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951.
MicroRNAs (miRNAs) are important nonprotein-coding genes involved in almost all biological processes during biotic and abiotic stresses in plants. To investigate the miRNA-mediated plant response to drought stress, two drought-tolerant (C-306 and NI-5439) and two drought-sensitive (HUW-468 and WL-711) wheat genotypes were exposed to 25 % PEG 6000 for 1, 12 and 24 h. Temporal expression patterns of 12 drought-responsive miRNAs and their corresponding nine targets were monitored by quantitative real-time PCR (qRT-PCR). The results showed differential expression of miRNAs and their targets with varying degree of upregulation and downregulation in drought-sensitive genotypes. Likewise, in drought-tolerant wheat genotypes, maximum accumulation of miR393a and miR397a was observed at 1 h of stress. In addition, nearly perfect negative correlation was observed in four miRNA and target pairs (miR164-NAC, miR168a-AGO, miR398-SOD and miR159a-MYB) across all the temporal period studied which could be a major player during drought response in wheat. We, for the first time, validated the presence of miR529a and miR1029 in wheat. These findings gives a clue for temporal and variety-specific differential regulation of miRNAs and their targets in wheat in response to osmotic shock and could help in defining the potential roles of miRNAs in plant adaptation to osmotic stress in future.  相似文献   
952.
For high-throughput screening (HTS) of Bacillus fastidiosus uricase mutants, a practical system was proposed. By error-prone PCR with final 1.5 mM MnCl2, two focused libraries of mutants for A1-V158 and V150-D212 were generated separately. After induced expression of individual clones in 48-well microplates, Escherichia coli cells (BL21) were lyzed by 1.0 M Tris-HCl at pH 9.0 in 96-well microplates at 25 °C for 7.5 ~ 10.5 h; uricase reaction was continuously monitored with 0.15 mM uric acid in 96-well plates by absorbance at 298 nm to estimate V m/K m by kinetic analysis of reaction curve for comparison. V m/K m was resistant to initial uric acid levels with an upper limit 3-fold over that of initial rates. By receiver-operator-characteristic analysis of the recognition of the one of higher activity in uricase pair whose specific activity ratio was 1.8 or 3.3, the area-under-the-curve was comparable to that with cell lysates prepared by sonication treatment. A cutoff for the maximum Youden index was thus developed to recognize positive mutants of 1-fold higher activity. Indeed, mutant L171I/Y182F/Y187F/A193S of higher activity but lower thermostability at pH 7.4 and mutant V144A of higher activity and consistent thermostability were discovered. Therefore, the proposed system was practical for HTS of uricase mutants.  相似文献   
953.
A novel β-agarase AgaJ11 belonging to the glycoside hydrolase (GH) 16 family was identified from an agar-degrading bacterium Gayadomonas joobiniege G7. AgaJ11 was composed of 317 amino acids (35 kDa), including a 26-amino acid signal peptide, and had the highest similarity (44 % identity) to a putative β-agarase from an agarolytic marine bacterium Agarivorans albus MKT 106. The agarase activity of purified AgaJ11 was confirmed by zymogram analysis. The optimum pH and temperature for AgaJ11 activity were determined to be 4.5 and 40 °C, respectively. Notably, AgaJ11 is an acidic β-agarase that was active only at a narrow pH range from 4 to 5, and less than 30 % of its enzymatic activity was retained at other pH conditions. The K m and V max of AgaJ11 for agarose were 21.42 mg/ml and 25 U/mg, respectively. AgaJ11 did not require metal ions for its activity, but severe inhibition by several metal ions was observed. Thin layer chromatography and agarose-liquefying analyses revealed that AgaJ11 is an endo-type β-agarase that hydrolyzes agarose into neoagarohexaose, neoagarotetraose, and neoagarobiose. Therefore, this study shows that AgaJ11 from G. joobiniege G7 is a novel GH16 β-agarase with an acidic enzymatic feature that may be useful for industrial applications.  相似文献   
954.
In this study, the gene encoding an α-amylase from a psychrophilic Arthrobacter agilis PAMC 27388 strain was cloned into a pET-28a(+) vector and heterologously expressed in Escherichia coli BL21(DE3). The recombinant α-amylase with a molecular mass of about 80 kDa was purified by using Ni2+-NTA affinity chromatography. This recombinant α-amylase exhibited optimal activity at pH 3.0 and 30 °C and was highly stable at varying temperatures (30–60 °C) and within the pH range of 4.0–8.0. Furthermore, α-amylase activity was enhanced in the presence of FeCl3 (1 mM) and β-mercaptoethanol (5 mM), while CoCl2 (1 mM), ammonium persulfate (5 mM), SDS (10 %), Triton X-100 (10 %), and urea (1 %) inhibited the enzymatic activity. Importantly, the presence of Ca2+ ions and phenylmethylsulfonyl fluoride (PMSF) did not affect enzymatic activity. Thin layer chromatography (TLC) analysis showed that recombinant A. agilis α-amylase hydrolyzed starch, maltotetraose, and maltotriose, producing maltose as the major end product. These results make recombinant A. agilis α-amylase an attractive potential candidate for industrial applications in the textile, paper, detergent, and pharmaceutical industries.  相似文献   
955.
In conjunction with an increasing public awareness of infectious diseases, the textile industry and scientists are developing hygienic fabrics by the addition of various antimicrobial and antiviral compounds. In the current study, sodium pentaborate pentahydrate and triclosan are applied to cotton fabrics in order to gain antimicrobial and antiviral properties for the first time. The antimicrobial activity of textiles treated with 3 % sodium pentaborate pentahydrate, 0.03 % triclosan, and 7 % Glucapon has been investigated against a broad range of microorganisms including bacteria, yeast, and fungi. Moreover, modified cotton fabrics were tested against adenovirus type 5 and poliovirus type 1. According to the test results, the modified textile goods attained very good antimicrobial and antiviral properties. Thus, the results of the present study clearly suggest that sodium pentaborate pentahydrate and triclosan solution-treated textiles can be considered in the development of antimicrobial and antiviral textile finishes.  相似文献   
956.
In this study, we investigated the enzymatic synthesis of a semi-synthetic cephalosporin, cefadroclor, from 7-aminodesacetoxymethyl-3-chlorocephalosporanic acid (7-ACCA) and p-OH-phenylglycine methyl ester (D-HPGM) using immobilized penicillin G acylase (IPA) in organic co-solvents. Ethylene glycol (EG) was employed as a component of the reaction mixture to improve the yield of cefadroclor. EG was found to increase the yield of cefadroclor by 15–45%. An investigation of altered reaction parameters including type and concentration of organic solvents, pH of reaction media, reaction temperature, molar ratio of substrates, enzyme loading, and IPA recycling was carried out in the buffer mixture. The best result was a 76.5% conversion of 7-ACCA, which was obtained from the reaction containing 20% EG (v/v), D-HPGM to 7-ACCA molar ratio of 4:1 and pH 6.2, catalyzed by 16 IU mL?1 IPA at 20 °C for 10 h. Under the optimum conditions, no significant loss of IPA activity was found after seven repeated reaction cycles. In addition, cefadroclor exhibited strong inhibitory activity against yeast, Bacillus subtilis NX-2, and Escherichia coli and weaker activity against Staphylococcus aureus and Pseudomonas aeruginosa. Cefadroclor is a potential antibiotic with activity against common pathogenic microorganisms.  相似文献   
957.
Immobilization methods and carriers were screened for immobilization of Euglena gracilis extract with laminaribiose phosphorylase activity. The extract was successfully immobilized on three different carriers via covalent linkage. Suitable immobilization carriers were Sepabeads EC-EP/S and ECR 8209M with epoxy groups and ECR 8309M with amino groups as functional units. Immobilization on Sepabeads EC-EP/S resulted in highest retained activity (65%). The immobilizates were characterized for pH, temperature, and buffer molarity preferences. The immobilized enzyme lost 48% of its activity when used seven times. Together with sucrose phosphorylase, laminaribiose phosphorylase was successfully applied for bienzymatic production of laminaribiose from sucrose and glucose with a final laminaribiose concentration of 14.3 ± 2.1 g/L (20% yield).  相似文献   
958.
A hyaluronate lyase was obtained by cultivating Arthrobacter globiformis strain A152. The enzyme was purified to homogeneity from the supernatant by ammonium sulfate fractionation, Q Sepharose Fast Flow, and Sephadex G-100 chromatography. The purification resulted in a 32.78-fold increase in hyaluronate lyase activity with specific activity of 297.2 U/mg. The molecular weight of the enzyme determined by SDS-PAGE was approximately 73.7 kDa. Using hyaluronic acid (HA) as a substrate, the maximal reaction rate (Vmax) and the Michaelis–Menten constant (Km) of hyaluronate lyase were found to be 4.76 μmol/min/ml and 0.11 mg/ml, respectively. The optimum pH and temperature values for hyaluronate lyase activity were pH 6.0 and 42 °C, respectively. This enzyme was stable at pH 4–10, 5–7, and 5–7 at 4, 37, and 42 °C, respectively. Investigation about temperature effects on hyaluronate lyase displayed that it was stable at 30–37 °C and also showed high activity at 37 °C. The enzymatic activity was enhanced by Ca2+ and was strongly inhibited by Cu2+ and SDS. These properties suggested that the hyaluronate lyase in this study could bring promising prospects in medical and industry applications.  相似文献   
959.
A novel β-1,3-glucanase gene, designated Ccglu17A, was cloned from the biological control fungus Chaetomium cupreum Ame. Its 1626-bp open reading frame encoded 541 amino acids. The corresponding amino acid sequence showed highest identity (67 %) with a glycoside hydrolase family 17 β-1,3-glucanase from Chaetomium globosum. The recombinant protein Ccglu17A was successfully expressed in Pichia pastoris, and the enzyme was purified to homogeneity with 10.1-fold purification and 47.8 % recovery yield. The protein’s molecular mass was approximately 65 kDa, and its maximum activity appeared at pH 5.0 and temperature 45 °C. Heavy metal ions Fe2+, Mn2+, Cu2+, Co2+, Ag+, and Hg2+ had inhibitory effects on Ccglu17A, but Ba2+ promoted the enzyme’s activity. Ccglu17A exhibited high substrate specificity, almost exclusively catalyzing β-1,3-glycosidic bond cleavage in various polysaccharoses to liberate glucose. The enzyme had a Km of 2.84 mg/mL and Vmax of 10.7 μmol glucose/min/mg protein for laminarin degradation under optimal conditions. Ccglu17A was an exoglucanase with transglycosylation activity based on its hydrolytic properties. It showed potential antifungal activity with a degradative effect on cell walls and inhibitory action against the germination of pathogenic fungus. In conclusion, Ccglu17A is the first functional exo-1,3-β-glucanase to be identified from C. cupreum and has potential applicability in industry and agriculture.  相似文献   
960.
Microbial fuel cells (MFCs) convert electrochemical energy into electrical energy immediately and have a big potential usage for the same time wastewater treatment and energy recovery via electro-active microorganisms. However, MFCs must be efficiently optimized due to its limitations such as high cost and low power production. Finding new materials to increase the cell performance and reduce cost for MFC anodes is mandatory. In the first step of this study, different inoculation sludges such as anaerobic gum industry wastewater, anaerobic brewery wastewater and anaerobic phosphate were tested, and MFC that was set up with anaerobic gum industry wastewater inoculation sludge exhibited the highest performance. In the second step of this study, various wastewaters such as chocolate industry, gum industry and slaughterhouse industry were investigated for anode bacteria sources. Several electrochemical techniques have been employed to elucidate how wastewaters affect the MFCs’ performance. Among all the mentioned wastewaters, the best performance was achieved by the MFCs fed with slaughterhouse wastewater; this device produced a maximum power density of 267 mW·m?2.  相似文献   
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