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101.
Assem M. Hussein Houssni El-Saied Mohamed H. Yasin 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,53(2):147-152
Rice hulls were treated using several sodium hydroxide concentrations and temperatures. The black liquor contents of silica, lignin and hemicelluloses increased with increase in temperature or sodium hydroxide concentration. Hexoses constituted the major part and pentoses the minor part of the black liquor hemicelluloses. The ratio of pentoses to hexoses increased slightly with the increase of treatment variables. The pentose content of the black liquor consisted of arabinose and xylose, while the hexose composition was mannose, galactose, rhamnose and glucose. On increasing the alkali concentration, the xylose and mannose concentrations increased greatly, while galactose and glucose increased only slightly. Using 10 soil samples several isolates of fungi and actinomycetes were obtained. These were identified as five species of the genus Aspergillus, three species of Paecilomyces, two species of Penicillium, one species each of Alternaria, Trichoderma, Chaetomium and Actinopolyspora. These fungi were cultivated on black liquor basal salts medium. The highest bioconversion rate of black liquor hemicelluloses into biomass and single-cell proteins was achieved by Aspergillus terreus, followed by Paecilomyces simplicissima then Actinopolyspora sp. 相似文献
102.
Young‐Su Lee Ji‐Young Huh So‐Hyun Nam Doman Kim Soo‐Bok Lee 《Journal of food science》2013,78(3):C411-C415
Enzymatic bioconversion of rutin to quercetin‐3‐O‐glucoside (Q‐3‐G) by Penicillium decumbens naringinase was increased with reaction pH increased approximately to pH 6.0. It resulted in greater than 92% production of Q‐3‐G due to the removal of the terminal rhamnose at the controlled pH 6.0. The enzymatic bioconversion of rutin to Q‐3‐G was repetitively performed, yielding 84% after 5 batches with little quercetin formation. Interestingly, the water solubility of Q‐3‐G was enhanced 69‐ and 328‐fold over those of rutin and quercetin, which may make Q‐3‐G more bioavailable in food. Q‐3‐G was approximately 6‐ and 1.4‐fold more potent than rutin as an inhibitor of human intestinal maltase and human DL‐3‐hydroxy‐3‐methylglutalyl coenzyme A reductase. Q‐3‐G was less potent (16‐ and 1.3‐fold, respectively) than quercetin as an inhibitor of these enzymes. However, the results suggest that Q‐3‐G may be confirmed more effective and bioavailable food component than rutin and even quercetin because of its enhanced solubility and inhibitory properties. Practical Application : Bioconverted intermediate, quercetin‐3‐O‐glucoside (Q‐3‐G), was found and confirmed to be largely more soluble than rutin and quercetin in water solution, which might make it more bioavailable as food ingredient. In addition, Q‐3‐G inhibited mildly the intestinal maltase, which might act as antidiabetic substance by modulating the adsorption of glucose in the intestine. 相似文献
103.
Carmen Lizette Del-Toro-Sánchez Eugenia Lugo-Cervantes Sergio Sánchez 《Food Biotechnology》2013,27(3):219-236
Ditaxis heterantha seeds are a source of the apocarotenoid heteranthin (methyl 3-oxo-12´-apo-?-caroten-12´-oate). Saccharomyces cerevisiae can degrade, utilize this apocarotenoid, and produce seven aromas (3-oxo-α-ionone, 3-oxo-α-ionol, 3-oxo-7,8-dihydro-α-ionone, 3-hydroxy-β-cyclocitral, safranal, 4-oxo-isophorone, and isophorone). However, nothing is known about the enzymology of this process or the steps to produce them. In the present work, cell-free extracts of S. cerevisiae from cells grown in the presence or absence of heteranthin were evaluated for its degradation. When grown in heteranthin, cell-free extracts produced the same seven aromas, while in its absence only four aromas (3-hydroxy-β-cyclocitral, safranal, 4-oxo-isophorone, and isophorone) were detected. Polyacrylamide gel electrophoresis (PAGE) of cell extracts previously grown in heteranthin yielded a protein band of 27.6 kDa able to cleave this apocarotenoid. Band intensity was proportional to the heteranthin concentration and was not present in extracts from cultures grown in the absence of heteranthin. A purified sample of 27.6 kDa protein produced 3-oxo-α-ionone from heteranthin as the only reaction product, suggesting oxidation of the apocarotenoid at the 9-10 position of its moiety. Maximal enzymatic production of 3-oxo-α-ionone was observed at pH 5.5 and 35°C with activation energy of 7.23 kJ mol?1. The enzyme exhibited a Km value of 27 μM for heteranthin and a Vmax of 135 μmoles min?1 mg?1. Our findings clearly supported the presence of at least two ways for heteranthin degradation in S. cerevisiae: one that is probably committed to the heteranthin-induced synthesis of 3-oxo-α-ionol, and the other, constitutive, likely committed to safranal production. 相似文献
104.
L-肉碱在脂肪代谢中起重要的作用,本文构建了T7启动子控制下的过表达质粒p ET28a-cai BCD和p ACYCD-cai F-cai T,并将其转入大肠杆菌BL21(DE3)(简写DE3)中,得到基因工程菌BL21(DE3)/cai BCD+cai F+cai T(简写DE3/BCD+F+T)。将此菌株接种到生长培养基中,并用终浓度为1 mmol/L的IPTG(异丙基硫代半乳糖苷)诱导培养,然后收集菌体细胞加入到含有巴豆甜菜碱盐酸盐的转化液中进行转化。结果显示,IPTG诱导4 h比诱导10 h后转化得到的L-肉碱量要高,转入了过表达质粒的工程菌DE3/BCD+F+T(7.244 g/L)比野生型DE3(0.5 g/L)提高了15倍。该巴豆甜菜碱盐酸盐转化生成L-肉碱的反应在2 h后基本达到稳定。 相似文献
105.
UG Chandrika ER Jansz ND Warnasuriya 《Journal of the science of food and agriculture》2005,85(2):186-190
Vitamin A deficiency is of public health importance in Sri Lanka. Carotenoids are a significant source of provitamin A. The objective of this study was to analyse the carotenoid composition of jackfruit (Artocarpus heterophyllus sinhala: Waraka) kernel using MPLC and visible spectrophotometry and to determine the bioavailability and bioconversion of carotenoids present in jackfruit kernel by monitoring (i) the growth and (ii) levels of retinol and carotenoids in the liver and serum of Wistar rats provided with jackfruit incorporated into a standard daily diet. Carotenoid pigments were extracted using petroleum ether/methanol and saponified using 10% methanolic potassium hydroxide. Six carotenoids were detected in jackfruit kernel. The carotenes β‐carotene, α‐carotene, β‐zeacarotene, α‐zeacarotene and β‐carotene‐5,6‐epoxide and a dicarboxylic carotenoid, crocetin, were identified, corresponding theoretically to 141.6 retinol equivalents (RE) per 100 g. Our study indicated that jackfruit is a good source of provitamin A carotenoids, though not as good as papaya. Serum retinol concentrations in rats supplemented with jackfruit carotenoids were significantly higher (p = 0.008) compared with the control group. The same was true for liver retinol (p = 0.006). Quantification was carried out by RP‐HPLC. These results show that the biological conversion of provitamin A in jackfruit kernel appears satisfactory. Thus increased consumption of ripe jackfruit could be advocated as part of a strategy to prevent and control vitamin A deficiency in Sri Lanka. Copyright © 2004 Society of Chemical Industry 相似文献
106.
107.
热带假丝酵母转化生产木糖醇条件优化 总被引:1,自引:0,他引:1
利用热带假丝酵母(Candida tropicalis)生物转化木糖醇工艺简单、能耗低并且产物稳定.该文研究了菌体培养时间、转化时间、pH值、初糖浓度、摇床转速、加入菌体量对转化率的的影响,从而确立了最佳条件,即菌体培养时间为16h、转化时间为10h、转化pH值为5.5、转化初糖浓度为20g/L、转化摇床转速为150r/min、加入菌体量为10%(v/v),优化后木糖醇生物转化率达90%. 相似文献
108.
109.
110.
Qinlu Lin Huaxi Xiao Jian Zhao Lihui Li F engxiang Yu Xing Liu Xiangxu Cheng 《International Journal of Food Science & Technology》2011,46(6):1194-1200
Isomalto‐oligosaccharides (IMO) belong to a group of prebiotics that can significantly increase the number of protective gut microflora. A one‐step method using neopullulanase (NPN) in conjunction with saccharifying α‐amylase (SAA) for the bioconversion of rice starch into IMO was investigated. Purified rice starch slurry (30% w/w) was mixed with NPN (3.5 U g?1 starch substrate) and SAA (6.5 U g?1 starch substrate) and the slurry was incubated at 57 °C for 92 h under constant stirring. The carbohydrate composition of the resulting syrup was analysed by high performance liquid chromatography (HPLC) and the dextrose equivalent (DE) determined by titration. The amount of IMO in the syrup reached maximum (59.2%, dry basis) after 72 h of bioconversion. The concentration of glucose and maltose, which were the main carbohydrate residues of the IMO syrup, was 25.5% while the concentration of other oligosaccharide residues was about 1.0%. The results demonstrate that rice starch is a suitable matrix for producing IMO syrup and the one‐step conversion procedure appears to be an efficient method for converting starch into IMO syrup. 相似文献