• 한국미생물·생명공학회지
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• 제23권3호
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• pp.365-371
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• 1995

슬러지 팽화의 원인이 되며 활성오니 공정운영상의 지표생물이 되는 사상세균과 원생동물을 동정하기 위하여 도시하수 활성오니 처리장 6개소와 산업폐수활성오니 처리장 5개소의 폭기조로부터 시료를 채취하여 현미경 경검법과 일부 생리학적 방법을 써서 미생물을 동정하였다. 가장 많이 출현하였던 사상세균은 Microthrix parvicella이었으며 다음이 type 0041, type 1701, Nocardia의 순이었다. 비록 시료수는 적었지만 이러한 출현빈도는 미국과 네덜란드에서 조사된 것과 비슷한 경향을 보였다. 사상세균의 형태는 이전의 문헌에서 보고된 것과 대체로 일치하였는데 type 1701의 경우에는 전형적인 형태에 비해 사상체(filament)의 직경이 약간 가늘었다. 이러한 사상세균들은 낮은 유기물부하 또는 낮은 DO와 관계가 있는 것들이었으므로 더 많은 조사가 이루어지면 지표생물로서의 활용이 가능할 것이다. 원생동물에 있어서는 Voricella가 가장 많이 출현하였고, 다음이 Aspidisca, Opercularia, Diffugia의 순이었다. 후생동물에 있어서는 Philodina가 유일하게 출현한 속이었다. 이러한 속들은 활성오니성 미생물로서 처리상황이 좋을때 우점적으로 나타나는 미생물이라고 알려져 있으므로 처리수의 수질과 관련하여 유추해 볼때 상당한 타당성이 인정되었다.

• 미생물학회지
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• 제28권4호
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• pp.337-344
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• 1990

미국 뉴저지주에 있는 10개의 회전원판 처리장에서 생물막 시료를 채취하여 사상세균에 대해 현미경적 연구를 실시하였다. 활성오니에서 부유형 성장을 하며 흔히 출현하는 Type 1701, Type 0041. Type 021N, Nocardia, Beggiatoa 및 Sphaerotilus가 회전원판체 생물막에서도 출현하였으나 수도(abundance)는 크게 달랐다. 여기서는 Beggiatoa의 출현빈도가 가장 높았으며, Sphaerotilus, Type 0041, Type 1701, Type 021N, Nocardia의 순이었다. 회전원판 생물막에서 발견된 Beggiatoa는 형태적으로 뚜렷히 구별되는 2가지 Type이 존재하였다. 회전원판체의 중심축으로 100cm 깊이에 존재하는 생물막과 외부의 생물막에 존재하는 사상세균의 군집에 대해 인자분서법에 의한 통계처리를 수행한 결과 대부분의 경우, 내부의 군집과 외부의 군집이 통계적으로 유의하게 달랐으며 장소(내부, 외부)와 단(stage) 사이에도 많은 경우 통계적으로 유의한 상호작용이 있었다.

• 한국물환경학회지
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• 제29권3호
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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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• 제42권3호
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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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• 제12권5호
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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.

• 한국환경보건학회지
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• 제30권1호
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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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• 제10권5호
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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.

• 한국물환경학회지
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• 제20권5호
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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.

• 한국물환경학회지
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• 제27권6호
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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.

• 한국어병학회지
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• 제9권1호
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• pp.33-40
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• 1996

자연산 보리새우(Penaeus japonicus) 모하의 병리검사 결과 사상체의 mollicute와 유사한 미생물의 감염을 확인하였다. 검사에 사용된 보리새우 모하는 일본산이며, 한국으로 수입되었다. 일반 조직검사 결과 병리학적인 변화는 관찰되지 않았다. 투과전자현미경적 관찰 결과 간췌장 상피세포에서 세포내 다형태성 사상체 세균의 광범위한 감염을 발견하였다. 사상체 세균은 직경이 약 60nm이며, 길이가 300nm에서 $1{\mu}m$ 이상의 크기를 나타내었다. 이 세균의 구조는 사상체이며, 끝마디를 가진 가지로 분지 되는 특징을 보였다. 세포벽은 없으며, 원형질막으로만 둘러싸여 있었으며, 전형적인 원핵세포성 리보소음과 선형 DNA와 유사한 가닥을 가지고 있었다. 그 외 다른 세포내 기관은 관찰되지 않았다. 이러한 형태적인 특징들과 세포내 감염부위로 볼 때 이 세균은 mollicutes로 판단된다.