Isolation and characterization of a strain with high microbial attachment in aerobic granular sludge

Aerobic granule is a special microbial aggregate associated with biofilm structure. The formation of aerobic granular sludge is primarily depending on its bacterial community and relevant microbiological properties. In this experiment, a strain with high microbial attachment was isolated from aerobic granular sludge, and the detailed characteristics were examined. Its high attachment ability could reach 2.34 (OD_600nm), while other low attachment values were only around 0.06-0.32, which indicated a big variation among the different bacteria. The strain exhibited a very special morphology with many fibric fingers under SEM observation. A distinctive behaviour was to form a spherical particle by themselves, which would be very beneficial for the formation and development of granular sludge. The EPS measurement showed that its PN content was higher than low attachment bacteria, and 3D-EEM confirmed that there were some different components. Based on the 16S rRNA analysis, it was identified to mostly belong to Stenotrophomonas. Its augmentation to particle sludge cultivation demonstrated that the strain could significantly promote the formation of aerobic granule. Conclusively, it was strongly suggested that it might be used as a good and potential model strain or chassis organism for the aerobic granular sludge formation and development.     

Effect of reclaimed water effluent on bacterial community structure in the Typha angustifolia L. rhizosphere soil of urbanized riverside wetland, China

In order to evaluate the impact of reclaimed water on the ecology of bacterial communities in the Typha angustifolia L. rhizosphere soil,bacterial community structure was investigated using a combination of terminal restriction fragment length polymorphism and 16S rRNA gene clone library. The results revealed significant spatial variation of bacterial communities along the river from upstream and downstream. For example,a higher relative abundance of γ-Proteobacteria,Firmicutes,Chloroflexi and a lower proportion ofβ-Proteobacteria and ε-Proteobacteria was detected at the downstream site compared to the upstream site. Additionally,with an increase of the reclaimed water interference intensity,the rhizosphere bacterial community showed a decrease in taxon richness,evenness and diversity. The relative abundance of bacteria closely related to the resistant of heavy-metal was markedly increased,while the bacteria related for carbon/nitrogen/phosphorus/sulfur cycling wasn't strikingly changed. Besides that,the pathogenic bacteria markedly increased in the downstream rhizosphere soil since reclaimed water supplement,while the possible plant growth-promoting rhizobacteria obviously reduced in the downstream sediment.Together these data suggest cause and effect between reclaimed water input into the wetland,shift in bacterial communities through habitat change,and alteration of capacity for biogeochemical cycling of contaminants.     

Variations of dominant microbial populations in groundwater in response to the leachate from Laogang Landfill

Temporal changes of dominant microbial populations in groundwater in response to the leachate from Shanghai Laogang Landfill were investigated. Concentrations of dissolved redox-relevant species in groundwater suggested that the dominating redox process had changed from denitrification to methane-production/sulfate-reduction due to landfilling. Dominant microbial populations were determined using restriction fragment length polymorphism(RFLP) analyses of 16S rRNA gene libraries, which were further studied by sequencing and phylogenetic analyses. The results indicated that obvious shifts of dominant microbial populations had occurred in groundwater in response to the pollution of leachate. The closest relatives of some dominant clones are accordant with the dominating redox processes determined by hydrochemical analyses, based on the GenBank‘s indications on the ability to perform redox reactions.     

Screening and degrading characteristics and community structure of a high molecular weight polycyclic aromatic hydrocarbon-degrading bacterial consortium from contaminated soil

Inoculation with effcient microbes had been proved to be the most important way for the bioremediation of polluted environments. For the treatment of abandoned site of Beijing Coking Chemical Plant contaminated with high level of high-molecular-weight polycyclic aromatic hydrocarbons(HMW-PAHs) ,a bacterial consortium capable of degrading HMW-PAHs,designated 1-18-1,was enriched and screened from HMW-PAHs contaminated soil.Its degrading ability was analyzed by high performance liquid chromatography(HPLC) ,and the community structure was investigated by construction and analyses of the 16S rRNA gene clone libraries(A,B and F) at different transfers.The results indicated that 1-18-1 was able to utilize pyrene,fluoranthene and benzoapyrene as sole carbon and energy source for growth.The degradation rate of pyrene and fluoranthene reached 82.8%and 96.2%after incubation for 8 days at 30°C,respectively;while the degradation rate of benzoapyrene was only 65.1%after incubation for 28 days at 30°C. Totally,108,100 and 100 valid clones were randomly selected and sequenced from the libraries A,B,and F.Phylogenetic analyses showed that all the clones could be divided into 5 groups,Bacteroidetes,α-Proteobacteria,Actinobacteria,β-Proteobacteria andγ-Proteobacteria.Sequence similarity analyses showed total 39 operational taxonomic units(OTUs) in the libraries.The predominant bacterial groups wereα-Proteobacteria(19 OTUs,48.7%) ,γ-Proteobacteria(9 OTUs,23.1%) andβ-Proteobacteria(8 OTUs,20.5%) . During the transfer process,the proportions ofα-Proteobacteria andβ-Proteobacteria increased greatly(from 47%to 93%) ,while γ-Proteobacteria decreased from 32%(library A) to 6%(library F) ;and Bacteroidetes group disappeared in libraries B and F.     

玉门油田污染荒漠土壤石油降解菌多样性

为探索石油污染荒漠土壤石油降解微生物多样性、筛选高效石油降解菌,采用涂布平板法从石油污染荒漠土壤分离具有石油降解能力细菌,采用细菌形态观察和16S rRNA基因序列分析其多样性,并设计特异性引物,对分离细菌降解相关基因进行检测.结果表明,分离的37株细菌分别属于放线菌纲(Actinobacteria)、γ变形菌纲(Gammaproteobacteria)、β变形菌纲(Betaproteobacteria)、芽孢杆菌纲(Bacilli)和α变形菌纲(Alphaproteobacteria),分别占35.14%、32.43%、13.51%、13.51%、5.41%,归属于21个属的34个种类.优势菌属为假单胞菌属(Pseudomonas)、红球菌属(Rhodococcus)、微球菌属(Micrococcus)、寡养单胞菌属(Stenotrophomonas)、无色杆菌属(Achromobacter)和葡萄球菌属(Staphylococcus),占总数的51.35%,其中有36株细菌能以石油为唯一碳源稳定生长,对原油有明显的降解能力.在石油质量浓度为1 500 mg/L的基础培养基中,菌株YM43在培养7 d后对石油的降解率达55.47%,另有8株细菌的降解率不低于30.55%,11株细菌的降解率介于10.05%~28.37%,18株细菌的降解率不高于8.05%. PCR检测表明,有25株细菌含有烷烃单加氧酶基因,6株含芳烃双加氧酶基因,6株含联苯双加氧酶基因,4株含萘双加氧酶基因,3株含甲苯双加氧酶基因,2株含邻苯二酚双加氧酶基因.研究显示,石油污染荒漠土壤中可培养细菌具有高度多样性,分离的菌株有较强的石油降解能力,其降解功能与所存在的降解基因有关.      

用12SrRNA基因序列研究潮龟科（BATAGURIDAE）闭壳龟类的进化

测定了潮龟科（Ｂａｔａｇｕｒｉｄａｅ）具闭壳结构的齿缘摄龟属（Ｃｙｃｌｅｍｙｓ）、锯缘摄龟属（Ｐｙｘｉｄｅａ）、闭壳龟属（Ｃｕｏｒａ）共６种线粒体１２ＳｒＲＮＡ基因片段的序列,结合潮龟科其它一些属的序列数据,探讨了具闭壳结构龟类的起源与进化以及闭壳龟属的分类学问题．认为闭壳龟属与锯缘摄龟属为姐妹群,两者与齿缘摄龟属的亲缘关系较远,提示这些具闭壳结构的龟类可能不是由一个共同祖先分化而来．本文的结果不支持将闭壳龟属拆分为闭壳龟属和盒龟属两属     

慢生型花生根瘤菌16S rRNA分析

以２１株分离自四川,云南不同花生产区的慢性型花生根瘤菌和６株参比菌株为材料,进行了１６ＳｒＤＮＡＰＣＲ－ＲＦＬＰ,结果除证实了慢性型花生根瘤菌同慢生型大豆根瘤菌（Ｂｒａｄｙｒｈｉｚｏｂｉｕｍｊａｐｏｎｉｃｕｍ）高度的遗传相似性外,还发现了一些菌株同Ｂｒａｄｙｒｈｉｚｏｉｂｉｕｍｌｉａｏｎｉｎｇｅｎｓｉｓ和Ｂｒａｄｙｒｈｉｚｏｂｉｕｍｅｌｋａｎｉｉ有较高的遗传相似性,菌株Ｓｐｒ１－２的１６ＳｒＲＮＡ     

DHA高产菌Schizochytrium sp.FJU-512的分离及其18S rRNA基因序列比较分析

采用松花粉垂钓法分离到一株Docosahexaenoicacid(DHA)高产菌FJU 512.该菌株DHA含量高(占总脂肪酸的56. 24 % ),其它长链杂酸含量少(仅有docosapentaenoicacid, DPA),极具开发应用价值.高密度培养可获得33gL-1生物量.该菌株行二分裂生长,没有分生胞子.对其18SrRNA基因进行了克隆测序并登录GenBank(AY758384).依据18SrRNA基因建立的系统进化树表明:该菌与Schizochytriumlimacinum具有紧密的亲源关系. 图7表2参29     

核糖体RNA基因在海洋动物分子系统学中的应用

随着分子遗传标记在分子系统学中应用的发展,核糖体RNA基因因其特殊的组成结构和演化方式被广泛应用于海洋动物分子系统学研究中.本文系统地介绍了真核生物核糖体RNA基因的组成和性质及其近年来在海洋动物系统进化、分类和种质鉴定、遗传多样性研究等方面研究中的应用.从中可以看出,核糖体RNA基因已经广泛应用于海洋动物的分子系统学研究中,但主要利用的是核糖体RNA基因的一级结构.图2参36