[Changes of bacterial community structure on reusing domestic sewage of Daoxianghujing Hotel to landscape water].

A 16S rDNA library was used to evaluate the bacterial diversity and identify dominant groups of bacteria in different treatment pools in the domestic sewage system of the Beijing Daoxianghujing Hotel. The results revealed that there were many types of bacteria in the hotel domestic sewage, and the bacterial Shannon-Weaver diversity index was 3.12. In addition, epsilon Proteobacteria was found to be the dominant group with the ratio of 32%. In addition, both the CFB phylum, Fusobacteria, gamma Proteobacteria and Firmicutes were also reached to 9%-15%. After treated with the reclaimed water station, the bacterial Shannon-Weaver diversity index was reduced to 2. 41 and beta Proteobacteria became the dominant group and occupied 73% of the total clones. However, following artificial wetland training, the bacterial Shannon-Weaver diversity index in the sample increased to 3.38, Actinobacteria arrived to 33% and became the most dominant group; Cyanobacteria reached to 26%, and was the second dominant group. But, the control sample comprised 38% Cyanobacteria, and mainly involved in Cyanobium, Synechoccus and Microcystis, with ratios of 47.1%, 17.6% and 8.8%, respectively. Some bacteria of Microcystis aenruginosa were also detected, which probably resulted in the light bloom finally. Therefore, the bacterial diversity and community structures changed in response to treatment of the hotel domestic sewage; there was no cyanobacteria bloom explosion in the treated water. This study will aid in investigation the changes of microbial ecology in different types of water and providing the useful information for enhancing the cyanobacteria blooms control from ecological angle.

Endophytic bacterial diversity in roots of Phragmites australis in constructed Beijing Cuihu Wetland (China).

The community structure and diversity of endophytic bacteria in reed (Phragmites australis) roots growing in the Beijing Cuihu Wetland, China was investigated using the 16S rRNA library technique. Primers 799f and 1492r were used to amplify the specific bacterial 16S rRNA fragments successfully and construct the clone library. In total, 166 individual sequences were verified by colony PCR and used to assess the diversity of endophytic bacteria in reed roots. Phylogenetic analysis revealed that 78.9% of the clones were affiliated with Proteobacteria and included all five classes. Other clones belonged to Firmicutes (9.0%), Cytophaga/Flexibacter/Bacteroids (6.6%), Fusobacteria (2.4%), and nearly 3.0% were unidentified bacteria. In Proteobacteria, the Alpha and Gamma subgroups were the most abundant, accounting for approximately 34.4% and 31.3% of all Proteobacteria, respectively, and the dominant genera included Pleomorphomonas, Azospirillum, and Aeromonas. In addition, nearly 13.6% of the Proteobacteria were very similar to some genera of sulfate-reducing bacteria (SRB) such as Dechloromonas, Desulfovibrio, and Sulfurospirillum. The bacteria in these genera are considered to play important roles in the metabolism of nitrogen, phosphorus, sulfur, and some organic compounds in wetland systems. Hence, this study demonstrates that within the diverse bacterial communities found in reed roots, endophytic strains might have a strong potential to enhance phytoremediation by reed wetlands.

[Effect of free surface flow wetland and subsurface flow wetland on bacterial diversity in Beijing Cuihu Wetland Park].

To achieve the effects of artificial wetland on the bacterial diversity, the culturable bacteria and total cell counts of three wetland cells, including sewage pond (SP), free surface wetland (SF) and subsurface flow wetland (SSF), were investigated using the traditional culture-dependent approach and flow cytometry method, based on the detecting the water quality. The bacterial diversity and dominant groups were also compared by PCR-DGGE profiles and 16S rDNA library technique based on its V3 region. Results show that SF and SSF cells can remove the nutrients effectively, the highest removal ratio of COD, total nitrogen, and total phosphorus reach to 42.33%, 52.92% and 41.4%, respectively; The total microbes are increased continuously with the treatment by SF and SSF, and the culturable bacteria clones are decreased after treatment by SF, and increased after further train by SSF. The Shannon-Weaver index is increased to 3.2850 from 3.0819 while the water flowing through SF, but decreased to 3.0181 after flowing through SSF; The dominant groups in SP include Actinobacteria, Cyanobacteria and alpha-Proteobacteria, reach to 38%, 18% and 18%, respectively; but the most dominant bacteria is changed to beta-Proteobacteria with the ratio of 32% and 44%, after treatment by SF and SSF, respectively. Cytophagal Flexibacter/Bacteroides (CFB) phylum is also increased to 24% finally. Therefore, while the Cuihu Wetland removing the nutrients,the bacterial counts, diversity and dominant groups are also changed,some beneficial bacteria in beta-Proteobacteria and CFB phylum increased, and part of those deleterious bacteria in Actinobacteria and Cyanobacteria decreased.

[Micro-ecology mechanism on microaerobic treatment performance at various influent COD concentrations or HRTs].

A lab-scale continuous experiment was designed to investigate the effect of influent COD concentrations (11,000, 15,000, 30,000 mg/L) or hydraulic retention time (HRT 42, 25 h) on the microareobic treatment performance of simulated high-strength organic wastewater. The molecular microbiological technologies, including Fluorescent in-situ hybridization-Flow Cytometry (FISH-FCM), Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE), and Biolog-FF assay method, were used to detect the variation of microbial community in the aerated column during the four pseudo-steady-state periods. The yeast contents remained > 99.9% throughout the overall experimental periods according to FISH-FCM. Increasing influent COD concentration brought on a rising MISS (2.0-7.3 g/L) and a reduced specific COD removal rate [2.3-1.7 kg/(kg x d)], structural (PCR-DGGE)/metabolic (Biolog FF) diversity index values of fungal community in the aerated column had an increase of (2.05-2.19)/(4.42-4.45). Shortening HRT brought on a reduced MISS (7.3-6.0 g/L) and a rising specific COD removal rate [1.7-2.8 kg/(kg x d)], structural (PCR-DGGE)/metabolic (Biolog FF) diversity index values of fungal community had a decrease of (2.19-0.79)/(4.45-4.36). Increasing influent COD concentration or shortening HRT has an absolutely adverse effect on the microaerobic treatment performance and micro-ecology in the aeration column although either of them can increase influent COD loading up to a higher level.