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Danjiangkou Reservoir is a critical water source for the South-to-North Water Diversion Project, which harbors a diverse bacterioplankton community with varying depths, and the understanding of its nitrogen and phosphorus cycle and associated driving factors remains limited. In this study, we selected five ecological sites within Danjiangkou Reservoir and conducted metagenomics analysis to investigate the vertical distribution of bacterioplankton communities in the surface, middle, and bottom layers. Furthermore, we analyzed and predicted the function of nitrogen and phosphorus cycles, along with their driving factors. Our findings revealed the dominance of Proteobacteria, Actinobacteria, and Planctomycetes in the Danjiangkou Reservoir. Significant differences were observed in the structure of bacterioplankton communities across different depths, with temperature （ T ）, oxidation-reduction potential （ORP）, dissolved oxygen （DO）, and Chla identified as primary factors influencing the bacterioplankton composition. Analysis of nitrogen cycle functional genes identified 39 genes, including gltB , glnA , gltD , gdhA , NRT , etc., which were involved in seven main pathways, encompassing nitrogen fixation, nitrification, denitrification, and dissimilatory nitrate reduction. Phosphorus cycle function gene analysis identified 54 genes, including pstS , ppx - gppA , glpQ , ppk1 , etc., primarily participating in six main pathways, including organic P mineralization, inorganic P solubilization, and regulatory. Cluster analysis indicated that different depths were significant factors influencing the composition and abundance of nitrogen and phosphorus cycle functional genes. The composition and abundance of nitrogen and phosphorus cycle functional genes in the surface and bottom layers differed and were generally higher than those in the middle layer. Deinococcus , Hydrogenophaga , Limnohabitans , Clavibacter , and others were identified as key species involved in the nitrogen and phosphorus cycle. Additionally, we found significant correlations between nitrogen and phosphorus cycle functional genes and environmental factors such as DO, pH, T , total dissolved solids （TDS）, electrical conductivity （EC）, and Chla. Furthermore, the content of these environmental factors exhibited depth-related changes in the Danjiangkou Reservoir, resulting in a distinct vertical distribution pattern of bacterioplankton nitrogen and phosphorus cycle functional genes. Overall, this study sheds light on the composition, function, and influencing factors of bacterioplankton communities across different layers of Danjiangkou Reservoir, offering valuable insights for the ecological function and diversity protection of bacterioplankton in this crucial reservoir ecosystem.

Lake wetlands are extremely important and special ecosystems, which are important for regional water resource storage, environmental protection, and biodiversity maintenance. Sediment bacteria are an important component of lake ecosystems and are a major driver of biogeochemical cycling in lakes. In order to investigate the community structure of bacteria in typical lake sediments in Yinchuan City and their influencing factors, three typical lakes in Yinchuan City (Yuehai Lake, Mingcui Lake, and Xiniu Lake) were selected for the study and surface sediments were collected in January, April, July, and October 2021. The composition of the sediment bacterial community was examined using 16S rDNA high-throughput sequencing technology, and the response relationships between them and heavy metals were explored. The results showed that the ecological hazard coefficient for heavy metals in the sediments of three typical lakes in Yinchuan City was far less than 40, and the ecological hazard index was far less than 150, all of which indicated a minor ecological hazard. There were no significant differences in bacterial community diversity among the three lakes, but there were significant variations in diversity among the lakes in different seasons and significant differences in community composition. The dominant phyla (top three in terms of relative abundance) in Yuehai Lake, Mingcui Lake, and Xiniu Lake were Proteobacteria, Bacteroidetes, and Chloroflexi. The dominant lower orders were Gammaproteobacteria, Alphaproteobacteria, and Deltaproteobacteria. The main divergent species that occurred at the phylum level in typical lakes in Yinchuan were Proteobacteria, Bacteroidetes, Euryarchaeota, Firmicutes, Actinobacteria, and Acidobacteria. The sediment bacterial community structure of Yuehai Lake was significantly correlated with Cu, Fe, Mn, Zn, As, and Pb; the sediment bacterial community structure of Lake Mingcui was significantly correlated with Fe, Pb, and Cr; and the sediment bacterial community structure of Xiniu Lake was not significantly correlated with heavy metals. The types and contents of sediment heavy metals had a significant effect on the bacterial community structure of sediments in Yinchuan Yuehai Lake and Mingcui Lake and were important environmental factors that caused changes in the bacterial community structure of lake sediments.

In this study, we used a high-throughput sequencing technology to survey the dry-wet seasonal change characteristics of soil ammonia-oxidizing bacteria (AOB) communities in the three restoration stages [i.e., Mallotus paniculatus community (early stage), Millettia leptobotrya community (middle stage), and Syzygium oblatum community (later stage)] of Xishuangbanna tropical forest ecosystems. We analyzed the effects of soil physicochemical characteristics on AOB community composition and diversity during tropical forest restoration. The results showed that tropical forest restoration significantly affected the relative abundance of dominant AOB phyla and their dry-wet seasonal variation. The maximum relative abundance of Proteobacteria (71.3%) was found in the early recovery stage, while that of Actinobacteria was found in the late recovery stage (1.0%). The abundances of Proteobacteria and Actinobacteria had the maximum ranges of dry-wet seasonal variation in the early and late stages, respectively. The abundance of dominant AOB genera and its dry-wet seasonal variation varied across tropical forest restoration stages. The maximum average relative abundance of Nitrosospira and Nitrosomonas in the late recovery stage was 66.2% and 1.5%, respectively. In contrast, the abundance of Nitrosovibrio reached its maximum (25.6%) in the early recovery stage. The maximum dry-wet seasonal variation in relative abundance of Nitrosospira and Nitrosomonas occurred in the early recovery stage, while that of Nitrosovibrio occurred in the middle recovery stage. The Chao1, Shannon, and Simpson diversity indices of AOB communities increased along the restoration stages, which were significantly higher in the wet season than in the dry season. The results of canonical correspondence analysis showed that soil easily oxidized carbon was the main factor controlling AOB community diversity and Actinobacteria abundance. Soil bulk density and temperature were the main factors affecting Proteobacteria abundance. Soil pH, microbial biomass carbon, water content, ammonium nitrogen, bulk density, and temperature were the main factors controlling the abundances of Nitrosospira , Nitrosomonas , and Nitrosovibrio . Therefore, tropical forest restoration can regulate the change of relative abundance of dominant AOB taxa via mediating the changes of soil temperature, bulk density, and readily oxidized carbon, leading to an increase in soil AOB community diversity.

Purpose: To explore the differences between oral and intestinal microorganisms of 860 children aged 1-6 years in Nanjing city., Methods: Eight hundred and sixty children aged 1-6 years who met the inclusion criteria were enrolled. 860 saliva samples and equivalent stool samples were collected. Microbial DNA was extracted and amplified using PCR. High-throughput sequencing was performed using Miseq sequencer, and bioinformatics analysis was performed to compare the differences of oral and intestinal microflora. SPSS 20.0 software package was used to perform the statistical analysis., Results: At phylum level, Bacteroidetes (39.98%), Proteobacteria (25.32%) and Firmicutes (21.78%) were the most common microbes in oral cavity, while Firmicutes (45.21%) and Bacteroidetes (37.21%) were the most abundant microbes in the gut. At genus level, the top three microbes in the oral cavity included Prevotella(26.11%), Neisseria (12.39%), Porphyromonas(10.13%), while the top three microbes in the gut included Bacteroidetes(20.11%), Prevotella (9.13%), and Faecalibacterium (5.13%). There were significant alpha and beta differences in oral and intestinal microbial diversity., Conclusions: Bacteroidetes and Proteobacteria are the dominant species in the oral cavity, while Firmicutes and Bacteroidetes are the dominant species in the gut. There are significant differences in species composition and abundance between oral and intestinal microorganisms.

[ OBJECTIVE] Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) was used as solid carbon source and biofilm carrier to remove nitrate from recirculating aquaculture system (RAS). Dynamics of microbial community structure in biofilm coating on carbon source packed into denitrification reactor were investigated. [METHODS] Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community in biofilm from denitrifiation reactor. Bacteria degrading PHBV were isolated from the reactor using pure culture method. [RESULTS] Nitrate decreased remarkably in the RAS connected with dentrification reactor. In contrast, Nitrate increased continuously in the conventional RAS without dentrification reactor. According to the phylogenetic analysis, the microbes in the biofilm samples from denitrification reactor were divided into Proteobacteria ( p-proteobacteria, γ-proteobacteria and δ- proteobacteria) , Firmicutes and Bacteroidetes. The major advantageous populations were Acidovorax and Bacillus in the 40-day reactor. The advantageous populations in the 150-day reactor were in order of Clostridium, Desulfitobacterium, Dechloromonas, Pseudoxanthomonas and Flavobacterium. Pure cultures of bacteria degrading PHBV isolated from denitrification reactor were classified into Acidovorax, Methylibium, Pseudoxanthomonas and Dechloromonas. [CONCLUSION] Nitrate could be removed effectively from RAS using PHBV as carbon source. Advantageous bacteria and their dynamic changes were ascertained in biofilm from denitrification reactor packed with PHBV.

The bacterial diversity in the biological desulfurization reactor operated continuously for 1 year was studied by the 16S rDNA cloning and sequencing method. Forty clones were randomly selected and their partial 16S rDNA genes (ca. 1,400 bp) were sequenced and blasted. The results indicated that there were dominant bacterias in the biological desulfurization reactor, where 33 clones belonged to 3 different published phyla, while 1 clone belonged to unknown phylum. The dominant bacterial community in the system was Proteobacteria, which accounted for 85.3%. The bacterial community succession was as follows: the gamma-Proteobacteria(55.9%), beta-Proteobacteria(17.6%), Actinobacteridae (8.8%), delta-Proteobacteria (5.9%) , alpha-Proteobacteria(5.9%), and Sphingobacteria (2.9%). Halothiobacillus sp. ST15 and Thiobacillus sp. UAM-I were the major desulfurization strains.

The objectives of this study were to explore the effects of long-term organic and inorganic fertilizations on the composition and abundance of nirS-type denitrifiers in black soil. Soil samples were collected from 4 treatments (i. e. no fertilizer treatment, CK; organic manure treatment, OM; chemical fertilizer treatment (NPK) and combination of organic and chemical fertilizers treatment (MNPK)) in Gongzhuling Long-term Fertilization Experiment Station. Composition and abundance of nirS-type denitrifiers were analyzed with terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR (Q-PCR), respectively. Denitrification enzyme activity (DEA) and soil properties were also measured. Application of organic fertilizers (OM and MNPK) significantly increased the DEAs of black soil, with the DEAs in OM and MNPK being 5.92 and 6.03 times higher than that in CK treatment, respectively, whereas there was no significant difference between NPK and CK. OM and MNPK treatments increased the abundances of nirS-type denitrifiers by 2.73 and 3.83 times relative to that of CK treatment, respectively. The abundance of nirS-type denitrifiers in NPK treatment was not significantly different from that of CK. The T-RFLP analysis of nirS genes showed significant differences in community composition between organic and inorganic treatments, with the emergence of a 79 bp T-RF, a significant decrease in relative abundance of the 84 bp T-RF and a loss of the 99 bp T-RF in all organic treatments. Phylogenetic analysis indicated that the airS-type denitrifiers in the black soil were mainly composed of alpha, beta and gamma-Proteobacteria. The 79 bp-type denitrifiers inhabiting exclusively in organic treatments (OM and MNPK) were affiliated to Pseudomonadaceae in gamma-Proteobacteria and Burkholderiales in beta-Proteobacteria. The 84 bp-types were related to Burkholderiales and Rhodocyclales. Correlation analysis indicated that pH, concentrations of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), nitrate (NO3(-) -N) and ammonia (NH4(+) -N) were significantly related to abundances of nirS-denitrifers (r = 0.724-0.922, P < 0.05) and the DEA (r = 0.453-0.938, P < 0.01). In addition, the DEAs were linearly and positively correlated with the abundances of nirS-type denitrifers (r = 0.85, P < 0.01). Redundancy analysis showed that except moisture, pH and concentrations of TP, TP, TOC, NH4(+) -N and NO3(-) -N were significantly correlated with the community structure of nirS-type denirifiers (r = 0.440-0.862, P < 0.01). Furthermore, the DEAs were significantly correlated with the compositions of nirS-denirifiers (r = 0.863, P < 0.01). In conclusion, the airS-type denitrifiers in the black soil are more responsive to the organic treatments than to the inorganic treatments in terms of community composition and abundance, both of which are correlated with the changes of DEAs.

Microbial communities of different depths (30, 60, 100, 150, 200cm) from the unexploited oilfield, gas field and control area were studied by PCR-DGGE and sequencing methods. The objectives of this study were to understand the microbial distribution in the regions of unexploited oil and gas fields, and to investigate the potential microbial indicators of oil and gas resources. The results showed that the Dice coefficients between different depths were very low (26-69.9). The microbial communities in the soil of 150 cm and 200 cm depth had greater richness (S > or = 19), diversity (H > or = 2.69) and evenness (E > or = 0. 90). The results of sequencing demonstrated that the bands from oilfield were mainly grouped into alpha-Proteobacteria, gamma-Proteobacteria, Actinobacteria, Acidobacteria with the predominance of gamma-Proteobacteria (75%). Most of the bands were related to oil-associated and hydrocarbon degrading bacteria, such as Methylophaga and Alcanivorax. While the gas field had alpha, beta, gamma, delta-Proteobacteria and Bacteroidetes, and gamma-Proteobacteria accounted for only 24%. More strains showed relativity to methanotrophs, such as Methylocystaceae. Thus, 150 cm and 200 cm were more suitable as the oil-gas exploration sampling depth. Methylocystaceae may act as potential indicators for gas resources, Methylophaga and Alcanivorax for oil.

A group of removing SO2 bacterium was obtained from the oxidation ditch of city sewage treatment plant by inductive domestication over 6 d with low concentration SO2 gas, and they have an ability with biodegradation rate of 888 mg x (L x h)(-1) and a degradation efficiency of 85% during 1.5 h for SO2 dissolved in water with their synergy. The clone library and two phylogenetic trees of the removing SO2 bacterium communities were obtained based on 16S rRNA DNA comparison by DNA extraction of the sample and in situ polymerase chain reaction (PCR). The phylogenetic analysis showed that 8 dominant desulfuration bacterium occupy about 69% of all removing SO2 bacterium, and some of them have a kindred with discovered desulfuration bacterium but not homogeneity, and there are four belong to alpha-Proteobacteria, another four belong to beta-Proteobacteria in them. The gene information about 16S rRNA sequence of the dominant desulfuration bacteria and domestication method provide a basic of looking for or domesticating removing SO2 bacterium for development microbial desulfurization technology of contained SO2 tail gas.

Objective: In order to investigated composition and diversity of bacterial in a cold sulfur spring in Xinjiang faulting zone., Methods: Environmental total DNA was directly extracted from the water of the No. 10 cold sulfur spring. The 16S rRNA genes were amplified from the total DNA by PCR with bacteria-specific primers and construction a clone library. Positive clones were randomly selected from the library and identified by restriction fragment length polymorphism (RFLP). The unique RFLP pattern corresponded sequences were sequenced, BLAST and then constructed phylogenetic tree., Result: In total, 228 positive clones were screened and grouped into 33 Operational Taxonomic Units (OTUs). The clone coverage C value was 92%. 33 Operational Taxonomic Units were divided into 3 phyla with Blast analysis and RDP classifer: Proteobacteria, Bacteroidetes, and Firmicutes. Proteobacteria (98%) was the absolutely dominant group, of which 20% of the clones were highly related to the known photoautotrophic and chemoautotrophic bacteria ( > 97% sequence similarity). Besides, 64% of the clones showed less than 96% of sequence similarity with sequence deposited in GenBank database, of them 54% sequences were affiliated to genus Legionella spp., Conclusion: Bacterial diversity in No. 10 cold sulfur spring was low, but maybe have a diversity of novel species and lineages. In addition, large number of novel species of Legionella were detected in the spring water may suggest the water potentially a source of Legionnaires disease and may constitute a menace to the health of human and livestock that lived down the spring.

The aim of this study was to determine the effect of long-term (16 years) application of nitrogen fertilizer on the diversity of nitrifying genes (amoA and hao) in paddy soil on the basis of long-term paddy field experimental station (started in 1990) located in Taoyuan, with the molecular approaches of PCR, constructing libraries and sequencing. The fertilizer was urea and no fertilizer was as control. The Shannon index showed that long-term application of nitrogen fertilizer made the diversity of amoA gene descend while no effect on the diversity of hao gene. The LIBSHUFF statistical analyses demonstrated that both amoA and hao libraries of CK and N treatments were significantly different from each other and the rarefaction curves of libraries failed to meet the plateaus indicating that there were lots kinds of genes haven't been detected. The results of blasting with GenBank and the phylogenetic tree showed that the amoA genes detected in our study had a similarity with the uncultured gene of amoA, which showed some similar to Nitrosospira. Otherwise, the hao genes cloned showed a relationship to the genes of cultured bacteria such as Silicibacteria, Nitrosospira and Methylococcus, and the hao genes found in the N treatment dominated in alpha-Proteobacteria. These results suggest that long-term fertilization of nitrogen had significant impacts on the diversity or community of amoA and hao genes.

Two granular activated carbon (GAC) samples with 1.5 a and 5 a age were collected, Bacterial genome DNA was extracted for the 16S rDNA gene amplification, and then a bacterial 16S rDNA gene clone library was constructed. After the phylogenetic analysis of 16S rDNA sequences, bacterial diversity and community structure of two activated carbon biofilm sample were studied. The results showed the bacteria in GAC with 5 a age could be divided into 11 groups, which were as follows alpha-Proteobacteria (26.5%), beta-Proteobacteria (16.3%), delta-Proteobacteria (16.3%), Planctomycetes (12.2%), Gemmatimonadetes (6.1%), Acidobacteria (4.1%), Nitrospira (2.0%), gamma-Proteobacteria (2.0%), Bacteroidetes (2.0%), Actinobacteria (2.0%), Unclassified Bacteria (10.2%). The bacteria in GAC with 1.5 a age could be divided into 10 groups, which were as follows alpha-Proteobacteria (21.6%), Planctomycetes( 10.8%), Bacteroidetes (10.8%), beta-Proteobacteria (9.0%), Acidobacteria (9.0%), Nitrospira (7.2%), detla-Proteobacteria (7.2%), Unclassified Proteobacteria (5.4%), Gemmatimonadetes (3.6%), Unclassified Bacteria (14.4%). The results revealed a variety of bacterial divisions on the studied GAC biofilm. Proteobacteria had the highest share in the two total clones, and alpha- and beta-Proteobacteria were on a dominant position. A relatively high proportion of delta-Proteobacteria was observed in the biofilm of GAC with 5 a age, and Nitrospira was in a minor proportion. However, a totally converse condition appeared in GAC with 1.5 a age. Two pathogenic bacteria, Afipia and Chryseobacterium, were detected in analyzed GACs, which implies a potential microbial risk in water supply.

Objective: To understand the impacts of anthropogenic activities on structure and composition of bacterial communities and to evaluate how bacterial communities respond to environmental gradients at coastal sediments., Methods: The diversity of bacterial communities in sediments from tourist and mariculture zones at coastal area of Dalian Changshan Islands was assessed using terminal restriction fragment length polymorphism (t-RFLP) and denaturing gradient gel electrophoresis (DGGE) approaches. Meanwhile, 16S rRNA clone library was constructed to reveal the composition and structure of bacterial communities in the most seriously polluted site (D4)., Results: There were much higher values of richness, Shannon-wiener and evenness index at D4 site by the analysis of terminal restriction fragments (t-RFs). The clustering result on the t-RFs areas and DGGE patterns showed that the bacterial diversity of tourist zone were more similar, while the distinction was increased with pollution levels among the tourist and mariculture zones. The 16S rRNA clone of D4 revealed that the Proteobacteria were the dominant phylum, and gamma-proteobacteria was the main class within Proteobacteria., Conclusion: The study documented changes in bacterial community structure by human impacts of mariculture than geographical location.

Phenol and phenolic compounds are main pollutants in wastewater of coking factories. To identify the bacteria responsible for phenol removal in the activated sludge of a coking factory, we isolated bacteria from the sludge directly or after enrichment. From two samples from the aerobic and anaerobic pools, 28 strains belonging to 28 species of 20 genera were obtained after identification with BOX-PCR and further 16S rDNA sequence analyses. Most of them belonged to beta- and gamma-Proteobacteria, four of which are potential novel species of low 16S rDNA sequence similarity to corresponding type strains. From the m-cresol enrichment community, two strains identified and named as Pseudomonas monteilii GCS-AE-J-1 and Pseudomonas plecoglossicida GCS-AN-J-3 were obtained as the efficient degraders; The former can remove 94.6% m-cresol (791 mg/L) in just 48 h; while the latter metabolized 92.2% m-cresol (763 mg/L). Furthermore, the phenol hydroxylase gene was surveyed by PCR from the phenol-degrading strains,and 4 were positively detected. Summarily, quite diverse bacteria were proved of high capability to degrade phenol and phenolic compounds in this report, which play important role in biotreatment of phenol compounds.

In order to study the variation of microbial community structure and the mechanism of denitrification on bio-carrier in recirculating aquaculture systems (RAS) during the periods of bio-film formation and operation the systems, traditional microbiological methods were applied to count the quantity of heterotrophic bacteria, ammonia oxidize bacteria and nitrite oxidize bacteria. The amplified products of variable V3 region of bacterial 16S rDNA were separated by using denaturing gradient gel electrophoresis (DGGE). And bacterial community DNA fingerprint was obtained. The sequences retrieved from the DGGE bands were used for homology analysis and construction of phylogenetic tree. It presented a trend that the quantity of the three types of bacteria increased gradually to a top and then fallen slowly to a stable level. The composition of microbial community of bio-carrier was very abundant in all periods, and the Shannon index was 1.53, 1.44, 1.57, 1.08, 1.27 and 1.30, respectively. During different periods, there was a certain shift in the microbial community structure, while the C(s) value (similar index) in two adjacent periods was high, indicating the variation and succession of the microbial community was slow and regular. Several bacteria had an effect on removal of pollutants for farming water and the effluent water quality could meet the requirements of high-density culture. Among them, Proteobacteria and Flavobacteria were main communities. The Nitrosomonas and some other facultative anaerobic bacteria (Flavobacteriaceae bacterium) were identified, which indicated that there may be coexisted pathways of nitrification and denitrification in bio-filter.

Magnetotactic bacteria (MTB) are widely distributed in aquatic environments. To assess the correlation between their evolutionary relatedness and geographic distribution, we analyzed 239 16S rDNA sequences available in the Genbank, and constructed phylogenetic trees based on the sequences. After elimination of redundant sequences by grouping those with identity > 97% into a single one, we analyzed in detail total 139 16S rDNA sequences, including 55 from marine MTB and 82 from freshwater sequences, and belonging to Proteobacteria and Nitrospirae. Phylogeny analysis based on those sequences suggests that the geographical distribution of MTB has certain regional distribution character: marine MTB is distinct from freshwater MTB, and off coast MTB are remotely related with ocean MTB. In contrast, the MTB from similar habitats, such as offshore in Brazil and the United States or freshwater lakes in Germany and China, are closely related. It is found that similar species have a large geographic distribution and tend to adopt the similar habitats, morphotypes of MTB and their living environment conditions have a significant relevance. This observation suggests that MTB may have multiple evolutionary origins. And also, it suggests the environmental conditions, as an important evolutionary pressure, play an important role in the long-term evolution of MTB.

By constructing 16S rDNA clone library with PCR-RFLP, the prokaryote diversity in the seawater and groundwater of land-ocean ecotone of Zhuhai City was investigated, and the similarity and cluster analyses were implemented with the database of the sequences in Genbank. In the seawater, Proteobacteria was dominant, followed by Archaeon, Gemmatimonadetes, Candidate division OP3 and OP8, and Planctomycetes, etc.; while in the groundwater, Archaeon was dominant, followed by Proteobacteria, Sphingobacteria, Candidate division OP3, Actinobacterium, and Pseudomonas. The dominant taxa in the groundwater had high similarity to the unculturable groups of marine microorganisms. Large amount of bacteria capable of degrading organic matter and purifying water body existed in the groundwater, suggesting that after long-term evolution, the land-ocean ecotone of Zhuhai City had the characteristics of both land and ocean.

An oil-contaminated groundwater sample was collected at an abandoned petrochemical factory.Bacterial genome DNA was extracted for the 16S rDNA gene amplification,and then a bacterial 16S rDNA gene clone library was constructed. After the phylogenetic analysis of 16S rDNA sequences, bacterial diversity and community structure of the groundwater were studied. The results showed the bacteria in the groundwater could be divided into 10 groups, which were as follows: gamma-Proteobacteria (49.1%), alpha-Proteobacteria (12.9%), beta-Proteobacteria (11.1%), Bacteroidetes (9.2%), Verrucomicrobia (6.7%), Acidobacteria (2.5%), delta-Proteobacteria (1.2%), Actinobacteria (1.2%), Planctomycetes (0.6%), unidentified bacteria (5.5%). Gamma-Proteobacteria was predominant in the ecosystem (near 50% of total clones), and especially Pseudomonas accounted for 35.6% of all bacteria. Many clones also affiliated with other degrading bacteria,such as Sphingomornas, Rhodococcus, Brevundimonas. Furthermore, a lot of 16S rDNA sequences in the clone library had high similarity to the ones originated from similar polluted environments, such as soil and groundwater contaminated with chlorinated hydrocarbon, soil and groundwater contaminated with polycyclic aromatic hydrocarbon, soil contaminated with PCBs, antibiotics production wastewater and activated sludge, which proved that there were lots of degrading bacteria population in the oil-contaminated water.

With the development of molecular biology, the research on microflora in the environment is accelerated and a new research method for oil reservoir microflora is provided. Based on the methods of PCR-DGGE, the change of the structure of dominant microbial population in selectiveactivation of stratal bacteria was studied. During activation, the change of samples' DGGE bandings under different pressure conditions (1 MPa and 10 MPa) was analyzed, the PCR alignment analysis of bacteria was studied, the dominant bacteria at different periods were explored, the phylogenetic tree of dominant DGGE banding sequence was build, and the groups of the main indigenous bacteria was also analyzed. The result showed that the structure and the quantity of stratal microorganism indicated obvious differences, under different pressure conditions. The species number of dominant microbial population increased, and the structure of dominant microbial population obviously changed after activation. Before activation, the main bacteria were belonged to Bacillales, and after injecting activation agent, the species of Proteobacteria increased.

Objective: We investigated endophytic bacterial diversity in Glycyrrhiza inflata Bat. from Xinjiang., Methods: We investigated endophytic bacterial diversity in root of Glycyrrhiza inflata Bat. from Xingjian by culture-independent method. Total DNA genome of Glycyrrhiza sample was extracted using CTAB (Hexadecyl trimethyl ammonium Bromide) procedure with some modifications. A pair of bacterial PCR primers were used for endophytic bacterial 16S rDNA gene amplification and a clone library was constructed for the Glycyrrhiza DNA samples. Clones screened from clone library on the basis of Hae III digestion patterns were sequenced and compared, flowed by constructing Neighbor-Joining tree., Results: In total 150 clones were grouped to 32 operational taxonomic units, most of the clones showed high similarity to the known cultured bacteria. Sequence analysis revealed diverse phyla of bacteria in the 16S rDNA library, which consisted of alpha, gamma subclasses of the Proteobacteria, Bacteroides, Firmicutes, Actinobacteria, and Uncultured bacteria; 74% of the clones were highly related to the known bacteria in the genus Sphingobium, Phyllobacterium, Hyphomonas, Agrobacterium etc (> 96% sequence similarity); whereas 26% of the clones showed lower affiliation with known genus (< 96% sequence similarity) and may represent novel taxa., Conclusion: There was abundant endophytic bacterial diversity in Glycyrrhiza inflata Bat. from Xinjiang as well as many unknown organisms.

By using PCR-RFLP, this paper studied the 16S rDNA gene diversity and phylogenesis of soil bacteria in primeval forest and degraded ecosystem in Karst region of Northwest Guangxi. More genotypes and higher diversity index were observed in the soil of primeval forest than in that of degraded ecosystem, and only two common genotypes were observed in the two soils. A clone from each genotype was randomly selected as representative for sequencing. The obtained 16S rDNA gene sequences had a similarity of 87%-100% with those in the GenBank (www. ncbi. nlm. nih. gov), and more than half of them had a similarity lower than 97%, being of new species. Based on phylogenetic analysis, the bacteria in the two soils were classified into 10 groups, with 5 groups in common. The dominant bacterial groups in the two soils differed obviously. In primeval forest soil, the dominant group was Proteobacteria, which had 39 genotypes, occupying 58.0% of all the clones; while in the soil of degraded ecosystem, the dominant groups were Acidobacteria and Proteobacteria, which had 19 and 15 genotypes, occupying 32.5% and 30.5% of all the clones, respectively. In the soil of degraded ecosystem, Proteobacteria group decreased while Acidobacteria group increased markedly, compared with those in primeval forest soil. Soil physical and chemical properties and environmental factors should be responsible for the difference of soil bacterial community between the two soils.

The composition of bacterial community in the Alexandrium tamarense culture was determined by analyzing the 16S rDNA clone libraries. 16S rRNA gene was amplified by using the total DNA extracted from the A. tamarense culture at three growth stages as templates. 34 different restriction fragment length polymorphism (RFLP) patterns of the clones were obtained from the three libraries. Clones representing each RFLP patterns were sequenced and phylogenetic analysis revealed that the Proteobacteria and the Bacteroidetes group can be the dominant component in the phycosphere microflora. Results showed that in the lag phase, alpha-Proteobacteria (36.4%), gamma-Proteobacteria (27.3%) and Bacteroidetes (27.3%) were the dominant group; in the late-exponential phase, the clones belonged to alpha-Proteobacteria (53.3%), beta-Proteobacteria (13.3%), gamma-Proteobacteria (6.7%), and Bacteroidetes (26.7%); and in the stationary phase, the community was comprised of alpha-Proteobacteria (47.8%), beta-Proteobacteria (8.7%), gamma-Proteobacteria (21.7%), delta-Proteobacteria (4.3%) and Bacteroidetes (17.4%). The results also suggest that a part of the bacteria associated with A. tamarense are uncultured and novel species. And these bacteria may play a major role in regulating the processes of algal bloom initiation, maintenance and decline. So these results may provide us great academic and practical importance in controlling the algal blooms by microbes.

Enhanced biological phosphorus removal (EBPR) process was operated in a laboratory-scale sequencing batch reactor (SBR) for one-month fed with acetate as the carbon source. The characteristic and the microbial population structure and space distribution dynamics of phosphate-accumulating organisms (PAOs) of start-up period were analyzed by fluorescent in situ hybridization (FISH). The relationship between enrichment of PAOs and phosphorus removal was discussed. PAOs could be enriched by recirculation activated sludge containing heterotrophs through anaerobic aerobic conditions. Portion of PAOs in the sludge increase from 11.5% to 40.48%. Bacteria population competition lasted 34 days. It started from PAOs replacing heterotrophs which cost 5 days then followed by 19 days intra-specific competition of PAOs. The last step was re-increasing of PAOs predominance. Phosphorus uptake by the enriched microbial community was not observed immediately. An accumulating-phase was necessary for PHA and poly-P storage. A lag-stage of 4-8 days existed when taking the performance of the reactor into consideration. Phosphorus removal by the predominant PAOs through intra-specific competition was achieved after accumulating-phase too. The FISH picture indicated that in the quickly growing phase PAOs cells were small and community structure was loose. The latter "accumulating-phase" cells became larger and the community structure clustered densely. This stage presented by better reactor performance.

The terms alpha- and beta-rhizobia were proposed to distinguish the rhizobial alpha- and beta-Proteorhizobia respectively. In this review we present recently development of rhizobial taxonomy about beta-rhizobia in the genus Burkholeria, Cupriavidus isolated from Mimosa and alpha-Proteorhizobia belonging to Methylobacterium, Devosia, Ochrobactrum, Phyllobacterium and Blastobacter lineage. Furthermore, we also introduced the evolution of symbiosis related genes such as nodA and nifH, and posed some questions in detecting rhizobia. Finally, we discuss the prospects of research on rhizoiba in future.

Ammonia oxidizing bacteria (AOB) play an important role in global nitrogen cycle. This paper reviewed the research advances on molecular ecology of ammonia oxidizing bacteria. The analysis of systematic evolution of AOB based on 16S rRNA reveals that the evolution of AOB is quite simple, which belongs to beta and gamma subgroup of Proteobacteria. This paper also introduced the main molecular ecological methods in the study of AOB, which included denature gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP), fluorescence in situ hybridization (FISH), and real-time PCR, summarized the effects of ecological factors on the communities and populations of AOB, and prospected the research directions on molecular ecology of AOB.

Bacterial community composition and predominant bacteria were analyzed by PCR-denaturing gradient gel electrophoresis (DGGE) in the Yellow Sea Cold Water Mass (YSCWM). The results analysed by Glyko Bandscan software showed that samples from all stations in April and stations in the YSCWM area in October had almost the same number of different DNA bands (17 and 16 respectively ) with high diversity. However, samples from the stations out of YSCWM area had fewer DNA bands (about 12) with lower diversity. 24 DGGE bands reflecting varying phylotypes were excised, cloned and sequenced. Phylogenetic analysis of 24 cloned bands showed that bacterial phylotypes were made up of two phyla bacteria, Proteobacteria and Bacteroides. Among these sequences, 16 were related to gamma-Proteobacteria and delta-Proteobacteria and 5 were related to Bacteroides. It indicated that bacterial community composition, as well as the predominant bacterial groups, from all sampling stations in April (the temperature of seawater was around 7-12 degrees C) and the inter of YSCWM in October (< or = 10 degrees C) was the same, different from the exterior of YSCWM (> or = 19 degrees C). By comparing, from samples of exterior of YSCWM, the predominant bacteria groups were different with the different sampling stations. So it suggested that bacterial community composition and the characteristic of predominant bacteria of the YSCWM may have something to do with the development of the YSCWM.

It is a brand-new method to isolate functional bacteria from high temperature petroleum reservoirs according to the sequence information obtained from PCR-DGGE patterns. Three-set primers of 16S rDNA high variable region, V3, V8, V9, were compared. The results showed that more microbial diversity information could be obtained from the PCR product of V9 region. Sequence analysis indicated that the dominant bacteria in the petroleum reservoir had high sequence similarity with bacteria from alpha, beta, gamma-Proteobacterias and Bacilli from the GenBank database. According to the sequences information, multi-cultivation technology including enrichment cultivation, special cultivation and direct cultivation methods were employed, and finally, five strains (three strains by traditional methods) were isolated from oil-water samples. Among them, three thermophilic hydrocarbon-degrading bacteria, which belonged to Bacillus sp., Geobacillus sp. and Petrobacter sp., respectively, could grow well under 55 degrees C in obligate anaerobic condition. The crude oil could be utilized by these strains with the degradation rate of 56.5%, 70.01% and 31.78% respectively along with the viscosity reduction rate of 40%, 54.55% and 29.09%, meanwhile the solidify points of crude oil were reduced by 3.7, 5.2 and 3.1 degrees C. Therefore, the combination of sequence information from PCR-DGGE and altering cultivation conditions is an available novel method to isolate more functional microorganisms which could be utilized for microbial enhanced oil recovery.

It was studied for community structure of microorganisms in the phosphorus removal processes under the circulating situation, and analyzed for microorganism's structure and behavior characteristics by the molecular biology technique with direct obtaining of DNA from samples of activated sludge, and by nested PCR and DGGE. It was also determined community structure of microorganisms. It was analyzed structures of Proteobacteria and Acidobacterium by 16S rDNA V3 area gene fragments sequences in activated sludge. By comparing gene sequences in the National Center of Biological Information (NCBI), were determined the kinds of part of microorganisms. Analyzing the low of changes of preponderant bacteria in anaerobic/aerobic and anaerobic/anoxic conditions takes to know, that under the stable situation of phosphorus removing, the system of microorganism's structure can kept mostly constant. Minority races that have changed in amount or kind has something to do with the variation of oxygen level in the system, but structure totally can adapt the environmental conditions of the processes, while it placed in dynamic varieties.

Both PCR-TGGE (temperature gradient gel electrophoresis, TGGE) and 16S rRNA gene clone library construction were used to comparatively analyze the microbial communities of a water injection well (WW) and an oil well (OW) in Dagang oilfield. TGGE analysis of the PCR amplified 16S rDNA V3 region products showed great difference between these two microbial communities. Six major bands were detected in the TGGE profile of the WW sample, while only one predominant band in the OW sample was found. Two 16S rRNA gene clone libraries were also constructed, and 108 and 50 clones were selected from the WW and OW library respectively for amplified ribosomal DNA restriction analysis (ARDRA). 33 taxanomic operational units (OTUs) were found in the WW library with 6 major OTUs, while only 8 OTUs were found in the OW library with one OTU predominant. The results of TGGE and clone library profiling analysis both indicated that microbial community of the WW had higher diversity than the OW. Sequence analysis of the representative clone of each OTU showed that most bacteria of the WW were affiliated with alpha, beta, and gamma Proteobacteria and Actinobacteria, especially Rhodobacter (47%). Most bacteria of the OW were affiliated with alpha, beta, and gamma Proteobacteria, especially Pseudomonas (62%). Molecular analysis of the microbial diversity in oilfield provides foundation for better application of MEOR (Microbial Enhanced Oil Recovery).

The environmental DNA was directly extracted from the sediment in Parece Vela Basin, Pacific Ocean, at a depth of 5010 m. Bacterial 16S rRNA gene library of 32 clones was generated using bacterial universal primers and 16S rDNA sequences were analyzed phylogenetically. 17 phylotypes were obtained. The library was dominated by gamma-Proteobacteria, alpha-Proteobacteria and marine uncultured bacteria. Sixty-two percent of the cloned sequences was highly related to the known bacteria in the genus Halomonas, Alcanivorax, Pseudomonas, Acinetobacter, Pseudoalteromonas (> 96% sequence similarity), while some of the cloned sequences showed less affiliation with known taxa (< 94% sequence similarity) and may represent novel taxa.