fused to cellobiohydrolase I signal peptide coding sequence was heterologously expressed in T. reesei. The lacA cDNA was under the control of the Aspergillus nidulans glyceraldehyde-3-phosphate dehydrogenase promoter. Native PAGE analysis indicated that two transformants, L8 and L38, were able to secrete recombinant laccase A, and their laccase activities corresponding to ABTS oxidation reached 3.62 IUml(-1) and 1.50 IUml(-1) respectively. Most of the characteristics of the recombinant laccase were similar to those of the native enzyme. Reducing sugar yields of L8 and L38 obtained from saccharification of corn residue by crude enzyme increased by 31.3% and 71.6% respectively compared to the host strain. These results indicated that the engineering strains developed in this work could be potentially used for laccase production and tailoring cellulase properties with laccase proteins through genetic manipulation would be a feasible strategy to improve saccharification efficiency of biomass by cellulase preparation. 相似文献
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Flavones isolated from celery varied in their stability and susceptibility to deglycosylation during thermal processing at pH 3, 5, or 7. Apigenin 7-O-apiosylglucoside was converted to apigenin 7-O-glucoside when heated at pH 3 and 100 °C. Apigenin 7-O-glucoside showed little conversion or degradation at any pH after 5 h at 100 °C. Apigenin, luteolin, and chrysoeriol were most stable at pH 3 but progressively degraded at pH 5 or 7. Chamomile and celery were used to test the effects of glycosidase-rich foods and thermal processing on the stability of flavone glycosides. Apigenin 7-O-glucoside in chamomile extract was readily converted to apigenin aglycone after combination with almond, flax seed, or chickpea flour. Apigenin 7-O-apiosylglucoside in celery leaves was resistant to conversion by β-glucosidase-rich ingredients, but was converted to apigenin 7-O-glucoside at pH 2.7 when processed at 100 °C for 90 min and could then be further deglycosylated when mixed with almond or flax seed. Thus, combinations of acid hydrolysis and glycosidase enzymes in almond and flax seed were most effective for developing a flavone-rich, high aglycone food ingredient from celery. 相似文献
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Rosanna Tofalo Giorgia Perpetuini Maria Schirone Aurora CiarrocchiGiuseppe Fasoli Giovanna SuzziAldo Corsetti 《LWT》2014
Culture-dependent and -independent approaches were applied to identify the bacterial species involved in Italian table olive fermentation. Bacterial identification showed that Lactobacillus pentosus was the dominant species although the presence of Lactobacillus plantarum, Lactobacillus casei, Enterococcus durans, Lactobacillus fermentum and Lactobacillus helveticus was observed. Rep-PCR allowed to obtain strain-specific profiles and to establish a correlation with table olive environment. PCR-DGGE (Denaturing Gradient Gel Electrophoresis) confirmed the heterogeneity of bacterial community structure in fermented table olives as well as the prevalence of L. pentosus. The strains were characterized on the basis of technological properties (NaCl tolerance, β-glucosidase activity and the ability to grow in synthetic brine and in presence of 1 g/100 mL oleuropein). L. pentosus showed a high capacity of adaptation to the different conditions characterizing the olive ecosystem. This species showed the highest percentage of strains able to grow in presence of 10 g/100 mL NaCl, oleuropein and in the synthetic brine. Moreover, all the strains belonging to L. pentosus and L. plantarum species showed a β-glucosidase activity. This study allowed both to identify the main species and strains associated to Italian table olives and to obtain a lactic acid bacteria collection to apply as starter culture in the process of olive fermentation. 相似文献
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Mimoza Basholli-Salihu Monika Mueller Sharareh Salar-Behzadi Frank M. Unger Helmut Viernstein 《LWT》2014
The benefit of disaccharide protectants for maintaining viability and β-glucosidase activity of Bifidobacterium infantis UV16PR during freeze-drying and storage in different food matrices was investigated. Protectants used were cellobiose, lactose, sucrose and trehalose. 相似文献
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Thermus thermophilus HB-8 is a source of trehalose synthase (GTase), which catalyses conversion of maltose into trehalose. Specific activity of maltose transglucosylation by cell-free extracts of the bacteria was about 0.1 U mg−1 protein and precipitation at 28% saturation of ammonium sulphate caused 3.5-fold enzyme purification. The optimum temperature for conversion of maltose into trehalose was 65 °C with about 27% of maximum activity at 85 °C. The highest GTase productivity was achieved at cultivation temperature over 60 °C and at NaCl concentration range of 0.1–0.5% (w/v). However, larger concentrations of sodium chloride in the growth media caused a remarkable decrease of GTase synthesis. The results, of ammonium sulphate fractionation and activity towards maltotriose (0.028 U mg−1), maltotetraose (0.16 U mg−1) and GlcαpNp (0.27 U mg−1), show that trehalose synthase and α-glucosidase activities reside in separate protein fractions of cell-free extracts from T. thermophilus cells. 相似文献
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Tectoridin could be hydrolyzed to tectorigenin by β-glucosidase-producing intestinal bacteria. In this study, nine strains of Lactobacillus and bifidobacteria were screened for high levels of β-glucosidase activity. We investigated their ability to transform tectoridin from Pueraria flos to tectorigenin. Lactobacillus reuteri DSM20016 showed the highest cell-envelope associated β-glucosidase activity, whereas the intracellular β-glucosidase activity from Bifidobacterium adolescentis ATCC15703 was higher than the other screened bacterial strains. L. reuteri DSM20016, Lactobacillus rhamnosus GGB41031 and B. adolescentis ATCC15703 showed high bioconversion rate of tectoridin. L. reuteri DSM20016 showed the highest bioconversion efficiency of tectoridin, 100% tectoridin was hydrolyzed and there was an approximate 185-fold increase in the concentration of tectorigenin after 24 h. The present study suggests that L. reuteri DSM20016, L. rhamnosus GGB41031 and B. adolescentis ATCC15703 have great potential for converting tectoridin from Pueraria flos to more bioactive tectorigenin. 相似文献
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An α-l-arabinofuranosidase (ABF3) from Penicillium purpurogenum was purified and its possible biotechnological application in the enhancement of wine flavour combined with P. purpurogenum β-glucosidase was studied. A must from Muscat of Alexandria was used to isolate the glycosides. The total monosaccharide (glucose, arabinose and xylose) levels in the glycosides were determined after acid hydrolysis, and were compared with the result of enzymatic hydrolysis. These results were analogous to those obtained in similar experiments using a commercial preparation, thus suggesting that the enzyme from P. purpurogenum may prove useful in this particular application. This prompted us to express the enzyme heterologously. The abf3 gene was thus expressed in Pichia pastoris. The recombinant enzyme was purified and it shows the same properties of the native ABF3 (substrate specificity, kinetic constants, pH and temperature optima and antibody cross-reactivity). 相似文献
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The ginsenoside Rg3(S), which is one of the exceptional components of Korean red ginseng extract, has been known to have anti-cancer, anti-metastatic, and anti-obesity effects. An enzymatic bioconversion method was developed to obtain the ginsenoside Rg3(S) with a high specificity, yield, and purity. Two glycoside hydrolases (BglBX10 and Abf22-3) were employed to produce Rg3(S) as a 100 g unit. The conversion reaction transformed ginsenoside Rc to Rd using Abf22-3, followed by Rb1 and Rd to Rg3(S), using BglBX10. It was performed in a 10 L jar fermenter at pH 6.0 and 37 °C for 24 h, with a high concentration of 50 mg/ml of purified ginsenoside mixture obtained from ginseng roots. Finally, 144 g of Rg3(S) was produced from 250 g of root extract with 78 ± 1.2% chromatographic purity. These results suggest that this enzymatic method would be useful in the preparation of ginsenoside Rg3(S) for the functional food and pharmaceutical industries. 相似文献