Spatial and seasonal variations in bacterial communities of the Yellow Sea by T-RFLP analysis

Four typical coastal sites(rocky shore,sandy shore,mud flat shore,and artificial harbor)at the Yellow Sea were chosen to investigate the spatial and seasonal variations in bacterial communities.This was accomplished by using terminal restriction fragment length polymorphism(T-RFLP)analysis of PCR amplified 16S rDNA fragments.Two kinds of tetrameric restriction enzymes,HhaI and MspI,were used in the experiment to depict the bacterial community diversity in different marine environments.It was found that the community compositions digested by the two enzymes separately were different.However,the results of bacterial community diversity derived from them were similar.The MDA analysis results of T-RFLP profiles coming from HhaI and MspI both exhibited a significant seasonal community shift for bacteria and a relatively low spatial variation among the four locations.With HhaI as the sample,the pair wise Ttests also revealed that variations were minor between each pair of marine environments,with R ranging from 0.198 to 0.349.However,the bacterial community structure in the mud flat site depicted a larger difference than each of the other three sites(R ranging from 0.282 to 0.349).

施肥模式对设施菜地根际土壤微生物群落结构和丰度的影响

以甘肃武威长期定位设施菜地为研究对象,设定CK(对照)、MNPK(有机肥和无机肥配施)、1/2MNPK(1/2有机肥和无机肥)、M(单有机肥)、NPK(单化肥)等5种施肥处理,采用末端限制性片段多态性分析(T-RFLP)和实时荧光定量PCR技术,研究了根际土壤中细菌、氨氧化细菌和nir K型反硝化细菌群落结构和丰度的变化。结果表明:施肥和根际效应均对设施菜地土壤中的细菌、氨氧化细菌和nir K型反硝化细菌群落结构和丰度产生影响。施肥模式影响根际细菌、氨氧化细菌和nir K型反硝化细菌的主要种群,但对不同功能微生物的影响有差异。细菌16S rRNA基因、amo A基因和nir K基因的最大丰度分别出现在M、MNPK和M处理,为每克干土6.60×109、1.85×108和3.49×107个拷贝数,是CK处理的2.74、2.81和3.46倍。土壤p H值、有机质和全磷含量是影响设施菜地根际细菌、氨氧化细菌和nir K型反硝化细菌丰度的关键因素。

套作对黄瓜根际土壤细菌群落结构的多样性影响

以设施蔬菜中的主要栽培种类黄瓜为研究对象,以毛葱、蒜为套作作物,利用T-RFLP(末端限制性片段长度多态性,Terminal Restriction Fragment Length Polymorphism)技术对套作黄瓜根际土壤细菌群落结构多样性进行了研究。结果表明:套作改变了黄瓜根际土壤细菌群落结构的多样性和优势菌群结构。套种毛葱的黄瓜根际土壤细菌群落结构多样性高于套种蒜的黄瓜根际土壤细菌群落结构多样性;在黄瓜定植前和拉秧期,套作处理的土壤细菌群落结构多样性有比对照高的趋势,而在根瓜期和盛瓜期套作处理的土壤细菌群落结构多样性有比对照低的趋势;毛葱的套作效果最佳,蒜套作次之。套作提高了黄瓜产量。

黄土高原六道沟流域8种植物根际细菌与AMF群落多样性研究

采用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)方法,研究了神木县六道沟流域8种植物根际细菌与丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)群落多样性及其相互关系.目的是获得有关植物根际细菌和AMF群落的多样性指数,为生态环境修复提供科学依据.结果表明,8种植物根际细菌和AMF的种类和数量有较大差异,其中刺槐根际细菌的Shannon指数最高(4.01),垂柳最低(2.18),根际AMF的Shannon指数最高为小叶杨(2.07),最低为沙棘(1.21);聚类分析(cluster analysis)和冗余分析(redundancy analysis)结果表明,不同植物根际细菌和AMF的群落结构有较大差异,但同时部分植物间也存在相似性;8种植物根际细菌和AMF的多样性指数总体呈极显著的正相关(P<0.01);冗余分析结果表明在根际土壤环境因子中,对根际微生物群落多样性影响最大的环境因子为有机质含量.植物种类和根际环境对根际微生物群落结构有较大影响,同时,刺槐的根际细菌和AMF群落多样性指数均较高,故可作为六道沟流域植被恢复的先锋树种.

Community dynamics of ammonia oxidizing bacteria in a fullscale wastewater treatment system with nitrification stability

To determine whether the functional stability of nitrification was correlated to a stable community structure of ammonia oxidizing bacteria(AOB)in a fullscale wastewater treatment plant,the AOB community dynamics in a wastewater treatment system was monitored over one year.The community dynamics were investigated using specific PCR followed by terminal restriction fragment length polymorphism(T-RFLP)analysis of the amoA gene.The T-RFLP results indicated that during the period of nitrification stability,the AOB community structure in the full-scale wastewater treatment system was relatively stable,and the average change rate every 15 d of the system was 6.6%±5.8%.The phylogenetic analysis of the cloned amoA gene showed clearly that the dominant AOB in the system was Nitrosomonas spp.The results of this study indicated that throughout the study period,the AOB community structure was relatively stable in the full-scale wastewater treatment system with functional stability of nitrification.

Responses of potential ammonia oxidation and ammonia oxidizers community to arsenic stress in seven types of soil

Soil arsenic contamination is of great concern because of its toxicity to human,crops,and soil microorganisms.However,the impacts of arsenic on soil ammonia oxidizers communities remain unclear.Seven types of soil spiked with 0 or 100 mg arsenic per kg soil were incubated for 180 days and sampled at days 1,15,30,90 and 180.The changes in the community composition and abundance of ammonia oxidizing bacteria(AOB)and ammonia oxidizing archaea(AOA)were analyzed by terminal restriction fragment length polymorphism(TRFLP)analysis,clone library sequencing,and quantitative PCR(qPCR)targeting amoA gene.Results revealed considerable variations in the potential ammonia oxidation(PAO)rates in different soils,but soil PAO was not consistently significantly inhibited by arsenic,probably due to the low bioavailable arsenic contents or the existence of functional redundancy between AOB and AOA.The variations in AOB and AOA communities were closely associated with the changes in arsenic fractionations.The amoA gene abundances of AOA increased after arsenic addition,whereas AOB decreased,which corroborated the notion that AOA and AOB might occupy different niches in arsenic-contaminated soils.Phylogenetic analysis of amoA gene-encoded proteins revealed that all AOB clone sequences belonged to the genus Nitrosospira,among which those belonging to Nitrosospira cluster 3a were dominant.The main AOA sequence detected belonged to Thaumarchaeal Group 1.1b,which was considered to have a high ability to adapt to environmental changes.Our results provide new insights into the impacts of arsenic on the soil nitrogen cycling.