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In activated sludge (AS) biotreatment, septic compounds such as volatile organic acids and reduced sulphur compounds have been frequently cited as a major cause of Thiothrix and Type 021N filamentous bulking. These filaments are common in Canadian pulp and paper biotreatment systems, where they cause settling problems in secondary clarifiers. We conducted a 14-week study of a TMP/newsprint mill effluent to characterize the septic compounds entering the biotreatment, and to determine correlations with AS biomass characteristics and biotreatment operating parameters. A significant correlation was found between the sludge volume index, the abundance of Type 021N, and the propionic acid (PA) concentration in the primary clarified effluent. PA also induced a significant change in the flocculating bacteria size distribution determined by digital imaging. Consequently, the correlation observed between PA and Type 021N bulking is an indirect effect of inhibition of floc-forming microorganisms, giving a competitive advantage to filaments.

Everyday huge amount of treated municipal wastewater is discharged into the coastal seawater. However, microbial biomarkers for the municipal effluent instead of the fecal species from raw sewage have not been proposed. Meanwhile, bacterial taxa for degrading large amounts of input organics have not been fully understood. In this study, raw effluent and serial water samples were collected from the coastal dispersal of two sewage treatment plants in Xiamen, China. Free-living (FL) and particle-associated (PA) bacterial communities were analyzed via high-throughput sequencing of 16S rRNA gene and quantitative PCR to measure bacterial abundance. The PA bacterial communities in our samples exhibited higher cell abundance, alpha diversity, and population dynamics than the FL bacterial communities, which supports greater environmental significance of the PA bacterial communities. Two non-fecal but typical genera in activated sludge, Zoogloea and Dechloromonas, exhibited decreased but readily detectable abundance along the effluent dispersal distance. Furthermore, the dominating microbial species near the outfalls were related to well-known marine indigenous taxa, such as SAR11 clade, OM60 clade, low-GC Actinobacteria, and unclassified Flavobacteriales, as well as the less understood taxa like Pseudohongiella and Microbacteriaceae. It is interesting that these taxa exhibited two types of correlation patterns with COD concentration. Our study suggested Zoogloea as a potential indicator of municipal effluents and also proposed potential utilizers of residual effluent COD in marine environments.

Pump and treat systems are widely used for hydrocarbon-contaminated groundwater remediation. Although biofouling (formation of clogging biofilms on pump surfaces) is a common problem in these systems, scarce information is available regarding the phylogenetic and functional complexity of such biofilms. Extensive information about the taxa and species as well as metabolic potential of a bacterial biofilm developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater is presented. Results shed light on a complex network of interconnected hydrocarbon-degrading chemoorganotrophic and chemolitotrophic bacteria. It was found that besides the well-known hydrocarbon-degrading aerobic/facultative anaerobic biofilm-forming organisms (e.g., Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), representatives of Fe(2+)-and Mn(2+)-oxidizing (Thiobacillus, Sideroxydans, Gallionella, Rhodopseudomonas, etc.) as well as of Fe(3+)- and Mn(4+)-respiring (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) bacteria were present in the biofilm. The predominance of β-Proteobacteria within the biofilm bacterial community in phylogenetic and functional point of view was revealed. Investigation of meta-cleavage dioxygenase and benzylsuccinate synthase (bssA) genes indicated that within the biofilm, Azoarcus, Leptothrix, Zoogloea, and Thauera species are most probably involved in intrinsic biodegradation of aromatic hydrocarbons. Polyphasic analysis of the biofilm shed light on the fact that subsurface microbial accretions might be reservoirs of novel putatively hydrocarbon-degrading bacterial species. Moreover, clogging biofilms besides their detrimental effects might supplement the efficiency of pump and treat systems.

Conductive carbon felts (Cf) were used as biofilm carriers in bioelectrochemical reactors to enhance the electrical stimulation on treatment of phenol-containing synthetic wastewater. In batch test, phenol biodegradation was accelerated under an optimum direct current (DC), which was 2mA for Cf biofilm carriers, lower than that for non-conductive white foam carriers. The stimulation effect was consistent with Adenosine Triphosphate contents in biofilms. The long-term operation further demonstrated that a high and stable phenol removal efficiency could be achieved with applied DC of 2mA, and intermittent DC application was better than continuous one, with phenol removal efficiency of over 97%. Although the quantities of whole microbial communities kept at a high level under all conditions, special microorganisms related with genera of Zoogloea and Desulfovibrio were distinctively enriched under intermittent applied DC pattern. This study shows that the electrical stimulation is potentially effective for biofilm reactors treating phenol-containing wastewater.

The use of mixed microbial cultures for the production of polyhydroxyalkanoates (PHAs) is emerging as a viable technology. In this study, 16S rRNA gene amplicon pyrosequencing was used to analyse fluctuations in populations over a 63-day period within a PHA-storing mixed microbial community enriched on fermented whey permeate. This community was dominated by the genera Flavisolibacter and Zoogloea as well as an unidentified organism belonging to the phylum Bacteroidetes. The population was observed to cycle through an increase in Zoogloea followed by a return to a community composition similar to the initial one (highly enriched in Flavisolibacter). It was found that the PHA accumulation capacity of the community was robust to population flux during enrichment and even PHA accumulation, with final polymer composition dependent on the overall proportion of acetic to propionic acids in the feed. This community adaptation suggests that mixed culture PHA production is a robust process.

In this study, sponges were used to immobilize domesticated sludge microbes in a limited space, forming an immobilized biosystem capable of algae and microcystins removal. The removal effects on algae, microcystins and UV260 of this biosystem and the mechanism of algae removal were studied. The results showed that active sludge from sewage treatment plants was able to remove algae from a eutrophic lake’s water after 7 d of domestication. The removal efficiency for algae, organic matter and microcystins increased when the domesticated sludge was immobilized on sponges. When the hydraulic retention time (HRT) was 5h, the removal rates of algae, microcystins and UV260 were 90%, 94.17% and 84%, respectively. The immobilized biosystem consisted mostly of bacteria, the Ciliata and Sarcodina protozoans and the Rotifer metazoans. Algal decomposition by zoogloea bacteria and preying by microcreatures were the two main modes of algal removal, which occurred in two steps: first, absorption by the zoogloea; second, decomposition by the zoogloea bacteria and the predacity of the microcreatures.

The purpose of this study was to identify microbial strains that have a strong ability to biodegrade lubricating oil. No. 20 lubricating oil was used as the sole carbon source in an isolation medium to screen bacteria from sludge that had been contaminated with crude oil. Through both morphological and biochemical methods, the bacterial strain that had the highest biodegrading capacity was identified as Zoogloea sp. On the basis of these preliminary results, a biological contact oxidation method was employed to further assess the ability of the Zoogloea sp. strain to treat wastewater contaminated by No. 20 lubricating oil using three oxidation cabins and two hydraulic retaining times (HRT). Results showed that the concentration of No. 20 lubricating oil with a 12 h hydraulic retaining time and 16.5 L h −1 inflow rate was reduced by 99.3% in 15 d, and with a 6 h hydraulic retaining time and 33 L h −1 inflow rate it decreased by 98.6% in 12 d. The results from this study indicated that Zoogloea sp. had a strong potential to be utilized in biodegradation of lubricating oil.

Trypsin (E.C. 3.4.21.4) was covalently immobilised onto a membrane of a cellulosic exopolysaccharide produced by Zoogloea sp. in sugarcane molasses. Carbonyl groups were introduced into the matrix by sodium metaperiodate oxidation and the enzyme was immobilised either directly or through bovine serum albumin (BSA) as a spacer. The trypsin-membrane and trypsin–BSA-membrane retained, respectively, 37.2% and 9.16% of the specific activity of the native enzyme acting on N -benzoil- dl -arginine- p -nitroanilide (BAPNA). No activity decrease was observed in both preparations after seven reutilisations as well as they showed to be more thermal stable than the native enzyme. The trypsin–BSA-membrane presented the same initial activity (99%) after 54 days stored in 0.1 M Tris–HCl buffer, pH 8.0, at 4 °C but the trypsin-membrane lost 15% of activity. Furthermore, the trypsin–BSA-membrane lost 31% of activity after reuse at 9 days interval during 54 days of storage at 4 °C whereas the trypsin-membrane lost 69% of activity under the same conditions. These results showed an additional application for this biofilm, namely, to act as a reusable matrix for trypsin immobilisation and the presence of BSA improved the derivative performance.

The environmental fate of polycyclic aromatic hydrocarbons (PAHs) in soils is motivated by their wide distribution, high persistence, and potentially deleterious effect on human health. Polycyclic aromatic hydrocarbons constitute the largest group of environmental contaminants released in the environment. Therefore, the potential biodegradation of these compounds is of vital importance. A biocarrier suitable for the colonization by micro-organisms for the purpose of purifying soil contaminated by polycyclic aromatic hydrocarbons was developed. The optimized composition of the biocarrier was polyvinyl alcohol (PVA) 10%, sodium alginate (SA) 0.5%, and powdered activated carbon (PAC) 5%. There was no observable cytotoxicity of biocarriers on immobilized cells and a viable cell population of 1.86 x 10(10) g(-1) was maintained for immobilized bacterium. Biocarriers made from chemical methods had a higher biodegradation but lower mechanical strengths. Immobilized bacterium Zoogloea sp. had an ideal capability of biodegradation for phenanthrene and pyrene over a relative wide concentration range. The study results showed that the biodegradation of phenanthrene and pyrene reached 87.0 and 75.4%, respectively, by using the optimal immobilized method of Zoogloea sp. cultivated in a sterilized soil. Immobilized Zoogloea sp. was found to be effective for biodegrading the soil contaminated with phenanthrene and pyrene. Even in natural (unsterilized) soil, the biodegradation of phenanthrene and pyrene using immobilized Zoogloea sp. reached 85.0 and 67.1%, respectively, after 168 h of cultivation, more than twice that achieved if the cells were not immobilized on the biocarrier. Therefore, the immobilization technology enhanced the competitive ability of introduced micro-organisms and represents an effective method for the biotreatment of soil contaminated with phenanthrene and pyrene.

The quaternary ammonium alcohols (QAAs) 2,3-dihydroxypropyl-trimethyl-ammonium (TM), dimethyl-diethanol-ammonium (DM) and methyl-triethanol-ammonium (MM) are hydrolysis products of their parent esterquat surfactants, which are widely used as softeners in fabric care. We isolated several bacteria growing with QAAs as the sole source of carbon and nitrogen. The strains were compared with a previously isolated TM-degrading bacterium, which was identified as a representative of the species Pseudomonas putida (Syst. Appl. Microbiol. 24 (2001) 252). Two bacteria were isolated with DM, referred to as strains DM 1 and DM 2, respectively. Based on 16S-rDNA analysis, they provided 97% (DM 1) and 98% (DM 2) identities to the closest related strain Zoogloea ramigera Itzigsohn 1868AL. Both strains were long, slim, motile rods but only DM 1 showed the floc forming activity, which is typical for representatives of the genus Zoogloea. Using MM we isolated a Gram-negative, non-motile rod referred to as strain MM 1. The 16S-rDNA sequence of the isolated bacterium revealed 94% identities (best match) to Rhodobacter sphaeroides only. The strains MM 1 and DM 1 exclusively grew with the QAA which was used for their isolation. DM 2 was also utilizing TM as sole source of carbon and nitrogen. However, all of the isolated bacteria were growing with the natural and structurally related compound choline.

For simultaneous identification of members of the betaproteobacterial order “ Rhodocyclales ” in environmental samples, a 16S rRNA gene-targeted oligonucleotide microarray (RHC-PhyloChip) consisting of 79 probes was developed. Probe design was based on phylogenetic analysis of available 16S rRNA sequences from all cultured and as yet uncultured members of the “ Rhodocyclales .” The multiple nested probe set was evaluated for microarray hybridization with 16S rRNA gene PCR amplicons from 29 reference organisms. Subsequently, the RHC-PhyloChip was successfully used for cultivation-independent “ Rhodocyclales ” diversity analysis in activated sludge from an industrial wastewater treatment plant. The implementation of a newly designed “ Rhodocyclales ”-selective PCR amplification system prior to microarray hybridization greatly enhanced the sensitivity of the RHC-PhyloChip and thus enabled the detection of “ Rhodocyclales ” populations with relative abundances of less than 1% of all bacteria (as determined by fluorescence in situ hybridization) in the activated sludge. The presence of as yet uncultured Zoogloea- , Ferribacterium / Dechloromonas -, and Sterolibacterium -related bacteria in the industrial activated sludge, as indicated by the RHC-PhyloChip analysis, was confirmed by retrieval of their 16S rRNA gene sequences and subsequent phylogenetic analysis, demonstrating the suitability of the RHC-PhyloChip as a novel monitoring tool for environmental microbiology.

Poly-3-hydroxybutyrate (PHB) granules of Zoogloea ramigera I-16-M contained two major PHB granule-associated proteins (PGA12 and PGA16) as revealed by sodium dodecyl sulfate-polyacrylamide gel elecrophoresis. N-terminal amino acid sequences of these proteins were determined. The genes encoding these proteins were cloned and sequenced. The structural genes of PGA12 and PGA16 were 351 and 447 bp long, which encode polypeptides with deduced molecular masses of 12.3 and 16.0 kDa, respectively. PGA12 and PGA16 were expressed in Escherichia coli. PHB granules were isolated from cells of recombinant strains of E. coli JM109, which harbored and expressed the PHB-synthetic genes of Ralstonia eutropha H16 and PGA12 or PGA16. These PHB granules contained PGA12 or PGA16 as a major protein. The presence of pga12 or pga16 did not affect the amount of PHB synthesized in E. coli. PGA12 and PGA16 bound to crystalline and amorphous PHB granules.

For preliminary screening for and characterization of free-living nitrogen-fixing bacteria from rhizoplane microflora, we used Winogradsky's mineral mixture-based nitrogen-free medium solidified with 0.3% gellan gum. The soft gel medium enabled some reference and wild free-living nitrogen-fixing bacteria to grow in characteristic colonies, including their reaction to oxygen and their motility change. Gellan gum is thus likely to be a better gel matrix than agarose for the investigation of root-associating, free-living nitrogen-fixing bacteria to identify their characteristic behaviors.

The enrichment and characterization of anaerobic ammonium-oxidizing biofilm cultures are ongoing in our laboratories. Biomass, with a predominately red color, demonstrating simultaneous removal of ammonium and nitrite under autotrophic and anoxic conditions, which is characteristic of anaerobic ammonium-oxidizing planctomycetes, was enriched and maintained for an extended period on a polyester nonwoven carrier. To investigate the bacterial composition of the mature biofilm community, 16S rDNA sequences were amplified by PCR and comparative analyses using DNA databases were conducted. Only one sequence had a notable similarity (92.2%) to that of the first discovered anaerobic ammonium-oxidizing planctomycete and lesser, yet significant, similarities to the 16S rDNA sequences of other recently reported anaerobic ammonium-oxidizing strains. The newly discovered strain (designated KSU-1) reported here was dominant among detectable members of the biofilm community. By fluorescence imaging, KSU-1 was shown to form spherical clusters wrapped in a thin layer of Zoogloea sp. Possible interactions and interdependencies of these two species are discussed with regard to the putative unculturability of the anaerobic ammonium-oxidizing planctomycetes.

A newly isolated marine bacterium, identified as Zoogloea sp., produced two different polysaccharides: one was water-soluble and the other was cell-bound. Both had non-Newtonian, pseudoplastic fluid behaviour and the solutions had low activation energies. The solutions of these polysaccharides showed rheological behaviour over a wide range of pH (2–12) and temperature (20–80 °C), and compatibility with NaCl.

Nitrogen is considered to be one of the most widespread pollutants leading to eutrophication of freshwater ecosystems, especially in drinking water reservoirs. In this study, an oligotrophic aerobic denitrifier was isolated from drinking water reservoir sediment. Nitrogen removal performance was explored. The strain was identified by 16S rRNA gene sequence analysis as Zoogloea sp. N299. This species exhibits a periplasmic nitrate reductase gene (napA). Its specific growth rate was 0.22 h−1. Obvious denitrification and perfect nitrogen removal performances occurred when cultured in nitrate and nitrite mediums, at rates of 75.53% ± 1.69% and 58.65% ± 0.61%, respectively. The ammonia removal rate reached 44.12% ± 1.61% in ammonia medium. Zoogloea sp. N299 was inoculated into sterilized and unsterilized reservoir source waters with a dissolved oxygen level of 5–9 mg/L, pH 8–9, and C/N 1.14:1. The total nitrogen removal rate reached 46.41% ± 3.17% (sterilized) and 44.88% ± 4.31% (unsterilized). The cell optical density suggested the strain could survive in oligotrophic drinking water reservoir water conditions and perform nitrogen removal. Sodium acetate was the most favorable carbon source for nitrogen removal by strain N299 (p &lt, 0.05). High C/N was beneficial for nitrate reduction (p &lt, 0.05). The nitrate removal efficiencies showed no significant differences among the tested inoculums dosage (p &gt, 0.05). Furthermore, strain N299 could efficiently remove nitrate at neutral and slightly alkaline and low temperature conditions. These results, therefore, demonstrate that Zoogloea sp. N299 has high removal characteristics, and can be used as a nitrogen removal microbial inoculum with simultaneous aerobic nitrification and denitrification in a micro-polluted reservoir water ecosystem.

This study aimed to investigate biofilm properties evolution coupled with different ages during the start-up period in a moving bed biofilm reactor system. Physicochemical characteristics including adhesion force, extracellular polymeric substances (EPS), morphology as well as volatile solid and microbial community were studied. Results showed that the formation and development of biofilms exhibited four stages, including (I) initial attachment and young biofilm formation, (II) biofilms accumulation, (III) biofilm sloughing and updating, and (IV) biofilm maturation. During the whole start-up period, adhesion force was positively and significantly correlated with the contents of EPS, especially the content of polysaccharide. In addition, increased adhesion force and EPS were beneficial for biofilm retention. Gram-negative bacteria mainly including Sphaerotilus, Zoogloea and Haliscomenobacter were predominant in the initial stage. Actinobacteria was beneficial to resist sloughing. Furthermore, filamentous bacteria were dominant in maturation biofilm.

A floc-forming, Gram-stain-negative, petroleum hydrocarbon-degrading bacterial strain, designated BucT, was isolated from a petroleum hydrocarbon-contaminated site in Hungary. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BucT formed a distinct phyletic lineage within the genus Zoogloea . Its closest relative was found to be Zoogloea caeni EMB43T (97.2 % 16S rRNA gene sequence similarity) followed by Zoogloea oryzae A-7T (95.9 %), Zoogloea ramigera ATCC 19544T (95.5 %) and Zoogloea resiniphila DhA-35T (95.4 %). The level of DNA–DNA relatedness between strain BucT and Z. caeni EMB43T was 31.6 %. Cells of strain BucT are facultatively aerobic, rod-shaped, and motile by means of a polar flagellum. The strain grew at temperatures of 5–35 °C (optimum 25–28 °C), and at pH 6.0–9.0 (optimum 6.5–7.5). The predominant fatty acids were C16 : 0, C10 : 0 3-OH, C12 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The major respiratory quinone was ubiquinone-8 (Q-8) and the predominant polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 63.2 mol%. On the basis of the chemotaxonomic, molecular and phenotypic data, isolate BucT is considered to represent a novel species of the genus Zoogloea , for which the name Zoogloea oleivorans sp. nov. is proposed. The type strain is BucT ( = DSM 28387T = NCAIM B 02570T).

In this study, Illumina high-throughput sequencing was used to reveal the community structures of nine coking wastewater treatment plants (CWWTPs) in China for the first time. The sludge systems exhibited a similar community composition at each taxonomic level. Compared to previous studies, some of the core genera in municipal wastewater treatment plants such as Zoogloea, Prosthecobacter and Gp6 were detected as minor species. Thiobacillus (20.83%), Comamonas (6.58%), Thauera (4.02%), Azoarcus (7.78%) and Rhodoplanes (1.42%) were the dominant genera shared by at least six CWWTPs. The percentages of autotrophic ammonia-oxidizing bacteria and nitrite-oxidizing bacteria were unexpectedly low, which were verified by both real-time PCR and fluorescence in situ hybridization analyses. Hierarchical clustering and canonical correspondence analysis indicated that operation mode, flow rate and temperature might be the key factors in community formation. This study provides new insights into our understanding of microbial community compositions and structures of CWWTPs.

Recently, a new type of organic pollution derived from pharmaceuticals and personal care products (PPCPs) is gradually on the rise. Wastewater treatment to remove PPCPs was investigated using an aerobic granular sludge sequencing bioreactor (GSBR). After optimization of influent organic load, hydraulic shear stress, sludge settling time, etc., aerobic granular sludge was analyzed for its physiological and biochemical characteristics and tested for its efficacy to remove PPCPs wastewater. The granular sludge effectively removed some but not all of the PPCPs tested; removal correlated with the microbial profiles in the granules, as assessed using Solexa sequencing technology. Sequencing revealed the presence of five phylogenetic groups: Proteobacteria, Bacteroidetes, Betaproteobacteria, an unclassified genus, and Zoogloea. The results demonstrated changes in the microbial profiles with time in response to the presence of PPCPs. The effects of PPCPs on microbial communities in granular sludge process are discussed.

In the last decades, research has focused on the capabilities of microbes to secrete exopolysaccharides (EPS), because these polymers differ from the commercial ones derived essentially from plants or algae in their numerous valuable qualities. These biopolymers have emerged as new polymeric materials with novel and unique physical characteristics that have found extensive applications. In marine microorganisms the produced EPS provide an instrument to survive in adverse conditions: They are found to envelope the cells by allowing the entrapment of nutrients or the adhesion to solid substrates. Even if the processes of synthesis and release of exopolysaccharides request high-energy investments for the bacterium, these biopolymers permit resistance under extreme environmental conditions. Marine bacteria like Bacillus, Halomonas, Planococcus, Enterobacter, Alteromonas, Pseudoalteromonas, Vibrio, Rhodococcus, Zoogloea but also Archaea as Haloferax and Thermococcus are here described as EPS producers underlining biopolymer hyperproduction, related fermentation strategies including the effects of the chemical composition of the media, the physical parameters of the growth conditions and the genetic and predicted experimental design tools. © 2014 by the authors; licensee MDPI.

The stimulation of groundwater bacteria to form biofilms, for the remediation of polluted aquifers, is subjected to environmental regulations that include measurement of effects on microbial biodiversity. Groundwater microorganisms contain a proportion of unidentified and uncharacterized ultramicrobacteria (UMB) that might play a major role in the bioclogging of geological materials. This study aimed to assess the changes in genetic and metabolic biodiversity when a community of UMB, isolated from groundwater, is stimulated to form biofilms on a ceramic surface. UMB were stimulated with aerobic conditions and injection of molasses, in reactors reproducing groundwater composition and temperature. Concentration of planktonic viable UMB, secretion of extracellular polymeric substances (EPS), and biofilm thickness were monitored. The assessment of changes in biodiversity was achieved by comparing the initial UMB community to the biofilm community, using the single strand conformational polymorphism (SSCP) method, the cloning and sequencing of 16S rRNA gene (16S rDNA) sequences, and the Biolog microplate system. The hypothesis stating that indigenous UMB would play a significant role of in the biofilm development was corroborated. Within 13 days of stimulation, the UMB produced 700 mg L?1 of planktonic EPS and formed a biofilm up to a thickness of 1100 mm. This stimulation led to a decrease in genetic diversity and an increase in metabolic diversity. The decrease in genetic diversity was shown by a reduced number of single strand DNA fragments in the SSCP profiles. As such, 16S rDNA sequences from the biofilm revealed the predominance of four bacterial groups: Zoogloea, Bacillus/Paenibacillus, Enterobacteriaceae, and Pseudomonads. A significant increase in metabolic diversity was shown by a highest substrate richness profile and a lower substrate evenness profile of the biofilm bacterial population (p = 0.0 and p = 0.09, respectively). This higher metabolic diversity might be a consequence of the stimulation that seemed to favor the growth of bacteria having a high nutritional versatility. Stimulation of UMB, isolated from groundwater, was effective to form a biofilm having a high metabolic biodiversity. This combination of molecular-based and metabolic-based methods expanded the insight into monitoring the changes in bacterial biodiversity.

An extracellular polysaccharide producing bacterium Zoogloea sp. was isolated from an agro-industrial environment in the north-eastern region of Brazil. The extracellular polysaccharide produced from sugarcane molasses was hydrolysed with trifluoroacetic acid (mild and strong conditions) giving 88% of soluble material. The main monosaccharides present in the soluble fraction were glucose (87.6%), xylose (8.6%), mannose (0.8%), ribose (1.7%), galactose (0.1%), arabinose (0.4%) and glucuronic acid (0.8%). Methylation analysis of the polysaccharide showed mainly 2,3,6-tri- O -methylhexitol (74.7%) and 2,3,-di- O -methylhexitol (17.7%). Enzyme hydrolysis of the polysaccharide with a cellulase confirmed the presence of (1→4)-β- d -glucopyranosyl residues.

Microscopic observations at an industrial wastewater treatment facility were conducted over a period of approximately 4 years to determine the relationship between the abundance of zoogleal clusters and sludge dewatering potential. Dewatering potential, measured as centrifuged solids content, was determined in sludge samples from an aeration basin. The abundance of zoogleal clusters and centrifuged solids content were negatively correlated, as determined by linear regression (r 2 = 0.62). Curve-fitting using an exponentially weighted moving average and a polynomial equation yielded r 2 = 0.82. Probing with small ribosomal subunit RNA (16S rRNA) oligonucleotide probes (ZRA and ZBE) indicated that the microorganisms forming these zoogleal clusters were not the same as previously classified Zoogloea ramigera strains (members of the beta subclass of Proteobacteria) isolated from other wastewater treatment systems. The microorganisms responsible for zoogleal cluster formation were identified using micromanipulator separation, cultivation, and 16S rRNA analysis. Distance matrix tree analysis of isolated strains revealed the presence of two types of microorganisms, referred to as mzt and mzl strains. The mzt isolates grouped most closely with members of the genus Thauera, whereas the mzl isolates grouped more closely with members of the genus Hydrogenophaga. Using 16S rRNA methods, a probe complementary to members of the genus Thauera (MZ1; S-G-Thau-0646-a-A-19) was designed to target mzt strains. Whole-cell hybridization with a fluorescein-labeled probe, coupled with epifluorescence microscopy, was used to verify the identity of the zoogleal cluster-forming organisms. Results indicated that the MZ1 probe hybridized specifically with zoogleal clusters present in sludge.

Background: Thiolases are ubiquitous and form a large family of dimeric or tetrameric enzymes with a conserved, five-layered α β α β α catalytic domain. Thiolases can function either degradatively, in the β -oxidation pathway of fatty acids, or biosynthetically. Biosynthetic thiolases catalyze the biological Claisen condensation of two molecules of acetyl-CoA to form acetoacetyl-CoA. This is one of the fundamental categories of carbon skeletal assembly patterns in biological systems and is the first step in a wide range of biosynthetic pathways, including those that generate cholesterol, steroid hormones, and various energy-storage molecules. Results: The crystal structure of the tetrameric biosynthetic thiolase from Zoogloea ramigera has been determined at 2.0 A resolution. The structure contains a striking and novel ‘cage-like' tetramerization motif, which allows for some hinge motion of the two tight dimers with respect to each other. The protein crystals were flash-frozen after a short soak with the enzyme's substrate, acetoacetyl-CoA. A reaction intermediate was thus trapped: the enzyme tetramer is acetylated at Cys89 and has a CoA molecule bound in each of its active-site pockets. Conclusions: The shape of the substrate-binding pocket reveals the basis for the short-chain substrate specificity of the enzyme. The active-site architecture, and in particular the position of the covalently attached acetyl group, allow a more detailed reaction mechanism to be proposed in which Cys378 is involved in both steps of the reaction. The structure also suggests an important role for the thioester oxygen atom of the acetylated enzyme in catalysis.

ImmobilizedZoogloea and zooglan in calcium alginate-silica matrix was shown to have a high adsorption capacity for Cu and Cd ions. Our results showed that Cu-ion uptake in the presence of Ca and Mg ions can be enhanced using immobilizedZoogloea and zooglan. Heavy metal ion adsorption efficiency decreased in the following order: Cu > Cd > Zn > Cr. The adsorbed metal ions were desorbed completely using sulfuric acid. ImmobilizedZoogloea and zooglan which was repetitively regenerated adsorbed heavy metal ions without a loss of adsorption capacity.

The addition effects of both Zoogloea ramigera and its extracellular zoogloeal polymer for enhancing the operation efficiency in biological wastewater treatment system were investigated. The zoogloeal culture which was composed of Zoogloea ramigera and its extracellular zoogloeal polymer was daily added to a lab‐scale activated sludge reactor for treating a tannery wastewater. Compared with controlled reactor without any addition of zoogloeal culture, COD and turbidity removal efficiency of activated sludge under the high organic loading and unbalanced nutrient condition were enhanced by the addition of the zoogloeal culture. Meanwhile, higher yield and lower decay of microorganisms were also obtained in zoogloeal culture added reactor. The activated sludge with the addition of zoogloea culture was well adapted with high organic loading and unbalanced nutrient condition.

Changes in bacterial colonisation on initially clean sand grains in an anaerobic fluidised bed reactor (FBR) were studied by scanning electron microscopy (SEM). The FBR was part of a laboratory-scale treatment system for nitrate removal from fish culture water. Denitrifying bacteria in the FBR were supplied with anaerobically digested fish feed as carbon and energy source and with nitrate as electron acceptor. Bacterial biofilm formation started rapidly with single rods settling in the fissures and cavities on the sand grain's surface. Rods (Pseudomonas-like and Zoogloea-like) divided and accumulated and after about 10 days were integrated in a biofilm which almost covered the entire grains. Apart from single rods, colonies of bacteria resembling Zoogloea developed from the second day onwards. After approximately 10 days, the zoogloeal colonies were overgrown by bacteria resembling Pseudomonas. A steady increase in these cells was observed, eventually leading to a situation in which the majority of grains were totally covered with a compact biofilm comprised of these bacteria. The biofilm increased in thickness with time and around day 20, sloughing was observed at parts of the biofilm surface. These sloughed areas were colonised once more with bacteria according to a similar succession pattern observed on the initially clean sand grains. The colonisation pattern on sand in the laboratory-scale FBR was compared to the colonisation on sand grains in an FBR, operating in a pilot-plant of a closed intensive fish culture system. The bacterial biofilm structure was similar in both reactors. In the pilot-plant FBR all different stages of colonisation, observed in the laboratory-scale FBR, occurred simultaneously. Also in the pilot-plant FBR, bacteria resembling Zoogloea and Pseudomonas were most abundant.

Zooglans with altered sugar composition were synthesized by Zoogloea ramigera by varying the glucose concentration and initial medium pH. The relative mol % of the sugar components, glucose and galactose, in the exopolymer made with 2% (w/v) glucose as the carbon source was 66 and 34%, respectively. By varying the glucose concentration and initial medium pH, the mol % ratios of glucose to galactose in zooglan ranged from 70 : 30 to 58 : 42. Also, glucose analogs, 3- O-methyl-D-glucose, 2-amino-2-deoxy-D-glucose, and 2-acetamido-2-deoxy-D-glucose, were used as a co-substrate with glucose to produce modified zooglans. The mol % ratios of glucose to galactose in exopolymers produced by co-feeding glucose analogs ranged from 70 : 30 to 9 : 91.

An aerobic granular sludge, cultivated with modified piggery wastewater, was capable of simultaneously removing COD and N at high COD and N loading rates. Confirmed to be identical with the DGGE band B9, isolate Thauera strain TN9 was the most dominant microorganism in the granular sludge. NirS and NosZ gene were amplified and sequenced from strain TN9 suggested it is crucial to N removal. Some other dominant DGGE bands belonged to Zoogloea and TM7, might play important roles in the formation and the stabilization of the granules. Meanwhile, no AOA amoA or anammox bacterium hzo gene was detected in the granules. All amoA clone libraries of AOB were clustered to Nitrosomonas. Yet those AOB were not present in DGGE dominant bands. Therefore, the heterotrophic nitrification and autotrophic nitrification coexist in the granules, the heterotrophic nitrification might contribute more to the N removal at high COD and N loading rates.

The effect of short-time aerobic digestion on bioflocculation of extracellular polymeric substances (EPSs) from waste activated sludge (WAS) was investigated. Bioflocculation of the EPS was found to be enhanced by 2∼6 h of WAS aerobic digestion under the conditions of natural sludge pH (about 7), high sludge concentration by gravity thickening, and dissolved oxygen of about 2 mg/L. With the same EPS extraction method, the total suspended solid content reduction of 0.20 and 0.36 g/L and the volatile suspended solid content reduction of 0.19 and 0.26 g/L were found for the WAS samples before and after aerobic digestion of 4 h. It indicates that more EPS is produced by short-time aerobic digestion of WAS. The scanning electron microscopy images of the WAS samples before and after aerobic digestion of 4 h showed that more EPS appeared on the surface of zoogloea by aerobic digestion, which reconfirmed that WAS aerobic digestion induced abundant formation of EPS. By WAS aerobic digestion, the flocculating rate of the EPS showed about 31 % growth, almost consistent with the growth of its yield (about 34 %). The EPSs obtained before and after the aerobic digestion presented nearly the same components, structures, and Fourier transform infrared spectra. These results revealed that short-time aerobic digestion of WAS enhanced the flocculation of the EPS by promoting its production.

The community of whole microbes and antibiotic resistance bacteria (ARB) in hospital wastewater treatment plants (WWTP) receiving domestic wastewater (DWW) and hospital wastewater (HWW) was investigated. Samples from an influent of a secondary clarifier, at each treatment train, were characterized for the whole microbial community and ARB on the antibiotic resistance database, based on high-throughput pyrosequencing. The pyrosequencing analysis revealed that the abundance of Bacteroidetes in the DWW sample was higher (~1.6 times) than in the HWW sample, whereas the abundance of Proteobacteria in the HWW sample was greater than in the DWW sample. At the top twenty of the genus level, distinct genera were observed—Saprospiraceae in the DWW and Zoogloea in the HWW. Apart from the top twenty genera, minor genera showed various antibiotic resistance types based on the antibiotic resistance gene database.

Eleven isolates capable of growth on the resin acid dehydroabietic acid (DhA) were obtained from a sequencing batch reactor designed to treat a high-strength process stream from a paper mill. The isolates belonged to two groups, represented by strains DhA-33 and DhA-35, which were characterized. In the bioreactor, bacteria like DhA-35 were more abundant than those like DhA-33. The population in the bioreactor of organisms capable of growth on DhA was estimated to be 1.1 x 10(6) propagules per ml, based on a most-probable-number determination. Analysis of small-subunit rRNA partial sequences indicated that DhA-33 was most closely related to Sphingomonas yanoikuyae (Sab = 0.875) and that DhA-35 was most closely related to Zoogloea ramigera (Sab = 0.849). Both isolates additionally grew on other abietanes, i.e., abietic and palustric acids, but not on the pimaranes, pimaric and isopimaric acids. For DhA-33 and DhA-35 with DhA as the sole organic substrate, doubling times were 2.7 and 2.2 h, respectively, and growth yields were 0.30 and 0.25 g of protein per g of DhA, respectively. Glucose as a cosubstrate stimulated growth of DhA-33 on DhA and stimulated DhA degradation by the culture. Pyruvate as a cosubstrate did not stimulate growth of DhA-35 on DhA and reduced the specific rate of DhA degradation of the culture. DhA induced DhA and abietic acid degradation activities in both strains, and these activities were heat labile. Cell suspensions of both strains consumed DhA at a rate of 6 mumol mg of protein-1 h-1.(ABSTRACT TRUNCATED AT 250 WORDS)

This study aimed to investigate the effect of temperature variation on membrane fouling and microbial community in a membrane bioreactor (MBRs). The results indicated that extracellular polymer substances (EPS) and soluble microbial products (SMPs) increased due to decreasing temperature, which triggered membrane fouling as evidenced by the trans-membrane pressure (TMP) increase rate. Moreover, fluorescent intensity variations in the excitation-emission matrix (EEM) fluorescence spectroscopy of SMPs were closely related to rapid increase in TMP, suggesting that they might be used to monitor SMPs variations and indicate membrane performance. In addition, 16S rRNA clone library and sequence analyses results demonstrated the predominant phyla were always Proteobacteria, Nitrospira and Bacteroidetes. However, at lower temperature, α-proteobacteria and some filamentous bacteria such as Actinobacteria, Haliscomenobacteria and Thiothrix were relatively rich. At higher temperature, Zoogloea showed its presence. Detrended correspondence analysis (DCA) and Mantel test results also demonstrated that temperature had strongly influence on microbial community.

Aerobic granular sludge is attractive for high-rate biological wastewater treatment. Biomass wash-out conditions stimulate the formation of aerobic granules. Deteriorated performances in biomass settling and nutrient removal during start-up have however often been reported. The effect of wash-out dynamics was investigated on bacterial selection, biomass settling behavior, and metabolic activities during the formation of early-stage granules from activated sludge of two wastewater treatment plants (WWTP) over start-up periods of maximum 60 days. Five bubble-column sequencing batch reactors were operated with feast-famine regimes consisting of rapid pulse or slow anaerobic feeding followed by aerobic starvation. Slow-settling fluffy granules were formed when an insufficient superficial air velocity (SAV; 1.8 cm s-1) was applied, when the inoculation sludge was taken from a WWTP removing organic matter only, or when reactors were operated at 30°C. Fast-settling dense granules were obtained with 4.0 cm s-1 SAV, or when the inoculation sludge was taken from a WWTP removing all nutrients biologically. However, only carbon was aerobically removed during start-up. Fluffy granules and dense granules were displaying distinct predominant phylotypes, namely filamentous Burkholderiales affiliates and Zoogloea relatives, respectively. The latter were predominant in dense granules independently from the feeding regime. A combination of insufficient solid retention time and of leakage of acetate into the aeration phase during intensive biomass wash-out was the cause for the proliferation of Zoogloea spp. in dense granules, and for the deterioration of BNR performances. It is however not certain that Zoogloea-like organisms are essential in granule formation. Optimal operation conditions should be elucidated for maintaining a balance between organisms with granulation propensity and nutrient removing organisms in order to form granules with BNR activities in short start-up periods.

Microbial biofilms formed on the inner-pipe surfaces of drinking water distribution systems (DWDS) can alter drinking water quality, particularly if they are mechanically detached from the pipe wall to the bulk water, such as due to changes in hydraulic conditions. Results are presented here from applying 454 pyrosequencing of the 16S ribosomal RNA (rRNA) gene to investigate the influence of different hydrological regimes on bacterial community structure and to study the potential mobilisation of material from the pipe walls to the network using a full scale, temperature-controlled experimental pipeline facility accurately representative of live DWDS. Analysis of pyrosequencing and water physico-chemical data showed that habitat type (water vs. biofilm) and hydraulic conditions influenced bacterial community structure and composition in our experimental DWDS. Bacterial community composition clearly differed between biofilms and bulk water samples. Gammaproteobacteria and Betaproteobacteria were the most abundant phyla in biofilms while Alphaproteobacteria was predominant in bulk water samples. This suggests that bacteria inhabiting biofilms, predominantly species belonging to genera Pseudomonas, Zooglea and Janthinobacterium, have an enhanced ability to express extracellular polymeric substances to adhere to surfaces and to favour co-aggregation between cells than those found in the bulk water. Highest species richness and diversity were detected in 28 days old biofilms with this being accentuated at highly varied flow conditions. Flushing altered the pipe-wall bacterial community structure but did not completely remove bacteria from the pipe walls, particularly under highly varied flow conditions, suggesting that under these conditions more compact biofilms were generated. This research brings new knowledge regarding the influence of different hydraulic regimes on the composition and structure of bacterial communities within DWDS and the implication that this might have on drinking water quality.

Polyhydroxyalkanoate (PHA) is a class of biodegradable plastics that have great potential applications in the near future. In this study, the micro-biodiversity and productivity of PHA-accumulating bacteria in activated sludge from a domestic wastewater treatment plant were investigated. A previously reported primer set and a selfdesigned primer set (phaCF1BO/phaCR2BO) were both used to amplify the PHA synthase (phaC) gene of isolated colonies. The new primers demonstrated higher sensitivity for phaC, and combining the PCR results of the two primer sets was able to widen the range of detected genera and raise the sensitivity to nearly 90%. Results showed that 85.3% of the identified bacteria were Gram-negative, with Ralstonia as the dominant genus, and 14.7% were Gram-positive. In addition, Zoogloea and Rhizobium contained the highest amounts of intracellular PHA. It is apparent that glucose was a better carbon source than pentone or tryptone for promoting PHA production in Micrococcus. Two different classes, class I and class II, of phaC were detected from alphaproteobacteria, betaproteobacteria, and gammaproteobacteria, indicating the wide diversity of PHA-accumulating bacteria in this particular sampling site. Simultaneous wastewater treatment and PHA production is promising by adopting the high PHAaccumulating bacteria isolated from activated sludge.

An extracellular polysaccharide producing bacterium Zoogloea sp. was isolated from marine environments. This strain could produce two different polysaccharides. One (water-soluble polysaccharide : WSP) was from cell-free liquid medium, the other (cell-bound polysaccharide : CBP) was obtained from cell surface. Both polysaccharides contained glucose, galactose and mannose as sugar components, but their molar ratios were different (WSP : 2:2:3, CBP : 1:2:2) and half of the sugar components existed as uronic acid form. Both polysaccharide productions started at the early stage of the logarithmic growth phase. The amount of WSP and CBP was influenced by culture conditions such as additional carbon and nitrogen sources. Isolated Zoogloea sp. showed a high product yield without the increase of cell mass.

An abundant growth of zoogloeal colonies was observed periodically during some experiments carried out on a bench-scale plant fed with a complex synthetic wastewater. The plant had a configuration with an enhanced regeneration-denitrification-nitrification (R-D-N) activated sludge process for low alkalinity wastewaters. Several operational changes were undertaken in order to suppress the excessive growth of zoogloeal colonies. They included: (1) changes in the wastewater composition, (2) volume changes in the compartmentalization of the anoxic selector, (3) increase of D.O. concentration in the regeneration and nitrification tanks. Conclusions from the plant operation observations give rise to a hypothesis that none of the operational changes provoked a significant restriction in the abundant zoogloeal growth. When a temporary improvement was observed, after acclimatization on the new operational conditions the microorganisms culture returned to its previous state and continued to grow in a wave-mode. The reason for the appearance of this type of sludge might be closely related to the composition of the synthetic wastewater.

The experimental study of aerobic granular sludge in sequencing batch reactor (SBR) was performed using a synthetic domestic wastewater and ordinary flocculent activated sludge from the third Sewage Treatment Plant in Xi'an as seeding sludge. The aerobic granular sludge was cultivated successfully when the superficial upflow air velocity was 1.06∼1.77 cm/s. The study suggests that the formation of granular sludge is a process of the formation of micro-ecological system. Hydraulic shear stress is a significant impact factor of its formation, which affects the composition of microbial population structure and distribution in aerobic granular sludge. From the analysis of the relationship between filamentous microorganisms and microbial community, zoogloea and filamentous bacteria depend on each other. The filamentous microorganisms formed floc skeleton, which provide the necessary condition for floc to form larger floc particles.

A crude oil degrading strain SY1 was isolated from the soil contaminated by crude oil. The strain SY1 could utilize crude oil as the sole carbon source. The strain was identified as a member in Zoogloea species (Zoogloea sp. Strain SY1). After the domestication of SY1, the biodegradation rate of crude oilcan reach 41.3% under the condition of without the addition of inorganic nutrients. Based on the experimental results, the optimal cultivation temperature, cultivation time, and the pHof the SY1 seed liquid were determined. The enzyme-catalyzed kinetic model was also established.

A variety of antibiotics and their metabolites at sub-inhibitory level concentrations are suspected to expand resistance genes in the environment. However, knowledge is limited on the causal correlation of trace antibiotics or their metabolites with resistance proliferation. In this study, erythromycin (ERY) resistance genes were screened on microbial consortia of sequencing batch reactors (SBRs) after one year acclimation to ERY (100 μg/L) or dehydrated erythromycin (ERY-H(2)O, 50 μg/L). The identified esterase gene ereA explains that ERY could be degraded to six products by microbes acclimated to ERY (100 μg/L). However, ERY could not be degraded by microbes acclimated to ERY-H(2)O (50 μg/L), which may be due to the less proliferated ereA gene. Biodegradation of ERY required the presence of exogenous carbon source (e.g., glucose) and nutrients (e.g., nitrogen, phosphorus) for assimilation, but overdosed ammonium-N (>40 mg/L) inhibited degradation of ERY. Zoogloea, a kind of biofilm formation bacteria, became predominant in the ERY degradation consortia, suggesting that the input of ERY could induce biofilm resistance to antibiotics. Our study highlights that lower μg/L level of ERY or ERY-H(2)O in the environment encourages expansion of resistance genes in microbes.

Phylogenetic relationships among strains of Zoogloea and related taxa were determined by 16S rDNA sequencing and genomic DNA hybridization techniques. The 16S rRNA gene was amplified by the polymerase chain reaction with a pair of eubacterial consensus primers and sequenced directly by using an automated fluorescent DNA sequencer. Sequence comparisons and distance matrix tree analysis revealed that Zoogloea ramigera IAM 12136 (= N. C. Dondero 106, type strain) and Zoogloea sp. ATCC 19324 formed a lineage with Rhodocyclus purpureus in the beta subclass of Proteobacteria. Z. ramigera IAM 12670 (= P. R. Dugan 115) was shown to belong to another cluster with Alcaligenes eutrophus and Pseudomonas cepacia in the beta subclass. In contrast, Z. ramigera IAM 12669 (= K. Crabtree I-16-M) proved to be a member of the alpha subclass of the Proteobacteria, closely related to Agrobacterium tumefaciens. Genomic DNA hybridization studies also showed that there is genetic diversity among the strains currently designated Z. ramigera, but typical Zoogloea strains, characterized by their production of rhodoquinones, are highly related to each other and can be regarded as a single species. On the basis of the molecular data, together with the early phenotypic and chemotaxonomic information, we have emended the generic description of Zoogloea.

The paper describes the appearance of non-filamentous bulking in a lab-scale activated sludge plant with nitrification-denitrification and reaeration of return sludge. The inlet part of the denitrification zone was operated as an anoxic selector. Although filamentous microorganisms regularly occurred, the sludge settled properly. Deterioration of SVIs was observed after increasing the oleic acid concentration in synthetic wastewater. The bulking period was related to the abundant growth of viscous zoogloeal colonies. The intensive foam production resulted from the excessive appearance of exocellular polymers. A structure of short intertwined fingered projections formed the zoogloeal flocs. After decreasing the oleic acid proportion in the synthetic wastewater to the original level the zoogloeal flocs gradually changed to the well-settling sludge in 3 weeks.

Single-walled carbon nanotubes (SWNTs) are likely to become increasingly widespread and yet their environmental impact is not well understood. The purpose of the current study was to evaluate the impact of SWNTs on microbial communities in a 'sentinel' environmental system, activated sludge batch-scale reactors.Triplicate batch reactors were exposed to SWNTs and compared to control reactors exposed to impurities associated with SWNTs. Automated ribosomal intergenic spacer analysis (ARISA) was used to assess bacterial community structure in each reactor. SWNT exposure was found to impact microbial community structure, while SWNT-associated impurities had no effect, compared to controls. 16S rRNA gene sequence analysis indicated that dominant phylotypes detected by ARISA included members of the families Sphingomonadaceae and Cytophagacaceae and the genus Zoogloea. ARISA results indicated an adverse impact of SWNTs on the sphingomonad relative to other community members. Changes in community structure also occurred in both SWNT-exposed and control reactors over the experimental time period and with the date on which activated sludge was obtained from a wastewater treatment facility.These results indicate that SWNTs differentially impact members of the activated sludge reactor bacterial community.The finding that community structure was affected by SWNTs indicates that this emerging contaminant differentially impacted members of the activated sludge bacterial community and raises the concern that SWNTs may also affect the services it provides.

An innovative shortcut biological nitrogen removal system, consisting of an aerobic submerged membrane bioreactor (MBR) and an anaerobic packed-bed biofilm reactor (PBBR), was evaluated for treating high strength ammonium-bearing wastewater. The system was seeded with enriched ammonia-oxidizing bacteria (AOB) and operated without sludge purge with a decreased hydraulic retention time (HRT) through three phases. MBR was successful in both maintaining nitrite ratio over 0.95 and nitrification efficiency higher than 98% at HRT of 24 h, and PBBR showed satisfactory denitrification efficiency with very low effluent nitrite and nitrate concentration (both below 3 mg/L). By examining the nitrification activity of microorganism, it was found that the specific ammonium oxidization rate (SAOR) increased from 0.17 to 0.51 g N/(g VSS x d) and then decreased to 0.22 g N/(g VSS x d) at the last phase, which resulted from the accumulation of extracellular polymers substances (EPS) and inert matters enwrapping around the zoogloea. In contrast, the average specific nitrite oxidization rate (SNOR) is 0.002 g N/(g VSS x d), only 1% of SAOR. Because very little Nitrobactor has been detected by fluorescence in situ hybridization (FISH), it is confirmed that the stability of high nitrite accumulation in MBR is caused by a large amount of AOB.

Two floc-forming, nitrogen-fixing bacteria, strains EMB43(T) and EMB61, obtained from activated sludge of a domestic wastewater treatment plant in Korea, were characterized. The two strains were very closely related, sharing 99.7 % 16S rRNA gene sequence similarity and showing a level of DNA-DNA relatedness of 93 %, which suggests that they represent members of a single species. Phylogenetic analysis based on 16S rRNA gene sequences showed that the two novel isolates formed a distinct phyletic lineage within the genus Zoogloea and were related most closely to Zoogloea resiniphila DhA-35(T) and Zoogloea oryzae A-7(T), with sequence similarities of 97.2 %. Levels of DNA-DNA relatedness between strain EMB43(T) and Z. resiniphila DhA-35(T) and Z. oryzae A-7(T) were 12.8 and 7.4 %, respectively. Cells of strains EMB43(T) and EMB61 were facultatively aerobic, rod-shaped, Gram-negative and motile by means of a polar flagellum. The strains grew at temperatures of 15-40 degrees C (optimum: 25-30 degrees C) and at pH 6.0-9.0 (optimum: pH 6.5-7.5). The predominant fatty acids were C(16 : 0), C(10 : 0) 3-OH and summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH), and the predominant polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 64.9-65.0 mol% and the major isoprenoid quinone was ubiquinone-8 (Q-8). On the basis of phenotypic, chemotaxonomic and molecular data, the isolates are considered to represent a novel species of the genus Zoogloea, for which the name Zoogloea caeni sp. nov. is proposed. The type strain is EMB43(T) (=KCTC 22084(T)=DSM 19389(T)).

A study was carried out taking low temperature domestic wastewater as target in laboratory, the composition of bacteria in activated sludge was analyzed and the degradation kinetics of organics was investigated. Six preponderant psychrotrophs were selected out, belonging to Zoogloea, Aeromonas, Flavobacterium, Micrococcus, Bacillus and Pseudomonaus, respectively. Results show that TTC-dehydrogenase activity of the psychrotroph is 25.44 mg/(L x h) which is 20.5 times more than that of ordinary activated sludge at 4 degrees C. The efficiency of COD biodegradation by psychrotrophs at low and normal temperature is 80.9% and 73.4%, respectively. Mesophilic bacteria almost lost their activity at low temperature. Kinetic analysis shows that biodegradation of organics by psychrotrophs at low and mesothermal temperature as well as mesophilic bacteria at mesothermal temperature are in accordance with the model of first-order reaction. Psychrotrophs, which assure the removal efficiency of organic pollutants at low and normal temperature, could keep the uniform reaction velocity as the mesophilic bacteria and also adapt wide ecological amplitude of temperature. Efficient psychrotrophs were immobilized on soft polyurethane foams which acted as carriers in the experiment at 4 degrees C, as a result of that, the removal efficiency of COD was increased about 18% higher than that of mobilized ones at low temperature, the biodegradation kinetics of COD by immobilized psychrotrophs also followed the first-order reaction model. With glucose in water as the source of nutriment, the reaction velocity of immobilized bacteria is 2.35 times higher than that of the mobilized ones. By the immobilized psychrotrophs biodegradation of varied nutriment, the effluent could achieve the first-degree B of pollutants discharge standard for municipal wastewater treatment plant.

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.

A lab-scale vermifilter for domestic wastewater treatment was evaluated to the operational characteristics of the ceramsite-vermifilter. The effective removal rates of COD, NH4-N and TSS in the vermifilter were 50.9±6.9%, 69.3±4.9% and 91.9±1.8%, respectively. Microscopic observation of the vermifilter system showed that in the biofilm, zoogloea, rotifer and vorticella were observed, which indicated the good quality of effluent. The key species, the earthworm Eisenia fetida, decomposed the organics in the wastewater and also devoured the solids synchronously. The vermifiltration technology is a cost-effective for wastewater treatment, and the effluent could reach the latest standards of irrigation water quality in China, and could be used for crop irrigation without much concern for infection by sewage-borne pathogens.