dCurrently, nitritation-anammox (anaerobic ammonium oxidation) bioreactors are designed to treat wastewaters with high ammonium concentrations at mesophilic temperatures (25 to 40°C). The implementation of this technology at ambient temperatures for nitrogen removal from municipal wastewater following carbon removal may lead to more-sustainable technology with energy and cost savings. However, the application of nitritation-anammox bioreactors at low temperatures (characteristic of municipal wastewaters except in tropical and subtropical regions) has not yet been explored. To this end, a laboratory-scale (5-liter) nitritation-anammox sequencing batch reactor was adapted to 12°C in 10 days and operated for more than 300 days to investigate the feasibility of nitrogen removal from synthetic pretreated municipal wastewater by the combination of aerobic ammonium-oxidizing bacteria (AOB) and anammox. The activities of both anammox and AOB were high enough to remove more than 90% of the supplied nitrogen. Multiple aspects, including the presence and activity of anammox, AOB, and aerobic nitrite oxidizers (NOB) and nitrous oxide (N 2 O) emission, were monitored to evaluate the stability of the bioreactor at 12°C. There was no nitrite accumulation throughout the operational period, indicating that anammox bacteria were active at 12°C and that AOB and anammox bacteria outcompeted NOB. Moreover, our results showed that sludge from wastewater treatment plants designed for treating high-ammonium-load wastewaters can be used as seeding sludge for wastewater treatment plants aimed at treating municipal wastewater that has a low temperature and low ammonium concentrations. N itrogen removal from wastewater treatment is necessary because of the significant adverse environmental impact of ammonia/ammonium, such as eutrophication and toxicity to aquatic life, on the receiving bodies. Generally, carbonaceous waste is removed in the first stage of wastewater treatment, which is followed by nitrogen removal systems. Conventionally, the removal of nitrogen (ammonium) is accomplished by the combination of nitrification and denitrification processes. Both of these are energy consuming and are associated with high costs. Moreover, these processes have an additional environmental impact due to high biomass production and greenhouse gas (CO 2 , N 2 O, etc.) emission, which promote global warming.Anaerobic ammonium-oxidizing (anammox) bacteria convert ammonium and nitrite directly to dinitrogen gas (N 2 ) under anoxic conditions. Since they were first detected in a denitrifying pilot plant by Mulder et al. in 1995 (1), anammox bacteria have been found in various oxygen-limited natural (2-4) and manmade ecosystems. The application of the anammox process in wastewater treatment results in significant energy reduction (60%) and greenhouse gas emission (90%) compared to those of traditional biological nitrogen removal processes (5-7). In fullscale nitritation-anammox wastewater treatment plants, ammonium-oxidizing bacteria (AOB) convert approx...

Autotrophic nitrogen removal in the mainstream wastewater treatment process is suggested to be a prerequisite of energy autarkic wastewater treatment plants (WWTP). Whilst the application of anammox-related technologies in the side-stream is at present state of the art, the feasibility of this energy-efficient process at mainstream conditions is still under development. Lower operating temperature and ammonium concentration, together with required high nitrogen removal efficiency, represent the main challenges to face in order to reach this appealing new frontier of the wastewater treatment field. In this study, we report the evaluation of the process in a plug-flow granular sludge-based pilot-scale reactor (4 m3) continuously fed with the actual effluent of the A-stage of the WWTP of Dokhaven, Rotterdam. The one-stage partial nitritation-anammox system was operated for more than 10 months at 19±1°C. Observed average N-removal and ammonium conversion rates were comparable or higher than those of conventional N-removal systems, with 182±46 and 315±33 mg-N L(-1) d(-1), respectively. Biochemical oxygen demand was also oxidized in the system with an average removal efficiency of 90%. Heterotrophic biomass grew preferentially in flocs and was efficiently washed out of the system. Throughout the experimentation, the main bottleneck was the nitritation process that resulted in nitrite-limiting conditions for the anammox conversion. Anammox bacteria were able to grow under mainstream WWTP conditions and new granules were formed and efficiently retained in the system.

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The Changjiang estuary and the coastal area of the East China Sea (ECS) represent important interfaces of terrestrial and marine environments. This study included analyses of water and sediments collected during different seasons in these regions to determine the composition of microbial assemblages by means of 16S rRNA gene clone libraries. We retrieved 1946 sequences and 779 distinct operational taxonomic units from 36 clone libraries. Shannon-Weaver diversity index values and rarefaction analysis indicated that bacterial diversity in the sediment samples was much higher than in the water samples. Proteobacteria (72.9%) was the most abundant phylum, followed by Firmicutes (6.4%), Bacteroidetes (4.6%) and Actinobacteria (4.1%). In the water, clone sequences related to Alphaproteobacteria were the most abundant, whereas in the sediment samples, sequences affiliated with Gammaproteobacteria were predominant. Principal coordinate analysis showed that water samples collected from the Changjiang estuary and the ECS clustered separately. However, this spatial pattern could not be observed in sediment samples, which were mainly distinguished from one another by the season. Bacterial diversity in the Changjiang estuary was higher than that in the ECS, which may be the result of the mixing of bacterial communities from the Changjiang River, the estuary and the coastal ocean.

Background The efficacy and factors associated with patient outcomes for a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (LFD) compared with traditional dietary advice (TDA) based on modified National Institute for Clinical Excellence guidelines for irritable bowel syndrome with diarrhea (IBS-D) in regions consuming a non-Western diet are unclear. Objectives We aimed to determine the efficacy of an LFD compared with TDA for the treatment of IBS-D in Chinese patients and to investigate the factors associated with favorable outcomes. Methods One hundred and eight Chinese IBS-D patients (Rome III criteria) were randomly assigned to an LFD or TDA. The primary endpoint was a ≥50-point reduction in the IBS Severity Scoring System at 3 wk. Fecal samples collected before and after the dietary intervention were assessed for changes in SCFAs and microbiota profiles. A logistic regression model was used to identify predictors of outcomes. Results Among the 100 patients who completed the study, the primary endpoint was met in a similar number of LFD (30 of 51, 59%) and TDA (26 of 49, 53%) patients (∆6%; 95% CI: −13%, 24%). Patients in the LFD group achieved earlier symptomatic improvement in stool frequency and excessive wind than those following TDA. LFD reduced carbohydrate-fermenting bacteria such as Bifidobacterium and Bacteroides, and decreased saccharolytic fermentation activity. This was associated with symptomatic improvement in the responders. High saccharolytic fermentation activity at baseline was associated with a higher symptom burden (P = 0.01) and a favorable therapeutic response to the LFD (log OR: 4.9; 95% CI: −0.1, 9.9; P = 0.05). Conclusions An LFD and TDA each reduced symptoms in Chinese IBS-D patients; however, the LFD achieved earlier symptomatic improvements in stool frequency and excessive wind. The therapeutic effect of the LFD was associated with changes in the fecal microbiota and the fecal fermentation index. At baseline, the presence of severe symptoms and microbial metabolic dysbiosis characterized by high saccharolytic capability predicted favorable outcomes to LFD intervention. This trial was registered at clinicaltrials.gov as NCT03304041.

Nitric oxide (NO) has important functions in biology and atmospheric chemistry as a toxin, signaling molecule, ozone depleting agent and the precursor of the greenhouse gas nitrous oxide (N2O). Although NO is a potent oxidant, and was available on Earth earlier than oxygen, it is unclear whether NO can be used by microorganisms for growth. Anaerobic ammonium-oxidizing (anammox) bacteria couple nitrite reduction to ammonium oxidation with NO and hydrazine as intermediates, and produce N2 and nitrate. Here, we show that the anammox bacterium Kuenenia stuttgartiensis is able to grow in the absence of nitrite by coupling ammonium oxidation to NO reduction, and produce only N2. Under these growth conditions, the transcription of proteins necessary for NO generation is downregulated. Our work has potential implications in the control of N2O and NO emissions from natural and manmade ecosystems, where anammox bacteria contribute significantly to N2 release to the atmosphere. We hypothesize that microbial NO-dependent ammonium oxidation may have existed on early Earth.

Anaerobic ammonium-oxidizing (anammox) bacteria are key players in the global nitrogen cycle and responsible for significant global nitrogen loss. Moreover, the anammox process is widely implemented for nitrogen removal from wastewaters as a cost-effective and environment-friendly alternative to conventional nitrification-denitrification systems. Currently, five genera of anammox bacteria have been identified, together forming a deep-branching order in the Planctomycetes-Verrucomicrobium-Chlamydiae superphylum. Members of all genera have been detected in wastewater treatment plants and have been enriched in lab-scale bioreactors, but genome information is not yet available for all genera. Here we report the metagenomic analysis of a granular sludge anammox reactor dominated (∼50%) by “Candidatus Jettenia asiatica.” The metagenome was sequenced using both Illumina and 454 pyrosequencing. After de novo assembly 37,432 contigs with an average length of 571 nt were obtained. The contigs were then analyzed by BLASTx searches against the protein sequences of “Candidatus Kuenenia stuttgartiensis” and a set of 25 genes essential in anammox metabolism were detected. Additionally all reads were mapped to the genome of an anammox strain KSU-1 and de novo assembly was performed again using the reads that could be mapped on KSU-1. Using this approach, a gene encoding copper-containing nitrite reductase NirK was identified in the genome, instead of cytochrome cd1-type nitrite reductase (NirS, present in “Ca. Kuenenia stuttgartiensis” and “Ca. Scalindua profunda”). Finally, the community composition was investigated through MetaCluster analysis, 16S rRNA gene analysis and read mapping, which showed the presence of other important community members such as aerobic ammonia-oxidizing bacteria, methanogens, and the denitrifying methanotroph “Ca. Methylomirabilis oxyfera”, indicating a possible active methane and nitrogen cycle in the bioreactor under the prevailing operational conditions.

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