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Izuddin Abdul Rahman Raja Noor Zaliha Raja Abdul Rahman Abu Bakar Salleh Mahiran Basri 《Journal of surfactants and detergents》2013,16(3):427-434
The use of enzymes in detergent formulations is becoming popular due to the concerns about the environment. T1 lipase (E.C. 3.1.1.3) was evaluated for its stability and performance in dishwashing along with other common components of an automatic dishwashing detergent. Therefore, the process of formulating the detergent would depend on the stability of T1 lipase, which may also reflect the performance during the washing. T1 lipase was mostly stable in nonionic surfactants, especially those that were made of polyhydric alcohols. T1 lipase was also stable in a mixture of sodium carbonate and glycine. However, sodium carbonate alone destabilized T1 lipase possibly due to the interaction between carbonates and Ca2+. These results indicated that polyhydric alcohols and glycine had stabilizing effects on T1 lipase. The dishwashing performance was evaluated in term of percent soil removed. The dishwashing performance of the formulated detergent was positively affected by the increase in temperature but negatively affected by the presence of hard water, specifically Ca2+ and Mg2+. However, T1 lipase was not negatively affected by the presence of hard water, and this enzyme was enhanced by the presence of polyacrylates. The presence of Ca2+ improved the structural integrity of T1 lipase. It is generally known that most enzymes that depend on Ca2+ for their structural integrity would be greatly destabilized in the presence of metal chelators; thus, stabilizing strategies such as adding glycine would be essential to maintain enzyme activity during the wash. 相似文献
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A novel thermophilic xylanase-producing fungus, Chaetomium sp. CQ31 produced 131 U ml−1 of xylanase when grown on a medium containing corncob (3.5%, w/v) at 37 °C for 6 days. A low molecular xylanase was purified 6.5-fold to homogeneity with a recovery yield of 17.5%. Its molecular mass was estimated to be 25.1 kDa by SDS–PAGE. The xylanase had an optimum pH of 7.5, and its optimal temperature was 65 °C. Apparent Km values of the xylanase for birchwood, beechwood and oat-spelt xylan were 1.3, 0.86 and 4.4 mg/ml, respectively. The influence of this xylanase on the quality of Chinese steamed bread (CSB) was further studied. Addition of xylanase in the range 2.5–5.0 ppm caused a 20–24.5% increase in specific volume over the control and remarkable decrease (8.9–24.2%) in firmness was also noticed. This is the first report on the purification, characterisation and application of a xylanase from Chaetomium sp. CQ31. 相似文献
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A xylanase-producing bacterium, isolated from deep sea sediments, was identified as the cold-adapted marine species Acinetobacter Johnsonii. A cold-adapted marine species Acinetobacter Johnsonii could grow at 4 ℃. The optimum temperature and pH of xylanase from a cold-adapted marine species Acinetobacter Johnsonii were 55 ℃ and pH 6.0. Xylanase from a cold-adapted marine species Acinetobacter Johnsonii remained at 80% activity after incubation for 1 h at 65 ℃. The xylanase activity was 1.2-fold higher in 4% ethanol solution than in ethanol free solution. Gibbs free energy of denaturation, ΔG, was higher in 4% ethanol solution than in ethanol free solution. Thermostable ethanol tolerant xylanase was valuable for bioethanol production by simultaneous saccharification and fermentation process with xylan as a carbon source. 相似文献
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Ki-Seok YoonKeiichi Fukuda Kiyoshi Fujisawa Hirofumi Nishihara 《International Journal of Hydrogen Energy》2011,36(12):7081-7088
The membrane-bound [NiFe]-hydrogenase from Hydrogenovibrio marinus (HmMBH) was purified homogeneously under anaerobic conditions. Its molecular weight was estimated as 110 kDa, consisting of a heterodimeric structure of 66 kDa and 37 kDa subunits. The purified enzyme exhibited high activity in a wide temperature range: 185 U/mg at 30 °C and 615 U/mg at 85 °C (the optimum temperature). The Km and kcat/Km values for H2 were, respectively, 12 μM and 8.58 × 107 M−1 s−1. The optimum reaction pH was 7.8, but its stability was particularly high at pH 4.0-7.0. Results show that HmMBH was remarkably thermostable and oxygen-resistant: its half-life was 75 h at 80 °C under H2, and more than 72 h at 4 °C under air. The air-oxidized HmMBH for 72 h showed only weak EPR signals of Ni-B, suggesting a structural feature in which the active center is not easily oxidized. 相似文献
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A thermophilic microorganism, SBS-4S, was isolated from a hot spring located in Gilgit, Northern Areas of Pakistan. It was found to be an aerobic, gram-positive, rod-shaped, thermophilic bacterium that grew on various sugars, carboxylic acids and hydrocarbons at temperatures between 45°C and 75°C. Complete 16S rRNA gene sequence of the microorganism exhibited homology to various species of genus Geobacillus. A highest homology of 99.8% was found with Geobacillus kaustophilus. A partial (0.7 kbp) chaperonin gene sequence also showed a highest homology of 99.4% to that of G. kaustophilus whereas biochemical characteristics of the microorganism were similar to Geobacillus uzenensis. Based on biochemical characterization, 16S rRNA and chaperonin gene sequences, we identified SBS-4S as a strain of genus Geobacillus. Strain SBS-4S produced several extracellular enzymes including amylase, protease and lipase. The lipase encoding gene was cloned, expressed in Escherichia coli and the gene product was characterized. The recombinant lipase was optimally active at 60°C with stability at wide pH range (6-12). The enzyme activity was enhanced remarkably in the presence of Ca(+2). The K(m) and the V(max) for the hydrolysis of p-nitrophenyl acetate were 3.8mM and 2273 μmol min(-1)mg(-1), respectively. The ability of the recombinant enzyme to be stable at a wide pH range makes it a potential candidate for use in industry. 相似文献
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M. Guncheva D. Zhiryakova N. Radchenkova M. Kambourova 《Journal of the American Oil Chemists' Society》2008,85(2):129-132
The catalytic efficiency of a lipase from Bacillus stearothermophilus MC7 (lipase MC7) was evaluated in acidolysis of tripalmitin with oleic acid to yield dioleoylpalmitoylglycerol, a structured
triglyceride used in health food. The immobilized enzyme exhibits good operational thermostability with a half-life of 50 days
at 60 °C in a solvent-free system. The degree of conversion exceeded 50% after 48 h. The side reaction of hydrolysis was suppressed.
However, the monosubstituted product was prevalent in the product mixture. Tested in a broad range of solvents, lipase MC7
showed tolerance towards medium polarity. 相似文献
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Purification and Characterization of a Lipase with High Thermostability and Polar Organic Solvent‐Tolerance from Aspergillus niger AN0512
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An extracellular lipase (EC 3.1.1.3, AN0512Lip) from Aspergillus niger AN0512 was purified and its characteristics were investigated. After the process of ammonium sulfate precipitation followed by ion‐exchange chromatography and gel filtration, the purified lipase was achieved with 203.6‐fold purification and 22.1 % recovery. AN0512Lip exhibited the highest activity at 50 °C and pH 5.0. It was thermostable and pH‐stable, as indicated by that more than 50 % activity retained at 60 °C for 20 h and more than 90 % activity retained at pH 3.0 for 20 h, respectively. AN0512Lip activity was stimulated by some divalent metal ions (especially Cu2+, Ca2+), while greatly suppressed by EDTA, indicating that AN0512Lip was a metal‐activated enzyme. Moreover, AN0512Lip exhibited high tolerance for various polar organic solvents with log P < 0.8, and the highest lipase activity (476 % of its original activity) was achieved after addition of 90 % (V/V) isopropanol to the reaction mixture. AN0512Lip also displayed 3‐regiospecificity and great affinity for the long‐chain fatty ester. The preliminary test showed that AN0512Lip was a candidate for enriching EPA and DHA in fish oil. All the unique properties, such as thermostability, Cu2+‐dependent, 3‐regiospecificity, and polar organic solvent‐tolerance, indicated that AN0512Lip could have potential applications in the food industry, even in organic synthesis and the pharmaceutical industry. 相似文献