[Effects of Aquaculture on Ammonia-oxidizing Prokaryotes in Sediments of Eastern Lake Taihu].

The abundance and diversity of ammonia-oxidizing microorganisms in sediments of an aquacultural area of Eastern Lake Taihu were investigated. Real-time quantitative PCR was used to analyze the abundance of archaeal and bacterial amoA genes. Cloned libraries were constructed to investigate the structure and diversity of the microbial community. By comparing community characteristics of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in different zones, we found that:①Copy numbers of the bacterial amoA gene outnumbered those of archaeal amoA genes in the aquacultural zone; ②Diversity of AOA and AOB was higher in the aquaculture zone and control zone, respectively; ③ The dominant cluster of AOA and AOB in both sediments of aquiculture zone and control zone was Nitrosopumilus and Nitrosospira respectively. It was therefore the community structure of AOA (rather than AOB) in lake sediments that was affected by aquacultural activity.

[Effects of Optimized Fish Farming on the Sediment Nutrients of Eastern Lake Taihu].

The farming of lake fisheries is an important part of the freshwater fishery industry in China. However, farming patterns of traditional fisheries maintain serious negative effects on the ecosystem of Eastern Lake Taihu. In recent years, the enclosure culture model of this lake has been optimized. In order to investigate the effects of aquaculture on the sediment properties, samples were collected from different areas of the lake (i.e. within the culture areas, outside the culture areas; from the crab-plant co-culture areas, mixed culture areas, ecological restoration areas, and control areas), in different months (January, March, April, August, and November), and at different depths (0-1 cm and 9-10 cm). The results of this sampling indicates that ① the concentrations of total nitrogen (TN) and total phosphorus (TP) in the sediments samples collected within the culture areas are slightly higher than samples collected outside the culture areas; ② compared to the crab-plant co-culture areas, lower concentrations of TN and TP are found in the samples collected from the mixed culture areas; ③ in the ecological restoration areas, aquatic plants exhibit certain positive effects with decreasing concentrations of TN and TP in the sediment. The lowest concentrations of TN and TP are detected in the sediment during the growing season of aquatic plants.

Wire-cylinder dielectric barrier discharge induced degradation of aqueous atrazine.

The wire-cylinder dielectric barrier discharge reactor was adopted for removal of aqueous atrazine. The effect of different parameters on the degradation efficiency of atrazine was investigated, and the degradation mechanism of atrazine was studied. The experimental results showed that when the discharge power was 50 W and the air flow rate was 140 L h(-1), 93.7% of atrazine was degraded after 18 min of discharge time. The concentrations of generated O3 and H2O2 increased with increasing discharge time. The pH decreased from 6.80 to 2.50, 12.7% of TOC was removed after 18 min. The concentrations of generated Cl(-) and NO3(-) increased significantly during the degradation process of atrazine, and the decreasing toxicity trend was observed for the treated atrazine solution. The degradation byproducts of atrazine were identified using liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS), which might be formed mainly in dechlorination hydroxylation, alkyl oxidation, dechlorination hydroxylation combined with alkyl oxidation and demethylation oxidation reactions.

[Effects of Corbicula fluminea bioturbation on the community composition and abundance of ammonia-oxidizing archaea and bacteria in surface sediments].

To better understand the effects of Corbicula fluminea bioturbation on the ammonia-oxidizing microorganisms in the surface sediment, sediment-water microcosms with different densities of Corbicula fluminea were constructed. Clone libraries and real-time qPCR were applied to analyze the community composition and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the surface sediments. The results obtained indicated that the bioturbation of Corbicula fluminea accelerated the release of nitrogen from the surface sediment. In the amoA gene clone libraries, the identified AOA amoA gene sequences affiliated with the two known clusters (marine and soil clusters). The identified AOB amoA gene sequences mostly belonged to the Nitrosomonas of beta-Proteobacteria. The abundance of the bacterial amoA gene was higher than that of the archaeal amoA gene in all treatments. With increasing density of Corbicula fluminea, decreased abundances of the bacterial amoA gene were observed. At the same time, the diversity of AOA and AOB reduced in the Corbicula fluminea containing microcosms. In conclusion, the bioturbation of Corbicula fluminea could affected the community composition and abundance of ammonia-oxidizing microorganisms in surface sediments.

Effects of benthic macrofauna bioturbation on the bacterial community composition in lake sediments.

Benthic macrofauna are considered to be an important part of the lacustrine ecosystem, and bioturbation may greatly affect the biogeochemical processes and microbial activities in sediments. In the present study, the bacterial community composition in sediments inhabited by 3 different types of benthic macrofauna (Corbicula fluminea, Chironomidae larvae, and tubificid worms) in the shallow and eutrophic Lake Taihu was studied to investigate the different effects of bioturbation on the composition of these communities. Microcosms were constructed, and culture-independent methods, including terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis, were performed to evaluate the bacterial communities. Analysis of similarities (ANOSIM) and multidimensional scaling (MDS) analysis of T-RFLP patterns demonstrated that differences in the bacterial community composition between the control and the macrofauna-inhabited sediments were not as great as expected, although the chemical properties of the sediments changed remarkably. Nevertheless, the dominant bacterial group in each type of macrofauna-inhabited sediment was different. Acidobacteria, Betaproteobacteria, and Deltaproteobacteria were the dominant bacterial groups in sediments inhabited by C. fluminea, tubificid worms, and Chironomidae larvae, respectively. The data obtained in this study are helpful for understanding the effects of bioturbation in a shallow, eutrophic lake.

Effects of submerged macrophytes on the abundance and community composition of ammonia-oxidizing prokaryotes in a eutrophic lake.

Abundances and community compositions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in unvegetated sediment and the rhizosphere sediments of three submerged macrophytes (Ceratophyllum demersum, Vallisneria spinulosa, and Potamogeton crispus) were investigated in a large, eutrophic freshwater lake, Lake Taihu. Abundances of archaeal ammonia monooxygenase alpha-subunit (amoA) gene (from 6.56 × 10(6) copies to 1.06 × 10(7) copies per gram of dry sediment) were higher than those of bacterial amoA (from 6.13 × 10(5) to 3.21 × 10(6) copies per gram of dry sediment) in all samples. Submerged macrophytes exhibited no significant effect on the abundance and diversity of archaeal amoA gene. C. demersum and V. spinulosa increased the abundance and diversity of bacterial amoA gene in their rhizosphere sediment. However, the diversity of bacterial amoA gene in the rhizosphere sediments of P. crispus was decreased. The data obtained in this study would be helpful to elucidate the roles of submerged macrophytes involved in the nitrogen cycling of eutrophic lake ecosystems.

Submerged macrophytes modify bacterial community composition in sediments in a large, shallow, freshwater lake.

Submerged aquatic macrophytes are an important part of the lacustrine ecosystem. In this study, the bacterial community compositions in the rhizosphere sediments from three kinds of submerged macrophytes (Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans) were investigated to determine whether submerged macrophytes could drive the variation of bacterial community in the eutrophic Taihu Lake, China. Molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries, were employed to analyze the bacterial community compositions. Remarkable differences of the T-RFLP patterns were observed among the different samples, and the results of LIBSHUFF analysis also confirmed that the bacterial community compositions in the rhizosphere sediments of three kinds of submerged macrophytes were statistically different from that of the unvegetated sediment. Acidobacteria, Deltaproteobacteria, and Betaproteobacteria were the dominant bacterial groups in the rhizosphere sediments of Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans, respectively, accounting for 15.38%, 29.03%, and 18.00% of the total bacterial abundances. Our study demonstrated that submerged macrophytes could influence the bacterial community compositions in their rhizosphere sediments, suggesting that macrophytes have an effect on the cycling and transportation of nutrients in the freshwater lake ecosystem.

Abundance and community composition of ammonia-oxidizing archaea and bacteria in two different zones of Lake Taihu.

The abundance and community composition of ammonia-oxidizing archaea and ammonia-oxidizing bacteria in the surface sediments of 2 different zones (Meiliang Bay and Eastern Lake Taihu) of Lake Taihu were investigated using real-time quantitative polymerase chain reaction and clone libraries. The amoA gene copy numbers in the surface sediment of Meiliang Bay ranged from 4.91 × 10(5) to 8.65 × 10(6) copies/g dry sediment for the archaeal amoA gene and from 3.74 × 10(4) to 3.86 × 10(5) copies/g dry sediment for the bacterial amoA gene, which were significantly higher than those of Eastern Lake Taihu (P < 0.05). Concentrations of ammonia (NH(4)(+)), total nitrogen, organic matter, and pH of the sediments exhibited significantly negative correlations with the abundance of ammonia-oxidizing archaea or ammonia-oxidizing bacteria (P < 0.05 or P < 0.01, respectively). The potential nitrification rates show remarkable correlations with the copy numbers of the archaeal amoA gene. Diversity of the archaeal amoA gene in Eastern Lake Taihu was significantly higher than that of Meiliang Bay, whereas the bacterial amoA gene diversity was comparable for the 2 lake zones. The data obtained in this study would be useful to elucidate the role of ammonia-oxidizing archaea and ammonia-oxidizing bacteria in the nitrogen cycle of freshwater ecosystems.

Genetic analysis of protoplast fusant Xhhh constructed for pharmaceutical wastewater treatment.

In order to analyse genetic relationships between functional strain Xhhh previously constructed through protoplast fusion for pharmaceutical wastewater treatment and its parents, random amplification polymorphic DNA (RAPD) and polymerase chain reaction (PCR) were used to investigate genetic similarities among the strains based on genome and functional genes analyses. A total of 739 clear and consistent bands were produced in the RAPD fingerprint analysis with 40 primers. The genetic similarity indices between Xhhh and parental strains PC (Phanerochaete chrysosporium), SC (Saccharomyces cerevisiae) and XZ (native bacterium Bacillus sp.) were 36.21%, 37.73% and 37.48%, respectively. With PCR amplification and DNA sequencing, Xhhh was found containing functional genes of mnp and lip from PC, FLO1 from SC and 16S rDNA fragments from XZ. Experimental results of genetic analyses were in accordance with Xhhh biochemical and phenotypic characteristics, and protoplast fusion technique is considered as a promising technique in environmental pollution control.

Spatial distribution of bacterial communities in sediment of a eutrophic lake revealed by denaturing gradient gel electrophoresis and multivariate analysis.

Bacterial community structure and the effects of several environmental factors on the microbial community distribution were investigated in the sediment of the eutrophic Lake Xuanwu. Profiles of bacterial communities were generated using denaturing gradient gel electrophoresis (DGGE), and the results were interpreted with multivariate statistical analysis. Five major variables in sediment were examined in a principal component analysis, which indicates notable differences of physicochemical parameters among different sites of the lake. To assess changes in the genetic diversity of bacterial communities of different sampling sites, DGGE band patterns were analyzed by multidimensional scaling analysis, which indicated that sampling sites having similar environmental characteristics also have the similar microbial communities. Canonical correspondence analysis demonstrated that pH and redox potential had significant effects on the bacterial community composition in the sediments. Analysis of DNA sequences revealed that the dominant bacterial groups in Lake Xuanwu belonged to Proteobacteria, Actinobacteria, Verrucomicrobia, and Nitrospirae, which are commonly isolated from freshwater ecosystems.

PTA wastewater molecular toxicity detected with gene chip.

The purified terephthalic acid (PTA) petrochemical wastewater molecular toxicity detected by use of Mouse Genome 430A 2.0 GeneChip was conducted in this research. The toxic dose to male mice was 0.03 g/(kg x d) of PTA in the wastewater. The mice liver total RNA was isolated as the temple for synthesis of cDNA and then the cDNA as the temple for synthesis of cRNA. Hybridizing the cRNA with the target genes on the gene chip, there were 232 genes expression levels up-regulated and 74 genes down-regulated discovered obviously. The foremost 40 genes for both the highest and the lowest expression levels involved endogenetic steroid and hormone metabolism, immune system, the leukocyte activity and inflammation, detoxification in liver, reproduction and growth hormone, regulation immune factors of anti-tumor and anti-infection and cancer to the mice sampled. The data suggest the PTA wastewater contained over 5 aromatics and their toxicities integrated were much higher than the pure chemical PTA. And the pure chemical PTA toxicities data cannot be used to evaluate the toxicity of the PTA wastewater instead.