Determination of Anaerobic and Anoxic Biodegradation Capacity of Sulfamethoxasole and the Effects on Mixed Microbial Culture

status: publishe

Methanogenic population dynamics in full-scale UASB reactors

Bu çalışmada, alkol distilasyon atıksularını arıtan, kısaca IUASB, TUASB ve CUASB olarak adlandırılan üç farklı gerçek ölçekli yukarı akışlı anaerobik çamur yatağı (UASB) reaktörünün 2002-2004 yılları arasındaki işletme performansları, Metan Arke komunite yapıları ve Potansiyel Metan Üretim (PMÜ) hızları tartışılmıştır. Aynı süreçte UASB reaktörlerinden 2-12 kg KOİ/m3.gün aralığındaki organik yükleme hızlarında, %60-95 aralığında KOİ giderim verimleri elde edilmiştir. Spesifik Metan Aktivite (SMA) test sonuçları IUASB, TUASB ve CUASB reaktörlerinin PMÜ hızlarının 2002 yılında sırasıyla 321, 344 ve 256 mL CH4/gUAKM.gün iken, 2004 yılında  sırasıyla 133, 109 ve 108 mL CH4/gUAKM.gün değerlerine düştüğünü göstermiştir. Reaktörlerden elde edilen gerçek metan üretim (GMÜ) hızları, reaktör çamurlarının PMÜ hızları ile oranlandığında elde edilen değerler, 0.1-0.4, reaktörlerin maksimum kapasitelerinin çok altında yüklendiklerini göstermektedir. Floresanlı yerinde hibritleşme (FISH) sonuçları her üç reaktörde de baskın metanojenlerin, asetoklastik bir cins olan Methanasaeta’ya ait olduğunu göstermiştir. Hidrojen kullanan metan arkelerinden Methanobacteriales TUASB ve CUASB reaktörlerinde, Methanococcales ise IUASB reaktöründe baskın halde bulunmaktadır. IUASB ve TUASB reaktörlerinin asetoklastik metan üretim kapasitelerinde meydana gelen, sırasıyla %59 ve %68’lik kayıplara pararel olarak, reaktörlerde rastlanan tek asetoklastik cins olan Methanosaeta’nın rölatif miktarında sırasıyla %25 ve %11’lik kayıplar, hidrojen kullanan metanojenlerin rölatif miktarlarında ise sırasıyla %20 ve %24’lük bir artış meydana gelmiştir. CUASB reaktöründeki metanojenik komünite yapısı zaman içerisinde stabil kalmıştır. Anahtar Kelimeler: Floresanlı yerinde hibritleşme, spesifik metan aktivite testi, metanojenler, UASB reaktör, alkollü içki endüstrisi atıksuları.A prerequisite for stable performance in an anaerobic treatment system is maintenance of active methanogenic populations in the system. However, there are few published studies available that assess performance of a full-scale anaerobic reactor in relation to the make up of reactor biomass in terms of qualitative and quantitative measures of methanogenic species and their activities. This study was undertaken to assess changes in performance of three full-scale upflow anaerobic sludge blanket (UASB) reactors, namely IUASB, TUASB and CUASB, at wastewater treatment plants of Istanbul Alcohol (Raki), Tekirdag Alcohol (Raki) and Canakkale Alcohol (Cognac) distilleries in relation to qualitative and quantitative measures of the relevant archaeal methanogenic populations. Composition and quantity of archaeal methanogens were determined using fluorescent in situ hybridization (FISH) combined with epifluorescence microscopy. Specific methanogenic activity (SMA) test was used to determine the potential methane production (PMP) rates of the anaerobic sludges. The IUASB reactor performed well achieving COD removal efficiencies of no lower than 80% at a range of OLRs from 6-11 kg COD m-3 day-1 in years between between 2001 and 2004. The TUASB reactor also performed well achieving COD removal efficiencies between 70% and 85% at OLRs in a range of 2-12 kg COD m-3 day-1 between 2001 and 2004. COD removal efficiency of the TUASB reactor varied between 60% and 80% at OLRs in a range of 2.5-12 kg COD m-3 day-1 between 2002 and 2004. According to the SMA tests results PMP rates of the IUASB, TUASB and CUASB sludges were 321, 344 and 256 mL CH4 gVSS-1 day-1 respectively in the year 2002 and decreased to 133, 109 and 108 CH4 gVSS-1 day-1 respectively after two years of operation. When the PMP rates were compared with actual methane production (AMP) rates obtained from the three UASB reactors, AMP/PMP ratios were evaluated to be between 0.1 and 0.4. These results can be interpreted that the three UASB reactors were under loaded compared to their potential acetoclastic methanogenic capacities. This could have been due to retaining high amount of granular sludges within the UASB reactors resulting in F/M (food to microorganisms) ratios in a range of 0.02-0.07 gCOD gTVS-1 day-1 which is much lower than the typical values reported for similar reactors in literature. Since all other operational parameters such as pH, temperature, alkalinity, nutrients etc. have been maintained within their typical ranges, it was concluded that the prolonged operation of  the three UASB reactors under very low F/M ratios might have lead to the significant decreases in the PMP rates of the reactor sludges. FISH results revealed that the relative abundance of archaeal cells within the IUASB, TUASB and CUASB sludges were in range of 14-18%, 15-17% and 14-15% respectively. Methanosaeta spp. were the predominant methanogen in all of the anaerobic sludges. However, over time the relative abundance of acetoclastic Methanosaeta in the IUASB and TUASB reactors reduced from 83% ± 1.6 and 90% ± 1.2 to 58% ± 2.1 and 79% ± 1.4 of the archaeal population respectively. These decreases coincided with 59% and 68% decreases in the acetoclastic methanogenic capacities and 20% and 24% increases in the relative abundance of hydrogenotrophic methanogens in the archaeal population of the IUASB and TUASB sludges respectively. Although a 58% decrease in the acetoclastic methanogenic capacity of the CUASB sludge was detected, the reactor sludge had stable archaeal community structure. Among the hydrogenotrophic methanogens, Methanococcales followed by Methanobacteriales were dominant methanogens within the IUASB reactor. This study is the first that reports dominance of Methanococcales among the hydrogenotrophic methanogens within UASB reactors. Methanobacteriales was the predominant hydrogenotrophic methanogen within the both TUASB and CUASB reactors. In this study the significant decreases in the activity of methanogens was detected at an early stage by using the SMA test so that process conditions can be changed, and collapse of the reactors can be avoided. The SMA test and FISH results showed that the reduction of acetoclastic methanogenic activity in IUASB and TUASB reactors is related to loss of Methanosaeta spp. However, acetoclastic methanogenic activity losses in the CUASB reactor were not reflected in the archaeal community structure of  the reactor sludge. Keywords: Fluorescence in situ hybridization, specific methanogenic activity, methanogens, UASB reactor, alcohol distillery effluents

Effect of sludge age on the diversity of nitrification bacteria and reactor stability

Bir arıtma tesisinin başarısı büyük ölçüde arıtma işini yapacak mikrobiyal komünitenin oluşumuna bağlıdır. Fonksiyonel öneme sahip populasyonların kaybolması veya aktivitesini yitirmesi arıtma sisteminde verim kaybına yol açar. Kısaca, bir sistemin kararlı halde çalışması sahip olduğu mikroorganizma türlerinin sistemde kararlı halde tutulabilmesine bağlıdır.Yeterli miktarda ve ceşitlilikte mikroorganizmanın sistemde tutulabilmesi, optimum çamur yaşının belirlenebilmesi ile mümkündür. Ancak, son yıllarda yapılan çalışmalarla, çevre veya işletme koşullarında bir farklılık olmadığı durumlarda dahi arıtma sistemlerinin bir süre sonra stabilitesini kaybettiği gösterilmiştir; ancak stabil (kararlı) arıtma verimi elde etmek için, kararlı bir komünite yapısına sahip olmak gerektiği hala kesinlik kazanmamıştır. Bu durum, düşük büyüme hızına sahip nitrifikasyon bakterileri için daha fazla önem arzetmektedir. Bu çalışmada nitrifikasyon prosesi model olarak seçilmiş ve bu sistemlerin kararlı yapısı üzerine araştırma yapılmıştır. Büyüme hızı ile doğrudan ilişkilendirilmesi nedeniyle çamur yaşı bifürkasyon parametresi olarak seçilmiş ve laboratuar ölçekli atıksu arıtma reaktörleri farklı iki çamur yaşında işletilmiştir. Kimyasal analizler yanında moleküler analizler kullanılarak reaktörlerdeki nitrifikasyon bakterilerinin sayısı ve yapısındaki değişimler incelenmiştir. Elde edilen sonuçlar, replika reaktörlerde toplam amonyağı oksitleyici bakteri (AOB) sayısı açısından anlamlı bir ilişki olmadığını göstermiştir. Bunun yanında; 3 gün çamur yaşına sahip tüm reaktörlerde, 10 gün çamur yaşına sahip reaktörlere göre AOB çeşitliliğinin daha fazla olduğu, ancak zamana bağlı olarak çeşitliliğin azaldığı görülmüştür. Çeşitlilikteki bu azalma, yüksek çamur yaşında işletilen reaktörlerde daha fazla gözlenmiştir. Dizi analizi sonucu baskın olan türlerin Nitrosomonas türleri ve henüz kültüre alınmamış beta-proteobakteri olduğu bulunmuştur.  Anahtar Kelimeler: Atıksu arıtma, nitrifikasyon, stabilite,  FISH, DGGE. Variations in the relative abundance of microbial species are proved responsible of problems in biological treatment reactors. Quantitative ecology of wastewater treatment processes is the way of understanding these variations in community composition. In this point of view, many studies have been performed not only to understand the microbial structure of a wastewater treatment plants, but also to link microbial community dynamics to process stability. There are studies which investigated the instability caused by environmental conditions using lab- and full-scale treatment reactors. However, it is still unclear that functional stability implies a persistent community. Purkhold et al. (2000) found, for example, that few of the nitrifying bacteria classically studied in the laboratory were present in full-scale nitrification systems and functionally stable ecosystem. Saikaly et al. (2005) studied the stability of the treatment performance of laboratory scale sequencing batch reactors operated under different sludge ages. Results of the work by Fernandez et al. (1999) revealed that an extremely dynamic community sustains a more reliable treatment performance in terms of stable efficiency. However, similar studies revealed differences in the community structure of any changes in AOB community structure. However, it is not clear whether persistent community composition secures to get stable treatment performance. This is especially important for the microorganisms which have lower growth rate (e.g. nitrifiers) as they would be less abundant compared to others (e.g. heterotrophs). Loss or alteration of key functional groups might cause unstable treatment performance. Therefore, nitrification process is selected as a main investigation subject in the present study. Samples were collected for chemical analysis and also for molecular analysis. FISH and DGGE were applied to reveal total AOB numbers and any changes in community composition. To achieve this, two sets of replicate reactors were operated under identical conditions under two different sludge ages (3 and 10 days) with the same external conditions. During the whole investigation period, reactor 1 and 2 (3 days sludge age) achieved more than 88% COD removal whilse reactor 3 and 4 (10 days sludge age) achieved more than 96% COD removal. Results also showed that replicate reactors with high sludge age performed more stable nitrification performance than the reactors with low sludge age. Nitrification performance was assessed with amommium, nitrite and nitrate concentrations. In reactor 1 and 2, nitrate concentrations were in a range of 0 and 28.48 mg/l; whilst it was up to 40 mg/l in reactor 3 and 4. Nitrite concentration was maximum 10 mg/l in reactor 1 and 2; whereas no higher than 2.5 mg/l in reactor 3 nd 4 during the first 30 days of experiment. FISH quantification revealed no correlation in total AOB numbers within  replicate reactors. DGGE analysis also revealed decreasing similarities between replicate reactors over time. This was more obvious in reactors with higher sludge. On the day 32, the similarity values were 70.6% and 26.7% between reactor 1-2 and reactor 3-4, respectively. Beside statistical analysis, predominant bands were excised from DGGE gels and sequenced. Results showed that they match to the following sequences:  Nitrosomonas oligotropha (97.6 % similarity; accession number: AF272422); Nitrosomonas sp. IS79A3 (97.4% similarity, accession number: AJ621026) and uncultered beta-proteobacteria (higher than 97.7% similarity; accession numbers: AY062126, DQ413103, DQ376558, AY064177). Sequencing results were in aggrement with the literature which states that Nitrosomonas species are  dominant in wastewater treatment reactors. This study is of particular importance as there is still a gap in knowledge on performance stability and community composition in wastewater treatment reactors. Since, replicate reactors were run under identical conditions, our findings could be helpful to solve the link between performance and microbial diversity. Furthermore, we hope that our findings would  be in use for designing treatment reactors with new strategy. Keywords: Wastewater treatment, nitrification, stability, FISH, DGGE

Effect of sludge age on the diversity of nitrification bacteria and reactor stability

Bir arıtma tesisinin başarısı büyük ölçüde arıtma işini yapacak mikrobiyal komünitenin oluşumuna bağlıdır. Fonksiyonel öneme sahip populasyonların kaybolması veya aktivitesini yitirmesi arıtma sisteminde verim kaybına yol açar. Kısaca, bir sistemin kararlı halde çalışması sahip olduğu mikroorganizma türlerinin sistemde kararlı halde tutulabilmesine bağlıdır.Yeterli miktarda ve ceşitlilikte mikroorganizmanın sistemde tutulabilmesi, optimum çamur yaşının belirlenebilmesi ile mümkündür. Ancak, son yıllarda yapılan çalışmalarla, çevre veya işletme koşullarında bir farklılık olmadığı durumlarda dahi arıtma sistemlerinin bir süre sonra stabilitesini kaybettiği gösterilmiştir; ancak stabil (kararlı) arıtma verimi elde etmek için, kararlı bir komünite yapısına sahip olmak gerektiği hala kesinlik kazanmamıştır. Bu durum, düşük büyüme hızına sahip nitrifikasyon bakterileri için daha fazla önem arz etmektedir. Bu çalışmada nitrifikasyon prosesi model olarak seçilmiş ve bu sistemlerin kararlı yapısı üzerine araştırma yapılmıştır. Büyüme hızı ile doğrudan ilişkilendirilmesi nedeniyle çamur yaşı bifürkasyon parametresi olarak seçilmiş ve laboratuar ölçekli atıksu arıtma reaktörleri farklı iki çamur yaşında işletilmiştir. Kimyasal analizler yanında moleküler analizler kullanılarak reaktörlerdeki nitrifikas-yon bakterilerinin sayısı ve yapısındaki değişimler incelenmiştir. Elde edilen sonuçlar, replika reaktörlerde toplam Amonyağı Oksitleyici Bakteri (AOB) sayısı açısından anlamlı bir ilişki olmadığını göstermiştir. Bunun yanında; bütün 3 gün çamur yaşına sahip reaktörlerde, 10 gün çamur yaşına sahip reaktörlere göre AOB çeşitliliğinin daha fazla olduğu, ancak zamana bağlı olarak çeşitliliğin azaldığı görülmüştür. Çeşitlilikteki bu azalma, yüksek çamur yaşında işletilen reaktörlerde daha fazla gözlenmiştir. Dizi analizi sonucu baskın olan türlerin Nitrosomonas türleri ve henüz kültüre alınmamış beta-proteobakteri olduğu bulunmuştur. Anahtar Kelimeler: Atıksu arıtma, nitrifikasyon, stabilite, FISH, DGGE.Variations in the relative abundance of microbial species are proved responsible of problems in biological treatment reactors. Quantitative ecology of wastewater treatment processes is the way of understanding these variations in community composition. In this point of view, many studies have been performed not only to understand the microbial structure of a wastewater treatment plants, but also to link microbial community dynamics to process stability. There are studies which investigated the instability caused by environmental conditions using lab- and full-scale treatment reactors. However, it is still unclear that functional stability implies a persistent community. Purkhold et al. (2000) found, for example, that few of the nitrifying bacteria classically studied in the laboratory were present in full-scale nitrification systems. and functionally stable ecosystem. Saikaly et al. (2005) studied the stability of the treatment performance of laboratory scale sequencing batch reactors operated under different sludge ages. Results of the work by Fernandez et al. (1999) revealed that an extremely dynamic community sustains a more reliable treatment performance in terms of stable efficiency. However, similar studies revealed differences in the community structure of any changes in AOB community structure. However, it is not clear whether persistent community composition secures to get stable treatment performance. This is especially important for the microorganisms which have lower growth rate (e.g. nitrifiers) as they would be less abundant compared to others (e.g. heterotrophs). Loss or alteration of key functional groups might cause unstable treatment performance. Therefore, nitrification process is selected as a main investigation subject in the present study. Samples were collected for chemical analysis and also for molecular analysis. FISH and DGGE were applied to reveal total AOB numbers and any changes in community composition. To achieve this, two sets of replicate reactors were operated under identical conditions under two different sludge ages (3 and 10 days) with the same external conditions. During the whole investigation period, reactor 1 and 2 (3 days sludge age) achieved more than 88% COD removal whilst reactor 3 and 4 (10 days sludge age) achieved more than 96% COD removal. Results also showed that replicate reactors with high sludge age performed more stable nitrification performance than the reactors with low sludge age. Nitrification performance was assessed with ammonium, nitrite and nitrate concentrations. In reactor 1 and 2, nitrate concentrations were in a range of 0 and 28.48 mg/L; whilst it was up to 40 mg/L in reactor 3 and 4. Nitrite concentration was maximum 10 mg/L in reactor 1 and 2; whereas no higher than 2.5 mg/L in reactor 3 and 4 during the first 30 days of experiment. FISH quantification revealed no correlation in total AOB numbers within replicate reactors. DGGE analysis also revealed decreasing similarities between replicate reactors over time. This was more obvious in reactors with higher sludge. On the day 32, the similarity values were 70.6% and 26.7% between reactor 1-2 and reactor 3-4, respectively. Beside statistical analysis, predominant bands were excised from DGGE gels and sequenced. Results showed that they match to the following sequences: Nitrosomonas oligotropha (97.6 % similarity; accession number: AF272422); Nitrosomonas sp. IS79A3 (97.4% similarity,accession number: AJ621026) and uncultered beta-proteobacteria (higher than 97.7% similarity; accession numbers: AY062126, DQ413103, DQ376558, AY064177). Sequencing results were in aggrement with the literature which states that Nitrosomonas species are dominant in wastewater treatment reactors. This study is of particular importance as there is still a gap in knowledge on performance stability and community composition in wastewater treatment reactors. Since, replicate reactors were run under identical conditions, our findings could be helpful to solve the link between performance and microbial diversity. Furthermore, we hope that our findings would be in use for designing treatment reactors with new strategy. Keywords: Wastewater treatment, nitrification, stability, FISH, DGGE

Role of the Mechanical Interdental Plaque Control in the Management of Periodontal Health: How Many Options Do We Have?

Untreated caries and severe periodontal disease are the most frequently encountered reasons for the tooth loss in adult population all over the world, which leads to reduced quality of life. For many years, a plethora of studies revealed the fundamental role of the microorganisms in oral biofilm in the development of caries and periodontal destruction. The primary means of oral biofilm control are through mechanical action. Although toothbrushing removes biofilm from the buccal, oral, and occlusal surfaces, it does not reach efficiently into the interdental areas. Today, several interdental cleaning devices are available over the counter for individual needs. On the other hand, this variety may be confusing for the patients to choose the right device for themselves. Therefore, dental professionals are responsible to guide their patients according to their specific needs with an evidence-based approach. Since direct evidence for the relation of interdental cleaning and periodontal disease prevention is on research, there is still a need for randomized controlled studies on interdental cleaning to increase the strength of evidence. From this standpoint, the aim of this chapter is to evaluate the cleaning efficacy of different interdental cleaning devices regarding in vitro and in vivo aspects together with patient preference and acceptance

Determination of the microbial community in pulp and paper mills effluents

Bu çalışmada, kâğıt endüstrisi atıksularını arıtan gerçek ölçekli bir anaerobik kontak reaktörün 3 farklı yüksekliğinden 2 farklı zamanda alınan çamur numunelerinin mikrobiyal komünite yapıları Denatüran Gradyan Jel Elektroforez (DGGE) yöntemi kullanılarak karşılaştırılmıştır. 2 aylık izleme dönemi içinde sistem 2 hafta süreyle bakıma alınmıştır. Kontak reaktörün 1.6-1.8 kg KOİ/m3.gün organik yükleme hızında, KOİ giderim verimi % 47-55, metan üretim verimi 0.18-0.20 m3CH4/kgKOİgiderilen aralığında değişmiştir. DGGE analizleri sonucu, arkeyal popülasyona ait 31, bakteriyel popülasyona ait 57 farklı tür tespit edilmiştir. Arkeyal popülasyona ait 3 farklı tür Ağustos 2005'te tespit edilememiş, buna karşın 6 yeni tür gözlenmiştir. Bakteriyel popülasyonda ise Temmuz 2005 numunesine ait 10 farklı tür Ağustos 2005 numunesinde tespit edilemezken Ağustos 2005'te 10 yeni türün varlığı gözlenmiştir. Bu çalışmada incelenen reaktöre ait asetoklastik metan üretim kapasitesi önceki bir çalışmada Spesifik Metan Aktivite (SMA) test düzeneği kullanılarak ölçülmüş ve potansiyel metan üretiminin yaklaşık % 45 azaldığı tespit edilmiştir. Sistemde bulunan metanojenlerin ve Sülfat İndirgeyici Bakterilerin (SRB) tür ve sayıları Floresanlı Yerinde Hibritleme (FISH) yöntemi ile belirlenmiştir. SMA testi ve FISH tekniği ile tespit edilen mikrobiyal komünite değişimi DGGE yöntemi ile de doğrulanmıştır. DGGE yöntemi, iki farklı zamanda alınan numunelere ait komünite değişimini açıkça yansıtmakla birlikte sayısal değerlendirmede yetersiz kalmaktadır. Bu nedenle, anaerobik reaktörlerin mikrobiyal komünite yapılarının gerek DGGE gibi detaylı kalitatif sonuç veren gerekse FISH gibi mikroskobik sayıma dayalı, kültürden bağımsız yöntemlerle çalışılması gerektiği sonucuna varılmıştır. Anahtar Kelimeler: Denatüran gradyan jel elektroforezi, arkeyal popülasyon, bakteriyel popülasyon, anaerobik kontak reaktör, kâğıt endüstrisi atıksuları.The use of anaerobic technologies in the fields of wastewater treatment, sludge stabilization, bioremediation and management of hazardous and solid wastes has grown in importance during the last few decades. Although the general processes occurring in anaerobic biological wastewater treatment plants, such as hydrolysis, fermentation, acetogenesis, methanogenesis and sulfidogenesis are well understood, the microbial community responsible for these conversions is often considered as a black box. Physical and chemical parameters only give rough estimations about the operational conditions of the system. Therefore, understanding the biodiversity and the dominant species of the microbial community is of great importance in studying contaminant degradation pathways, optimizing treatment processes, and improving removal efficiencies of engineer-designed systems. The culture dependent methods used for the investigation of the biomass are not sufficient for the identification of the complex microbial diversity in wastewater treatment systems. The use of the culture-independent methods in microbial ecology allowed the determination of the complex microbial populations and community contents more representatively. Denaturing Gradient Gel Electrophoresis (DGGE) is a Polymerase Chain Reaction (PCR) dependent method used for the electrophoretic separation of the 16S rDNA genes due to the difference in the nucleotide sequences. The separation is observed as an individual band on the DGGE gel. Every DGGE band represents a single species and the DGGE pattern gives the fingerprint of that community. Since DGGE technique allows the analysis of many samples simultaneously and gives rapid results, the use of DGGE is getting extensive in the investigation of bioreactors and natural ecosystems which inhabit rich microbial diversity. In the context of this study, a full-scale anaerobic contact reactor treating pulp and paper mills effluents was investigated. Samples were taken from 3 different levels at 2 different times. There was a 2-week off-period of the reactor between sampling times. Denaturing Gradient Gel Electrophoresis (DGGE) was used for the fingerprinting of the microbial community in the sludge samples. Performance of the reactor in terms of COD removal efficiency and methane yield varied between 47% and 55% and 0.18 and 0.20 m3CH4/kgCODremoved at Organic Loading Rates (OLRs) in a range of 1.6-1.8 kg COD/m3day, respectively. DGGE analysis revealed that 31 species from archaeal population and 57 species from bacterial population were present in the anaerobic reactor. 3 species from the archaeal population were not detected in August 2005 whereas 6 species were newly observed. In bacterial population, 10 species belonging to July 2005 samples were not detected where 10 other species were found in August 2005. Acetoclastic methanogenic activity of the reactor had previously been investigated by specific Methanogenic Activity (SMA) test. A decrease of 45% in the potential methane production was observed during the monitoring period of 2 months. The quantities and species of methanogens and Sulfate Reducing Bacteria (SRB) in the reactor were determined by Fluorescent In Situ Hybridization (FISH). Parallel to SMA results, the quantities of SRB and methanogens were decreased in August 2005. The shift in the microbial community observed by SMA test and FISH quantifications were supported by DGGE analysis. During the monitoring of 2 months, 2 weeks shut-down of the anaerobic reactor might have caused activity loss and microbial community change. DGGE allows the comparison of microbial communities taken from the anaerobic reactor at two different sampling times and FISH informs quantities of present microbial species in the reactor. However, DGGE does not give numerical information but clearly depicts the community shift. Therefore, it is concluded that, the microbial community structures of anaerobic reactors should be determined by culture independent methods of both qualitative and quantitative techniques such as DGGE and FISH respectively. Keywords: Denaturing gradient gel electrophoresis, archaeal population, bacterial population, anaerobic contact reactor, pulp and paper mills effluents

A case of down syndrome with basal ganglia calcification

Sekiz yasında, Down sendromlu, erkek hasta pnömoni ve solunum yetmezligiyle ÇocukYogun BakımÜnitesine kabul edildi. Izleminde tremor, strabismus, idrar retansiyonu ve klonus fark edildi. Bu nörolojik bulgular için çekilen bilgisayarlı beyin tomografisinde bilateral bazal gangliyon kalsifikasyonu gösterildi. Ayrıca nörolojik bulgular kusmalarını önlemek amacıyla baslanan metoklopramide baglandı. Hastanın bazal gangliyon kalsifikasyonunun TORCH, metabolik ve endokrin nedenlere baglı olmadıgı gösterilerek Down sendromuna baglı oldugudüsünüldü.Eight-year-old boy with Down syndrome was accepted to The Pediatric Intensive Care Unit for pneumonia and respiratory failure. Tremor, strabismus, urinary retantion and clonus were observed during his hospitalization. Bilateral basal ganglia calcification was demonstrated by computerized tomography neurologic findings were included to be due to metoclopramid which had been begun for vomiting. Bilateral basal ganglia calcification was decided to be due toDownsyndrome after excludingTORCH,metabolic and endocrin causes