Quinone Profiling of Bacterial Communities in Natural and Synthetic Sewage Activated Sludge for Enhanced Phosphate Removal

Multicomponent synthesis of 3-(1H-indol-3-yl)-2-phenyl-1H-benzo[f]indole-4,9-dione derivatives

Herein, we report a one-pot greener methodology for the synthesis of 3-(1H-indol-3-yl)-2-phenyl-1H-benzo[f]indole-4,9-dione derivatives by the multicomponent reaction of arylglyoxal monohydrate, 2-amino-1,4-naphthoquinone, and indole in acetonitrile medium under reflux conditions in the presence of 10 mol% sulfamic acid as a catalyst in 20-30 min of reaction time. Three new bonds have formed (2 C-C, 1 C-N) in this methodology. Bioactive moieties such as indole, pyrrole and naphthoquinone are present in our product. This methodology is also applicable in gram-scale synthesis. A wide variety of substrates were tested to find the generality of the methodology and good yield of the products were obtained in a very short reaction time. Along with the operational simplicity of the methodology, purification process of the products is easier by simple recrystallization process. All the synthesized products were characterized by spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, and HRMS.

Preservation of Underground Microbial Diversity in Ancient Subsurface Deposits (>6 Ma) of the Rio Tinto Basement

The drilling of the Rio Tinto basement has provided evidence of an underground microbial community primarily sustained by the Fe and S metabolism through the biooxidation of pyrite orebodies. Although the gossan is the microbial activity product, which dates back to the Oligocene (25 Ma), no molecular evidence of such activity in the past has been reported yet. A Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) molecular analysis of a subsurface sample in the Peña de Hierro basement has provided novel data of the ancient underground microbial community. It shows that the microbial remains are preserved in a mineral matrix composed of laminated Fe-oxysulfates and K- and Na-bearing sulfates alternating with secondary silica. In such a mineral substrate, the biomolecule traces are found in five different microstructure associations, (1) <15 micron-sized nodular microstructures composed of POn(2≤n≤4)-, (2) <30 micron-size micronodules containing fatty acids, acylglycerides, and alkanol chains, (3) <20 micro-sized nodules containing NOn-(2≤n≤3) ions, (4) 40-micron size nodules with NH4+ and traces of peptides, and (5) >200-micron thick layer with N-bearing adducts, and sphingolipid and/or peptide traces. It suggests the mineralization of at least five microbial preserved entities with different metabolic capabilities, including: (1) Acidiphilium/Tessaracoccus-like phosphate mineralizers, (2) microbial patches preserving phosphate-free acylglycerides bacteria, (3) nitrogen oxidizing bacteria (e.g., Acidovorax sp.), (4) traces of heterotrophic ammonifying bacteria, and (5) sphingolipid bearing bacteria (e.g., Sphingomonadales, and δ-Proteobacteria) and/or mineralized biofilms. The primary biooxidation process acted as a preservation mechanism to release the inorganic ions that ultimately mineralized the microbial structures.

Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov., two novel species of the family Bacillaceae isolated from kimchi

To date, all species in the genus Salicibibacter have been isolated in Korean commercial kimchi. We aimed to describe the taxonomic characteristics of two strains, NKC5-3T and NKC21-4T, isolated from commercial kimchi collected from various regions in the Republic of Korea. Cells of these strains were rod-shaped, Gram-positive, aerobic, oxidase- and catalase-positive, non-motile, halophilic, and alkalitolerant. Both strains, unlike other species of the genus Salicibibacter, could not grow without NaCl. Strains NKC5-3T and NKC21-4T could tolerate up to 25.0% (w/v) NaCl (optimum 10%) and grow at pH 7.0-10.0 (optimum 8.5) and 8.0-9.0 (optimum 8.5), respectively; they showed 97.1% 16S rRNA gene sequence similarity to each other and were most closely related to S. kimchii NKC1-1T (97.0% and 96.8% similarity, respectively). The genome of strain NKC5-3T was nearly 4.6 Mb in size, with 4,456 protein-coding sequences (CDSs), whereas NKC21-4T genome was nearly 3.9 Mb in size, with 3,717 CDSs. OrthoANI values between the novel strains and S. kimchii NKC1-1T were far lower than the species demarcation threshold. NKC5-3T and NKC21-4T clustered together to form branches that were distinct from the other Salicibibacter species. The major fatty acids in these strains were anteiso-C15:0 and anteiso-C17:0, and the predominant menaquinone was menaquinone-7. The polar lipids of NKC5-3T included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), and five unidentified phospholipids (PL), and those of NKC21-4T included DPG, PG, seven unidentified PLs, and an unidentified lipid. Both isolates had DPG, which is the first case in the genus Salicibibacter. The genomic G + C content of strains NKC5-3T and NKC21-4T was 44.7 and 44.9 mol%, respectively. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic analyses, strains NKC5-3T (= KACC 22040T = DSM 111417T) and NKC21-4T (= KACC 22041T = DSM 111418T) represent two novel species of the genus Salicibibacter, for which the names Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov. are proposed.

Adsorption of phosphate onto lanthanum-doped coal fly ash-Blast furnace cement composite

We develop a high-performance adsorbent for phosphate removal from water or wastewater by impregnating lanthanum (La) on a coal fly ash-blast furnace cement composite (La-FACC). The optimized impregnation percentage of La and calcination conditions of the La-FACC were 1% and 800 ℃ for 2 h, respectively. The adsorption kinetics of phosphate onto the La-FACC was well fit by the intra-particle diffusion model, indicating that film and intra-particle diffusion were the rate-controlling step in the adsorption process of phosphate onto the La-FACC. The pseudo second-order kinetic model could also describe the adsorption kinetics of phosphate. Hence, adsorption of phosphate onto the La-FACC occurred mainly via chemisorption. The Langmuir isotherm was appropriate for describing the phosphate adsorption behavior onto the La-FACC. The monolayer maximum adsorption capacity was 24.9 mg-P g^-1. The La-FACC showed high adsorption capacity and selectivity for phosphate with a wide range of pH, and with high concentrations of coexisting ions attributed to both formation of inner sphere complexes and electrostatic interaction. Magnesium ion slightly inhibited the adsorption of phosphate. Hence, the La-FACC developed in this study is a promising adsorbent for water treatment with a wide pH range and high ion strength.

Metagenomic analysis reveals enhanced biodiversity and composting efficiency of lignocellulosic waste by thermoacidophilic effective microorganism (tEM)

Composting is a microbiological process that converts organic waste into organic soil amendment. We reveal enhanced biodiversity and microbial population with subsequent enhancement of composting efficiency of lignocellulosic waste using thermoacidophilic effective microorganisms (tEM). Composting with tEM + shading (tEMA) or tEM without shading (tEMB) increased the average microbial population by 12.0% or 6.7%, respectively compared to non-tEM composting without shading/control (C). The biodiversity in tEMA or tEMB treated groups was increased by 34.7% or 43.7%, respectively, compared to C. The highest increase in population (31.7% and 9.4%) and diversity (91.2% and 91.6%) were observed in tEMA and tEMB at 30 d, respectively. Regarding microbial structure, the most dominant phylum shifted from Proteobacteria to Bacteroidetes during composting. From 60 to 120 d, tEM notably improved the average abundance of Firmicutes (mainly Bacillus) by 166.7% and 75.8% in tEMA and tEMB groups, respectively. The overall gradation rate of large compost granules (<2 mm) increased by 36.4% and 24.7%, following tEMA and tEMB treatment, respectively. The average rate of increase in bulk density was 42.6% or 33.3% by tEMA or tEMB, respectively, compared to C. We reveal the major differences in microbial structure, including a higher abundance of beneficial microbes like Bacillus in tEM treated composts. The study revealed that tEM could improve biodiversity and population of microbes, especially during thermophilic phase (above 45 °C), with a subsequent increase in composting rate, mineralization, and product quality. The results of this study are particularly invaluable in the areas of environmental conservation and organic agriculture.

Sewer biofilm microbiome and antibiotic resistance genes as function of pipe material, source of microbes, and disinfection: field and laboratory studies

Wastewater systems are recognized pathways for the spread of antibiotic resistant bacteria, but relatively little is known about the microbial ecology of the sewer environment. Sewer biofilm colonization by antibiotic resistance gene (ARG) carrying bacteria may impact interpretations of sewage epidemiology data, water quality during sewer overflows, and hazard to utility workers. The objectives of this research were to evaluate the (1) microbiome of real and simulated sewer biofilms and their potential to accumulate ARGs and (2) susceptibility of simulated sewer biofilms to bleach disinfection. First, biofilm samples were collected from sewer municipal systems. Next, an annular biofilm reactor was used to simulate the sewer environment while controlling the pipe material (concrete vs. PVC). The reactor was operated either as fed semi-batch with sewer sediment and synthetic wastewater (Sed-SB) or fed with a continuous flow of raw sewage (WW-CF). The abundance of ARGs, human fecal marker HF183, and 16S rRNA gene copies in these biofilm samples was measured with qPCR. Amplicon sequencing was performed to compare the prokaryotic diversity between samples. Finally, the susceptibility of reactor biofilm to a 4.6% bleach disnfection protocol was evaluated using viability qPCR and amplicon sequencing. Field and WW-CF biofilms contained the most ARG copies and the microbial community compositions varied between the different biofilm samples (field, Sed-SB, and WW-CF). Pipe material did not affect the abundance of ARGs in the reactor samples. However, log removal following bleach treatment suggested that the biofilm grown on PVC surface was primarily dislodged from the surface by the bleach treatment whereas more bacteria were lysed within the biofilm that remained on the concrete surface. Viable bacteria carrying ARGs were observed following 10 minutes of treatment. This study showed that sewer biofilms can accumulate bacteria carrying ARGs and that while bleach can reduce sewer biofilm density, the protocol tested here will not completely remove the biofilms.

Lentibacillus cibarius sp. nov., isolated from kimchi, a Korean fermented food

Two bacterial strains designated NKC220-2^T and NKC851-2 were isolated from commercial kimchi from different areas in Korea. The strains were Gram-positive, aerobic, oxidaseand catalase-positive, rod-shaped, spore-forming, non-motile, and halophilic bacteria. Both strains grew without NaCl, unlike type species in the genus Lentibacillus. The optimal pH for growth was 8.0, higher than that of the type species in the genus Lentibacillus, although growth was observed at pH 5.5-9.0. 16S rRNA gene sequence-based phylogenetic analysis indicated that the two strains (99.3-99.9% similarity) are grouped within the genus Lentibacillus and most closely related to Lentibacillus juripiscarius IS40-3^T (97.4-97.6% similarity) isolated from fish sauce in Thailand. OrthoANI value between two novel strains and Lentibacillus lipolyticus SSKP1-9^T (79.5-79.6% similarity) was far lower than the species demarcation threshold. Comparative genomic analysis displayed differences between the two strains as well as among other strains belonging to Lentibacillus. Furthermore, each isolate had strain-specific groups of orthologous genes based on pangenome analysis. Genomic G + C contents of strains NKC-220-2^T and NKC851-2 were 41.9 and 42.2 mol%, respectively. The strains contained meso-diaminopimelic acid in their cell walls, and the major menaquinone was menaquinone-7. Phosphatidylglycerol, diphosphatidylglycerol, and an unidentified glycolipid, aminophospholipid, and phospholipid were the major polar lipid components of both strains. The major cellular fatty acids of the strains were anteiso-C_15:0 and anteiso-C_17:0. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic features, strains NKC220-2^T and NKC851-2 represent novel species of the genus Lentibacillus, for which the name Lentibacillus cibarius sp. nov. is proposed. The type strain is NKC220-2^T (= KACC 21232^T = JCM 33390^T).

Haloactinobacterium glacieicola sp. nov., isolated from an ice core

A Gram-stain-positive, rod-shaped and motile bacterium with lateral flagellum, designated T3246-1T, was isolated from an ice core, which was drilled from Hariqin Glacier on the Tibetan Plateau, PR China. It grew optimally at 20 °C, pH 7-8 and in the presence of 3 % (w/v) NaCl. The major fatty acid of strain T3246-1T was anteiso-C15 : 0. Major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. MK-8 was the dominant isoprenoid quinone. The whole-cell sugars were rhamnose, xylose and mannose. The major cell-wall peptidoglycan was lysine. The genomic DNA G+C content of the strain was 71.4 mol%. Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain T3246-1T formed a lineage within the genus Haloactinobacterium and was closely related to Haloactinobacterium album YIM 93306T with 95.99 % similarity. The average nucleotide identity value between strain T3246-1T and Haloactinobacterium album YIM 93306T was 76.65 %. Based on phenotypic and chemotaxonomic characteristics, strain T3246-1T was considered to represent a novel species of the genus Haloactinobacterium, for which the name Haloactinobacterium glacieicola sp. nov. is proposed. The type strain is T3246-1T (=CGMCC 1.13535T=JCM 32923T).

New framework for automated article selection applied to a literature review of Enhanced Biological Phosphorus Removal

AIMS

Enhanced Biological Phosphorus Removal (EBPR) is a technology widely used in wastewater treatment to remove phosphorus (P) and prevent eutrophication. Establishing its operating efficiency and stability is an active research field that has generated almost 3000 publications in the last 40 years. Due to its size, including over 119 review articles, it is an example of a field where it becomes increasingly difficult to manually recognize its key research contributions, especially for non-experts or newcomers. Therefore, this work included two distinct but complementary objectives. First, to assemble for the first time a collection of bibliometric techniques into a framework for automating the article selection process when preparing a literature review (section 2). Second, to demonstrate it by applying it to the field of EBPR, producing a bibliometric analysis and a review of the key findings of EBPR research over time (section 3).

FINDINGS

The joint analysis of citation networks, keywords, citation profiles, as well as of specific benchmarks for the identification of highly-cited publications revealed 12 research topics. Their content and evolution could be manually reviewed using a selection of articles consisting of approximately only 5% of the original set of publications. The largest topics addressed the identification of relevant microorganisms, the characterization of their metabolism, including denitrification and the competition between them (Clusters A-D). Emerging and influential topics, as determined by different citation indicators and temporal analysis, were related to volatile fatty acid production, P-recovery from waste activated sludge and aerobic granules for better process efficiency and stability (Clusters F-H).

CONCLUSIONS

The framework enabled key contributions in each of the constituent topics to be highlighted in a way that may have otherwise been biased by conventional citation-based ranking. Further, it reduced the need for manual input and a priori expertise compared to a traditional literature review. Hence, in an era of accelerated production of information and publications, this work contributed to the way that we are able to use computer-aided approaches to curate information and manage knowledge.

Erythrobacter nanhaiensis sp. nov., A Novel Member of the Genus Erythrobacter Isolated from the South China Sea

A Gram-negative, motile, rod-shaped, aerobic bacterial strain with tufty polar flagella, JLT1363^T, was isolated from the South China Sea. The bacteria formed yellow colonies on rich organic medium. The major cellular fatty acids present in JLT1363^T were C_18:1 ω7c and/or C_18:1 ω6c (36.06%), C_17:1 ω6c (17.04%), C_14:0 2-OH (9.85%), and C_16:0 (8.09%). The genome size was ~3.12 Mbps with a G+C content of 64.9%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JLT1363^T fell within the genus Erythrobacter. The 16S rRNA gene sequence similarity between strain JLT1363^T and the type strains of Erythrobacter species ranged from 95.0% (with Erythromicrobium ramosum) to 98.7% (with Erythrobacter lutimaris). The Average Nucleotide Identity (ANI) value between genome sequences of strain JLT1363^T and Erythrobacter lutimaris KCTC 42109^T was 82.2%. Strain JLT1363^T lacked bacteriochlorophyll a, and the major polar lipids were sphingoglycolipids, diphosphatidylglycerol, phosphatidylcholine, and phosphatidylglycerol. Phylogenetic and phenotypic properties indicated that strain JLT1363^T represents a novel species of the genus Erythrobacter, for which the name Erythrobacter nanhaiensis sp. nov. is proposed. The type strain is JLT1363^T (=CGMCC 1.7293^T = LMG 24872^T).

Phosphorus removal performance and biological dephosphorization process in treating reclaimed water by Integrated Vertical-flow Constructed Wetlands (IVCWs)

Phosphorous removal in adsorption had been extensively researched; however, the biological dephosphorization process and optimum operating parameters have not been discussed or quantified in Integrated Vertical-flow Constructed Wetlands (IVCWs). In this study, IVCWs planted with different plants were employed to evaluate total phosphorus (TP) treatment performance under different hydraulic retention times (HRTs), in summer and autumn. The results showed that the systems planted with Canna generalis showed the highest TP removal efficiency (77%) under a three-day HRT in autumn. The activities of exopolyphosphatase (PPX) and polyphosphate kinase (PPK) were determined, and it was found that PPK activity was seasonably variable and had been more active in autumn than that in summer (p<0.05). Highly significant correlation was revealed between PPK activity and TP removal efficiency (p<0.05). The 16S rDNA high-throughput sequencing results indicated that Pseudomonas genus might be the main participant in phosphorus aerobic biological adsorption in IVCWs.

Massilia neuiana sp. nov., isolated from wet soil

A novel aerobic, Gram-stain-negative, rod-shaped, motile bacterium, strain PTW21^T, was isolated from wet soil. 16S rRNA gene sequence phylogenetic analysis of strain PTW21^T revealed an affiliation to the genus Massilia and it shared 98.5 and 98.1 % similarity with Massilianiastensis 5516 S-1^T and Massilia tieshanensis TS3^T, respectively. Growth occurred at 10-45 °C, pH 4.5-12.5 and NaCl concentrations up to 2 % (w/v). The major fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) and C16 : 0. The predominant respiratory quinone was Q-8. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain PTW21^T was 64.6 mol%. The results of DNA-DNA hybridization revealed that strain PTW21^T showed 37.4 % relatedness with Massilia niastensis 5516 S-1^T and 40.0 % with M. tieshanensis TS3^T. Based on phenotypic, chemotaxonomic and phylogenetic differences, strain PTW21^T (=CICC 24113^T=BCRC 81061^T) is proposed as the type strain of novel species of the genus Massilia with the names Massilia neuiana sp. nov.

Genetic diversity of marine anaerobic ammonium-oxidizing bacteria as revealed by genomic and proteomic analyses of 'Candidatus Scalindua japonica'

Anaerobic ammonium-oxidizing (anammox) bacteria affiliated with the genus 'Candidatus Scalindua' are responsible for significant nitrogen loss in oceans, and thus their ecophysiology is of great interest. Here, we enriched a marine anammox bacterium, 'Ca. S. japonica' from a Hiroshima bay sediment in Japan, and comparative genomic and proteomic analyses of 'Ca. S. japonica' were conducted. Sequence of the 4.81-Mb genome containing 4019 coding regions of genes (CDSs) composed of 47 contigs was determined. In the proteome, 1762 out of 4019 CDSs in the 'Ca. S. japonica' genome were detected. Based on the genomic and proteomic data, the core anammox process and carbon fixation of 'Ca. S. japonica' were further investigated. Additionally, the present study provides the first detailed insights into the genetic background responsible for iron acquisition and menaquinone biosynthesis in anammox bacterial cells. Comparative analysis of the 'Ca. Scalindua' genomes revealed that the 1502 genes found in the 'Ca. S. japonica' genome were not present in the 'Ca. S. profunda' and 'Ca. S. rubra' genomes, showing a high genomic diversity. This result may reflect a high phylogenetic diversity of the genus 'Ca. Scalindua'.

Massilia glaciei sp. nov., isolated from the Muztagh Glacier

A Gram-stain-negative, rod-shaped, bacterial strain, B448-2^T, was isolated from an ice core from the Muztagh Glacier, on the Tibetan Plateau. B448-2^T grew optimally at pH 7.0 and 20 °C in the presence of 0-1.0 % (w/v) NaCl. The results of 16S rRNA gene sequence similarity analysis indicated that B448-2^T was closely related to Massilia eurypsychrophila CGMCC 1.12828^T, Rugamonas rubra CCM3730^T and Duganella zoogloeoides JCM20729^T at levels of 97.8, 97.7  and 97.3 %, respectively. The predominant fatty acids of B448-2^T were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The predominant isoprenoid quinone was Q-8. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G+C content of the strain was 66.1 mol%. In DNA-DNA hybridization tests, B448-2^T shared 37.6 % DNA-DNA relatedness with Massilia eurypsychrophila CGMCC 1.12828^T. On the basis of the results for phenotypic and chemotaxonomic characteristics, B448-2^T was considered to represent a novel species of the genus Massilia, for which the name Massiliaglaciei sp. nov. is proposed. The type strain is B448-2^T (=JCM 30271^T=CGMCC 1.12920^T).

Description of Conyzicola nivalis sp. nov., isolated from glacial snow, and emended description of the genus Conyzicola and Conyzicola lurida

A cold-tolerant, translucent, yellow-pigmented, Gram-stain-positive, non-motile, rod-shaped bacteria was isolated from snow of the Zadang Glacier on the Tibetan Plateau, PR China. 16S rRNA gene sequence similarity analysis indicated that the isolate was closely related to Conyzicola lurida KCTC 29231T and Leifsonia psychrotolerans DSM 22824T at a level of 97.72 and 97.49 %, respectively. Other close relatives had a 16S rRNA gene sequence similarity of less than 97 %. The major cell-wall amino acid was 2,4-diaminobutyric acid. The cell-wall sugars were rhamnose, ribose, glucose, galactose and mannose. The major menaquinones were MK-9, MK-10 and MK-11. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The predominant fatty acids were anteiso-C15 : 0 and iso-C16 : 0. In DNA-DNA hybridization tests, strain ZD5-4T shared 43.6 and 34.2 % relatedness with C. lurida KCTC 29231T and L. psychrotolerans DSM 22824T, respectively. Based on phenotypic and chemotaxonomic characteristics, strain ZD5-4T was considered to represent a novel species of the genus Conyzicola, for which the name Conyzicola nivalis sp. nov. is proposed. The type strain is ZD5-4T (=JCM 30076T=CGMCC 1.12813T). Emended descriptions of the genus Conyzicola and Conyzicola lurida are also provided.

Sphingomonas montana sp. nov., isolated from a soil sample from the Tanggula Mountain in the Qinghai Tibetan Plateau

An orange pigmented, Gram-staining negative, aerobic, motile, rod-shaped bacterium isolated from a soil from the Tanggula Mountain, China was studied using a polyphasic approach. Based on 16S rRNA gene sequence similarity, strain W16RD^T was found to be closely related to Sphingomonas prati DSM 103336^T (99%), Sphingomonas fennica DSM 13665^T (97.21%), followed by Sphingomonas laterariae DSM 25432^T (96.44%), Sphingomonas haloaromaticamans CGMCC 1.10206 ^T (96.36%) and Sphingomonas formosensis DSM 24164^T (96.06%). The strain was found to be catalase and oxidase positive and was found to grow optimally at temperatures of 20-25 °C, pH 8 and tolerated NaCl concentration up to 1% (w/v). The major fatty acids identified were summed feature eight comprising C_18:1 ω 7c and/or C_18:1 ω 6c (39.2%), summed feature three comprising of C_16:1 ω7c and/or C_16:1 ω6c (36.7%) and C_16:0 (7.0%). The polar lipids detected were phosphatidylcholine, sphingoglycolipid, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidyldimethylethanolamine, phosphatidylmonomethylethanolamine, and three unidentified lipids. The strain possessed ubiquinone-10 (Q-10) as the predominant respiratory quinone. Along with other distinguishing characteristics, we also describe the draft genome of strain W16RD^T. The final assembled draft genome sequence is 3,722,743 bp with 3390 coding and 48 RNA (45 tRNA and 3 rRNA) genes. The DNA G+C content of the genomic DNA was determined to be 67%. The DNA-DNA relatedness value between the strain W16RD^T and its closest phylogenetic relatives S. prati DSM 103336^T, S. fennica DSM 13665^T, S. laterariae DSM 25432^T, and S. haloaromaticamans CGMCC 1.10206^T were 52.17, 47.60, 20.93 and 17.09% respectively. The strain W16RD^T could be distinguished genotypically and phenotypically from the recognized species belonging to the genus Sphingomonas and thus represents a novel species, for which the name Sphingomonas montana sp. nov. is proposed. The type strain is W16RD^T (=CGMCC 1.15646^T = DSM 103337^T).

Mucilaginibacterpsychrotolerans sp. nov., isolated from peatlands

A Gram-stain-negative, rod-shaped, non-flagellated, pink, cold-tolerant bacterial strain, NH7-4T, was isolated from the Riganqiao peatlands on the Tibetan Plateau. The 16S rRNA gene sequence of the novel isolate shared a pairwise similarity ranging from 96.84 to 93.02 % with type strains of species of the genus Mucilaginibacter. Growth of strain NH7-4T occurred between 0 and 30 °C and at pH 5.0-9.0, with an optimum growth temperature at 20 °C and an optimum pH for growth of approximately 7.0. The major isoprenoid quinone was MK-7. The major cellular fatty acids were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 0, iso-C15 : 0 3-OH and C16 : 1ω5c. The major polar lipid of strain NH7-4T was phosphatidylethanolamine. Strain NH7-4T did not assimilate any substrates in API 20NE strips without low concentrations of yeast extract being present and had a lower optimal growth temperature, which distinguished it from other type strains of species of the genus Mucilaginibacter. The DNA G+C content of strain NH7-4T was 48.6 mol%. Based on phylogenetic, phenotypic and chemotaxonomic data, strain NH7-4T (=JCM 30607T=CGMCC1.14937T) represents a novel species of the genus Mucilaginibacter for which the name Mucilaginibacter psychrotolerans sp. nov. is proposed.

Chryseobacterium zhengzhouense sp. nov., isolated from groundwater of the well in a vegetable field, and emended description of the genus Chryseobacterium

A Gram-negative, strictly aerobic, non-motile, asporogenous rod-shaped bacterium, designated M05W1-39A1(T), was isolated from a Chinese cabbage farmland located in Zhengzhou. China, and subjected to a taxonomic study. Strain M05W1-39A1(T) was found to grow optimally at 25-30 °C, at pH 6.0-7.0 and in the presence of 0.5-2.0 % (w/v) NaCl. According to phylogenetic analysis using 16S rRNA gene sequences, strain M05W1-39A1(T) belongs to the genus Chryseobacterium and is closely related to Chryseobacterium arachidis LMG 27813(T) (98.8 %) and Chryseobacterium geocarposphaera LMG 27811(T) (98.1 %). The DNA G + C content was determined to be 35.3 mol%. The respiratory quinone was identified as MK-6 and the predominant cellular fatty acids as iso-C15:0, Summed feature 3 (C16:1 ω7c/C16:1 ω6c), iso-C17:0 3-OH and Summed feature 9 (iso-C17:1 ω9c). Based on the genotypic, chemotaxonomic and phenotypic data, strain M05W1-39A1(T) is concluded to represent a novel species of the genus Chryseobacterium, for which the name Chryseobacterium zhengzhouense sp. nov. is proposed. The type strain is M05W1-39A1(T) (=HNMC11208(T) = CGMCC 1.15067(T) = JCM 30863(T)).

Chelatococcus reniformis sp. nov., isolated from a glacier

A Gram-stain-negative, non-motile, reniform bacterial strain, B2974T, was isolated from an ice core of the Muztagh Glacier, on the Tibetan Plateau, China. Strain B2974T grew optimally at pH 7.0-7.5 and 25-30 °C in the presence of 0-2.0 % (w/v) NaCl. 16S rRNA gene sequence similarity analysis indicated that strain B2974T was closely related to Chelatococcus asaccharovorans LMG 25503T at a level of 97.1 %. The major quinone of strain B2974T was ubiquinone Q10. The predominant fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C19 : 0 cyclo ω8c. sym-Homospermidine was the major polyamine. The genomic DNA G+C content of the strain was 64 mol%. In DNA-DNA hybridization tests, strain B2974T shared 49.32 % DNA-DNA relatedness with the type strain of Chelatococcus asaccharovorans LMG 25503T. Based on the results of phenotypic and chemotaxonomic characteristics, strain B2974T was considered as a novel species of the genus Chelatococcus, for which the name Chelatococcus reniformis sp. nov. is proposed. The type strain is B2974T (=JCM 30308T=CGMCC 1.12919T).

Pedobacterpsychrotolerans sp. nov., isolated from soil

A Gram-stain-negative, non-motile, light-pink-pigmented, aerobic, rod-shaped bacterium, designated V5RDT, was isolated from soil of Damxung county in the Qinghai-Tibetan Plateau. Strain V5RDT grew luxuriously at 10 °C, at pH 9.0 and in the presence of 1 % NaCl (w/v). Phylogenetic analysis of 16S rRNA gene sequences placed strain V5RDT in the genus Pedobacter and found that it was most closely related to Pedobacter alluvionis DSM 19624T (97.3 %), Pedobacter ginsenosidimutans JCM 16721T (96.84 %), Pedobacter agri DSM 19486T (96.28 %), Pedobacter roseus JCM 13399T (96.22 %), Pedobacter sandarakinus KCTC 12559T (95.92 %) and Pedobacter borealis DSM 19626T (95.85 %). The G+C content of the genomic DNA of the type strain V5RDT was 37.40 mol%. DNA-DNA relatedness for the type strain V5RDT with respect to its closest phylogenetic relative, P. alluvionis DSM 19624T, was 62.5±1.7 %. The polar lipid profile of the strain consisted of phosphatidylethanolamine, one unidentified aminolipid, one unidentified glycolipid and two unidentified polar lipids. Menaquinone MK-7 was the predominant respiratory quinone, and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c), iso-C15 : 0 and iso-C17 : 0 3-OH were the major fatty acids. With respect to phenotypic characteristics, biochemical properties and phylogenetic inference, strain V5RDT represents a novel species of the genus Pedobacter, for which the name Pedobacter psychrotolerans sp. nov is proposed. The type strain is V5RDT (=CGMCC 1.15644T=DSM 103236T).

Massilia psychrophila sp. nov., isolated from an ice core

A Gram-stain-negative, aerobic, rod-shaped, motile bacterium, strain B1555-1T, was isolated from an ice core drilled from Ulugh Muztagh Glacier, China. The optimum growth temperature of strain B1555-1T was 15 °C and optimum pH was 7. The major fatty acids of strain B1555-1T were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The predominant respiratory quinone was Q-8. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain B1555-1T was 66.0 mol%. In 16S rRNA gene sequence comparisons, strain B1555-1T was affiliated to the genus Massilia and shared 98.30 and 97.13 % similarity with Massilia eurypsychrophila B528-3T and Massilia niabensis 5420S-26T, respectively. The results of DNA-DNA hybridization revealed that strain B1555-1T showed 49.8 % relatedness with M. eurypsychrophila B528-3T and 38.5 % with M. niabensis 5420S-26T. Based on the genotypic and phenotypic evidence presented in this study, strain B1555-1T represents a novel species of the genus Massilia, for which the name Massilia psychrophila sp. nov. is proposed. The type strain is B1555-1T (=CGMCC 1.15196T=JCM 30813T).

Detection of nitrifiers and evaluation of partial nitrification for wastewater treatment: A review

Partial nitrification has gained broad interests in the biological nitrogen removal (BNR) from wastewater, since it alleviates carbon limitation issues and acts as a shortcut nitrogen removal system combined with anaerobic ammonium oxidation (Anammox) process. The occurrence and maintenance of partial nitrification relies on various conditions, which favor ammonium oxidizing bacteria (AOB) but inhibit or limit nitrite oxidizing bacteria (NOB). The studies of the AOB and NOB activities have been conducted by state-of-the-art molecular techniques, such as Polymerase Chain Reaction (PCR), Quantitative PCR, denaturing gradient gel electrophoresis (DGGE), Fluorescence in situ hybridization (FISH) technique, Terminal Restriction Fragment Length Polymorphism (T-RFLP), Live/Dead BacLight, and quinone profile. Furthermore, control strategies for obtaining partial nitrification are mainly focused on the pH, temperature, dissolved oxygen concentration, real-time aeration control, sludge retention time, substrate concentration, alternating anoxic and aerobic operation, inhibitor and ultrasonic treatment. Existing problems and further perspectives for the scale-up of partial nitrification are also proposed and suggested.

Massilia eurypsychrophila sp. nov. a facultatively psychrophilic bacteria isolated from ice core

Strain B528-3T, a Gram-stain-negative, rod-shaped, aerobic, facultatively psychrophilic bacterium with polar flagella, was isolated from an ice core drilled from Muztagh Glacier, Xinjiang, China. The novel isolate was classified into the genus Massilia. The 16S rRNA gene sequence of the novel isolate shares a pairwise similarity of less than 97 % with those of all the type strains of the genus Massilia. The major fatty acids of strain B528-3T were summed feature 3 (C16:1ω7c and/or iso-C15:0 2-OH) (57.31 %), C16:0 (11.46 %) and C18:1ω7c (14.72 %). The predominant isoprenoid quinone was Q-8. The DNA G+C content was 62.2 mol% (T m). The major polar lipids of this bacterium were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. From the genotypic and phenotypic data, it is evident that strain B528-3T represents a novel species of the genus Massilia, for which the name Massilia eurypsychrophila sp. nov. is proposed. The type strain is B528-3T ( = JCM 30074T = CGMCC 1.12828T).

Physiological characterization of anaerobic ammonium oxidizing bacterium 'Candidatus Jettenia caeni'

To date, six candidate genera of anaerobic ammonium-oxidizing (anammox) bacteria have been identified, and numerous studies have been conducted to understand their ecophysiology. In this study, we examined the physiological characteristics of an anammox bacterium in the genus 'Candidatus Jettenia'. Planctomycete KSU-1 was found to be a mesophilic (20-42.5°C) and neutrophilic (pH 6.5-8.5) bacterium with a maximum growth rate of 0.0020 h(-1) . Planctomycete KSU-1 cells showed typical physiological and structural features of anammox bacteria; i.e. (29) N2 gas production by coupling of (15) NH4 (+) and (14) NO2 (-) , accumulation of hydrazine with the consumption of hydroxylamine and the presence of anammoxosome. In addition, the cells were capable of respiratory ammonification with oxidation of acetate. Notably, the cells contained menaquinone-7 as a dominant respiratory quinone. Proteomic analysis was performed to examine underlying core metabolisms, and high expressions of hydrazine synthase, hydrazine dehydrogenase, hydroxylamine dehydrogenase, nitrite/nitrate oxidoreductase and carbon monoxide dehydrogenase/acetyl-CoA synthase were detected. These proteins require iron or copper as a metal cofactor, and both were dominant in planctomycete KSU-1 cells. On the basis of these experimental results, we proposed the name 'Ca. Jettenia caeni' sp. nov. for the bacterial clade of the planctomycete KSU-1.

Arcticibacter eurypsychrophilus sp. nov., isolated from ice core

A Gram-stain-negative, rod-shaped, non-flagellated bacterium, strain MJ9-5(T), was isolated from ice core of Muji Glacier. Colonies of strain MJ9-5(T) were pink, convex and round on R2A agar. Strain MJ9-5(T) grew between -1 to 25 °C with an optimum growth temperature of 10-15 °C. The strain tolerated 0-1.2 % (w/v) NaCl with an optimum of 1 %. The major cellular fatty acids of strain MJ9-5(T) were iso-C15 : 0, summed feature 3 (C16 : 1ω6c and/or C1 6 : 1ω7c). The G+C content of the genomic DNA was 38.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MJ9-5(T) was related to members of the genus Arcticibacter. On the basis of the phenotypic characteristics and phylogenetic analysis, a novel species of this genus, Arcticibacter eurypsychrophilus sp. nov., is proposed. The type strain is MJ9-5(T) ( = KCTC 42008(T) = JCM 19862(T)).

Coralslurrinella hongkonensis gen. nov., sp. nov., a novel bacterium in the family Psychromonadaceae, isolated from the coral Platygyra carnosus

A novel bacterial strain, JLT2006T, was isolated from the scleractinian coral Platygyra carnosus, located in Hong Kong, China. Cells of this strain were Gram-negative, rod-shaped or oval-shaped and motile by the means of polar flagella. They formed faint-yellow, round colonies on marine agar medium. Phylogenetic analyses based on the 16S rRNA gene sequence indicated that the strain JLT2006T belonged to the class Gammaproteobacteria and was most closely related to Alteromonas-like bacteria of the genera Psychromonas, Pseudoalteromonas, Moritella, Shewanella and Ferrimonas, with less than 93 % sequence similarity. The predominant fatty acids were identified as C18:1x7c/C18:1x6c (23.0 %), C16:1x7c/C16:1x6c (18.2 %) and C16:0 (16.4 %). The quinone was menaquinone-7 (100 %). The polar lipids were determined to be phosphatidylglycerol, phosphatidylethanolamine, phospholipid, glycolipid and lipid. The genomic DNA G?C content was 40.3 mol%. Based on the 16S rRNA gene sequence as well as the physiological and biochemical features that separate the strain JLT2006T from other recognized bacteria, a novel species of a new genus with the name Coralslurrinella hongkonensis gen. nov., sp. nov. is proposed. The type strain is JLT2006T (=JCM 18796T = CGMCC 1.10992T).

A comparative analysis of the characteristics of a range of real and synthetic wastewaters

Synthetic wastewaters are widely used in many fields of wastewater research and operational management. However, few comparative studies have been conducted on the large number of published formulations. Eleven synthetic formulations simulating municipal wastewaters were selected based on their frequency of use, relative complexity, ease of formulation and cost and compared to two real municipal wastewaters. Synthetic wastewaters vary significantly in their compositions and characteristics, especially in terms of alkalinity, BOD K 1, SOUR, BODU, COD/BOD and C/N/P ratio, although they are portrayed as 'typical' in terms of characteristics and suitability for use. The pH, alkalinity and the presence of Ca and Mg should be considered in combination with the diluent used. Where the diluent is tap water, then the presence of treatment chemicals should also be considered. The effects of the micronutrients present are also an important factor. The study found that no single formulation is appropriate for all situations. Both the Syntho and Synthes formulations attempt to simulate real wastewater, whereas other formulations primarily act as readily biodegradable vectors for toxicity analyses, characterisation studies and treatment process evaluations. The criteria for choosing a particular synthetic wastewater very much depend on its intended application and require careful selection.

Do biological-based strategies hold promise to biofouling control in MBRs?

Biofouling in membrane bioreactors (MBRs) remains a primary challenge for their wider application, despite the growing acceptance of MBRs worldwide. Research studies on membrane fouling are extensive in the literature, with more than 200 publications on MBR fouling in the last 3 years; yet, improvements in practice on biofouling control and management have been remarkably slow. Commonly applied cleaning methods are only partially effective and membrane replacement often becomes frequent. The reason for the slow advancement in successful control of biofouling is largely attributed to the complex interactions of involved biological compounds and the lack of representative-for-practice experimental approaches to evaluate potential effective control strategies. Biofouling is driven by microorganisms and their associated extra-cellular polymeric substances (EPS) and microbial products. Microorganisms and their products convene together to form matrices that are commonly treated as a black box in conventional control approaches. Biological-based antifouling strategies seem to be a promising constituent of an effective integrated control approach since they target the essence of biofouling problems. However, biological-based strategies are in their developmental phase and several questions should be addressed to set a roadmap for translating existing and new information into sustainable and effective control techniques. This paper investigates membrane biofouling in MBRs from the microbiological perspective to evaluate the potential of biological-based strategies in offering viable control alternatives. Limitations of available control methods highlight the importance of an integrated anti-fouling approach including biological strategies. Successful development of these strategies requires detailed characterization of microorganisms and EPS through the proper selection of analytical tools and assembly of results. Existing microbiological/EPS studies reveal a number of implications as well as knowledge gaps, warranting future targeted research. Systematic and representative microbiological studies, complementary utilization of molecular and biofilm characterization tools, standardized experimental methods and validation of successful biological-based antifouling strategies for MBR applications are needed. Specifically, in addition, linking these studies to relevant operational conditions in MBRs is an essential step to ultimately develop a better understanding and more effective and directed control strategy for biofouling.

Dyadobacter tibetensis sp. nov., isolated from glacial ice core

A Gram-stain-negative, rod-shaped, aerobic, non-motile bacterium, designated Y620-1T, was isolated from a glacier on the Tibetan Plateau, China. The 16S rRNA gene sequence of the novel isolate shared 93.6–95.1 % similarity with type strains of species of the genus Dyadobacter . The major fatty acids of strain Y620-1T were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), iso-C15 : 0, C16 : 1ω5c and iso-C17 : 0 3-OH. The predominant isoprenoid quinone and polar lipid were MK-7 and phosphatidylethanolamine (PE), respectively. The DNA G+C content was 44.4±0.3 mol% (T m). Flexirubin-type pigment was produced. The novel isolate was classified in the genus Dyadobacter , but a number of phenotypic characteristics distinguished the novel isolate from type strains of species of the genus Dyadobacter . From these genotypic and phenotypic data, it is evident that strain Y620-1T represents a novel species of the genus Dyadobacter , for which the name Dyadobacter tibetensis sp. nov. is proposed. The type strain is Y620-1T ( = JCM 18589T = CGMCC 1.12215T).

Altuibacter lentus gen. nov., sp. nov., a novel member of family Flavobacteriaceae isolated from deep seawater of the South China Sea

A novel chemoheterotrophic, aerobic, Gram-negative, rod-shaped, yellow-pigmented, bacterial strain JLT2010(T) was isolated from deep seawater of the South China Sea. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain JLT2010(T) belongs to the family Flavobacteriaceae and is most closely related to Ulvibacter antarcticus IMCC3101(T) with 95.7 % similarity. Some phenotypic characteristics such as the absence of flexirubin-type pigments, growth at 37 °C, hydrolysis of casein differentiated strain JLT2010(T) from the genus Ulvibacter as well as other genera in the family Flavobacteriaceae. The DNA G+C content of the strain JLT2010(T) was found to be 35.7 mol% and the major respiratory quinone was found to be MK-6. On the basis of phenotypic and phylogenetic features, JLT2010(T) is classified as a novel genus and species within the family Flavobacteriaceae, for which the name Altuibacter lentus gen. nov., sp. nov. is proposed. The type strain is JLT2010(T) (=JCM 18884(T) = CGMCC 1.12167(T)).

Mycetocola zhadangensis sp. nov., isolated from snow

A Gram-stain-positive, aerobic, short rod-shaped bacterium, strain ZD1-4T, was isolated from the Zhadang Glacier snow pit. The 16S rRNA gene sequence of the isolate showed highest similarity (98.8 %) to that of Mycetocola manganoxydans MB1-14T. The major fatty acids of strain ZD1-4T were anteiso-C15 : 0, C16 : 0, C18 : 0 and anteiso-C17 : 0. It possessed diphosphatidylglycerol as one of the major polar lipids, and MK-10 and MK-11 as the predominant isoprenoid quinones. The DNA G+C content of strain ZD1-4T was 63.8±0.2 mol% (T m). A number of phenotypic characteristics distinguished this bacterium from the type strains of other species of the genus Mycetocola . Moreover, the novel isolate showed only approximately 50 % DNA–DNA relatedness with M. manganoxydans MB1-14T. According to these genotypic and phenotypic data, it is evident that strain ZD1-4T represents a novel species of the genus Mycetocola , for which the name Mycetocola zhadangensis sp. nov. is proposed. The type strain is ZD1-4T ( = KACC 16570T = CGMCC 1.12042T).

Systematic analysis of biomass characteristics associated membrane fouling during start-up of a hybrid membrane bioreactor using worm reactor for sludge reduction

This study focused on the effect of predated sludge recycle on microbial community development in MBR coupled with Static Sequencing Batch Worm Reactor (SSBWR-MBR). The microbial activities and community were evaluated. The results indicated that the SSBWR-MBR fed with the predated sludge obtained excellent wastewater treatment performance and membrane permeability. In addition, the LIVE/DEAD staining analyses clearly showed that the viability of sludge in SSBWR-MBR was slightly lower than that in Control-MBR, indicating that SSBWR-MBR had a good ability to digest predated sludge. Changed EPS and SMP characteristics and low EPS production, as the major contributors for the mitigated membrane fouling, were closely associated with microbial community development. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the bacterial communities in the two reactors were different. Further identification of the bacterial populations suggested that decrease of Betaproteobacteria and Gammaproteobacteria and change in Alphaproteobacteria might be responsible for membrane fouling mitigation.

Massilia yuzhufengensis sp. nov., isolated from an ice core

A Gram-negative, rod-shaped, aerobic, motile bacterium, strain Y1243-1T, was isolated from an ice core drilled from Yuzhufeng Glacier, Tibetan Plateau, China. Cells had polar flagella. The novel strain shared 94.7–97.6 % 16S rRNA gene sequence similarity with the type strains of species of the genus Massilia . The novel isolate is thus classified in the genus Massilia . The major fatty acids of strain Y1243-1T were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) (43.98 %), C16 : 0 (27.86 %), C10 : 0 3-OH (7.10 %), C18 : 0 (6.95 %) and C18 : 1ω7c (5.01 %). The predominant isoprenoid quinone was Q-8. The DNA G+C content of strain Y1243-1T was 65.7 mol% (T m). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. A number of phenotypic characteristics distinguished the novel isolate from the type strains of recognized Massilia species. Furthermore, in DNA–DNA hybridization tests, strain Y1243-1T shared 45 % relatedness with its closest phylogenetic relative, Massilia consociata CCUG 58010T. From the genotypic and phenotypic data, it is evident that strain Y1243-1T represents a novel species of the genus Massilia , for which the name Massilia yuzhufengensis sp. nov. is proposed. The type strain is Y1243-1T ( = KACC 16569T = CGMCC 1.12041T).

Acetate oxidation by syntrophic association between Geobacter sulfurreducens and a hydrogen-utilizing exoelectrogen

Anodic microbial communities in acetate-fed microbial fuel cells (MFCs) were analyzed using stable-isotope probing of 16S rRNA genes followed by denaturing gradient gel electrophoresis. The results revealed that Geobacter sulfurreducens and Hydrogenophaga sp. predominated in the anodic biofilm. Although the predominance of Geobacter sp. as acetoclastic exoelectrogens in acetate-fed MFC systems has been often reported, the ecophysiological role of Hydrogenophaga sp. is unknown. Therefore, we isolated and characterized a bacterium closely related to Hydrogenophaga sp. (designated strain AR20). The newly isolated strain AR20 could use molecular hydrogen (H2), but not acetate, with carbon electrode as the electron acceptor, indicating that the strain AR20 was a hydrogenotrophic exoelectrogen. This evidence raises a hypothesis that acetate was oxidized by G. sulfurreducens in syntrophic cooperation with the strain AR20 as a hydrogen-consuming partner in the acetate-fed MFC. To prove this hypothesis, G. sulfurreducens strain PCA was cocultivated with the strain AR20 in the acetate-fed MFC without any dissolved electron acceptors. In the coculture MFC of G. sulfurreducens and strain AR20, current generation and acetate degradation were the highest, and the growth of strain AR20 was observed. No current generation, acetate degradation and cell growth occurred in the strain AR20 pure culture MFC. These results show for the first time that G. sulfurreducens can oxidize acetate in syntrophic cooperation with the isolated Hydrogenophaga sp. strain AR20, with electrode as the electron acceptor.

Microbial community composition of polyhydroxyalkanoate-accumulating organisms in full-scale wastewater treatment plants operated in fully aerobic mode

The removal of biodegradable organic matter is one of the most important objectives in biological wastewater treatments. Polyhydroxyalkanoate (PHA)-accumulating organisms (PHAAOs) significantly contribute to the removal of biodegradable organic matter; however, their microbial community composition is mostly unknown. In the present study, the microbial community composition of PHAAOs was investigated at 8 full-scale wastewater treatment plants (WWTPs), operated in fully aerobic mode, by fluorescence in situ hybridization (FISH) analysis and post-FISH Nile blue A (NBA) staining techniques. Our results demonstrated that 1) PHAAOs were in the range of 11–18% in the total number of cells, and 2) the microbial community composition of PHAAOs was similar at the bacterial domain/phylum/class/order level among the 8 full-scale WWTPs, and dominant PHAAOs were members of the class Alphaproteobacteria and Betaproteobacteria. The microbial community composition of α- and β-proteobacterial PHAAOs was examined by 16S rRNA gene clone library analysis and further by applying a set of newly designed oligonucleotide probes targeting 16S rRNA gene sequences of α- or β-proteobacterial PHAAOs. The results demonstrated that the microbial community composition of PHAAOs differed in the class Alphaproteobacteria and Betaproteobacteria, which possibly resulted in a different PHA accumulation capacity among the WWTPs (8.5–38.2 mg-C g-VSS⁻¹ h⁻¹). The present study extended the knowledge of the microbial diversity of PHAAOs in full-scale WWTPs operated in fully aerobic mode.