枯草芽胞杆菌甘露聚糖酶发酵条件优化

旨在以枯草芽胞杆菌Bacillus subtilis J为生产菌株,发酵生产β-甘露聚糖酶,通过优化产酶条件,以达到提高β-甘露聚糖酶产量的目的。利用DNS比色法检测β-甘露聚糖酶活力,采用单因素试验,研究碳氮源种类及碳氮源浓度、温度、pH、接种量和装液量对菌株Bacillus subtilis J发酵产β-甘露聚糖酶的影响,结合响应面试验设计确定菌株Bacillus subtilis J发酵产甘露聚糖酶的最优发酵培养条件。单因素试验和响应面试验得到最优的发酵条件为魔芋粉28 g/L,胰蛋白胨21 g/L,K₂HPO₄ 6 g/L,MgSO₄·7H₂O 1 g/L,温度31 ℃,pH值 8.5,接种量1%（体积分数）,装液量50 mL/250 mL,发酵周期24 h。利用优化后的培养基生产β-甘露聚糖酶,其酶活力达到84.38 U/mL,是初始发酵培养基产酶活力的3.36倍。通过对发酵条件的优化,大幅度提高了β-甘露聚糖酶的产量,为其工业生产提供数据参考。     

枯草芽孢杆菌产β-甘露聚糖酶固体发酵条件的优化*

芽孢杆菌是产甘露聚糖酶的优良菌株,首次研究芽孢杆菌固体发酵条件的优化。以天然麸皮作为基本原料,研究利用枯草芽孢杆菌WY34固体发酵生产β-甘露聚糖酶的发酵条件。最佳固体发酵培养条件为:麸皮5 g,初始水分含量71%,初始pH 7.0,接种量为2 mL,1%Tween-80,0.4 g魔芋粉,培养温度50℃。在最适条件下培养5 d,甘露聚糖酶酶活高达7,650 U/g干基,是未优化前酶活的2.78倍。     

枯草芽孢杆菌产β-甘露聚糖酶固体发酵条件的优化

芽孢杆菌是产甘露聚糖酶的优良菌株,首次研究芽孢杆菌固体发酵条件的优化。以天然麸皮作为基本原料,研究利用枯草芽孢杆菌WY34固体发酵生产β-片露聚糖酶的发酵条件。最佳固体发酵培养条件为：麸皮5g,初始水分含量71％,初始pH7．0,接种量为2mL,1％Tween-80,0.4g魔芋粉,培养温度50℃。在最适条件下培养5d,甘露聚糖酶酶活高达7,650U／g干基,是未优化前酶活的2．78倍。     

共表达透明颤菌血红蛋白对毕赤酵母产β-甘露聚糖酶发酵过程的影响

为了改善高密度发酵生产β-甘露聚糖酶过程中的溶氧限制,提高β-甘露聚糖酶产量,将VHb和β-甘露聚糖酶基因置于AOX1启动子调控之下,进行VHb和β-甘露聚糖酶基因在毕赤酵母中的共表达。经密码子优化合成VHb基因,插入表达载体p PICZαA,整合到β-甘露聚糖酶工程菌中,通过G418和Zeocin抗性筛选共表达VHb基因的重组酵母工程菌。在30 L发酵罐水平上分析共表达VHb菌株(VHb+)与初始菌株(VHb-)对β-甘露聚糖酶表达的差异。结果显示,限氧条件下,VHb+菌株的β-甘露聚糖酶的表达量比对照菌株VH b-高90%,且透明颤菌血红蛋白提高了甲醇耐受性,缩短发酵周期约40 h。     

黑曲霉固态发酵苹果渣生产木聚糖酶与β-甘露聚糖酶

[目的]采用黑曲霉固态发酵苹果渣生产木聚糖酶与β-甘露聚糖酶,以降低生产成本,同时提高苹果渣的综合利用水平。[方法]采用单因素试验和响应面法对固态发酵工艺进行优化。[结果]培养基最佳组成为苹果渣60%(W/W)、棉粕40%(W/W)、(NH4)2SO41.36%(W/W)、KH2PO40.076%(W/W)、初始含水量55.6%(W/W),最佳培养温度为27.5℃;在所优化的条件下发酵48h,木聚糖酶活力可达5736 U/g,β-甘露聚糖酶活力可达896.24 U/g;培养物中自由棉酚残留量为24.6μg/g,低于饲料中自由棉酚的安全标准。[结论]采用黑曲霉固态发酵苹果渣生产木聚糖酶与β-甘露聚糖酶是可行的,发酵产物可用作饲料添加剂。     

产β-甘露聚糖酶菌株的筛选鉴定及产酶条件的优化

利用刚果红染色法从土壤中筛选到一株产β-甘露聚糖酶的菌株MY271,该菌株经形态学、生理生化及系统发育学方法鉴定为路德维希肠杆菌(Enterobacter ludwigii)。该菌株在初始条件下培养48 h,发酵上清液中β-甘露聚糖酶酶活可达2.87 U/m L。利用单因素试验对该菌产酶发酵条件进行优化以提高酶活,优化所得最佳发酵条件为:接种量9%,装液量50 m L/250 m L,初始p H7.0,发酵温度31℃,发酵周期48 h。最佳碳源为魔芋精粉(添加量0.8%),最佳氮源为蛋白胨(添加量1.9%)。在最佳条件下发酵48 h,发酵上清液中β-甘露聚糖酶活提升到38.42 U/m L,是优化前的13.4倍。     

黑曲霉固态发酵苹果渣产β-甘露聚糖酶的工艺优化

目的:对黑曲霉SL-08固态发酵苹果渣生产β-甘露聚糖酶的生产工艺进行优化,旨在探寻苹果渣的综合利用方式,降低β-甘露聚糖酶的生产成本。方法:采用Plackett-Burman试验设计和响应面法进行优化。结果:最佳培养基组成为苹果渣与棉粕1∶1(w/w)、尿素2%(w/w)、KH2PO40.1%(w/w)、初始含水率59%(w/w)、CaCl20.2%(w/w)、MgCl20.1%(w/w),30℃恒温培养48h,β-甘露聚糖酶酶活力可达539U/g干曲,比基础培养基提高了28.3%,达到了以豆粕与麸皮为生产原料时的产酶水平。结论:采用黑曲霉SL-08对苹果渣进行固态发酵是一种有效的生物转化方式,既可用于β-甘露聚糖酶的生产,取代豆粕与麸皮等常规原料,降低生产成本;也可以对苹果渣进行综合利用。     

Armillariella tabescens EJLY2098 β-甘露聚糖酶atMAN47的纯化及酶学性质分析

以魔芋精粉为唯一碳源, 对假蜜环菌(Armillariella tabescens) EJLY2098进行培养, 诱导其产生β-甘露聚糖酶。经DEAE－阴离子交换层析后, 分离纯化出β-甘露聚糖酶atMAN47。酶学性质分析: 该酶分子量约为47 kD, 酶的最适反应温度为50°C, 在pH 5.0~6.5之间该酶的稳定性较好; Na+ 和Ba2+ 对该酶有激活作用, 用TLC对酶产物分析, 表明该酶为内切β-甘露聚糖酶。该酶为偏酸性的内切甘露聚糖酶, 适合发展为饲料的酶制剂, 具有良好的应用前景。     

魔芋葡甘露低聚糖的酶法制备工艺的初步研究

利用β-甘露聚糖酶产品水解魔芋胶制备魔芋葡甘露低聚糖的工艺条件。在加样顺序、pH、酶添加量、时间、温度等单因素试验的基础上,进一步通过正交试验确定的最佳工艺条件为:魔芋胶浓度10g/L,酶添加量为100U/g,pH5.5,45℃条件下,酶解时间1.5h。再利用酵母发酵去除可发酵性糖的方法,以获得最终产物为100%的魔芋葡甘露低聚糖。     

产β－甘露聚糖酶地衣芽孢杆菌的分离筛选及发酵条件

从上样中分离筛选出产β－甘露聚糖酶的地衣芽孢杆菌,经紫外线诱变处理后（１５Ｗ,３０ｃｍ照射４０ｓ）获得高酶活力ＮＫ－２７菌株,在以魔芋粉、豆饼粉为碳、氮源添加无机盐的发酵培养基中,β－甘露聚糖酶活力达１１０．４９ｕ／ｍｌ。初始ＰＨ值、装液量、培养温度和培养时间对产酶有一定影响。     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV     

Similar aerosol emission rates and viral loads in upper respiratory tracts for COVID-19 patients with Delta and Omicron variant infection

Highlights
1 Aerosol emission rates of Delta or Omicron patients were similar.
2 Viral loads in upper respiratory tract of Alpha, Delta and Omicron patients were similar.
3 Viral loads in upper respiratory tract of vaccinated or unvaccinated Delta patients had no difference.     

Recombinant human interferon-α1b inhibits SARS-CoV-2 better than interferon-α2b in vitro

Highlights
1) A comprehensive evaluation method for anti-SARS-CoV-2 drugs was established based on RT-qPCR, TCID₅₀ method, and immunofluorescence.
2) A significant antiviral effect of rHuIFN-α1b was shown with EC₅₀=0.12 IU/mL in Vero cells and EC₅₀=0.52 IU/mL in Calu-3 cells, which was better than rHuIFN-α2b (EC₅₀=0.25 IU/mL in Vero cells and EC₅₀=2.48 IU/mL in Calu-3 cells).
3) rHuIFN-α1b has a good potential in the application of anti-COVID-19 therapy.