Application of Response Surface Methodology in Optimization of Precursors for Taxol Production by Fusarium mairei K178 / 中国生物工程杂志

The concentration of precursors for the production of taxol with Fusarium mairei K178 was optimized by response surface methodology.Firstly,Plackett-Burman design was undertaken to evaluate the effects of eight factors.With statistic regression analysis,the significant factors affecting taxol production were determined as follows: phenylalanine,sodium acetate and sodium benzoate.Box-Behnken design was used to optimize the three critical internal factors mentioned above,and the optimum concentration levels and the relationships among these factors was found out.By quadratic regression model equation with Design-Expert statistic methods,the optimal concentration of the variables were determined as: phenylalanine 2.8mg/L,sodium acetate 3.3g/L,sodium benzoate 31.8mg/L.Under such conditions,the taxol production was increased to 242.6?g/L,which was 15.6% higher than the maximum value in the single factor tests.The experiment values under the optimal conditions agreed with the predicted values,which indicated that the model was proper and effective.

Inhibitory effect of weikangfu recipe on growth of mouse S180 tumor and its apoptotic induction / 中国中药杂志

<p><b>OBJECTIVE</b>To study the growth inhibition of Weikangfu recipe on S180 tumor and its apoptotic induction.</p><p><b>METHOD</b>S180-bearing mice were orally administrated with different dosages of Weikangfu recipe, and the growth inhibition was evaluated; apoptotic cells induced were detected by flow cytometry and DNA agarose gel electrophoresis.</p><p><b>RESULT</b>Weikangfu recipe showed significant inhibition on the growth of S180 tumor in a dose-dependent manner, compared with the control group. From apoptotic analyses, Weikangfu recipe induced a dose-dependent apoptosis of S180 tumor cells and arrested the cell cycle distribution at G0-G1 phase. At the same time, the up-regulation of p53 and bax and down-regulation of bcl-2 were observed in S180 tumor cells of the treated groups.</p><p><b>CONCLUSION</b>Our findings demonstrate that Weikangfu recipe can significantly inhibit the growth of S180 tumor and induce apoptosis through expression alteration of p53, bax and bcl-2.</p>

Identification and mode of action of a xylanase A purified from the culture filtrate of Bacillus pumilus WL-11 / 生物工程学报

Microbial xylanases have received a great deal of attention in the last two decades for their potential applications in food, paper making and animal feed industries. Bacillus pumilus WL-11 was identified as a producer of alkane xylanase free of cellulase after screening soil samples of paper-making factories. The xylanase A (XylA) was purified to homogeneity from the culture filtrate of Bacillus pumilus WL-11 by (NH4) 2SO4 precipitation, CM-Sephadex and Sephadex G-75 chromatographies. The molecular mass of XylA is estimated to be 26.0 kD by SDS-PAGE and its isoelectric point is 9.5. The apparent Km is 16.6 mg/mL and V(max) is 1263 micromol/(min x mg) towards oat spelt xylan. XylA is optimally active between pH 7.2 and 8.0, and stable at pH 6.0 to 10.4. The enzyme is optimally active at 45 degrees C - 55 degrees C and stable at temperature below 45 degrees C, with its half time of activity of 35 min and 15 min at 55 degrees C and 60 degrees C respectively. HPLC analysis revealed that hydrolysis patterns of xylans from oat spelt, birch wood and beech wood by purified XylA were different. The XylA is determined to be an endo-beta-1,4-xylanase, as it generated mainly xylotriose and no xylose was detected among the three hydrolysates. XylA has strong hydrolytic activity towards the pentose in the hydrolysates of beech wood and birch wood xylans, but was not active to the pentose in the hydrolysate of oat spelt xylan. The crude WL-11 enzyme can efficiently hydrolyze oat spelt xylan to a series of xylo-oligosaccharides, suggesting its potential application in nutraceutical industry.

Screening of Lipase-producing Strain for Catalytic Synthesis of Ester in Organic Media / 微生物学通报

An organic solvent tolerant isolate A213 originating from soil samples were successfully isolated via direct plating method using 10g/L of toluene as the sole carbon source and transparent cycle plate assay method.It was identified as Yarrowia based on its characteris- tics.The results in shake flask cultivation showed that the suitable tipase producing media were(g/L):yeast extract 40,vegetable oil 10, MgSO_4?7H_2O1,KH_2PO_4 5.Under optimal culture conditions (27℃and pH 6.5 ),the maximal lipase activity could reach 67.8 IU/ mL The optimal pH and temperature for the hydrolysis of p-nitrophenyl acetate by crude lipase were pH6.5 and 40℃The enzyme was sta- ble under 70℃and pH 5.5～8.5.Then isolate A213 was found to produce the lipase which can synthesize L-ascorbyl palmitate in tert-amyl alcohol validated by the thin-layer chromatography.

Advances in the Research on Microbial Phytases / 微生物学通报

Phytases are studied widely in plants and microorganisms. Interest in these enzymes has been stimulated by the fact that phytase has the advantage in forage, food process and medicine. This paper reviews recent trends on the production, purification, properties and gene of microbial phytases.

DEEP FERMENTATION TECHNIQUE OF TRICHOLOMA MATSUTAKE MYCELIUM / 微生物学通报

The deep fermentation technique of Tricholoma matsutake is systemically studied in this paper firstly. The best culture determined by orthogonal test is 3g/L of cornflour, 1g/L of glucose, 1g/L of bean cake flour, 1mL/L of corn steep liquid, 1g/L of KH 2PO 4. The best fermenting condition is: 25℃, rotating speed 160 r/min, pH5.0,inoculating amount 10%, 120mL culture medium per 500mL flask. Under these conditions, the mycelia reach 12.94g/L after fermenting 12d.