海洋假单胞杆菌QD80低温碱性蛋白酶的化学修饰

海洋假单胞杆菌QD80低温碱性蛋白酶(QDAPr)具有良好的低温适应性,且与常见的增稠剂及表面活性剂有良好的配伍性.因此该蛋白酶在日用化学领域,尤其是低温洗涤领域,具有广泛的应用价值.为研究其结构与功能之间的关系,用EDC、PMSF、N-AI、2,3-丁二酮等8种化学修饰剂修饰该低温碱性蛋白酶,然后检测残余酶活力,借以研究酶分子中氨基酸侧链基团与酶活性中心的关系.结果表明,羧基、丝氨酸、ε-氨基、巯基等残基与酶活性无关;而色氨酸、组氨酸、酪氨酸残基侧链的化学修饰引起酶活性的大幅度下降,说明色氨酸、组氨酸、酪氨酸残基是酶活力所必需的基团.精氨酸残基侧链的化学修饰引起酶活性的轻微下降,说明精氨酸对酶活性具有一定贡献,但不处于活性中心.图5表2参18     

石油降解菌株G5 16S rDNA全序列的系统学分析

用PCR方法扩增了一株石油降解菌株G5的16S rRNA基因全序列，并对其进行了克隆和测序．对该序列在GenBank中的BLAST结果表明，所有与该序列高度同源的序列都是假单胞菌的16S rRNA基因．其中假单胞菌的代表菌株Pseudomonas aeruginosa，P．fluoroscens，P .putida，P.syringae的16S rRNA基因序列与G5的16S rRNA基因序列同源性分别为93．4％，98．4％，96．3％，97．5％．对G5和其他39株假单胞菌的16S rRNA基因序列进行聚类分析，获得的系统发育树与RDP(Ribosomal Database Project)报道的系统发育树基本一致，其中菌株G5与5株P．chlororaphis聚类在一起．图2参7     

不同质量浓度的磷对铜绿微囊藻生长及细胞内磷的影响

通过室内模拟的方法研究了在磷质量浓度不同的水体条件下,在铜绿微囊藻水华形成过程中微囊藻的增殖特征及细胞内磷、可溶性磷的变化特征.在模拟的太湖水体中,随着外源磷的增加,藻生长最终限制因素由磷限制(ρ(TP)≤0.045 mg/L)发展到光限制(ρ(TP)≥0.445 mg/L),而ρ(TP)=0.445 mg/L是微囊藻最适生长浓度;同时,微囊藻细胞内磷含量(QP)、水体可溶性磷(DTP)也随藻类生长而发生变化,在水体ρ(TP)＜0.445mg/L时,细胞内磷对微囊藻增殖有促进作用,而在ρ(TP)＞0.445 mg/L的水体中,磷对微囊藻增殖有抑制作用.     

一株石化废水中脱氮产微生物絮凝剂菌株的鉴定与性能

筛选出了一株适用于石化污水处理的异养硝化-好氧反硝化产微生物絮凝剂菌株HAD-2,鉴定其为门多萨假单胞菌(Pseudomonas mendocina),考察了其最佳硝化条件、反硝化性能及在模拟污水中的脱氮能力。菌株为耐热菌,偏碱性(pH=8.5)和高碳氮比(25∶1)时硝化性能最佳。在异养硝化体系中,12 h时菌株对氨氮的去除率达到92.29%,硝酸盐和亚硝酸盐积累少;在反硝化体系中,12 h时菌株对亚硝酸盐和硝酸盐的去除率分别达到86.40%和84.92%;在模拟废水中,48 h时菌株对氨氮、硝态氮和亚硝态氮的降解率分别达到95.25%、65.47%和72.40%。菌株在多种培养基中可产微生物絮凝剂,在葡萄糖培养基中絮凝能力最佳,絮凝率为94%。     

恶臭假单胞菌原位还原Pd(0) NPs对微生物电子传递性能及活性的影响

微生物原位合成零价金属纳米颗粒在材料合成和环境应用领域引起了广泛关注和研究.本研究利用Pseudomonas putida(P.putida)合成Pd(0)纳米颗粒(NPs),通过FESEM、TEM、XPS等对合成的纳米颗粒进行形貌、价态表征,并对其电化学性能及微生物抑制作用进行分析.结果表明,在厌氧条件下,P.putida在胞外及细胞周质空间可原位合成粒径约10 nm的Pd(0)NPs.CV实验表明,相比P.putida,含Pd(0)NPs的P.putida有更高的氧化还原电流;随着初始反应Pd(Ⅱ)浓度增加至0.07和0.1 mmol·L~(-1),恒电位实验中的乳酸氧化电流分别升至(10.6±5.2)和(22.5±9.7)nA,分别为P.putida((5.7±2.8)nA)的1.85和3.95倍;TTC-ETS和INT-ETS分别提升至89.02和209.09μg·mg~(-1)·h~(-1),分别是P.putida的1.64和1.34倍.以上结果证明了Pd(0)NPs对微生物胞外电子传递(Extracellular Electron Transfer,EET)的正面影响.抑菌圈实验和激光共聚焦图像表明,低量Pd(0)NPs具有较好的生物相容性,过多Pd(Ⅱ)和Pd(0)NPs对微生物有一定的毒性.     

高效铜绿微囊藻溶藻菌WJ6的分离鉴定及溶藻特性

以铜绿微囊藻为研究对象,从富营养化水体分离了一株高效溶藻菌,通过分析形态学、生理生化特征及16S rDNA序列比对,鉴定了该溶藻菌株,分析了该菌株对铜绿微囊藻的溶藻方式、溶藻特性及其不同培养时期、不同浓度菌液及不同环境因子对溶藻效果的影响,并探讨了其可能的溶藻机制.研究表明：WJ6属于沙雷氏菌属（Serratia sp.GenBank登录号为KY462187）;溶藻菌WJ6以胞外释放溶藻物质为主直接溶藻为辅的溶藻方式;溶藻菌WJ6处于对数期时的溶藻率最高达87.50%;菌液浓度达1.4×10⁹CFU/mL以上,溶藻率最高为95.69%;在30℃、pH8条件下,溶藻率达90.00%;改良的基本培养基培养的溶藻菌溶藻率最高达98.50%;铵离子浓度大于2mol/L时,溶藻菌的溶藻率98.33%;当盐度为0.5%时,溶藻率较高为92.77%.溶藻菌株WJ6是1株高效溶铜绿微囊藻菌,在富营养化治理方面具有较好的应用前景.     

Repeated batch and continuous degradation of chlorpyrifos by Pseudomonas putida

The present study was undertaken with the objective of studying repeated batch and continuous degradation of chlorpyrifos (O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) using Ca-alginate immobilized cells of Pseudomonas putida isolated from an agricultural soil, and to study the genes and enzymes involved in degradation. The study was carried out to reduce the toxicity of chlorpyrifos by degrading it to less toxic metabolites. Long-term stability of pesticide degradation was studied during repeated batch degradation of chlorpyrifos, which was carried out over a period of 50 days. Immobilized cells were able to show 65% degradation of chlorpyrifos at the end of the 50th cycle with a cell leakage of 112 × 10³ cfu mL^?1. During continuous treatment, 100% degradation was observed at 100 mL h^?1 flow rate with 2% chlorpyrifos, and with 10% concentration of chlorpyrifos 98% and 80% degradation was recorded at 20 mL h^?1 and 100 mL h^?1 flow rate respectively. The products of degradation detected by liquid chromatography–mass spectrometry analysis were 3,5,6-trichloro-2-pyridinol and chlorpyrifos oxon. Plasmid curing experiments with ethidium bromide indicated that genes responsible for the degradation of chlorpyrifos are present on the chromosome and not on the plasmid. The results of Polymerase chain reaction indicate that a ~890-bp product expected for mpd gene was present in Ps. putida. Enzymatic degradation studies indicated that the enzymes involved in the degradation of chlorpyrifos are membrane-bound. The study indicates that immobilized cells of Ps. putida have the potential to be used in bioremediation of water contaminated with chlorpyrifos.     

Effects of cyanobacteria producing microcystins on seed germination and seedling growth of several agricultural plants

The effects of cyanobacteria aqueous extracts containing Microcystin-LR (MC-LR) on the seed germination and growth of Pisum sativum, Lens esculenta, Zea mays and Triticum durum were investigated. Experiments were carried out on a range of doses of the extract (equivalent to 0, 1.6, 2.9, 5.8, 8.7 and 11.6 μ g MC-LR/mL). The results confirm that these plants were sensitive to cell-free extracts of a toxic Microcystis and that germination inhibition was dose dependent. One-way analysis of variance (ANOVA) showed that P. sativum is the most sensitive tested species with a 97% germination rate reduction and L. esculenta was the most resistant. At the 8th day, the exposure to the microcystins (MC) resulted in a significant decrease of plant epicotyls length, roots length and a net inhibition of lateral root formation. It is concluded that MC could affect also terrestrial plants seedling germination and growth. Therefore, the use of water for irrigation contaminated by MC could exert negative biochemical effects on seed and plant metabolism which might influence the agricultural crops.     

n(NO3--N)/n(NO2--N)对混培养菌与纯培养菌同步脱氮除硫的影响

在温度30℃、pH为7、硫氮比为5/3、厌氧条件下,对比研究了不同n(NO-3-N)/n(NO-2-N)对荧光假单胞菌和铜绿假单胞菌混培养菌同步脱氮除硫影响.随着n(NO-3-N)/n(NO-2-N)减小,荧光假单胞菌、铜绿假单胞菌对NOx-N去除率逐渐增高,而S2-去除率却依次减少,混培养菌对NOx-N去除效率先增加后趋于平稳.n(NO-3-N)/n(NO-2-N)对混培养菌去除S2-几乎没有影响.荧光假单胞菌能迅速将NO-3-N转化为NO-2-N,但NO-2-N转为N2却相对缓慢,培养液中出现NO-2-N累积;而铜绿假单胞菌将NO-2-N还原N2的能力明显比荧光假单胞菌强,培养液未反应的NOx-N以NO-3-N为主,未出现NO-2-N累积.混培养菌对NOx-N转化的情况介于荧光假单胞菌与铜绿假单胞菌之间.荧光假单胞菌同时获得较高NOx-N、S2-去除的n(NO-3-N)/n(NO-2-N)为5/5,铜绿假单胞菌为10/0,混培养菌为5.0/5.0.混培养菌对NOx-N、S2-的同步去除效果优于单菌株荧光假单胞菌和铜绿假单胞菌.     

Pseudomonas sp. QJX-1的锰氧化特性研究

从锰矿土壤样品中分离、纯化出1株高效锰氧化细菌(QJX-1),经16S rDNA序列鉴定为Pseudomonas sp.QJX-1.研究表明,Pseudomonas sp.QJX-1含有锰氧化的必需成分多铜氧化酶基因CumA,当初始Mn2+为5.05 mg·L-1,菌密度D600为0.020时,该菌可在48 h内将Mn2+转化,且转化率高达99.4%.在寡营养条件下该菌锰氧化速率较富营养条件下有显著提高;添加石英砂滤料促使生物膜的快速形成,进而促进Mn2+的生物转化.根据研究结果推测地下水处理过程中生物锰氧化速率较快.