油气田土壤样品中可培养丁烷氧化菌多样性研究

分别采用丁烷或丁醇选择培养法,对采自四川省达州市普光气田和湖北省江汉油田的土壤样品中的丁烷氧化菌进行了分离、纯化、16S rRNA基因序列测定及系统发育研究,探讨不同油田不同环境中烃氧化菌数量、系统发育地位以及种群多样性的差异.结果表明,初步分离获得共25株丁烷氧化菌,分属于厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)和变形菌门(Proteobacteria).2个油田样品分离出的丁烷氧化菌群落结构简单,均包括芽孢杆菌(Bacillus)、假单胞菌(Pseudomonas)、红球菌(Rhodococcus)和节杆菌(Arthrobacter)4个属的细菌,苍白杆菌属(Ochrobactrum)和分支杆菌属(Mycobacterium)的细菌分离自普光气田.普光气田分离出的丁烷氧化细菌数量和多样性略高于江汉油田.     

接合子细胞强化对生物反应器降解2，4-D效应研究

研究了接合性质粒pJP4在2株纯菌E．coliDH5α、Alcaligenes sp．及好氧颗粒污泥混合菌群中的水平转移情况,并以获得pJP4质粒的接合子Alcaligenes sp．：：pJP4为强化菌种,考察了接合子细胞强化对好氧颗粒反应器和生物膜反应器中难降解有机物2,4-二氯苯氧乙酸（2,4-D）的去除效应．结...     

脱硫石膏对稻田CH4释放及其功能微生物种群的影响

为探究脱硫石膏对温室气体CH_4排放及其功能微生物种群的影响,采用静态暗箱/气相色谱法,高通量测序和荧光定量PCR技术,研究了FGDG0(0 t·hm~(-2))、FGDG1(2 t·hm~(-2))、FGDG2(4 t·hm~(-2))、FGDG3(8 t·hm~(-2))、FGDG4(16 t·hm~(-2))这5个施加脱硫石膏处理下CH_4排放特征、稻田细菌群落结构及产甲烷菌和甲烷氧化菌丰度的变化.结果表明施加脱硫石膏后,土壤p H显著提高(P0.05),土壤氧化还原电位、有机质、速效钾含量增加,但处理间无显著差异(P0.05);稻田CH_4平均排放通量随着脱硫石膏用量增加而降低,且FGDG1FGDG2FGDG3FGDG4,较对照分别减少31.56%、57.30%、83.60%、90.66%;与对照相比,FGDG1、FGDG2处理增加了土壤细菌丰富度和多样性,但用量超过4 t·hm~(-2)后,细菌丰富度和多样性逐渐降低;与对照相比,稻田土壤硫酸盐还原菌属相对丰度显著提高6.98%~13.56%,甲烷氧化菌pmo A基因丰度增加0.3%~6.2%,产甲烷菌mrc A基因丰度显著下降2.4%~15.8%,且丰度比(pmo A/mcr A)随着脱硫石膏用量增加而增大;相关性分析表明,CH_4平均排放通量与土壤中硫酸盐还原菌属相对丰度呈显著负相关,与产甲烷菌mcr A基因丰度呈显著正相关,与pmo A/mcr A比呈显著负相关.综上,脱硫石膏能够提高稻田土壤细菌群落多样性,抑制稻田CH_4排放.     

利用氧化亚氮还原酶基因 (nosZ) 评价人工湿地系统中的反硝化菌

应用人工潜流湿地净化微污染地表水,出水用于补给人工景观河.利用定量PCR测定了湿地植物根际土壤和景观河底泥中16S rDNA和nosZ的丰度,并采用PCR-DGGE技术考察了样品中含nosZ基因的群落结构及其相似性.定量PCR结果表明,潜流湿地及人工景观河16S rDNA、nosZ平均绝对丰度(以DNA计)分别为1.91E+07、1.26E+06和2.68E+07、8.37E+05 copies.ng-1,以干土计时分别为1.45E+11、9.31E+09和5.31E+11、1.45E+10 copies.g-1.景观河底泥中微生物总量和反硝化菌数量要高于湿地根际土壤,但是后者nosZ相对丰度(3.8%～10.1%)则明显高于前者(1.7%～4.1%).根际土壤和底泥样品聚类分析相似度低,根际土壤优势菌种大部分与红杆菌目(Rhodobacearales)、根瘤菌目(Rhizobiales)和伯克氏菌目(Burkholderiales)的细菌相似,而底泥的优势菌种均为不可培养的微生物.     

Profiling the antibiotic resistome in soils between pristine and human-affected sites on the Tibetan Plateau

With increasing pressure from anthropogenic activity in pristine environments, the comprehensive profiling of antibiotic resistance genes(ARGs) is essential to evaluate the potential risks from human-induced antibiotic resistance in these under-studied places. Here, we characterized the microbial resistome in relatively pristine soil samples collected from four distinct habitats on the Tibetan Plateau, using a Smart chip based high-throughput q PCR approach. We compared these to soils from the s...     

工程菌及其固定化细胞对有机磷农药的降解

将抗性库蚊解毒酶酯酶B1基因片段引入融合表达载体pThioHisA中,转化入大肠杆菌DH5α,在IPTG诱导下,经过8h,酯酶B1在大肠杆菌中获得融合高效表达。重组质粒pThioHisA-B1表达的酯酶融合蛋白具有较高的酯酶B1活性,能高效降解酯酶的特异性底物α-乙酸萘酯(α-NA)和β-乙酸萘酯(β-NA),将工程菌固定化后,固定化细胞在3h内对1000mg/L的甲基对硫磷降解率>65%。     

1,2,4-三氯苯双加氧酶和脱氢酶基因克隆与序列分析

通过PseudomonasnitroreducensJ5-1对不同氯苯类底物的降解实验,发现其降解能力大小顺序为:1,2,4-三氯苯,1,3-二氯苯,1,2-=氯苯,氯苯,与已报道的1,2,4-三氯苯降解菌株在底物利用的特性方面存在差异.采用PCR技术从J5-1中扩增获得氯苯降解过程中的关键酶--氯苯双加氧酶和脱氢酶的基因序列,分别命名为tcbA和tcbB,序列比对发现其与Burkholderia sp-PS12的氯苯双加氧酶和脱氢酶的基因序列同源性最高.通过J5-1的氯苯双加氧酶.亚基(TcbAa)与PS12的氯苯双加氧酶a亚基(TecAl)的氨基酸序列比对发现,在307-310位置有连续4个氨基酸残基的差异(1307L、M308T、1309V、Q310E),这可能是造成2株菌对1,2,4,5-四氯苯降解偏好性差异的原因.此外,通过催化芳香化合物降解的双力D氧酶a亚基的系统进化分析,认为TcbAa属于甲苯/联苯亚科,且与多取代氯苯双加氧酶e亚基的同源性最大.     

Complex effects of habitat amount and fragmentation on functional connectivity and inbreeding in a giant panda population

The relationships between habitat amount and fragmentation level and functional connectivity and inbreeding remain unclear. Thus, we used genetic algorithms to optimize the transformation of habitat area and fragmentation variables into resistance surfaces to predict genetic structure and examined habitat area and fragmentation effects on inbreeding through a moving window and spatial autoregressive modeling approach. We applied these approaches to a wild giant panda population. The amount of habitat and its level of fragmentation had nonlinear effects on functional connectivity (gene flow) and inbreeding. Functional connectivity was highest when approximately 80% of the surrounding landscape was habitat. Although the relationship between habitat amount and inbreeding was also nonlinear, inbreeding increased as habitat increased until about 20% of the local landscape contained habitat, after which inbreeding decreased as habitat increased. Because habitat fragmentation also had nonlinear relationships with functional connectivity and inbreeding, we suggest these important responses cannot be effectively managed by minimizing or maximizing habitat or fragmentation. Our work offers insights for prioritization of protected areas.