陶厄氏菌Thauera sp.K11对酚类化合物降解作用及途径研究

旨在分析陶厄氏菌属(Genus Thuaera)中的一株菌株Thauera sp.K11对含酚废水中酚类化合物的降解作用和途径。以石化污水厂分离菌株K11为研究对象,克隆其16S r RNA基因和关键酶基因,并进行系统发育分析,在基因水平探究苯酚降解机理;利用气相色谱技术检测酚类化合物降解效果和苯酚降解机理。结果显示,利用16S r RNA系统学分析发现K11是陶厄氏菌属的一株细菌。该菌对11种酚类化合物具有降解作用,其中5种酚类化合物72 h的降解率90%。克隆并获得了K11的苯酚羟化酶和邻苯二酚双加氧酶基因。酶活性测定表明,K11通过苯酚羟化酶催化苯酚转化为邻苯二酚,然后利用邻苯二酚-2,3-双加氧酶催化产生2-HMSA。陶厄氏菌Thauera sp.K11是一株能够降解多种酚类化合物的菌株,具有较强的酚类污染物降解能力,其通过苯酚→邻苯二酚→2-HMSA途径进行苯酚降解。     

微生物降解邻苯二酚的动力学研究

以一株产邻苯二酚双加氧酶的假单胞菌84103为试验菌,对其降解邻苯二酚的动力学进行了研究。结果表明,该降解过程为酶催化反应,测定了反应最适温度、最适pH、饱和菌量、Km值及诱导作用等。     

好氧氯苯降解菌的分离鉴定

【目的】分离好氧氯苯降解菌,并通过研究降解特性为应用提供理论依据。【方法】利用富集培养技术分离菌株,通过形态、生理生化反应特征及16S rRNA基因序列分析鉴定菌株,测定培养液中氯苯、其它氯苯类化合物和氯离子的浓度以及菌体细胞的密度和菌体细胞粗提液中邻苯二酚双加氧酶的活性,研究菌株的降解特性。【结果】16S rRNA基因序列相似性比较表明,分离出的菌株与乙酸钙不动杆菌(Acinetobacter calcoaceticus)的相似性高达98.5%。以初始浓度为50mg/L的氯苯为唯一碳源和能源时,120h内菌株对氯苯的降解率高达98.2%,氯离子净释放量和氯苯降解量的摩尔比范围为1:1.85-1:1.39,菌体细胞粗提液中邻苯二酚1,2-双加氧酶的平均活性为0.538U/mg蛋白质。加入葡萄糖后,菌体细胞数量和氯离子浓度明显增加,但单位细胞的氯苯降解能力明显下降。在二氯苯和三氯苯共存时,菌株对氯苯的降解能力受到明显的抑制作用,但对二氯苯有一定的降解作用,降解能力大小顺序为:1,3-二氯苯1,2-二氯苯1,4-二氯苯。【结论】分离出的好氧氯苯降解菌属于Acinetobacter属菌株,该菌株对氯苯和二氯苯均具有降解作用,可能通过邻位裂环途径降解氯苯,氯苯对菌株的降解能力和邻苯二酚1,2-双加氧酶的活性具有明显的增强作用。     

波茨坦短芽孢杆菌降解苯酚特性及动力学研究

从活性污泥中分离筛选出一株高效苯酚降解菌,经形态特征、生理生化试验及16S rDNA鉴定,该菌株为波茨坦短芽孢杆菌。该菌能以苯酚为唯一碳源和能源,最佳降解条件为:温度30℃,初始pH7.0,摇床转速为160 r/min。苯酚降解试验表明,该菌可在72 h内将初始浓度为1 600 mg/L苯酚完全降解。随着苯酚浓度的增加,底物抑制作用增强。应用Haldane方程对菌株的生长过程进行动力学模拟,拟合曲线与试验测定值相关性良好,各参数分别为μmax(最大比增长率)0.334 h-1,Ks(半饱和常数)14.07 mg/L,Ki(抑制常数)196.89 mg/L,且该菌株苯酚降解动力学与其生长动力学表现出相似的趋势。代谢机制研究表明,苯酚可诱导该菌合成邻苯二酚1,2-加氧酶降解苯酚。     

蜡状芽孢杆菌菌株Jp-A的分离鉴定及其降解苯酚特性

从某钢铁厂处理废水的活性污泥中驯化分离一株能高效降解苯酚的细菌（Jp-A）.通过形态观察、生理生化实验和16srRNA序列分析,初步鉴定Jp A为蜡状芽孢杆菌（Bacillus cereus）.在实验条件下,该菌在16、24和32 h内能将浓度分别为5、10和15 mmol·L^-1的苯酚完全降解,而30 mmol·L^-1的苯酚则完全抑制该菌的生长.该菌也能以甲苯、氯酚类和硝基酚类等芳香烃类物质作为唯一碳源和能源生长.双加氧酶检测表明,其通过间位途径开环裂解苯酚,该途径的关键酶邻苯二酚2,3 双加氧酶主要定位在细胞膜上,为诱导酶,补加葡萄糖能抑制该酶的产生.     

对硝基苯酚降解菌Pseudomonas sp. PDS-7的降解特性及 其降解相关基因的克隆

[目的]本研究的目的是分离对硝基苯酚(PNP)降解菌,研究其对PNP的降解特性;克隆其降解相关基因,并进行表达.[方法]本研究通过富集培养法和系列稀释平板涂布法分离PNP降解菌株;采用形态观察、生理生化特征测定和16S rDNA分析对菌株进行初步鉴定;通过摇瓶试验研究菌株降解特性;利用SEFA-PCR技术克隆降解相关基因,并亚克隆到表达载体pET29a中,构建重组表达质粒pETpnpC,再转入受体菌E.coli BL21(DE3)中进行诱导表达;通过分光光度法测定表达产物的酶活力.[结果]分离到一株PNP降解菌PDS-7,将该菌株鉴定为假单胞菌属(Pseudomonassp.);该菌株能够以PNP作为唯一碳源、氮源和能源生长,菌株对PNP的最高耐受浓度为80 mg/L,最适降解温度为30℃,偏碱性条件有利于菌株对PNP的降解;克隆了PNP降解过程中的偏苯三酚1,2-双加氧酶基因pnpC及马来酰醋酸还原酶基因pnpD(GenBank登陆号EU233791);将pnpC在E.coli BL21(DE3)菌株进行了诱导表达,表达产物对偏苯三酚和邻苯二酚均有邻位开环活性,比活力分别为0.45 U/mg protein和0.37 U/mg protein,表明偏苯三酚1,2-双加氧酶基因pnpC得到了活性表达.[结论]分离鉴定了一株PNP降解菌Pseudomonas sp.PDS-7,研究了该菌株的降解特性,克隆和表达了降解相关基因.     

氯苯降解菌的筛选及降解条件研究

从活性污泥中筛选到一株具有降解氯苯功能的菌株JH02,依据菌落特征形态和生理生化反应鉴定该菌株属于链球菌属(Streptococcus)。分别考察培养温度、培养时间、氯苯浓度、pH值、菌悬液接种量及摇床转速等因素对菌株降解性能的影响。确定菌株StreptococcusJH02的对氯苯的最适降解条件为:培养温度为37℃,培养时间24 h,菌悬液接种量体积分数为4%,pH8.0,摇床转速140 r.min-1,此条件下氯苯的降解率可达94.7%。     

嗜吡啶红球菌 R04的联苯降解途径的研究

通过GC-MS测定出嗜吡啶红球菌R04菌降解联苯的中间代谢物2,3二氢二羟基联苯、2,3二羟基联苯和苯甲酸,并测定了该菌的2,3二羟基联苯双加氧酶、2羟基6酮基6苯基2,3己二烯酸(HOPDA)水解酶和苯甲酸双加氧酶活性。最终确定了R04菌降解联苯的途径为2,3二羟基联苯双加氧酶途径。     

一株芘降解菌的分离鉴定及其降解效果

以芘为唯一碳源,采用平板升华法,从徐州市卧牛山焦化厂周围污染土壤中分离得到一株芘降解菌SE12.经形态观察、生理生化试验和16S rDNA鉴定,该菌株属于分枝杆菌属(Mycobacterium sp.)菌株,与快速生长型非致病性南非分枝杆菌(M.austroa fricanum ATCC33464)的同源性达到98%.SE12降解芘的最适pH和温度为pH9和30℃.当土壤芘初始含量为100和200mg.kg-1,SE12接种量为107CFU.g-1时,30℃培养28d后土壤芘降解率分别达到97%和99%.利用双加氧酶基因的同源序列引物nidAF/nidAR和nidBF/nidBR进行扩增,得出了该菌株编码双加氧酶大亚基和小亚基的基因片段,它们与已知降解芘的分枝杆菌的双加氧酶基因具有高度同源性.     

嗜吡啶红球菌R04的联苯降解途径的研究

通过GC-MS测定出嗜吡啶红球菌R04菌降解联苯的中间代谢物2,3-二氢二羟基联苯、2,3-二羟基联苯和苯甲酸,并测定了该菌的2,3-二羟基联苯双加氧酶、2-羟基-6-酮基-6-苯基-2,3-己二烯酸(HOPDA)水解酶和苯甲酸双加氧酶活性。最终确定了R04菌降解联苯的途径为2,3-二羟基联苯双加氧酶途径。     

Plant-Parasitic Nematodes of South Viet Nam

Between 1974 and 1978, 2,842 identifications of plant-parasitic nematodes were made from more than 1,700 soil and plant samples collected in eight provinces of South Viet Nam. Species in nine genera—Helicotylenchus, Criconemoides, Meloidogyne, Pratylenchus, Tylenchorhynchus, Hoplolaimus, Hirschmanniella, Xiphinema, and Rotylenchulus—comprised 96.1% of the identifications; the remaining 3.9% were species of 11 genera. Fourteen genera were associated with rice which was grown on about 2,500,000 ha in 1970. Of these, Ditylenchus, Hirschmanniella, and Meloidogyne were most important. Ditylenchus angustus caused severe damage to about 50,000 ha of flooded rice in the Mekong Delta in 1976. Hirschmanniella spp. were found in all samples examined from flooded rice fields. Meloidogyne spp. were common in rice seedbeds, upland rice, and rice not kept flooded continuously. Meloidogyne and Pratylenchus spp. were found in roots of 22 of the 32 crop plants sampled. Little or no attempt was made in South Viet Nam to control nematodes.     

Identification key for European strand-forming house-rot fungi

An identification key for 20 common strand-forming indoor wood decay fungi is given. The key is based on observations of material from affected buildings and on wood samples that have been incubated in the laboratory. The key is with macro- and microscopic photographs.     

Multilocus phylogenetic analysis of the genus Aeromonas

A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several “bona fide” strains representing all described species.     

Bacterial flora in the alimentary tract of chickens infected with Eimeria brunetti and in chickens immunized with Eimeria maxima and cross-infected with Eimeria brunetti

Differential bacterial counts were made on the intestinal and caecal contents of chickens after inoculation with a standard dose of 320 000 freshly sporulated oocysts of Eimeria brunetti.     

Semicircular canal system in early primates

Mammals with more rapid and agile locomotion have larger semicircular canals relative to body mass than species that move more slowly. Measurements of semicircular canals in extant mammals with known locomotor behaviours can provide a basis for testing hypotheses about locomotion in fossil primates that is independent of postcranial remains, and a means of reconstructing locomotor behaviour in species known only from cranial material. Semicircular canal radii were measured using ultra high resolution X-ray CT data for 9 stem primates (“plesiadapiforms”; n = 11), 7 adapoids (n = 12), 4 omomyoids (n = 5), and the possible omomyoid Rooneyia viejaensis (n = 1). These were compared with a modern sample (210 species including 91 primates) with known locomotor behaviours. The predicted locomotor agilities for extinct primates generally follow expectations based on known postcrania for those taxa. “Plesiadapiforms” and adapids have relatively small semicircular canals, suggesting they practiced less agile locomotion than other fossil primates in the sample, which is consistent with reconstructions of them as less specialized for leaping. The derived notharctid adapoids (excluding Cantius) and all omomyoids sampled have relatively larger semicircular canals, suggesting that they were more agile, with Microchoerus in particular being reconstructed as having had very jerky locomotion with relatively high magnitude accelerations of the head. Rooneyia viejaensis is reconstructed as having been similarly agile to omomyids and derived notharctid adapoids, which suggests that when postcranial material is found for this species it will exhibit features for some leaping behaviour, or for a locomotor mode requiring a similar degree of agility.     

Middle Pleistocene fossil Cercopithecidae from Asbole, Afar Region, Ethiopia

A sample of 117 fossil cercopithecids has been collected from the Middle Pleistocene site of Asbole, Afar Region, Ethiopia. A minimum of five species is present. There are two species of Cercopithecini, here recognized as cf. Chlorocebus aff. aethiops, and cf. Chlorocebus cf. patas. There are also two species of Papionini: Papio hamadryas ssp. indet. and Theropithecus oswaldi leakeyi. Finally, there is a single species of colobine present, Colobus sp. indet. The assemblage is chronologically constrained and is derived from sediments dated to approximately 600 ka. Within this sample Colobus sp. is by far the most common species present, outnumbering the other four species combined. The cercopithecid assemblage is most consistent with a woodland habitat, corroborating an earlier interpretation based on the non-primate fauna. Taxonomic, biogeographic, and evolutionary implications of the assemblage are also discussed.