Evolution of quantum states via Weyl expansion in dissipative channel

Based on the Weyl expansion representation of Wigner operator and its invariant property under similar transformation,we derived the relationship between input state and output state after a unitary transformation including Wigner function and density operator.It is shown that they can be related by a transformation matrix corresponding to the unitary evolution.In addition,for any density operator going through a dissipative channel,the evolution formula of the Wigner function is also derived.As applications,we considered further the two-mode squeezed vacuum as inputs,and obtained the resulted Wigner function and density operator within normal ordering form.Our method is clear and concise,and can be easily extended to deal with other problems involved in quantum metrology,steering,and quantum information with continuous variable.

Efficient secretory expression of phospholipase D for the high-yield production of phosphatidylserine and phospholipid derivates from soybean lecithin

Phospholipase D(PLD)is an essential biocatalyst for the biological production of phosphatidylserine and phospholipid modification.However,the efficient heterologous expression of PLD is limited by its cell toxicity.In this study,a PLD was secretory expressed efficiently in Bacillus subtilis with an activity around 100 U/mL.A secretory expression system containing the signal peptide SPEstA and the dual-promoter PHpaII-SrfA was estab-lished,and the extracellular PLD activity further reached 119.22 U/mL through scale-up fermentation,191.30-fold higher than that of the control.Under optimum reaction conditions,a 61.61%conversion ratio and 21.07 g/L of phosphatidylserine production were achieved.Finally,the synthesis system of PL derivates was established,which could efficiently synthesis novel PL derivates.The results highlight that the secretory expression system constructed in this study provides a promising PLD producing strain in industrial application,and laid the foundation for the biosynthesis of phosphatidylserine and other PL derivates.As far as we know,this work re-ports the highest level of extracellular PLD expression to date and the enzymatic production of several PL der-ivates for the first time.

Transcriptomics reveals the effect of ammonia nitrogen concentration on Pseudomonas stutzeri F2 assimilation and the analysis of amtB function

The biological treatment of wastewater with high concentrations of ammonia nitrogen has become a hot research issue,but there are limited reports on the mechanism of ammonia nitrogen utilization by microorganisms.In this paper,a transcriptomic approach was used to investigate the differences in gene expression at 500.0 mg/L(Amo 500)and 100.0 mg/L(Amo 100)ammonium concentrations to reveal the mechanism of ammonia nitrogen removal from water by Pseudomonas stutzeri F2.The transcriptome data showed 1015(459 up-regulated and 556 down-regulated)differentially expressed genes with functional gene annotation related to nitrogen source metabolism,glycolysis,tricarboxylic acid cycle,extracellular polysaccharide synthesis,energy conversion and transmembrane transport,revealing the metabolic process of ammonium nitrogen conversion to biological ni-trogen in P.stutzeri F2 through assimilation.To verify the effect of ammonium transporter protein(AmtB)of cell membrane on assimilation,a P.stutzeri F2-ΔamtB mutant strain was obtained by constructing a knockout plasmid(pK18mobsacB-ΔamtB),and it was found that the growth characteristics and ammonium removal rate of the mutant strain were significantly reduced at high ammonium concentration.The carbon source components and dissolved oxygen conditions were optimized after analyzing the transcriptome data,and the ammonium removal rate was increased from 41.23%to 94.92%with 500.0 mg/L ammonium concentration.The study of P.stutzeri F2 transcript level reveals the mechanism of ammonia nitrogen influence on microbial assimilation process and improvement strategy,which provides a new strategy for the treatment of ammonia nitrogen wastewater.

采用常压室温等离子体诱变技术获得一株高产雄甾-4-烯-3,17-二酮的突变菌株Mycobacterium neoaurum ZADF-4（英文）

目的:获得一株高产雄甾-4-烯-3,17-二酮(AD)的Mycobacterium neoaurum突变株。创新点:获得了一株3-甾酮-Δ1-脱氢酶(KSDD)酶活缺陷型的高产AD的诱变菌株Mycobacterium neoaurum ZADF-4,并采用菌落显色法筛选KSDD酶活缺陷型M.neoaurum突变株。方法:(1)诱变方法:采用常压室温等离子体(ARTP)诱变技术来处理出发菌株M.neoaurum ZAD。ARTP诱变条件如下:功率40 W,气流量12.5 L/min,辐射距离1 cm,样品体积10μl,辐射时间为60、90、120、150和180 s;致死率统计优化后,最适辐射时间为150 s,致死率为90%~96%。(2)筛选方法:将ARTP诱变处理后的菌株点种在硝酸纤维滤膜上,30°C培养2 d,然后将长有菌落的滤膜小心取出并漂浮在4 mg/ml二氯靛酚(DCPIP)溶液(0.1 mmol/L磷酸缓冲液p H 7.0),30°C培养1 d直到全部菌落染成蓝色。然后将该滤膜取出,漂浮在250 mmol/L AD溶液(2%甲醇和50 mmol/L Tris p H 7.0缓冲液),室温放置15 min左右,观察菌落颜色变化。KSDD在底物AD存在时会脱氢产生雄甾-1,4-二烯-3,17-二酮(ADD)和H+,H+可以使被DCPIP染成蓝色的菌株褪色。因此,酶活缺陷型的菌株会仍保持蓝色,而酶活高的菌株会褪色为黄色(图3)。(3)对获得的潜在的高产AD菌株进行进一步的酶活检测以及产量验证,以期获得最优的突变株。结论:获得了4株具有潜在的高产AD能力的菌株,其中,最优的突变株ZADF-4的KSDD酶活相较于出发菌株ZAD下降了81.2%(图4),活性胶也证明其KSDD酶活相较于出发菌株下降明显(图5)。薄层色谱法(TLC)和高效液相色谱法(HPLC)实验证明突变株ZADF-4中,AD的产量有了明显的提高(图6和图7),提高到了(6.28±0.11)g/L,AD/ADD提高到8:1,AD的摩尔产率达到60.3%(表1)。对出发菌株ZAD和突变株ZADF-4的ksdd基因进行克隆和序列比对,发现ZADF-4的ksdd序列在5'端缺失9个核苷酸(atgttctac),导致3个氨基酸(MFY)的缺失;还发生了两个点突变,其中一个是无义突变(g.15a>6t),另一个是有义突变(g.413c>404t),并引起了相应位置上的氨基酸变化(p.138S>135L)。上述的基因突变及其引起的氨基酸序列的变化可能是引起M.neoaurum ZADF-4中KSDD酶活降低及AD产量提高的主要原因。