Effects of Bacillus subtilis subsp. on the microbial community and aroma components of flue-cured tobacco leaves based on metagenome analysis.

To improve the sensory quality of aged flue-cured tobacco (FCT), Bacillus subtilis subsp, H11 was inoculated on aged FCT leaves named Pingdingshan DCFB. The metagenome and thecharacteristic aroma substances of aged FCT with different fermentation times (0 h, 12 h, 24 h, and 36 h) were systematically analyzed. The results showed that the content of aroma components and sensory quality of aged FCT were significantly improved when the strain was treated at 35 °C with 25% moisture for 24 h. The inoculation of H11 had a strong influence on the microbial composition and metabolism of the aged FCT leaf surface. Five microorganisms Pantoea (35.04%, 20.12-56.95%), Enterobacter (22.16, 13.60-39.82%), Pseudomonas (12.12, 3.13-26.17%), Terribacillus (8.00%, 4.65-13.01%) and Bacillus (6.54%, 0.67-16.96%) accounted for the largest proportion during the process of fermentation. The content of most neutral flavor components such as ketones and aldehydes in FCT after fermentation was higher than that priorto fermentation. After 24 h fermentation, 3-furfural, 5-methylfurfural, dihydrokiwi lactone and megalotrienone increased by 71.42%, 49.19%, 21.09%, and 10.56%, respectively. Correlation analysis between groups showed that Pseudomonas was significantly correlated with (E, E)-2, 4-heptadienal (P < 0.05), Franconibacter was correlated with damascus ketone (P < 0.05), and Terribacillus was related to the production of ß-citral (P < 0.05). GH9 may be involved in the formation of damasone (P < 0.05), and 4-cyclopentene-1, 3-dione was significantly correlated with glycoside hydrolase family 5 (GH5) (P < 0.05). The correlation between 4-oxyisophorone and GH31, GH103, GH73, and GH3 was significant (P < 0.05). Microorganisms and GHs may play important roles in FCT fermentation.

Isolation, Identification and Characterization of Growth Parameters of Pseudomonas putida HSM-C2 with Coumarin-Degrading Bacteria.

Natural coumarins contribute to the aroma of licorice, and they are often used as a flavoring and stabilizing agents. However, coumarins usage in food has been banned by various countries due to its toxic effect. In this study, a strain of HSM-C2 that can biodegrade coumarin with high efficiency was isolated from soil and identified as Pseudomonas putida through performing 16S rDNA sequence analysis. The HSM-C2 catalyzed the biodegradation up to 99.83% of 1 mg/mL coumarin within 24 h under optimal culture conditions, such as 30 °C and pH 7, which highlights the strong coumarin biodegrading potential of this strain. The product, such as dihydrocoumarin, generated after the biodegradation of coumarin was identified by performing GC-MS analysis. The present study provides a theoretical basis and microbial resource for further research on coumarin biodegradation.

Asymmetry in interdependence makes a multilayer system more robust against cascading failures.

Multilayer networked systems are ubiquitous in nature and engineering, and the robustness of these systems against failures is of great interest. A main line of theoretical pursuit has been percolation-induced cascading failures, where interdependence between network layers is conveniently and tacitly assumed to be symmetric. In the real world, interdependent interactions are generally asymmetric. To uncover and quantify the impact of asymmetry in interdependence on network robustness, we focus on percolation dynamics in double-layer systems and implement the following failure mechanism: Once a node in a network layer fails, the damage it can cause depends not only on its position in the layer but also on the position of its counterpart neighbor in the other layer. We find that the characteristics of the percolation transition depend on the degree of asymmetry, where the striking phenomenon of a switch in the nature of the phase transition from first to second order arises. We derive a theory to calculate the percolation transition points in both network layers, as well as the transition switching point, with strong numerical support from synthetic and empirical networks. Not only does our work shed light on the factors that determine the robustness of multilayer networks against cascading failures, but it also provides a scenario by which the system can be designed or controlled to reach a desirable level of resilience.

Fabrication of monodisperse poly (allyl glycidyl ether-co-divinyl benzene) microspheres and their application in anion-exchange stationary phase.

Micron-sized poly (allyl glycidyl ether-co-divinyl benzene) microspheres were prepared by a seed swelling and polymerization method and applied to prepare anion-exchange stationary phases by direct quaternization. The mono-dispersity, diameters, surface characteristics and porosity of microspheres were measured by scanning electron microscope and nitrogen adsorption-desorption measurements. The anion-exchange stationary phases were characterized by Fourier Transform Infrared Spectrum, Elemental Analysis, Breakthrough Curve, etc. The chromatographic properties of this self-fabricated anion-exchange column were investigated by separating conventional anions and organic weak acids. According to the results, poly (allyl glycidyl ether-co-divinyl benzene) microsphere possesses good compatibility in the whole pH range of 1-14; the presence of epoxy group guarantees the microsphere's superior reaction activity. The prepared poly (allyl glycidyl ether-co-divinyl benzene) microsphere is promising to replace poly (styrene-divinylbenzene) and poly (glycidylmethacrylate-divinylbenzene) and becomes a generation of support for the preparation of anion exchangers.

Draft Genome Sequence of Novosphingobium sp. Strain HII-3, a Bacterium Capable of Degrading the Cembranoid α(ß)-2,7,11-Cembratriene-4,6-Diol to Farnesal.

Novosphingobium sp. HII-3, the first bacterium confirmed to degrade the cembranoid α(ß)-2,7,11-cembratriene-4,6-diol to farnesal, was isolated from cured tobacco leaf in Henan, China. Here, we report the annotated draft genome sequence of strain HII-3, which has an estimated size of 4.45 Mb and comprises 4,072 coding sequences.

Cascading failures in coupled networks: The critical role of node-coupling strength across networks.

The robustness of coupled networks against node failure has been of interest in the past several years, while most of the researches have considered a very strong node-coupling method, i.e., once a node fails, its dependency partner in the other network will fail immediately. However, this scenario cannot cover all the dependency situations in real world, and in most cases, some nodes cannot go so far as to fail due to theirs self-sustaining ability in case of the failures of their dependency partners. In this paper, we use the percolation framework to study the robustness of interdependent networks with weak node-coupling strength across networks analytically and numerically, where the node-coupling strength is controlled by an introduced parameter α. If a node fails, each link of its dependency partner will be removed with a probability 1-α. By tuning the fraction of initial preserved nodes p, we find a rich phase diagram in the plane p-α, with a crossover point at which a first-order percolation transition changes to a second-order percolation transition.

Cascading failures in coupled networks with both inner-dependency and inter-dependency links.

We study the percolation in coupled networks with both inner-dependency and inter-dependency links, where the inner- and inter-dependency links represent the dependencies between nodes in the same or different networks, respectively. We find that when most of dependency links are inner- or inter-ones, the coupled networks system is fragile and makes a discontinuous percolation transition. However, when the numbers of two types of dependency links are close to each other, the system is robust and makes a continuous percolation transition. This indicates that the high density of dependency links could not always lead to a discontinuous percolation transition as the previous studies. More interestingly, although the robustness of the system can be optimized by adjusting the ratio of the two types of dependency links, there exists a critical average degree of the networks for coupled random networks, below which the crossover of the two types of percolation transitions disappears, and the system will always demonstrate a discontinuous percolation transition. We also develop an approach to analyze this model, which is agreement with the simulation results well.

Protein-templated cobaltous phosphate nanocomposites for the highly sensitive and selective detection of platelet-derived growth factor-BB.

We synthesized novel Co3(PO4)2-based nanocomposites with 3D porous architectures via self-assembly; here, bovine serum albumin (BSA) and aptamer were used as organic phases to produce Co3(PO4)2@BSA and Co3(PO4)2@Apt nanocomposites, respectively. The formation mechanism of Co3(PO4)2-based nanocomposites was described based on characterizations of their physio-chemical performance, and the developed nanocomposites were applied as scaffold materials to construct a novel electrochemical aptasensor and detect platelet-derived growth factor-BB (PDGF-BB). The PDGF-BB targeting aptamer must be immobilized onto the Co3(PO4)2@BSA-modified electrode to detect PDGF-BB, whereas Co3(PO4)2@Apt-based aptasensor may be directly used to determine the target protein. Electrochemical impedance spectroscopy results showed that the developed Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors present highly sensitive detection ability toward PDGF-BB. Due to the special nanoflower structure, the Co3(PO4)2@BSA-based aptasensor features a detection limit of 3.7 pg mL(-1); while the limit of detection of the Co3(PO4)2@Apt-based aptasensor is 61.5 pg mL(-1), which is the possible bioactivity loss of the aptamer in Co3(PO4)2@Apt nanocomposite. The two detection limits obtained are still much lower than or comparable with those of previously reported aptasensors. The Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors showed high selectivity, stability, and applicability for detecting the desired protein. This finding indicates that the Co3(PO4)2-based nanocomposites could be used as an electrochemical biosensor for various detection procedures in the biomedical field.

Purification and characterization of a novel ß-carotene-9',10'-oxygenase from Saccharomyces cerevisiae ULI3.

OBJECTIVES: A novel ß-carotene-9,10'-oxygenase (ScBCO2) has been characterized from Saccharomyces cerevisiae ULI3 to convert ß-carotene to ß-apo-10'-carotenal, which is a precursor of the plant hormone strigolactone. RESULTS: The ScBCO2 enzyme was purified to homogeneity by ammonium sulfate precipitation, Q sepharose and Superdex-200 chromatography. The molecular mass of the enzyme was ~50 kDa by SDS-PAGE. The purified ScBCO2 enzyme displayed optimal activity at 45 °C and pH 8. Tween 20 (1%, w/v), Trition X-100 (1%, w/v), Mg(2+) (5 mM), Zn(2+) (5 mM), Cu(2+) (5 mM), Ca(2+) (5 mM) or DTT (5 mM) increased in the activity by 3, 7, 14, 17, 23, 26 and 27%, respectively. ScBCO2 only exhibited cleavage activity towards carotenoid substrates containing two ß-ionone rings and its catalytic efficiency (kcat/Km) followed the order ß-carotene > α-carotene > lutein. CONCLUSION: ScBCO2 could be used as a potential candidate for the enzymatic biotransformation of ß-carotene to ß-apo-10'-carotenal in biotechnological applications.

Characterization of a novel thermophilic phospholipase B from Thermotoga lettingae TMO: applicability in enzymatic degumming of vegetable oils.

A novel phospholipase B (TLPLB) from Thermotoga lettingae TMO has been cloned, functionally overexpressed in Escherichia coli and purified to homogeneity. Gas chromatography indicated that the enzyme could efficiently hydrolyze both the sn-1 and sn-2 ester bonds of 1-palmitoyl-2-oleoyl phosphatidylcholine as phospholipase B. TLPLB was optimally active at 70 °C and pH 5.5, respectively. Its thermostability is relatively high with a half-life of 240 min at 90 °C. TLPLB also displayed remarkable organic solvent tolerance and maintained approximately 91-161 % of its initial activity in 20 and 50 % (v/v) hydrophobic organic solvents after incubation for 168 h. Furthermore, TLPLB exhibited high degumming activity towards rapeseed, soybean, peanut and sunflower seed oils, where the phosphorus contents were decreased from 225.2, 189.3, 85.6 and 70.4 mg/kg to 4.9, 4.7, 3.2 and 2.2 mg/kg within 5 h, respectively. TLPLB could therefore be used for the degumming of vegetable oils.

Purification and evaluation of the enzymatic properties of a novel fructosyltransferase from Aspergillus oryzae: a potential biocatalyst for the synthesis of sucrose 6-acetate.

A novel fructosyltransferase (AoFT) capable of synthesizing sucrose 6-acetate (S6A) from sucrose and glucose 6-acetate has been purified to homogeneity from Aspergillus oryzae ZZ-01. Its molecular mass was ~50 kDa by SDS-PAGE; optimal activity was at 45 °C and it was stable from pH 4.5 to 7.5 with an optimum pH of 6. Mg(2+), K(+) (5 mM), propanol, toluene (50%, v/v), Tween 20 or Triton X-100 (1%, w/v) increased the transfructosylation activity by 20, 17, 17, 10, 25 and 20%, respectively. An overall conversion of 32% was achieved under optimal conditions over 24 h. This is the first report that the purified and characterized the fructosyltransferase from Aspergillus capable of synthesis of S6A from sucrose and glucose 6-acetate.

Analysis of flavonoids by non-aqueous capillary electrophoresis with 1-ethyl-3-methylimidazolium ionic-liquids as background electrolytes.

The separation of three flavonoids, kaempferol, quercetin and luteolin, by capillary zone electrophoresis with three 1-ethyl-3-methylimidazolium ionic liquids (ILs), namely chloride, hydrogen sulfate and tetrafluoroborate salts, under non-aqueous conditions using acetonitrile as solvent was investigated. Depending on the IL, the three flavonoids can be separated under positive voltage with a low IL concentration and negative voltage with a high IL concentration. The separations are based on heteroconjungation between the IL anions and the analytes. The heteroconjungation between the anions of the ILs and the analytes is proton sensitive and only a very small amount of protic solvents, such as methanol, added into the electrolyte solution can harm the separation, but higher IL concentrations can overcome this higher amount of protic solvents. Using a high concentration of IL in the sample was used to enhance the flavonoid solubility by as much as 10, overcoming the problem of the low solubility during NACE analysis with ACN as the solvent. Finally, kaempferol, quercetin and luteolin in Semen Plantaginis were analysed by nonaqueous capillary electrophoresis with low concentration of the hydrogen sulfate ionic liquid with excellent results.

Preparative isolation and structural characterization of sucrose ester isomers from oriental tobacco.

To date, the structures of the sucrose tetraester (STE) isomers, a main kind of sucrose esters (SEs) in Solanum, have not been conclusively assigned. In this study, three groups of STE isomers with the molecular weight 650, 664 and 678 (designated as STE I, STE II and STE III, respectively) have been isolated and purified from the oriental tobacco-Komotini Basma using a semi-preparative RP-HPLC method. The full characterization of the isomers in the three groups of STE were investigated for the first time by MS (HRMS, MS(2)) and NMR ((1)H, (13)C, HSQC) spectroscopy combined with alkaline hydrolysis and STE derivation experiments. The STE III (a single compound) was confirmed as a known sucrose tetraester. Furthermore, the STE II was found to contain three isomers and the structures were first unambiguously established as 6-O-acetyl (2,3 or 2,4 or 3,4)-di-O-3-methylvaleryl-(4 or 3 or 2)-O-2-methylbutyryl-α-d-glucopyranosyl-ß-d-fructofuranoside. Finally, the STE I was discovered to contain seven isomers and the structures were elucidated as 6-O-acetyl (2 or 3 or 4)-O-3-methylvaleryl-(3,4 or 2,4 or 2,3)-di-O-2-methylbutyryl-α-d-glucopyranosyl-ß-d-fructofuranoside, 6-O-acetyl (2 or 3 or 4)-O-3-methylvaleryl-(3,4 or 2,4 or 2,3)-di-O-isovaleryl-α-d-glucopyranosyl-ß-d-fructofuranoside and 6-O-acetyl (2,3 or 2,4 or 3,4)-di-O-3-methylvaleryl-(4 or 3 or 2)-O-isobutyryl-α-d-glucopyranosyl-ß-d-fructofuranoside (one of the 3 isomers).

Bis[2,6-bis-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine]di-µ(3)-iodido-diiodidotetra-copper(I).

In the title centrosymmetric tetra-nuclear complex, [Cu(4)I(4)(C(15)H(17)N(5))(2)], the two distinct Cu(I) atoms adopt similar tetra-hedral arrangements, each being ligated by two I atoms, and two N atoms from one 2,6-bis-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine ligand. In the crystal, there are no hydrogen bonds present, and only very weak π-π inter-actions are observed [centroid-centroid distance = 3.985 (4) Å], which connect neighbouring tetra-nuclear units into a chain motif along the b axis.

Information filtering based on transferring similarity.

In this Brief Report, we propose an index of user similarity, namely, the transferring similarity, which involves all high-order similarities between users. Accordingly, we design a modified collaborative filtering algorithm, which provides remarkably higher accurate predictions than the standard collaborative filtering. More interestingly, we find that the algorithmic performance will approach its optimal value when the parameter, contained in the definition of transferring similarity, gets close to its critical value, before which the series expansion of transferring similarity is convergent and after which it is divergent. Our study is complementary to the one reported in [E. A. Leicht, P. Holme, and M. E. J. Newman, Phys. Rev. E 73, 026120 (2006)], and is relevant to the missing link prediction problem.

[Studies on chemical constituents in essential oil from wild Atractylodes lancea in dabie mountains].

The chemical constituents in essential oil of wild Atractylodes lancea (Thumb.) DC. from Dabie Mountains were studied. The essential oil was extracted by simultaneous distillation and extraction equipment and analyzed by gas chromatography-mass spectrometry method. 49 compounds were identified and they represent 92.49% of the total peak aeras. The extraction method and solvent selection of the essential oil were studied. The oil yields and major constituents from Atractylodes lancea (Thumb.) DC. from Dabie Mountains were contrasted to that had been reported. The results showed that Atractylodes lancea (Thumb.) DC. from Dabie Mountains had more essential oil (10.14%) and there were more constituents in it. The main constituents in the essential oil were hinesol, beta-eudesmol, 1H-cyclopropa (a) naphthalene, 1a,2,3,5,6,7,7a,7b-octaphdro-1,1,7,7a-tetramethyl-, [1aR-(1a. alpha, 7. alpha, 7a. alpha,7b. alpha-)] -and gamma-eudesmol. Both the major constituents and contents were different from that had been reported.