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1.
《Biocatalysis and Biotransformation》2013,31(6):354-358
AbstractPowdered biomass of Aspergillus sp. (RBD01) was used to carry out esterification of long chain fatty acids for biodiesel production. Dry biomass of Aspergillus sp. at 20% (w/w) with respect to the fatty acid was able to completely esterify oleic acid to ethyl ester at 35°C, in 36 h, with step wise addition of alcohol. Similar conditions also resulted in yield of 64.5% and 58% of ethyl ester from stearic acid and palmitic acid, respectively. However, the presence of methanol resulted in 87.5%, 71% and 41% of methyl ester from oleic, palmitic and stearic acid. Furthermore, it was found that the efficiency of biomass decreased by only 10% with its repeated use up to four cycles. 相似文献
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Papanikolaou S Dimou A Fakas S Diamantopoulou P Philippoussis A Galiotou-Panayotou M Aggelis G 《Journal of applied microbiology》2011,110(5):1138-1150
Aims: In this study, we have investigated the biochemical behaviour of Aspergillus sp. (five strains) and Penicillium expansum (one strain) fungi cultivated on waste cooking olive oil. The production of lipid‐rich biomass was the main target of the work. In parallel, the biosynthesis of other extracellular metabolites (organic acids) and enzyme (lipase) and the substrate fatty acid specificity of the strains were studied. Methods and Results: Carbon‐limited cultures were performed on waste oil, added in the growth medium at 15 g l?1, and high biomass quantities were produced (up to c. 18 g l?1, conversion yield of c. 1·0 g of dry biomass formed per g of fat consumed or higher). Cellular lipids were accumulated in notable quantities in almost all cultures. Aspergillus sp. ATHUM 3482 accumulated lipid up to 64·0% (w/w) in dry fungal mass. In parallel, extracellular lipase activity was quantified, and it was revealed to be strain and fermentation time dependent, with a maximum quantity of 645 U ml?1 being obtained by Aspergillus niger NRRL 363. Storage lipid content significantly decreased at the stationary growth phase. Some differences in the fatty acid composition of both cellular and residual lipids when compared with the initial substrate fat used were observed; in various cases, cellular lipids more saturated and enriched with arachidic acid were produced. Aspergillus strains produced oxalic acid up to 5·0 g l?1. Conclusions: Aspergillus and Penicillium strains are able to convert waste cooking olive oil into high‐added‐value products. Significance and Impact of the Study: Increasing fatty wastes amounts are annually produced. The current study provided an alternative way of biovalourization of these materials, by using them as substrates, to produce added‐value compounds. 相似文献
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Aspergillus sp.脂肪酶发酵条件优化及酶学性质的研究 总被引:2,自引:0,他引:2
作者为了得到一种热稳定性较好的脂肪酶新酶种,通过研究分离白极端环境的Aspergillus sp.的最佳产酶条件及其所产脂肪酶的酶学性质,得出了该菌产酶的最佳发酵条件为:以1%黄豆饼粉为氮源、0.2%玉米淀粉为碳源,1.5%橄榄油为诱导物,起始pH6.0左右。装量10mL(250mL三角瓶。摇瓶转速180r/min)、发酵时间为96h。在最佳发酵条件下可得最大发酵酶活36U/mL。Aspergillus sp.所产的脂肪酶的酶学性质是:最适pH为9.0,在pH5.0—10.0于20℃下放置24h后,残余酶活仍保持在起始酶活的90%以上;该酶的最适温度为50℃,50℃保温60min后仍保留70%以上的酶活。Aspergillus sp.所产脂肪酶的热稳定性较好。 相似文献
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植物细胞离析酶的制备和应用 总被引:2,自引:0,他引:2
用 Aspergillus sp.A-19菌经固体发酵研制成一种新的植物细胞离析酶(SeparatasezA—P)。其离析单细胞的酶活力平均为70 767u/g,有效作用的pH在3.0—7.0,温度为20—45℃。发酵培养基配方是麸皮:桔皮粉:(NH4)2SO4(w/w)为100:100:O.63,料水比为1 :2.0,培养适宜条件为25℃、60小时。 相似文献
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银杏叶内生真菌Aspergillus sp. YXf3活性次生代谢产物的研究 总被引:1,自引:0,他引:1
采用多种柱层析技术,从银杏叶内生真菌Aspergillus sp.YXf3发酵液的乙酸乙酯提取物中分离得到5个化合物,根据理化性质和波谱数据鉴定其结构分别为terreinol(1)、cyclo-(L-Leu-L-Trp)(2)、sphaeropsidin A(3)、sphaeropsidin B(4)和4-hydroxy-3-(3’-methyl-2’-butenyl)benzoic acid(5)。以上化合物均为首次从银杏内生真菌中分离得到。神经氨酸酶抑制剂活性测试结果表明,化合物2和4具有较强的抑制活性,其IC50分别为4.67和3.40μM。 相似文献
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《Biocatalysis and Biotransformation》2013,31(5-6):403-407
AbstractThe present study was carried out to examine the effect of different frying times of edible oil on the extent of transesterification catalyzed by the whole-cell biocatalyst, Aspergillus (RBD01). Cottonseed oil was chosen as a conventional and cost-effective edible oil used commercially in India. The results showed that increased frying time of the oil decreased the extent of the transesterification reaction and hence alkyl ester production. Nearly complete (>98%) transesterification to ethyl alcohol was observed with used oil containing a free fatty acid (FFA) content of 3.7%, whereas beyond an FFA content of 4.0% the yield was reduced. Biocatalyzed hydrolysis (in the absence of the ethyl alcohol acceptor) of used frying oil resulted in decreasing yield of FFA from 84.0% to 27.6% with increasing frying time. With fried oil capable of a hydrolysis yield of 82–41% FFA, transesterification reactions were nearly complete. With the lower hydrolysis yields of 38–27% FFA, the transesterified ethyl ester yield decreased to 61–51%. These observations indicate that factors other than the presence of FFA and moisture influence the biocatalytic transesterification of used cooking oils. 相似文献
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Justyna Kulig Amina Frese Wolfgang Kroutil Martina Pohl Dörte Rother 《Biotechnology and bioengineering》2013,110(7):1838-1848
Stereoselective reduction towards pharmaceutically potent products with multi‐chiral centers is an ongoing hot topic, but up to now catalysts for reductions of bulky aromatic substrates are rare. The NADPH‐dependent alcohol dehydrogenase from Ralstonia sp. (RADH) is an exception as it prefers sterically demanding substrates. Recent studies with this enzyme indicated outstanding potential for the reduction of various alpha‐hydroxy ketones, but were performed with crude cell extract, which hampered its detailed characterization. We have established a procedure for the purification and storage of RADH and found a significantly stabilizing effect by addition of CaCl2. Detailed analysis of the pH‐dependent activity and stability yielded a broad pH‐optimum (pH 6–9.5) for the reduction reaction and a sharp optimum of pH 10–11.5 for the oxidation reaction. The enzyme exhibits highest stability at pH 5.5–8 and 8–15°C; nevertheless, biotransformations can also be carried out at 25°C (half‐life 80 h). Under optimized reaction parameters a thorough study of the substrate range of RADH including the reduction of different aldehydes and ketones and the oxidation of a broad range of alcohols was conducted. In contrast to most other known alcohol dehydrogenases, RADH clearly prefers aromatic and cyclic aliphatic compounds, which makes this enzyme unique for conversion of space demanding substrates. Further, reductions are catalyzed with extremely high stereoselectivity (>99% enantio‐ and diastereomeric excess). In order to identify appropriate substrate and cofactor concentrations for biotransformations, kinetic parameters were determined for NADP(H) and selected substrates. Among these, we studied the reduction of both enantiomers of 2‐hydroxypropiophenone in more detail. Biotechnol. Bioeng. 2013; 110: 1838–1848. © 2013 Wiley Periodicals, Inc. 相似文献
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《Biocatalysis and Biotransformation》2013,31(2-3):54-59
AbstractAspergillus sp. PTCC 5266 exhibited nitrile-hydrating activity over a broad pH range from 6.0 to 10.0 at 26°C. It hydrated 4-nitrophenylacetonitrile, 2-chlorobenzonitrile and 3-chlorobenzonitrile to their corresponding carboxylic acids and amides, while benzyl cyanide, benzonitrile, 4-tolunitrile, cyclohexanecarbonitrile, 4-chlorobutyronitrile and isobutyronitrile gave carboxylic acids as the sole products. The maximum whole-cell nitrile-hydrating activity was observed at pH 7.0. 相似文献
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Abstract Intact conidia of Aspergillus sp. were able to degrade pectin 'in vitro' even when protein synthesis was inhibited, thus indicating the presence of cell bound pectinases. At least an exo-pectinase was found and this enzyme was also present in the mycelium of Aspergillus sp. Its presence was not dependent on the carbon source used for growth, suggesting its constitutive nature. This exo-pectinase could be released from conidia or mycelium by incubation at different pH values and the amount of enzyme released could be increased by treatments with chemical agents and hydrolytic enzymes. 相似文献
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A microbial biosensor was developed for monitoring microbiologically influenced corrosion (MIC) of metallic materials in industrial systems. The Pseudomonas sp. isolated from corroded metal surface was immobilized on acetylcellulose membrane and its respiratory activity was estimated by measuring oxygen consumption. The microbial biosensor was used for the measurement of sulfuric acid in a batch culture medium contaminated by microorganisms. A linear relationship between the microbial sensor response and the concentration of sulfuric acid was observed. The response time of biosensor was 5 min and was dependent on the immobilized cell loading of Pseudomonas sp., pH, temperature and corrosive environments. The microbial biosensor response was stable, reproducible and specific for sensing of sulfur oxidizing bacterial activity. 相似文献
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The bioremediation of chromate and tannic acid in synthetic tannery wastewater was studied in a batch culture system using free and immobilized spores and mycelia of A. niger and A. parasiticus. Significant (p< .001) decreases in total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), Cr(VI), and tannic acid concentrations were observed in cultures of both fungi after 96 h of growth. The A. niger culture medium had significantly lower TDS (p< .001), BOD, and tannic acid concentration (p< .05) compared to that of A. parasiticus. Immobilization of both spores and mycelia of the two fungi on Ca-alginate resulted in significantly (p< .05–.001) lower residual Cr(VI) concentrations within 24 h hydraulic retention time (HRT). Chromate removal increased significantly (p< .05) as the number of beads of immobilized spore/mycelia increased from 10 to 100; the increase in Cr(VI) removal ranging from 40.3% to 47.9% with 10 beads and 97.4% to 98.6% with 100 beads. Similarly, tannic acid removal by spores and mycelia of the fungi was significantly (p< .05) enhanced by immobilization. Repeated use of the alginate entrapped spores/mycelia of both fungi up to 3 cycles of 72-h HRT showed no significant change in their ability to carryout Cr(VI) removal. 相似文献
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微小杆菌(Exiguobacterium sp.)对肉桂酸降解行为 总被引:1,自引:0,他引:1
【目的】为有效缓解自毒物质肉桂酸对西瓜等作物生长的危害,从宁夏中卫硒砂瓜连作土壤中分离筛选得到一株高效降解肉桂酸的菌株,研究其基本降解特性。【方法】分离筛选得到一株能有效利用肉桂酸生长的菌株,采用16S r RNA基因序列分析进行菌株鉴定,运用高效液相色谱法和西瓜幼苗生长毒性实验检测降解特性。【结果】从多年西瓜连作土壤中筛选得到一株高效降解肉桂酸的细菌R30,鉴定为Exiguobacterium sp.,其96 h内对肉桂酸的降解率可达99%以上,最适降解温度和p H分别为30°C、p H 7.0。除肉桂酸外,该菌也能够高效降解香豆酸、阿魏酸、苯甲酸等其他酚酸类物质,表现出一定的底物广谱性;检测96 h降解液对西瓜种子萌发直至幼苗生长阶段的影响表明,该菌株可有效缓解肉桂酸对西瓜幼苗的生长抑制作用。【结论】菌株R30在肉桂酸、香豆酸、阿魏酸、苯甲酸等酚酸类物质导致的农作物连作障碍治理领域具有潜在的开发应用价值。 相似文献
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考察种子培养基中谷氨酸钠质量浓度和NaCl质量浓度(盐度)对Schizochytrium sp. HX-308菌种质量及发酵性能的影响。结果表明:40 g/L谷氨酸钠条件下培养菌种,发酵后DHA质量分数达到(53.25±0.48)%,而其油产量、油脂质量分数和DHA产量分别为(24.9±0.4)g/L、(45.2±0.6)%、(8.6±0.35)g/L; 利用不含谷氨酸钠的种子培养基发酵,其油产量、油脂质量分数和DHA产量分别为(30.1±0.8)g/L、(54.3±0.5)%、(12.1±0.5)g/L,比含40 g/L谷氨酸钠时分别提高了20.88%、20.13%和40.70%,为菌种驯化提供了新的思路和方向。此外,低盐度培养条件有利于菌种生产性能的发挥,6.25 g/L NaCl条件下发酵后油质量分数、DHA产量及DHA质量分数最高,分别为(62.1±0.8)%、(10.0±0.3)g/L、(48.97±0.42)%。 相似文献
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Fungi isolated from soil were screened for exogenous lipolytic activity. The highest lipase activity was found in a new soil isolate of Aspergillus sp. Some optimal cultural parameters influencing the growth and production of extracellular lipase from this Aspergillus sp. were investigated. The lipase yield was maximum on day 4 of incubation of the culture at pH 5.5 and 30 °C. When the medium was prepared using olive oil as carbon source and peptone as a nitrogen source, better lipase yields were obtained. Aeration enhanced growth and lipase production. 相似文献
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《Bioscience, biotechnology, and biochemistry》2013,77(7):1590-1593
Two microorganisms (NDKK48 and NDKY76A) that degrade long-chain cyclic alkanes (c-alkanes) were isolated from soil samples. Strains NDKK48 and NDKY76A were identified as Rhodococcus sp. and Gordonia sp., respectively. Both strains used not only normal alkane (n-alkane) but also c-alkane as a sole carbon and energy source, and the strains degraded more than 27% of car engine base oil (1% addition). 相似文献
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Ana Flora D. Vasconcelos Aneli M. Barbosa Robert F.H. Dekker Ieda S. Scarminio Maria Inês Rezende 《Process Biochemistry》2000,35(10):1131-1138
Botryosphaeria sp. produced two laccases (PPO-I and PPO-II) constitutively, whose titers were enhanced by veratryl alcohol. The effect of veratryl alcohol and yeast extract concentration, time of cultivation and agitation speed were evaluated by factorial analysis to select variables for optimizing the production of laccases. Maximal laccase production was determined using a second-order central-composite design and analyzed by the response-surface method. Veratryl alcohol concentration and time of cultivation were the main factors increasing laccase production, while yeast extract had no influence within the range 0.2–2.0% w/v. Response-surface analysis showed that 30.4 mM veratryl alcohol, for 4.5 days at 28°C and 180 rpm, were the optimal conditions to maximize PPO-I production, while conditions for maximal PPO-II production occurred within a range of 28–35 mM veratryl alcohol over a growth period of 4–5.5 days. The model predicted 5.6 U ml−1 for PPO-I, and 0.6–1.0 U ml−1 for PPO-II, which agreed with the experimentally observed results. 相似文献