聚乙烯醇高效降解菌的筛选及降解特性研究

以聚乙烯醇为唯一碳源从环境中筛选获得了高效降解聚乙烯醇的微生物菌株XT11,初步鉴定为假单胞菌属(Pseudomonas sp.).对菌株Pseudomonas XT11的生长过程及PVA降解过程进行了研究,发现该菌株在54 h内可将1 g/L的聚乙烯醇(PVA)降解.同时研究了温度、pH值及酵母膏浓度对该菌株降解PVA的影响,结果表明其最适温度、pH值和酵母膏浓度分别为30℃、7.0和0.5 g/L.研究了PVA浓度对PVA降解率的影响,发现随着PVA浓度的增大,PVA的降解率降低.     

聚乙烯醇高效降解菌的筛选及降解特性研究

以聚乙烯醇为唯一碳源从环境中筛选获得了高效降解聚乙烯醇的微生物菌株XT11, 初步鉴定为假单胞菌属(Pseudomonas sp.)。对菌株Pseudomonas XT11的生长过程及PVA降解过程进行了研究, 发现该菌株在54 h内可将1 g/L的聚乙烯醇(PVA)降解。同时研究了温度、pH值及酵母膏浓度对该菌株降解PVA的影响, 结果表明其最适温度、pH值和酵母膏浓度分别为30℃、7.0和0.5 g/L。研究了PVA浓度对PVA降解率的影响, 发现随着PVA浓度的增大, PVA的降解率降低。     

溴氨酸降解菌株的分离和特性

从化工厂污泥中中分离到4个对蒽醌染料中间体溴氨酸有显降解和脱色作用的菌株。经鉴定,4株菌均为假单胞菌属（Pseudomonas sp.）。脱色效果最好的N1菌株能以溴酸为唯一碳源生长,其脱色效果受温度和pH影响较大,最佳生长条件是30℃,pH7.2。     

蓖麻碱降解菌的选育及脱毒效果的研究

以蓖麻碱为底物,从牛瘤胃液中选育出脱毒能力强、生长旺盛的菌株4-2w,经初步鉴定为假单胞菌(pseydomonas sp．),其最适生长温度为36℃,最适pH为7．0。经脱毒实验,4-2w菌降解蓖麻碱的脱除率达到90%以上,且该菌株未降解其中的蛋白质。     

蓖麻碱降解菌的选育及脱毒效果的研究

以蓖麻碱为底物,从牛瘤胃液中选育出脱毒能力强、生长旺盛的菌株4-2w,经初步鉴定为假单胞菌(pseydomonas sp．),其最适生长温度为36℃,最适pH为7．0。经脱毒实验,4-2w菌降解蓖麻碱的脱除率达到90%以上,且该菌株未降解其中的蛋白质。     

溴氨酸降解菌株的分离和特性*

从化工厂污泥中分离到 4个对蒽醌染料中间体溴氨酸有显著降解和脱色作用的菌株。经鉴定 ,4株菌均为假单胞菌属 (Pseudomonassp )。脱色效果最好的N1菌株能以溴氨酸为唯一碳源生长 ,其脱色效果受温度和 pH影响较大 ,最佳生长条件是 30℃ ,pH7 2。     

一株油脂降解菌的筛选鉴定及降解效果分析

为了筛选分离得到一株具有油脂降解能力的菌株,同时探究菌株的特性和降解能力。以屠宰场污染土作为菌源,通过梯度驯化法最终筛选分离得到能够将橄榄油作为单一碳源生长的降解菌。随后通过形态特征观察、Biolog生理生化测试以及16S rRNA基因序列比对分析鉴定,实验菌株为革兰氏阴性菌,属于无色杆菌属（Achromobacter sp.）,在构建的系统发育树上与Achromobacter pulmonis聚为一支。综合运用紫外分光光度法和高效液相色谱法检测,测得实验菌株培养4~5 d时对橄榄油的降解率可以达到90%,同时测得菌株降解油脂的最适pH和最适温度分别为7.5和35 ℃,该菌株在盐浓度低于40 g·L-1环境中降解率较高。此外实验结果表明,实验菌株对各类型油脂均具有较高的降解效率,具有广泛的应用前景。     

一株PCBs降解菌株分离鉴定及其酶学性质

从废旧变压器周围采取的土样中分离出一株多氯联苯降解菌,实验证明该菌株能以联苯作为唯一的碳源生长,经分子生物学鉴定,确定为枯草杆菌,编号为WF1。分别研究温度、pH值、底物浓度等因素对2,3’,4’,5—四氯联苯降解率的影响,确定其最佳产酶条件为发酵温度35℃、pH值7.0、装液量100 mL以下、接种量4%、PCBs起始浓度0.2 mg/L,250 mL三角烧瓶中150 r/min下振荡培养3 d。酶促反应的最适反应温度为35℃,最适pH值7.5。     

阿特拉津降解菌株的分离和鉴定

从农药厂废水中分离到6株能以除草剂阿特拉津为唯一氮源生长的细菌,即假单胞菌（Pseudomonas spp,.)AD1,AD2和AD6,土壤杆菌（Agrobacterium sp.)AD4,黄单胞菌（Xanthomonas sp.)AD5,欧氏菌（Erwinia sp.)AD7,AD1菌株能使无机盐培养基中的0．3g/L阿特拉津在72h内降解99．9％,当以AD1,AD2,AD4,AD5,AD6和AD7菌株的总DNA为模板进行PCR扩增时,除AD2菌株以外,均得到了与献报道的假单胞菌ADP菌株的阿特拉津氯水解酶基因（atzA)同源的PCR产物。     

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.     

Characterization of Arthrobacter nicotinovorans HIM, an atrazine-degrading bacterium, from agricultural soil New Zealand

Arthrobacter nicotinovorans HIM was isolated directly from an agricultural sandy dune soil 6 months after a single application of atrazine. It grew in minimal medium with atrazine as sole nitrogen source but was unable to mineralize 14C-ring-labelled atrazine. Atrazine was degraded to cyanuric acid. In addition to atrazine the bacterium degraded simazine, terbuthylazine, propazine, cyanazine and prometryn but was unable to grow on terbumeton. When added to soil, A. nicotinovorans HIM did enhance mineralization of 14C-ring-labelled atrazine and simazine, in combination with naturally occurring cyanuric acid degrading microbes resident in the soil. Using PCR, the atrazine-degradation genes atzABC were identified in A. nicotinovorans HIM. Cloning of the atzABC genes revealed significant homology (>99%) with the atrazine degradation genes of Pseudomonas sp. strain ADP. The atrazine degradation genes were held on a 96 kbp plasmid.     

Isolation and Characterization of Atrazine Mineralizing Bacillus subtilis Strain HB-6

Atrazine is a widely used herbicide with great environmental concern due to its high potential to contaminate soil and waters. An atrazine-degrading bacterial strain HB-6 was isolated from industrial wastewater and the 16S rRNA gene sequencing identified HB-6 as a Bacillus subtilis. PCR assays indicated that HB-6 contained atrazine-degrading genes trzN, atzB and atzC. The strain HB-6 was capable of utilizing atrazine and cyanuric acid as a sole nitrogen source for growth and even cleaved the s-triazine ring and mineralized atrazine. The strain demonstrated a very high efficiency of atrazine biodegradation with a broad optimum pH and temperature ranges and could be enhanced by cooperating with other bacteria, suggesting its huge potential for remediation of atrazine-contaminated sites. To our knowledge, there are few Bacillus subtilis strains reported that can mineralize atrazine, therefore, the present work might provide some new insights on atrazine remediation.     

Mineralization of the herbicide atrazine as a carbon source by a Pseudomonas strain.

Strain YAYA6 was isolated from a mixed microbial community that was growing on atrazine as a sole carbon source and formed quantitative amounts of chloride and nitrate. This strain was identified as a member of the true pseudomonad group (RNA group I) and was given the designation DMS 93-99. The growth yield when atrazine was the sole carbon and nitrogen source was 80 g (dry weight) of cells per mol of atrazine, and the cell doubling time was around 11 h. Approximately 20% of [U-ring 14C]atrazine was mineralized during primary degradation of atrazine. After atrazine disappeared from the culture supernatant, mineralization continued until the level of mineralization was more than 50%. Under different experimental conditions 10% of the atrazine supplied initially was converted to cyanuric acid and < 1% was converted to other s-triazines after prolonged incubation. Degradation proceeded via dechlorination and N-dealkylation. Atrazine was degraded until the concentration was circa 0.1 milligrams/liter. We obtained evidence showing that strain YAYA6 has specific uptake mechanisms for atrazine but less specific degradation mechanisms for s-triazines.     

Isolation and characterisation of Nocardioides sp. SP12, an atrazine-degrading bacterial strain possessing the gene trzN from bulk- and maize rhizosphere soil

We report the characterisation of Nocardioides sp. SP12, an atrazine-degrading bacteria isolated from atrazine-treated bulk- and maize rhizosphere soil. Based on 16S rDNA alignment, strain SP12 showed close phylogenic relationships with Nocardioides sp. C157 and Nocardioides simplex. Internal transcribed spacer (ITS) sequences of strain SP12 were longer than those of other Nocardioides sp. and present Ala- and Ile-tRNA unlike Actinomycetales. Nocardioides sp. SP12 presents a novel atrazine catabolic pathway combining trzN with atzB and atzC. Atrazine biodegradation ends in a metabolite that co-eluted in HPLC with cyanuric acid. This metabolite shows an absorption spectrum identical to that of cyanuric acid with a maximal absorption at 214.6 nm. The mass of the atrazine metabolite is in concordance with that of cyanuric acid according to mass spectrometry analysis. Quantitative PCR revealed that the ITS sequence of Nocardioides sp. SP12 was at a lower number than the one of trzN in atrazine-treated soil samples. It suggests that trzN could also be present in other atrazine degrading bacteria. The numbers of trzN and ITS sequences of Nocardioides sp. SP12 were higher in the maize rhizosphere than in bulk soil.     

Arthrobacter aurescens TC1 metabolizes diverse s-triazine ring compounds

Arthrobacter aurescens strain TC1 was isolated without enrichment by plating atrazine-contaminated soil directly onto atrazine-clearing plates. A. aurescens TC1 grew in liquid medium with atrazine as the sole source of nitrogen, carbon, and energy, consuming up to 3,000 mg of atrazine per liter. A. aurescens TC1 is metabolically diverse and grew on a wider range of s-triazine compounds than any bacterium previously characterized. The 23 s-triazine substrates serving as the sole nitrogen source included the herbicides ametryn, atratone, cyanazine, prometryn, and simazine. Moreover, atrazine substrate analogs containing fluorine, mercaptan, and cyano groups in place of the chlorine substituent were also growth substrates. Analogs containing hydrogen, azido, and amino functionalities in place of chlorine were not growth substrates. A. aurescens TC1 also metabolized compounds containing chlorine plus N-ethyl, N-propyl, N-butyl, N-s-butyl, N-isobutyl, or N-t-butyl substituents on the s-triazine ring. Atrazine was metabolized to alkylamines and cyanuric acid, the latter accumulating stoichiometrically. Ethylamine and isopropylamine each served as the source of carbon and nitrogen for growth. PCR experiments identified genes with high sequence identity to atzB and atzC, but not to atzA, from Pseudomonas sp. strain ADP.     

Characterization of an atrazine-degrading Pseudaminobacter sp. isolated from Canadian and French agricultural soils

Atrazine, a herbicide widely used in corn production, is a frequently detected groundwater contaminant. Fourteen bacterial strains able to use this herbicide as a sole source of nitrogen were isolated from soils obtained from two farms in Canada and two farms in France. These strains were indistinguishable from each other based on repetitive extragenic palindromic PCR genomic fingerprinting performed with primers ERIC1R, ERIC2, and BOXA1R. Based on 16S rRNA sequence analysis of one representative isolate, strain C147, the isolates belong to the genus Pseudaminobacter in the family Rhizobiaceae. Strain C147 did not form nodules on the legumes alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), red clover (Trifolium pratense L.), chickpea (Cicer arietinum L.), and soybean (Glycine max L.). A number of chloro-substituted s-triazine herbicides were degraded, but methylthio-substituted s-triazine herbicides were not degraded. Based on metabolite identification data, the fact that oxygen was not required, and hybridization of genomic DNA to the atzABC genes, atrazine degradation occurred via a series of hydrolytic reactions initiated by dechlorination and followed by dealkylation. Most strains could mineralize [ring-U-(14)C]atrazine, and those that could not mineralize atrazine lacked atzB or atzBC. The atzABC genes, which were plasmid borne in every atrazine-degrading isolate examined, were unstable and were not always clustered together on the same plasmid. Loss of atzB was accompanied by loss of a copy of IS1071. Our results indicate that an atrazine-degrading Pseudaminobacter sp. with remarkably little diversity is widely distributed in agricultural soils and that genes of the atrazine degradation pathway carried by independent isolates of this organism are not clustered, can be independently lost, and may be associated with a catabolic transposon. We propose that the widespread distribution of the atrazine-degrading Pseudaminobacter sp. in agricultural soils exposed to atrazine is due to the characteristic ability of this organism to utilize alkylamines, and therefore atrazine, as sole sources of carbon when the atzABC genes are acquired.     

阿特拉津降解菌Arthrobacter sp.AG1降解基因研究

菌株Arthrobacter sp. AG1能以4000mg/L的阿特拉津(AT)为唯一碳源、氮源和能源生长。通过设计特异引物从AG1中扩增出阿特拉津氯水解酶基因trzN的全序列,该基因与已报道的trzN基因序列相似性为99%。AG1菌株中含有两个大于100kb的质粒,Southern杂交结果显示trzN和atzB基因均位于其中较大的一个质粒pAG1上。将AG1菌株在LB液体培养基中转接三代后,发现34%的细菌细胞丢失了降解活性,但却未发现丢失质粒,PCR扩增结果表明突变子丢失了trzN基因,但atzB和atzC基因未丢失,说明降解活性的缺失是trzN基因片段从质粒上丢失的结果,表明trzN基因在环境中存在水平转移现象,暗示菌株AG1中的阿特拉津降解基因是基因的水平转移重组的结果。     

一株阿特拉津降解菌的分离鉴定及降解特性

从农药厂废水处理池的活性污泥中分离到一株阿特拉津降解菌X-4, 根据其生理生化特性和16S rRNA基因序列相似性分析, 将其初步鉴定为节杆菌属(Arthrobacter sp.)。该菌能以阿特拉津为唯一碳氮源生长, 42 h内对100 mg/L的阿特拉津降解效果为95.7%, 降解阿特拉津的最适温度为30 °C, pH为7.0。该菌对多种重金属离子都存在抗性, 显示了其在去除阿特拉津和重金属复合污染方面的应用潜力。对其降解基因的初步研究显示, 该菌含有trzN、atzB和atzC 3个阿特拉津降解相关基因。     

阿特拉津降解菌ATR3的分离鉴定与土壤修复

阿特拉津因效率高、价格低廉,是我国玉米田施用最广泛的除草剂之一,但其结构稳定,残留时间长,因此对生态环境和人类健康造成了一定的危害。从长期受阿特拉津污染的玉米田土壤中筛选并鉴定阿特拉津降解菌,明确其在不同类型土壤中的去除能力。对分离出的阿特拉津降解菌ATR3进行生理生化分析和16S rRNA序列鉴定,确定菌株ATR3为节杆菌属（Arthrobacter sp.）。该菌株以阿特拉津为唯一氮源,培养48 h后对1 000 mg/L阿特拉津的去除率达到97%以上。敏感作物盆栽试验结果表明,阿特拉津在棕壤上去除最快,褐土次之,黑土最慢,说明阿特拉津在土壤中的去除过程与土壤本身的理化性质呈相关关系。同时,该菌株处理14 d后,能明显恢复玉米的各项生物学指标,说明该菌株对阿特拉津污染土壤具有良好的修复能力。为阿特拉津降解菌剂的推广利用提供参考。     

阿特拉津降解菌株DNS32的降解特性及分类鉴定与降解途径研究

【目的】研究阿特拉津降解菌株DNS32的菌种分类、降解特性及降解途径,丰富阿特拉津降解菌菌种资源。【方法】在长期施用阿特拉津的东北地区寒地黑土中筛选出一株以阿特拉津为唯一氮源生长的降解菌株DNS32,测定其基本降解特性,通过16S rRNA序列分析进行分类鉴定,并利用阿特拉津降解基因PCR扩增技术及降解产物生成量的测定,进一步揭示其降解途径。【结果】实验结果发现DNS32菌株具有较好的降解能力,且在相对较低温度下也具有一定的降解能力。16S rRNA序列分析结果表明DNS32与鲁氏不动杆菌(Acinetobacter lwoffii)16S rRNA序列同源性高达99%。成功地扩增降解基因trzN、atzB及atzC,实验结果表明DNS32遵循Arthrobacter aurescens TC1的降解模式,可将阿特拉津降解为氰尿酸,降解产物的生成量测定也证明了这一点。【结论】实验结果丰富了阿特拉津降解菌菌种资源,为不动杆菌属的阿特拉津降解菌研究提供了参考。