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81.
黑曲霉固态发酵及酶解玉米皮 总被引:2,自引:0,他引:2
以玉米提取淀粉后的玉米皮渣为主要原料,采用黑曲霉固态发酵法产酶再酶解的二步法降解玉米皮中纤维素类物质。经Plackett-Burman法及响应面设计优化发酵条件得:温度30℃,接种量10%,初始水分体积分数60%,物料厚度2.47 cm,初始pH 5.79,发酵时间6 d;滤纸比酶活可达11.01 U/g,较原始酶活提高了40.61%;产酶结束后加入pH 4.8醋酸-醋酸钠缓冲液,置于50℃下酶解144 h,中性洗涤纤维与酸性洗涤纤维降解率分别为46.09%、48.82%,还原糖质量分数达到9.02%。 相似文献
82.
采用单因素试验和响应面分析法优化灵芪菌质多糖固态发酵条件.优化后发酵条件为:采用药性固体发酵培养基,初始pH6.5,接种量10.16ml/100g,发酵温度30.65℃,相对湿度59.54%,发酵周期28d.利用此优化条件进行灵芪菌质多糖发酵,灵芪菌质多糖含量可达9.12±0.09mg/g,较优化前8.06±0.07 ... 相似文献
83.
84.
运用响应面法对松茸产多糖的发酵培养条件进行优化研究。首先根据C、N源实验结果,利用Plackett-Bur-man设计,对影响多糖产量的相关因素进行评估,筛选出具有显著效应的3个因素:玉米粉、豆粕和KH2PO4。在此基础上,利用最陡爬坡试验逼近以上3个因素的最大响应区域,采用Box-Behnken设计法对各因素的水平组合进行优化,获得松茸产多糖优化发酵的培养条件:玉米粉质量分数4.54%,豆粕质量分数4.96%,KH2PO4质量分数0.15%,MgSO4.7H2O质量分数0.05%,VB1质量分数0.001%,初始pH5.5,摇床转速180 r/min,发酵时间10 d。在此优化培养条件下松茸总多糖产量可达5.97 g/L。 相似文献
85.
Aaron E. Carnes Jeremy M. Luke Justin M. Vincent Angela Schukar Sheryl Anderson Clague P. Hodgson James A. Williams 《Biotechnology and bioengineering》2011,108(2):354-363
Industrial plasmid DNA manufacturing processes are needed to meet the quality, economy, and scale requirements projected for future commercial products. We report development of a modified plasmid fermentation copy number induction profile that increases gene vaccination/therapy vector yields up to 2,600 mg/L. We determined that, in contrast to recombinant protein production, secretion of the metabolic byproduct acetate into the media had only a minor negative effect on plasmid replication. We also investigated the impact of differences in epigenetic dcm methylase‐directed cytosine methylation on plasmid production, transgene expression, and immunogenicity. While Escherichia coli plasmid production yield and quality are unaffected, dcm− versions of CMV and CMV‐HTLV‐I R promoter plasmids had increased transgene expression in human cells. Surprisingly, despite improved expression, dcm− plasmid is less immunogenic. Our results demonstrate that it is critical to lock the plasmid methylation pattern (i.e., production strain) early in product development and that dcm− strains may be superior for gene therapy applications wherein reduced immunogenicity is desirable and for in vitro transient transfection applications such as AAV production where improved expression is beneficial. Biotechnol. Bioeng. 2011;108: 354–363. © 2010 Wiley Periodicals, Inc. 相似文献
86.
Metabolic activities of four Bacillus strains to transform glucose into hydrogen (H2) and polyhydroxybutyrate (PHB) in two stages were investigated in this study. Under batch culture conditions, Bacillus thuringiensis EGU45 and Bacillus cereus EGU44 evolved 1.67–1.92 mol H2/mol glucose, respectively during the initial 3 days of incubation at 37°C. In the next 2 days, the residual glucose solutions
along with B. thuringiensis EGU45 shaken at 200 rpm was found to produce PHB yield of 11.3% of dry cell mass. This is the first report among the non-photosynthetic
microbes, where the Bacillus spp.—B. thuringiensis and B. cereus strains have been shown to produce H2 and PHB in same medium under different conditions. 相似文献
87.
88.
The simultaneous utilization of efficient respiration and inefficient fermentation even in the presence of abundant oxygen is a puzzling phenomenon commonly observed in bacteria, yeasts, and cancer cells. Despite extensive research, the biochemical basis for this phenomenon remains obscure. We hypothesize that the outcome of a competition for membrane space between glucose transporters and respiratory chain (which we refer to as economics of membrane occupancy) proteins influences respiration and fermentation. By incorporating a sole constraint based on this concept in the genome‐scale metabolic model of Escherichia coli, we were able to simulate respiro‐fermentation. Further analysis of the impact of this constraint revealed differential utilization of the cytochromes and faster glucose uptake under anaerobic conditions than under aerobic conditions. Based on these simulations, we propose that bacterial cells manage the composition of their cytoplasmic membrane to maintain optimal ATP production by switching between oxidative and substrate‐level phosphorylation. These results suggest that the membrane occupancy constraint may be a fundamental governing constraint of cellular metabolism and physiology, and establishes a direct link between cell morphology and physiology. 相似文献
89.
目的:研究重组人小分子抗体ScFv-Fc在毕赤酵母中分泌表达的最佳条件,以及ScFv-Fc的纯化方法。方法:分别从甲醇浓度、pH、诱导时间等方面对毕赤酵母重组菌株产生ScFv-Fc的发酵过程进行了优化;通过硫酸铵沉淀结合protein A亲和层析柱,对ScFv-Fc的纯化方法进行了研究。结果:确定ScFv-Fc在毕赤酵母中分泌表达的最佳条件为:在pH5.2的条件下,以0.5%甲醇诱导72 h。经过protein A亲和层析柱纯化后,ScFv-Fc纯度可达94%以上。结论:确定了ScFv-Fc在毕赤酵母中分泌表达的最佳条件以及纯化方法,为重组抗体分子诊断、治疗试剂的开发以及抗体的人源化奠定了物质基础。 相似文献
90.
Jae-Hoon HwangJeong-A Choi Reda A.I. Abou-Shanab Booki MinHocheol Song Yongje Kim Eung Seok LeeByong-Hun Jeon 《Bioresource technology》2011,102(2):1051-1058
Anaerobic fermentation for hydrogen (H2) production was studied in a two-stage fermentation system fed with different ripened fruit feedstocks (apple, pear, and grape). Among the feedstocks, ripened apple was the most efficient substrate for cumulative H2 production (4463.7 mL-H2 L−1-culture) with a maximum H2 yield (2.2 mol H2 mol−1 glucose) in the first stage at a hydraulic retention time (HRT) of 18 h. The additional cumulative biohydrogen (3337.4 mL-H2 L−1-culture) was produced in the second stage with the reused residual substrate from the first stage. The major byproducts in this study were butyrate, acetate, and ethanol, and butyrate was dominant among them in all test runs. During the two-stage system, the energy efficiency (H2 conversion) obtained from mixed ripened fruits (RF) increased from 4.6% (in the first stage) to 15.5% (in the second stage), which indicated the energy efficiency can be improved by combined hydrogen production process. The RF could be used as substrates for biohydrogen fermentation in a two-stage (dark/dark) fermentation system. 相似文献