Advanced Materials Research Vols. 236-238

Abstract: A strain CG08 was isolated which could selectively hydrogenate cinnamaldehyde to cinnamyl alcohol. The strain was idetified as Citrobacter freundii. The yield of cinnamyl alcohol was determined by UV spectroscopy. The optimized degradation conditions were found as 30 g/L glucose,16 g/L peptone with the initial cinnamaldehyde addition amount of 2 mL/L at pH 6.0, 30 °C for 40 hours of reaction. The secondary addition amount was 1 mL/L for 32 hours. Under the optimized conditions, the conversion of cinnamaldehyde was 100 %, the selectivity for cinnamyl alcohol was 90.1 %. And the yield of cinnamyl alcohol was up to 2.88 g/L, which was 26.3 % higher than the previously reported one.

Abstract: Two-phase thin solid films consisted of Au nanoparticles imbedded in an amorphous matrix were prepared via a series of galvanic replacement reactions between chloroauric acid solution and reducing metals. The Au nanoparticles were in situ crystallized from the amorphous films rather than precipitated from solution directly. Amorphous films with partly crystallized Au nanoparticles only existed stably in dilute chloroauric acid solution. The higher concentration of chloroauric acid evidently promoted the strain-induced crystallization process and accelerated the crystallization of amorphous films into Au nanoparticles with many stacking faults, twins and dislocations. The coexistence of amorphous and crystalline Au nanoparticles makes it possible to synthesize two-phase nanostructured films.

Abstract: Chitin deacetylase (CDA) catalyzes the conversion of chitin to chitosan by the deacetylation of N-acetyl-D-glucosamine residues. The results of the fundamental enzymatic properties of chitin deacetylase producing from the high productivity chitin deacetylase strain Z7 show that, the optimum temperature of strain Z7 was 40°C, the optimum pH was 6.5, under the concentration of 1mmol/L, Mg²⁺, K⁺, Ca²⁺ and Fe²⁺ had activation effect, of which the strongest activation effect was Mg²⁺. Pb²⁺, Cu²⁺ and Mn²⁺ had inhibitory effect, of which the strongest inhibitory effect was Mn²⁺.

Abstract: Taylor Couette flow in bioreactor at different Re values is researched numerically by means of establishing a simplified model. Numerical results indicate that vortex appears earlier in the vicinity of bottom wall than in the vicinity of top free surface. As Re number increases, vortexes generate from both ends towards middle area of flow field and will fill the whole space when critical Re value is reached. Although all vortexes look the same in structure, intensities of them are widely divergent. The strength of vortex at bottom wall is more intensive than that at top free surface, while the vortex at middle position is the weakest.

Abstract: The influence of pH and dissolved oxygen tension (DOT) on mycelium growth and cellulase production by Trichoderma reesei was studied in this paper. The experiments were carried out with a cellulose of 10 g/l in a 10 L steam sterilizable bioreactor. The results have shown that H+ concentration was highly fluctuated in the growing and metabolizing periods of mycelium, which went against mycelium growth and cellulase production. Controlling pH to 4.8 was favorable to mycelium growth and cellulase production; the maximum mycelium mass concentration was increased from 2.60 g/l to 2.77 g/l; the maximum filter paper activity was raised from 1.87 IU/ml to 2.79 IU/ml. Meanwhile, the growth and metabolism of mycelium demand an appropriate dissolved oxygen tension (DOT). When the velocity of aeration was increased from 0.4 to 0.5vvm to improve the condition of dissolving oxygen, the mycelium mass concentration was increased from 2.77 g/l to 2.98g/l, and the filter paper activity was raised from 2.79 IU/ml to 2.98 IU/ml.

Abstract: In this paper, lignin could partly replaced phenol to prepare lignin-phenolic(LPF) foam. The effects of amount of lignin on mechanical properties, thermal stability, fire-retardant and micro-structure of LPF foam. The results indicated that the addition of lignin decreased the brittleness and flexibility of foam, and the foam hole became larger in diameter and distributed more unevenly. When the lignin replacement amount was lower, the foam had regular foam hole structure and even distribution of foam hole, the size of foam hole increased with an increase of lignin content, SEM observations were in accordance with the early research of the mechanical properties of foams. And the addition of lignin slightly affected the fire-retardant and thermal stability of foam. When lignin replacement amount was 30% and 40%, the critical oxygen index of foam was even slightly higher than the pure PF foam.

Abstract: The heteropoly acid catalyst of H₅PMo₁₀V₂O₄₀ supported on SBA-15 mesoporous mole-cular sieve was prepared by an impregnation method and characterized by nitrogen physisorption, FT-IR,SEM, and used in catalytic synthesis of tributyl citrate. The results show that the heteropoly acid catalyst has fine dispersion characteristics, structural stability, high catalytic activity and better reusability.

Abstract: Discuss the effect of microwave irradiation and water bath on the primary and secondary structure of α –amylase. The result showed that, α -amylase’s molecular mass didn’t change under two different condition, it means that α -amylase’s primary structure didn’t change; While the peak height (at λ=193nm) of the CD spectra of the samples treated by microwave irradiation and water bath both reduced, the reduced rate by microwave irradiation ranged from 140 % to 220 %, while the reduced rate by water bath ranged from 60 % to 140 %; the peak of the sample treated by microwave irradiation for 60 min disappeared at λ=193nm, while showed a wake peak by water bath; the negative peak position by microwave irradiation emerged a blue shift in the range of 5 ~ 8 nm at λ=204 nm and λ=220 nm, while emerged a blue shift in the range of 3 ~ 5 nm by water bath. With time going, both microwave irradiation and water bath have prompted the secondary structure on α-helix, β-sheet, β-turn and random coil’s mutual transformations, but the trends were different.

Abstract: Study is on the solid-state fermentation of tannase with the Gallnut by Aspergillus niger B-0201.The experiments involved in the process and conditions of solid-state fermentation and factors influencing characters of tannase. The results indicated that the unpasteurized method before fermentation was in favor of the higher enzymic activity than the sterilized method. With the unpasteurized method, the tannase activity got the best level(51.2U/gds) ,when 5.0g of culture medium containing the 1g of Gallnut powder, 4g of the bran powder, 1% (w/w) of (NH₄)₂SO₄, 0.1%(w/w) of NaCl, 0.1%(w/w) of MgSO₄·7H₂O, 8ml of water, 1.6:1 of the solid-to-liquid ratio and 1ml（1×10⁸spores per milliliter）of inoculum size to a 250 ml conical flask was incubated at 30°C, initial pH6.0 for 96 hours. At the same time, the conditions of fermentation were further optimized using the Response Surface Design(RSM). The tannase activity got at 56.2U/gds with the .Gallnut(17%,w/w) and the solid-to-liquid ratio(1.5：1) in the medium under 32°C. The optimum temperature and pH of tannase was respectively 40°C and 5.0. Fe³⁺，Cu²⁺，Fe²⁺, Ba²⁺，Mn²⁺，Ca²⁺，Al³⁺were the inhibitor of tannase at 2.0mM concentration. The optimum concentration of propylgallate as the substrate catalyzed by Tannase was 1mM. The value of K_mwas 0.514mM and V_max was 71.8μmol·(L·min)^-1.

Abstract: A laccase cDNA lcc1 (GenBank accession number HM137002), without native signal peptide, was cloned by RT-PCR from total RNA of Coriolus versicolor. Recombination expression vector pPICZαA-lcc1 was constructed and transformed into Pichia pastoris KM71H after lineared. Recombination laccase was expressed at a higher level. Single factors of fermentation conditions of Pichia pastoris KM71H for laccase production were optimized. The results showed optimal culture conditions were as follows: medium initial pH 7.5, Cu²⁺ concentration 0.5mmol/L, methanol additive amount 1.0% and shaker rotate speed 210r/min. Furthermore, induction at low temperature was more suitable for lcc1 secretion. And addition of appropriate amount peptone and tyrosine in culture medium could enhanced lcc1 yields and reduce its degradation.