[Enhanced Removal of Pollutants in Constructed Wetlands with Manganese Sands].

Manganese (Mn) sands have been widely used in water purification due to their strong oxidation and adsorption abilities. However, there are few reports on the use of manganese sands as filler material in constructed wetlands. Based on previous studies, we speculated that the addition of manganese sands in constructed wetlands would enhance the removal of pollutants from the source water, and the resulting Mn(Ⅱ) could then be oxidized by the rhizosphere and soil microorganisms in the wetlands. To test this hypothesis, this study explored the enhanced removal of pollutants in wetlands constructed with manganese sands as substrates and Phragmites as plants, and also examined the role of Phragmites rhizosphere microorganisms in water purification. By comparing the treatment effects between the wetlands constructed with and without manganese sands (control), we found that the wetland containing manganese sands exhibited significantly improved removal of dissolved organic carbon and total nitrogen, as well as removal of ammonia nitrogen during periods of lower temperature. The 16S rRNA sequencing showed that the addition of manganese sands could increase the richness and diversity of Phragmites rhizosphere microorganisms, but had limited impacts on the microbial community structure, which might be an important factor for enhancing the water treatment performance of constructed wetlands. This study provides a new method for the technological optimization of constructed wetlands.

[Universality and Potential Application of Mn(â ¡) Oxidation Triggered by Microbial Interspecies Interactions].

Mn(Ⅱ)-oxidizing microorganisms can catalytically increase the oxidation rate of divalent manganese by several orders of magnitude, and affect the valence state and fate of elemental manganese. In addition to Mn(Ⅱ)-oxidization by a single microbial strain, our previous studies revealed that interspecies interactions between two bacterial strains (Sphingopyxis sp. QXT-31 and Arthrobacter sp. QXT-31) could trigger the Mn(Ⅱ)-oxidizing activities of Arthrobacter sp. QXT-31. In order to further explore its universality, mechanism, and potential engineering applications, research was conducted on three other Sphingopyxis strains using culture-dependent experiments, comparative genomic analysis, and transcriptome analysis. The results showed that one Sphingopyxis strain could also trigger the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31, which could be regarded as a hint for the prevalence of Mn(Ⅱ) oxidation triggered by microbial interspecies interactions in the natural environment. Furthermore, the upregulation of the antibiotic synthesis pathway in Sphingopyxis was observed just before the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31 was triggered, thus suggesting its possible involvement in stimulating the Mn(Ⅱ)-oxidizing activity of Arthrobacter sp. QXT-31. Finally, we demonstrated that using microbial interspecies interactions to enhance the oxidative removal of Mn(Ⅱ) in a manganese removal reactor is potentially feasible.

[Metabolic Functional Analysis of Dominant Microbial Communities in the Rapid Sand Filters for Drinking Water].

Rapid sand filter (RSF) is widely used in drinking water treatment plants. Rapid filtration is always considered a physicochemical process, but the effect of the microorganisms that attach to the filter media remain inadequately investigated. In order to understand the composition and functional characteristics of microbial communities in RSFs, influent water, effluent water, and filter materials from eleven RSFs in eight Chinese cities were sampled and analyzed. After filtration, dissolved organic carbon (DOC) showed a slight but significant removal due to the growth of heterotrophic microbes. The activity of ammonia-oxidizing microbes and nitrite-oxidizing microbes promoted a significant decrease in ammonia nitrogen (NH4+-N) and a significant increase in nitrate nitrogen (NO3--N) in water. No significant changes in total nitrogen (TN) were observed, indicating that denitrification and anammox were weak in the RSFs. The composition and function of the microbial communities of RSFs were assessed using metagenomic methods. Genera in the top 10% with respect to relative abundance (14 genera in total) were identified as the dominant genera, including the two ammonia-oxidizing bacteria Nitrospira and Nitrosomonas. Functional gene information for the dominant genera was also extracted for analysis. The dominant genera exhibited higher relative abundances of carbohydrate, nitrogen, sulfur, and xenobiotic metabolic pathways. Aeromonas had the highest relative abundance of carbohydrate metabolic genes, and Bradyrhizobium had the highest relative abundance of nitrogen, sulfur, and xenobiotics metabolic genes, indicating that these two genera play an important role in the transformation of substances in drinking water. Finally, the metabolic potential of the dominant genera on xenobiotics was evaluated, and the results showed that Bradyrhizobium, Sphingomonas, Methyloglobulus, Sphingopyxis, and Klebsiella were the key bacterial genera for the removal of micropollutants in RSFs.

[Removal of Organic Matter from Water by Chemical Preoxidation Coupled with Biogenic Manganese Oxidation].

In the process of drinking water treatment, potassium permanganate and iron-manganese oxides are typical pre-oxidation methods that can not only effectively remove organic matters in drinking water, but also reduce the production of disinfection by-products (DBPs). However these two pre-oxidation methods will produce Mn2+ that is genotoxic. In order to solve this problem, a concept was proposed to connect biogenic-manganese oxidation technology after chemical oxidation. The manganese-oxidizing microbe may convert Mn2+ into the bio-manganese oxide, which can further remove the pollutants by its strong oxidative and adsorption capacity to improve water purification. In the simulated contaminated water composed of natural organic tyrosine (Tyr) and synthetic organic 2-Hydroxy-4-Methoxybenzophenone-5-Sulfonic Acid (BP-4), we verified the proposed the concept. Pre-oxidation by potassium permanganate or iron-manganese oxides efficiently removed Tyr, but had negligible effect on BP-4. During this, Mn2+ was generated. In the subsequent biological system, the manganese-oxidizing bacteria Pseudomonas sp. QJX-1 could utilize the Tyr for growth and oxidize Mn2+ to Mn4+ oxide. The generated manganese oxides could then effectively remove BP-4. In comparison, the moderate potassium permanganate preoxidation coupled with bio-manganese oxidation had a desirable treatment effect, with 100%, 50%, and 98.9% removals for Tyr, BP-4, and Mn2+, respectively. Importantly, the study provides a new method for drinking water treatment.

[Application of FCM-qPCR to Quantify the Common Water Pathogens].

In the past, fecal E. coli was always regarded as the indicator organism for estimation of pathogens in water. However, a weak relation between fecal E. coli and water viruses or bacterial pathogens has been demonstrated by previous studies. Therefore, for water pathogen study, it is essential to select and quantify typical pathogens. In this study, a combination of quantitative PCR ( qPCR) with flow cytometry (FCM) was established to detect the concentrations of viruses, bacteria and several typical pathogens (e.g., E. coli, Legionnella, HAdV, Giardia, Cryptosporidium) in water. The method was applied to measure the pathogen concentrations in the influent and effluent of a wastewater treatment plant (WWTP), as well as its receiving river. The results revealed that the WWTP treated the pathogens with high removal efficiency ( > 93%); the effluent of WWTP did not show a negative effect on pathogen concentration of the receiving river. The study provides a technical support for the evaluation of WWTP treatment effect and the ecological impact of WWTP effluent on receiving river.

[Competitive Microbial Oxidation and Reduction of Arsenic].

Filters are widely applied in drinking water treatment plants. Our previous study, which explored the asenic redox in a filter of drinking water plant treating underground water, found that As3+ could be oxidized to As5+ by biogenic manganese oxides, while As5+ could be reduced to As3+ by some microbial arsenic reductases in the biofilter system. This microbial competition could influence the system stability and treatment efficiency. To explore its mechanism, this study selected a manganese-oxidizing bacterial strain (Pseudomonas sp. QJX-1) and a arsenic-reducing strain (Brevibacterium sp. LSJ-9) to investigate their competitive relationship in nutrient acquisition and arsenic redox in the presence of Mn2+, As3+ or As5+ The results revealed that the concentration and valence of Mn and As varied with different reaction time; biological manganese oxides dominated the arsenic redox by rapidly oxidizing the As3+ in the existing system and the As3+ generated by arsenic reductase into As. PCR and RT-PCR results indicated that the arsenic reductase (arsC) was inhibited by the manganese oxidase (cumA). The expression of 16S rRNA in QJX-1 was two orders of magnitude higher than that in LSJ-9, which implied QJX-1 was dominant in the bacterial growth. Our data revealed that hydraulic retention time was critical to the valence of arsenic in the effluent of filter in drinking water treatment plant.

[Application of FISH-NanoSIMS technique in environmental microbial ecology study].

With the development of microbial ecology techniques, it is possible to analyze the distribution and function of microorganisms simultaneously in complex ecosystems. To explore the application of FISH-NanoSIMS in environmental microbial ecology study, our study used the stable isotope labeled compounds 13C-C6H12O6, and 15N-NH4Cl as C and N sources for cultivating the pure culture (manganese oxidizing bacteria, Pseudomonas sp. QJX-1) and environmental samples (the shallow soil and anaerobic sludge). FISH-NanoSIMS was used to detect the distribution of microorganisms and relatively quantify secondary ions (12C-, 13C-, 12C(14)N-, 12C15N-) in cultivated samples, in order to explore the utilization of C and N isotopes sources by the pure culture and microorganisms in environment samples. The results showed that the contents of 13C and 5N in the area of bacteria were significantly greater than the natural abundance in all samples. It indicated that Pseudomonas sp. QJX-1 and some specific bacteria in environmental samples could metabolize 13C-C6H12O6 and 15N-NH4C1. Furthermore, this study revealed that for Pseudomonas sp. QJX-1, the manganese oxidation only occurred when the carbon and nitrogen were consumed to a low level. For environmental samples, the bacterial nitrification and denitrification were both observed in the shallow soil and anaerobic sludge. In a word, our study demonstrated that the combination of FISH and NanoSIMS could simultaneously examine microbial distribution and microbial metabolic activity in environmental samples, which will help us to obtain the eco-physiology information of microbial community.

[Characterization of manganese oxidation by Pseudomonas sp. QJX-1].

A manganese-oxidizing bacteria (QJX-1) was isolated from the soil of a manganese mine. It was identified as Pseudomonas sp. QJX-1 by 16S rDNA sequencing. Experimental results showed that the Pseudomonas sp. QJX-1 has a multi-copper oxidase gene CumA, which is an essential component for manganese oxidation by Pseudomonas sp. Under the condition of low initial inoculum level (D600, 0.020), 5.05 mg x L(-1 Mn2+ could be oxidized by QJX-1 within 48 h with a conversion rate of as high as 99.4%. In comparison with the eutrophic conditions, the oligotrophic condition dramatically increased the biological manganese oxidation rate. Biofilm formation by employing the quartz sand could further improve the oxidation rate of Mn2+. Based on these results, it is speculated that biological manganese oxidation in underground water treatment is comparatively high.

[Biodegradation and adsorption of bio-zeolite on pyridine and quinoline].

The study was to explore the treatment of pyridine, quinoline and their transformation product, NH(4+) -N, by the biodegradation and adsorption of a natural and a modified bio-zeolites. The experiment results demonstrated that the mixed bacteria on the bio-zeolites, a pyridine-degrading bacterium and a quinoline-degrading bacterium, could degrade pyridine and quinoline simultaneously. The NH(4+) -N transformed from pyridine and quinoline could be adsorbed by the natural and modified zeolites. The adsorption capacity of the modified zeolite was lower than that of the natural zeolite. However, more microorganisms could attach on the surface of the modified zeolite, so the application of the modified bio-zeolite has a better prospect in actual treatment of pyridine and/ or quinoline pollution.

[Study on the function of plasmid in pyridine-degrading bacteria].

In order to identify the characteristics of the plasmids of degrading bacterial strains and the relationship between the plasmids' function and biodegradation, plasmids were isolated from two bacterial strains (Paracoccus sp. BW001 and Shinella zoogloeoides BC026) and pulse-field gel electrophoresis was used to identify the distribution of plasmids and their molecular size. Two large plasmids with 190-245 kb and one small plasmid with 4.5-5.0 kb were found in the BW001, and at least 3 large plasmids over 200 kb were harbored in the BC026. The plasmid curing was conducted by high temperature-SDS method and the results indicated the biodegradation genes might locate in the plasmids of two bacterial strains. After transforming the plasmids of BW001 into E. coli 5alpha by electroporation, the new bacterial strain could tolerate pyridine.

[Isolation, identification, and biodegradation characteristics of a quinoline-degrading bacterium].

A bacterial strain BW003, which could utilize quinoline as sole carbon, nitrogen and energy source, was isolated from the activated sludge in a coking wastewater treatment plant. According to the 16S rRNA gene sequence analysis, the strain was identified as Pseudomonas sp. Biodegradation experiments showed that the strain could degrade 192-911 mg/L of quinoline efficiently within 3-8 h, and the removal rates of quinoline were ranged from 96% to 98%. The optimum conditions for the degradation were 30 degrees C and pH 8. Metabolic products analysis revealed that at least 43% quinoline was first transformed into 2-hydroxyquinoline, 0.69% 2-hydroxyquinoline was then transformed into 2,8-dihydroxyquinoline, and subsequently into 8-hydroxycoumarin in the process of biodegradation. Additionally, at least 48% of nitrogen in quinoline was transformed into NH3-N directly and external carbon source could promote the nitrogen transformation, demonstrating that the quinoline and its metabolic products could be eliminated if controlling proper C/N ratio.

[Biodegradation of pyridine by Shinella zoogloeoides BC026].

A bacterial strain BC026 capable of utilizing pyridine as its sole source of carbon and nitrogen was isolated from the activated sludge in a coking wastewater treatment plant. The bacterium featured flocculability and antibiotic resistance to kanamycin, ampicillin and spectinomycine. It could grow well in Ashby nitrogen free culture medium. The strain was identified as Shinella zoogloeoides according to the results of 16S rRNA sequence analysis and Biolog microbial identification system. The experiments of pyridine biodegradation by the pure culture showed that pyridine of 400 mg/L could be degraded completely in 17 h under the condition of inoculum 0.1 g/L, 30 degrees C, 180 r/min and pH 7. BC026 could keep high degradative activity in mineral salt medium containing pyridine with a concentration ranging from 99 mg/L to 1 806 mg/L. Higher initial concentration of pyridine caused repression on BC026 to a certain extent, however, the degradation rate became faster after the strain had been accommodated. The optimal conditions for the degradation were 30-35 degrees C and pH 8. The research on metabolic pathway of pyridine by BC026 indicated that the first step of pyridine degradation was C-N bonds cleavage, generating NH4+ and glutaraldehyde. Then glutaraldehyde was oxidized into glutaric acid, and finally into CO2 and H2O. 59.5% nitrogen from pyridine was transferred into ammonium in the whole degradation.