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通过实验探讨胰蛋白酶作为牛奶蛋白质水解的优化条件。结果表明:最适宜的酶解温度为45℃;最适加酶量为每500mL牛乳加0.05g胰蛋白酶;酶解时间为30min。在确定了牛奶水解度的优化条件以后,以水解牛乳为基料,根据母乳营养特点,对蛋白质比例、脂肪酸组成及其它营养成分进行调配,设计液态婴儿乳的配方为:每1000mL成品中,水解液330.4mL,乳清粉69.66g,精练植物油7.13g,糖添加的总量7.22g,复合维生素及微量元素的添加量分别为0.58g和0.385g,水667mL。 相似文献
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本实验探讨胰蛋白酶作为牛奶蛋白质水解的优化条件。结果表明：最适宜的酶解温度为45℃;最适加酶量为每500mL牛乳加0．05g胰蛋白酶;酶解时间为30min。在确定了牛奶水解度的优化条件以后,以水解牛乳为基料,根据母乳营养特点,对蛋白质比例、脂肪酸组成及其它营养成分进行调配,设计液态婴儿乳的配方为：每1000mL成品中,水解液330．4mL,乳清粉69．66g,精练植物油7．13g,糖添加的总量7．22g,复合维生素及微量元素的添加量分别为0．58g和0．385g,水667mL。 相似文献
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通过实验探讨胰蛋白酶作为牛奶蛋白质水解的优化条件。结果表明：最适宜的酶解温度为45℃；最适加酶量为每500mL牛乳加0．05g胰蛋白酶；酶解时间为30min。在确定了牛奶水解度的优化条件以后，以水解牛乳为基料，根据母乳营养特点，对蛋白质比例、脂肪酸组成及其它营养成分进行调配，设计液态婴儿乳的配方为：每1000mL成品中，水解液330．4mL，乳清粉69．66g，精练植物油7．13g，糖添加的总量7．22g，复合维生素及微量元素的添加量分别为0．58g和0．385g，水667mL。 相似文献
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发酵玉米芯酶水解液生产木糖醇的研究 总被引：5，自引：0，他引：5
假丝酵母(Candida sp.)菌株经驯化后显著地提高了对水解液中发酵抑制物质的耐受力,从而增加了木糖利用率和木糖醇得率。玉米芯经酶水解得到水解液,在30℃下采用假丝酵母菌株直接发酵生产木糖醇。对发酵条件进行了优化,优化结果为:接种量5%(体积比),种子龄20 h,氮源组成:2.5 g/L的酵母浸膏,2.5 g/L的胰蛋白胨,250 mL三角瓶装液100 mL,初始pH值6。在此条件下,木糖醇得率达65%。该方法大大降低了预处理的成本,显示了良好的应用前景。 相似文献
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羊皮下脚料中明胶和水解蛋白的提取研究 总被引：1，自引：0，他引：1
采用化学及生物化学处理方法，从羊皮下脚料中提取明胶和水解蛋白，通过正交多因子试验，确定最佳化学反应条件及分离方法，试验结果证明：明胶的提取率为８％，水解蛋白的提取率为２５％。 相似文献
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BackgroundBiologically active peptides produced from fish wastes are gaining attention because their health benefits. Proteases produced by halophilic microorganisms are considered as a source of active enzymes in high salt systems like fish residues. Hence, the aim of this study was the bioprospection of halophilic microorganisms for the production of proteases to prove their application for peptide production.ResultsHalophilic microorganisms were isolated from saline soils of Mexico and Bolivia. An enzymatic screening was carried out for the detection of lipases, esterases, pHB depolymerases, chitinases, and proteases. Most of the strains were able to produce lipases, esterases, and proteases, and larger hydrolysis halos were detected for protease activity. Halobacillus andaensis was selected to be studied for proteolytic activity production; the microorganism was able to grow on gelatin, yeast extract, skim milk, casein, peptone, fish muscle (Cyprinus carpio), and soy flour as protein sources, and among these sources, fish muscle protein was the best inducer of proteolytic activity, achieving a protease production of 571 U/mL. The extracellular protease was active at 50°C, pH 8, and 1.4 M NaCl and was inhibited by phenylmethylsulfonyl fluoride. The proteolytic activity of H. andaensis was used to hydrolyze fish muscle protein for peptide production. The peptides obtained showed a MW of 5.3 kDa and a radical scavenging ability of 10 to 30% on 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and a ferric reducing ability of plasma.ConclusionThe use of noncommercial extracellular protease produced by H. andaensis for biologically active peptide production using fish muscle as the protein source presents a great opportunity for high-value peptide production.How to cite: Delgado-García M, Flores-Gallegos AC, Kirchmayr M, et al. Bioprospection of proteases from Halobacillus andaensis for bioactive peptide production from fish muscle protein. Electron J Biotechnol 2019;39. https://doi.org/10.1016/j.ejbt.2019.03.001. 相似文献
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BackgroundEndoglucanase plays a major role in initiating cellulose hydrolysis. Various wild-type strains were searched to produce this enzyme, but mostly low extracellular enzyme activities were obtained. To improve extracellular enzyme production for potential industrial applications, the endoglucanase gene of Bacillus subtilis M015, isolated from Thai higher termite, was expressed in a periplasmic-leaky Escherichia coli. Then, the crude recombinant endoglucanase (EglS) along with a commercial cellulase (Cel) was used for hydrolyzing celluloses and microbial hydrolysis using whole bacterial cells.ResultsE. coli Glu5 expressing endoglucanase at high levels was successfully constructed. It produced EglS (55 kDa) with extracellular activity of 18.56 U/mg total protein at optimal hydrolytic conditions (pH 4.8 and 50°C). EglS was highly stable (over 80% activity retained) at 40–50°C after 100 h. The addition of EglS significantly improved the initial sugar production rates of Cel on the hydrolysis of carboxymethyl cellulose (CMC), microcrystalline cellulose, and corncob about 5.2-, 1.7-, and 4.0-folds, respectively, compared to those with Cel alone. E. coli Glu5 could secrete EglS with high activity in the presence of glucose (1% w/v) and Tween 80 (5% w/v) with low glucose consumption. Microbial hydrolysis of CMC using E. coli Glu5 yielded 26 mg reducing sugar/g CMC at pH 7.0 and 37°C after 48 h.ConclusionsThe recombinant endoglucanase activity improved by 17 times compared with that of the native strain and could greatly enhance the enzymatic hydrolysis of all studied celluloses when combined with a commercial cellulase. 相似文献
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BackgroundThe 11S globulin from amaranth is the most abundant storage protein in mature seeds and is well recognized for its nutritional value. We used this globulin to engineer a new protein by adding a four valine-tyrosine antihypertensive peptide at its C-terminal end to improve its functionality. The new protein was named AMR5 and expressed in the Escherichia coli BL21-CodonPlus(DE3)-RIL strain using a custom medium (F8PW) designed for this work.ResultsThe alternative medium allowed for the production of 652 mg/L expressed protein at the flask level, mostly in an insoluble form, and this protein was subjected to in vitro refolding. The spectrometric analysis suggests that the protein adopts a β/α structure with a small increment of α-helix conformation relative to the native amaranth 11S globulin. Thermal and urea denaturation experiments determined apparent Tm and C1/2 values of 50.4°C and 3.04 M, respectively, thus indicating that the antihypertensive peptide insertion destabilized the modified protein relative to the native one. AMR5 hydrolyzed by trypsin and chymotrypsin showed 14- and 1.3-fold stronger inhibitory activity against angiotensin I-converting enzyme (IC50 of 0.034 mg/mL) than the unmodified protein and the previously reported amaranth acidic subunit modified with antihypertensive peptides, respectively.ConclusionThe inserted peptide decreases the structural stability of amaranth 11S globulin and improves its antihypertensive activity.How to cite: Espinosa-Hernández E, Morales-Camacho JI, Fernández-Velasco DA, et al. The insertion of bioactive peptides at the C terminal end of an 11S globulin changes the structural stability and improves the antihypertensive activity. Electron J Biotechnol 2019;37. https://doi.org/10.1016/j.ejbt.2018.11.001. 相似文献
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Buchegger W Haller A van den Driesche S Kraft M Lendl B Vellekoop M 《Biomicrofluidics》2012,6(1):12803-128039
In this study, the pre-steady state development of enzymatic bioreactions using a microfluidic mixer is presented. To follow such reactions fast mixing of reagents (enzyme and substrate) is crucial. By using a highly efficient passive micromixer based on multilaminar flow, mixing times in the low millisecond range are reached. Four lamination layers in a shallow channel reduce the diffusion lengths to a few micrometers only, enabling very fast mixing. This was proven by confocal fluorescence measurements in the channel’s cross sectional area. Adjusting the overall flow rate in the 200 μm wide and 900 μm long mixing and observation channel makes it possible to investigate enzyme reactions over several seconds. Further, the device enables changing the enzyme/substrate ratio from 1:1 up to 3:1, while still providing high mixing efficiency, as shown for the enzymatic hydrolysis using β-galactosidase. This way, the early kinetics of the enzyme reaction at multiple enzyme/substrate concentrations can be collected in a very short time (minutes). The fast and easy handling of the mixing device makes it a very powerful and convenient instrument for millisecond temporal analysis of bioreactions. 相似文献
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BackgroundProtein glutaminase specifically deamidates glutamine residue in protein and therefore significantly improves protein solubility and colloidal stability of protein solution. In order to improve its preparation efficiency, we exploited the possibility for its secretory expression mediated by twin-arginine translocation (Tat) pathway in Bacillus licheniformis.ResultsThe B. licheniformis genome-wide twin-arginine signal peptides were analyzed. Of which, eleven candidates were cloned for construction of expression vectors to mediate the expression of Chryseobacterium proteolyticum protein glutaminase (PGA). The signal peptide of GlmU was confirmed that it significantly mediated PGA secretion into media with the maximum activity of 0.16 U/ml in Bacillus subtilis WB600. A mutant GlmU-R, being replaced the third residue aspartic acid of GlmU twin-arginine signal peptide with arginine by site-directed mutagenesis, mediated the improved secretion of PGA with about 40% increased (0.23 U/ml). In B. licheniformis CBBD302, GlmU-R mediated PGA expression in active form with the maximum yield of 6.8 U/ml in a 25-l bioreactor.ConclusionsPGA can be produced and secreted efficiently in active form via Tat pathway of B. licheniformis, an alternative expression system for the industrial-scale production of PGA.How to cite: Niu D, Li C, Wang P, et al. Twin-arginine signal peptide of Bacillus licheniformis GlmU efficiently mediated secretory expression of protein glutaminase. Electron J Biotechnol 2019;42. https://doi.org/10.1016/j.ejbt.2019.10.006 相似文献
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对蚝油酶水解产物及其稳定性进行了初步研究,结果表明：在最佳酶解条件下,蚝干的解产物（水解液及潭的混合物）中加盐保温,全氮利用率大幅度提高;以进口淀粉６－７为主要增稠剂,并配以卡拉胶,可得到色泽、体态、风味、稳定性良好的蚝油调味品。 相似文献
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BackgroundXylanase from bacteria finds use in prebleaching process and bioconversion of lignocelluloses into feedstocks. The xylanolytic enzyme brings about the hydrolysis of complex biomolecules into simple monomer units. This study aims to optimize the cellulase-free xylanase production and cell biomass of Bacillus tequilensis strain ARMATI using response surface methodology (RSM).ResultsStatistical screening of medium constituents and the physical factors affecting xylanase and biomass yield of the isolate were optimized by RSM using central composite design at N = 30, namely 30 experimental runs with 4 independent variables. The central composite design showed 3.7 fold and 1.5 fold increased xylanase production and biomass yield of the isolate respectively compared to ‘one factor at a time approach’, in the presence of the basal medium containing birchwood xylan (1.5% w/v) and yeast extract (1% w/v), incubated at 40°C for 24 h. Analysis of variance (ANOVA) revealed high coefficient of determination (R2) of 0.9978 and 0.9906 for the respective responses at significant level (p < 0.05). The crude xylanase obtained from the isolate showed stability at high temperature (60°C) and alkaline condition (pH 9) up to 4 h of incubation.ConclusionsThe cellulase-free xylanase showed an alkali-tolerant and thermo-stable property with potentially applicable nature at industrial scale. This statistical approach established a major contribution in enzyme production from the isolate by optimizing independent factors and represents a first reference on the enhanced production of thermo-alkali stable cellulase-free xylanase from B. tequilensis. 相似文献