• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.365-371
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• 1995

Filamentous bacteria and other large microorganisms, which are useful indicators of bulking and poeration, were identified by microscopic observation. Activated sludge samples were taken from the aeration basin of 5 municipal wasterwater plants and 6 industrial ones. Among the filamentous bacteria founds, Microthrix parvicella was most frequently present, followed by type 0041, type 1701 and Nocardia. This frequency of occurrence was similar to those reorted in USA and the Neterland. The morphology of filamentous bacteria observed were generally identical with those previously reported. except type 1701 which had slender filament diameter. Among protozoa, Vorticella was most frequently present, followed by Aspidisca, Opercularia and Difflugia. Philodina was the only metazoa observed. Both filamentous bacteria and protozoa would be useful indicator organisms. The potential for these organisms as indicators were discussed.

• Korean Journal of Microbiology
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• v.28 no.4
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• pp.337-344
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• 1990

Slime sampless from 10 ratating biological contactor (RBC) plants in New Jersey were microscopically examined. Filamentous bacteria such as Type 1701, Type 0041, Type 021N, Nocardia, Beggiatoa, and Sphaerotilus, which are commonly present as suspended forms also were found in RBC slimes growing as attached forms. However, the abundance wwas much different from that of activated sludge. In RBC slimes, Beggiatoa was most frequently observed filamentous bacteria and Sphaerotilus, Type 0041, Type 1701, Type 021N and Nocardia were present in decreasing order of abundance. There were morphologically two different types of Behhiatia in RBC slimes. The statistical anaysis shows that filamentous bacterial poulations between the 100 cm inside and the outside the RBC were different in most cases with significant interactions between the location and stage.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.377-382
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• 2013

Enriching anammox bacteria (AMX) in a lab-scale granular sequencing batch reactor using local digester centrate, we observed the significant enrichment of the filamentous-like bacterial population. These bacteria were revealed as novel bacterial species (termed CHL) belonging to Chlorobi/Bacteroidetes phyla via Denaturing Gradient Gel Electrophoresis (DGGE). Further, niche differentiation of AMX and CHL quantification was observed in granule and filament biomass, suggesting AMX was dominant in the granule and CHL was dominant in the filament. Therefore, it was confirmed the structural role of CHL was indeed to aid the granule formation of the AMX. In parallel, the physiological role of CHL was suspected to degrade biopolymers in the digester centrate using nitrate as an electron acceptor.

• Molecules and Cells
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• v.42 no.3
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• pp.228-236
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• 2019

CD4 T cells differentiate into $ROR{\gamma}t/IL$-17A-expressing cells in the small intestine following colonization by segmented filamentous bacteria (SFB). However, it remains unclear whether SFB-specific CD4 T cells can differentiate directly from naïve precursors, and whether their effector differentiation is solely directed towards the Th17 lineage. In this study, we used adoptive T cell transfer experiments and showed that naïve CD4 T cells can migrate to the small intestinal lamina propria (sLP) and differentiate into effector T cells that synthesize IL-17A in response to SFB colonization. Using single cell RT-PCR analysis, we showed that the progenies of SFB responding T cells are not uniform but composed of transcriptionally divergent populations including Th1, Th17 and follicular helper T cells. We further confirmed this finding using in vitro culture of SFB specific intestinal CD4 T cells in the presence of cognate antigens, which also generated heterogeneous population with similar features. Collectively, these findings indicate that a single species of intestinal bacteria can generate a divergent population of antigen-specific effector CD4 T cells, rather than it provides a cytokine milieu for the development of a particular effector T cell subset.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.834-837
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• 2002

A fluorescent glucose analogue,2-[N-(7-nitrobenz-2-ox a-1,3-diazol-4-yl) amino] -2- deoxy-D-glucose (2-NBDG), which had previously been developed for the analysis of glucose uptake in living cells, was investigated to determine its biological activity on microorganisms.2-NBDG did not show any inhibitory effect on growth of yeast cells and bacteria. In contrast, 2-NBDG exhibited strong inhibitory effects on filamentous fungal growth. The growth of filamentous fungi was completely inhibited, when 2-NBDG was supplemented as sole carbon source. The inhibitory effect was decreased by the addition of glucose in the test medium. Furthermore, 2-NBDC inhibited chitinase activity of Trichoderma sp. These results suggested that the inhibitory effects of 2-NBDG on filamentous fungi might be partially due to the inhibition of chitinase.

• Journal of Environmental Health Sciences
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• v.30 no.1
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• pp.7-14
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• 2004

The change in filamentous bacteria appearance was observed by adjusting factors such as organic and nurient concentration of feed wastewater and the aeration rate in the reactor. In case that COD:N:P and DO were 100:10:1 and 6.1 m1/1 respectively, the mean SVI was 122 ml/g and the filaments were developed normally in flocs. For the low DO con- dition, however, the SVI averaged 186 ml/g and the appearance of outgrowing filaments were more frequent. When the high organic was supplied into the reactor, the average SVI was 274 ml/g and the distinct filamentous bulking was observed. Meanwhile when COD:N:P was maintained at 100: 1 :0.5, the SVI was as low as 87 ml/g and the appearance of filaments were minimal and the size of flocs was small comparing other experimental conditions. For normal, low aeration and high organic concentration, predominant filaments in the early stage of experiments were commonly Type 021N,S. natans which were usually found in low DO condition. However, Type 041, Type 1851, Type 0961 became predominant as experiments extended. Meanwhile, in low nutrient condition, Type 0675, Type 1851, and Type 0961 were observed. The filamentous bacteria appearance for SVI< 150(ml/g), Type 0041, Type 0961 (usually low organic in feed wastewater) were predominantly observed and SVI > 150(ml/g), S. natans and Type 021N(usually low DO in aeration basin) was predominant.

• Membrane and Water Treatment
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• v.10 no.5
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• pp.331-338
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• 2019

This study aimed to investigate the membrane fouling and sludge characteristics in a pilot-scale submerged membrane bioreactor (MBR) operated under low temperature ($7^{\circ}C$). To elucidate the mechanisms of membrane fouling at low temperature, we studied the correlation between MBR performances and physicochemical properties of sludge including extracellular polymeric substance (EPS), relative hydrophobicity (RH) and floc size during long-term operation. The MBR was shown able to remove chemical oxygen demand (COD) stably and efficiently (>90 %) in the case of overgrowth of filamentous bacteria (bulking sludge) at low temperature. On the other hand, the occurrence of filamentous bulking greatly accelerated membrane fouling, as indicated by membrane filtration period of 14 days for filamentous bulking at $7^{\circ}C$, in comparison with that of 27 days for non-bulking sludge at $24^{\circ}C$ The overgrowth of filamentous bacteria resulting from low-temperature condition led to an increased release of EPS, higher RH, smaller floc size and lower fractal dimension of sludge. These factors accelerated the formation of compact cake layer on membrane surface in association with performance diminution in terms of increase in transmembrane pressure (TMP) of the membrane and thus the decrease in membrane permeability.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.506-511
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• 2004

Maintaining dissolved oxygen (DO) at sufficiently low concentration in the aeration tank at a wastewater treatment plant (WWTP) is essential for reduction of the costs of operation and maintenance. On the other hand, the low DO level may result in adverse effect on the integrity of the activated sludge, A typical and disastrous outcome frequently experienced is the outgrowth of filamentous microorganisms, which is called as filamentous bulking, In addition to the traditional methods such as sludge settleability and microscopic observation of the culture, molecular techniques including polymerase chain reaction (PCR) amplification followed by 16S rRNA sequencing were applied to identify filamentous bacteria present in bulking sludge under a condition of low DO concentration, Two morphologically distinct groups, presumably consisting of Sphaerofilus nafans, and Eikelboom Type 1701 or Type 1851, were identified through microscopic observation. They were further confirmed by subsequent 16S rRNA sequencing. Dominant filamentous bacteria identified by the molecular techniques were consisted of three major groups. Sequences of partial 16S rRNA cloned showed that the filamentous bulking organisms were closely related to Eikelboom Type 021N and Eikelboom Type 1701, and Sphaerotilus natans, respectively. Molecular methods were found to possess a strong potential of direct examination of the microbial community of an activated sludge system.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.754-759
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• 2011

A sequencing batch reactor (SBR) was operated under different pH conditions to better understand the influence of pH to granulation in enhanced biological phosphorus removal systems. Granules from the SBR were also investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Considerable decreases in the amount of phosphorus released per substrate provided under anaerobic conditions and the content of biomass polyphosphate under aerobic conditions were observed when pH was changed from 7.5 to 7.0, followed by 6.5. Aerobic granulation was also observed at pH 7.0. A number of bacteria with the typical morphological traits of tetrad-forming organisms (TFOs) were observed at pH 7.0, including large members of cluster. Filamentous bacteria were also there in large numbers. The occurrence and growth of granules were further enhanced at pH 6.5. A SEM analysis showed that the aerobic granules had a compact microbial structure with shaperical shape and morphologically consisted of aggregates of small coccoid bacteria and filamentous bacteria encapsulated by extracellular polymeric substance. The main material ions identified by EDX moreover revealed that the structural materials for polyphosphate in the granules include phosphorus, potassium and calcium. Therefore, these results strongly suggested that PAOs are a dominant population in the microbial community of the aerobic granules.

• Journal of fish pathology
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• v.9 no.1
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• pp.33-40
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• 1996

A filamentous form of mollicute-like bacterium was detected during a routine health survey of wild adult kuruma shrimp Penaeus japonicus. The kuruma shrimp were native to Japan and were imported to Korea. The histology showed no pathological changes. Transmission electron microscopy revealed extensive infections of hepatopancreatic epithelial cell by a pleomorphic, filamentous intracellular bacterium. The filamentous bacterium was of about 60 nm in diameter and 300 nm to more than $1{\mu}m$ in length. Teh morphology of bacteria were filamentous and branched with terminal blebs, or knobs, on the branches. They lacked the cell wall, and were bounded by the plasma membrane. They contained typical prokaryotic ribosomes and fibrillar DNA-like strands. No additional internal structure has been observed. They are considered to be mollicutes, based upon the morphological appearance and upon the cellular location.