一株海藻糖合成酶产生菌的鉴定及产酶条件优化

目的对一株海洋来源的产海藻糖合成酶菌株进行鉴定及产酶条件的初步优化。方法通过16SrDNA基因序列的同源性分析,对一株来源于东海海水的海藻糖合成酶产生菌进行鉴定,并通过单因素分析初步研究其培养特性和最佳的发酵条件。结果该菌16SrDNA序列与GenBank中已知序列相比,最高相似度为100％,鉴定为假单胞菌属（Pseudomonas）,命名为Pseudomonassp．A50。其最佳碳源和氮源分别为2％麦芽糖和0．5％酵母膏,最佳NaCl浓度为2．5％,在初始pH7．8,接种量1％,装液量125mL／250mL,28℃,130r／min发酵48h,海藻糖合成酶活力达到最高。结论此产海藻糖合成酶菌株为假单胞菌属,优化后,海藻糖合成酶活力达到14．16U／mL。     

甲醇利用型吡咯喹啉醌产生菌的筛选及鉴定

从虎杖内生细菌和黏细菌中筛选吡咯喹啉醌(PQQ)产生菌。采用3种以甲醇为唯一碳源的培养基对160株供试菌株进行摇瓶培养发酵,发酵产物采用光谱学分析法及HPLC法筛选。结果显示,通过初筛和复筛共得到甲醇利用型菌134株,PQQ产生菌4株,其中菌株083114的PQQ产量为64.34 mg/L。菌株083114的16S rRNA基因序列分析结果显示,其序列与酸快生芽孢杆菌(Bacillus acidiceler)的系统发育关系最近。虎杖内生细菌及黏细菌中存在PQQ产生菌。     

海洋中海藻糖产生菌的筛选及发酵条件优化

从180余份海水、海泥样品中筛选得到60株产海藻糖较高的菌株,编号为2-14的菌株海藻糖产量最高,为127.9mg/g cell。对2-14菌株进行形态特征、培养特征及生理生化试验,鉴定该菌株为红酵母属(Rhodotorula sp.)。研究摇瓶发酵条件对红酵母海藻糖产量的影响,结果为:初始pH5.5,发酵温度28℃,装液量75mL(250mL三角瓶中)。采用优化后发酵条件红酵母海藻糖产量为193.3mg/g cell,优化前对照值为132.1mg/g cell,优化后的结果是优化前的1.46倍。在5L发酵罐中培养得到最佳发酵时间为54h,发酵罐培养发酵液中海藻糖含量最高达2.5g/L,为摇瓶培养的1.6倍。     

黄原胶生产菌无色素黄单胞菌的选育和发酵条件的研究

从实验室保存菌株黄原胶生产菌野油菜黄单胞菌XG30-1出发,经亚硝基胍诱变,筛选到一株不产生黄色素的突变菌株XG30-1-SW,发酵产物的红外吸收图谱鉴定与出发菌株一致。该菌株以葡萄糖或蔗糖为碳源、大豆粉或大豆分离蛋白为氮源、pH7．0为最适发酵条件,产量最高可达33g/L,连续多次传代后突变性状能稳定遗传。     

胶样菌CB39产海藻糖的研究

从长白山天池水中筛选到一株低温条件下产糖的细菌。通过薄层层析、成脎反应、毛细管等速电泳以及红外光谱法确定该糖为海藻糖;经鉴定此菌株是胶样菌属中的一个新种(ColloidesSp.)定名为CB39;与已报道的产海藻糖菌株不同的是,菌株CB39能将产生的海藻糖分泌到细胞外,18℃时其培养液中海藻糖含量为2562mg/g干菌体;采用紫外诱变法筛选到一株在25℃条件下产海藻糖量为4167mg/g干菌体的高产突变株5,产糖量是同温度下野生菌的8倍。     

高酶活菌株的筛选及漆酶特性

通过Bavendamn氏反应和液体发酵实验筛选出漆酶高产菌株 ,并对其产酶条件和酶活性进行了研究。结果表明 71株实验真菌中有 64株Bavendamn氏反应呈阳性 ,且阳性菌株都具有漆酶活性 ;不同菌株产酶培养基最适碳源、氮源不同 ,采绒革盖菌以淀粉为碳源、干酪素为氮源 ,毛栓菌以麦草粉为碳源、硫酸铵为氮源 ,有利于酶的分泌 ;不同来源漆酶性质不尽相同 ,采绒革盖菌漆酶最适酶解温度为 2 5℃ ,最适酶解pH值为4.6,毛栓菌则分别为 3 0℃和 pH 4.0 ;K+ ,Zn2 + 等对 2种漆酶均有激活作用 ,Ag+ 则能明显抑制漆酶活性。     

高产谷胱甘肽新菌种的选育及其发酵条件的研究

通过对谷胱甘肽新产生菌——藤黄八叠球菌进行紫外诱变处理,筛选到一株抗乙硫氨酸和氯化锌的抗性菌株,该突变株发酵生产谷胱甘肽的产量比出发菌株提高268．9％。通过对碳源、氮源、温度、初始pH等发酵条件对该菌株生物合成谷胱甘肽的影响研究,表明突变株HY78在发酵温度37℃、初始pH7.0、摇床转速180r／min条件下,摇瓶发酵26h,该高产菌株在发酵液中合成谷胱甘肽的产量可达160．628mg／L。     

利用木糖-葡萄糖为原料产乙醇酵母的筛选、鉴定及发酵试验

建立筛选利用木糖为碳源产乙醇酵母模型,获得一株适合利用木质纤维素为原料产乙醇的酵母菌株。样品经麦芽汁培养基培养后,以木糖为唯一碳源的筛选培养基初筛,再以重铬酸钾显色法复筛。通过生理生化和26D1/D2区对筛选得到的菌株进行分析和鉴定,该菌初步鉴定为Pichia caribbica。经过筛选得到的菌株Y2-3以木糖（40g/L）为唯一碳源发酵时：生物量为23.5g/L,木糖利用率为94.7 %,乙醇终产量为4.57 g/L;以混合糖（葡萄糖40 g/L,木糖20 g/L）发酵时：生物量为28.6 g/L,木糖利用率为94.2 %,葡萄糖利用率为95.6%,乙醇终产量为20.6 g/L。Pichia caribbica是可以转化木糖及木糖-葡萄糖混合糖为乙醇的酵母菌株,为利用木质纤维素发酵乙醇的进一步研究奠定了基础。     

产黄曲霉毒素B1降解酶菌株的筛选鉴定及发酵条件优化

以香豆素为唯一碳源筛选到27株能高效降解黄曲霉毒素B1(AFB1)的微生物菌株.用高效液相色谱检测AFB1含量的方法进行AFB1降解酶活力测定.以不同菌株发酵上清液中AFB1降解酶活力高低为复筛条件,筛选到AFB1降解酶活力最高的一株菌并命名为HSD8.该菌株经形态学、生理生化及系统发育学方法鉴定为Sinomonas sp..筛选所得最优菌株的发酵上清液中酶活达443 U/mL,通过单因素试验对其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:装液量50 mL/250 mL,发酵周期48 h,初始pH 5.0,接种量8％,发酵温度37℃,摇床转速160r/min.在最佳发酵条件下,该菌株发酵上清液中酶活可达548 U/mL,比优化前提高23.7％.优选菌株HSD8在生物降解黄曲霉毒素B1方面具有应用潜力,值得进一步研究开发.     

一株非还原性二糖——海藻糖产生菌的筛选

报导了一株非还原性二糖———海藻糖产生菌的筛选过程。通过平板初筛和摇瓶产酶转化试验 ,经TLC及HPLC检测 ,确证得到一株海藻糖产生菌 ,转化率为 13.8% ,对该菌株形状的研究 ,初步可断定其为Micrococcus属的一个种     

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     

Mink Circovirus Can Infect Minks,Foxes and Raccoon Dogs

正Dear Editor,Mink circovirus (MiCV), which is clustered in the genus Circovirus of the family Circoviridae, was first described in minks from farms in Dalian, China in 2013 (Lian et al.2014). The complete single-stranded circular genome of the virus is 1,753 nucleotides long and contains two major open reading frames (ORFs), designated ORF1 (Rep gene)and ORF2 (Cap gene)(Lian et al. 2014; Ge et al. 2018).Sequence analysis has shown that MiCV is most closely     

CypA Regulates AIP4-Mediated M1 Ubiquitination of Influenza A Virus

Cyclophilin A (CypA) is a peptidyl-prolyl cis/trans isomerase that interacts with the matrix protein (M1) of influenza A virus (IAV) and restricts virus replication by regulating the ubiquitin–proteasome-mediated degradation of M1. However,the mechanism by which CypA regulates M1 ubiquitination remains unknown. In this study, we reported that E3 ubiquitin ligase AIP4 promoted K48-linked ubiquitination of M1 at K102 and K104, and accelerated ubiquitin–proteasome-mediated degradation of M1. The recombinant IAV with mutant M1 (K102 R/K104 R) could not be rescued, suggesting that the ubiquitination of M1 at K102/K104 was essential for IAV replication. Furthermore, CypA inhibited AIP4-mediated M1 ubiquitination by impairing the interaction between AIP4 and M1. More importantly, both the mutations of M1 (K102 R/K104 R) and CypA inhibited the nuclear export of M1, indicating that CypA regulates the cellular localization of M1 via inhibition of AIP4-mediated M1 ubiquitination at K102 and K104, which results in the reduced replication of IAV.Collectively, our findings reveal a novel ubiquitination-based mechanism by which CypA regulates the replication of IAV.