• Journal of Ecology and Environment
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• 제34권4호
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• pp.401-410
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• 2011

We assayed the effects of simulated acid rain on the mass loss, $CO_2$ evolution, dehydrogenase activity, and microbial biomass-C of decomposing Sorbus alnifolia leaf litter at the microcosm. The dilute sulfuric acid solution composed the simulated acid rain, and the microcosm decomposition experiment was performed at 23$^{\circ}C$ and 40% humidity. During the early decomposition stage, decomposition rate of S. alnifolia leaf litter, and microbial biomass, $CO_2$ evolution and dehydrogenase activity were inhibited at a lower pH; however, during the late decomposition stage, these characteristics were not affected by pH level. The fungal component of the microbial community was conspicuous at lower pH levels and at the late decomposition stage. Conversely, the bacterial community was most evident during the initial decomposition phase and was especially dominant at higher pH levels. These changes in microbial community structure resulting from changes in microcosm acidity suggest that pH is an important aspect in the maintenance of the decomposition process. Litter decomposition exhibited a positive, linear relationship with both microbial respiration and microbial biomass. Fungal biomass exhibited a significant, positive relationship with $CO_2$ evolution from the decaying litter. Acid rain had a significant effect on microbial biomass and microbial community structure according to acid tolerance of each microbial species. Fungal biomass and decomposition activities were not only more important at a low pH than at a high pH but also fungal activity, such as $CO_2$ evolution, was closely related with litter decomposition rate.

• Journal of Microbiology and Biotechnology
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• 제19권9호
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• pp.858-868
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• 2009

The abundance, biomass, size distribution, and taxonomic composition of bacterial and protistan (heterotrophic and autotrophic nanoflagellates and ciliates) communities were investigated in six lakes of Masurian Lake District (north-eastern Poland) differing in trophic state. Samples were taken from the trophogenic water layer during summer stratification periods. Image analysis techniques with fluorescent in situ hybridization (FISH) as well as [$^3H$]-methyl-thymidine incorporation methods were applied to analyze differences in the composition and activity of bacterial communities. The greatest differences in trophic parameters were found between the humic lake and remaining non-humic ones. The same bacterial and heterotrophic nanoflagellate (HNF) cell size classes dominated in all the studied lakes. However, distinct increases in the contributions of large bacterial (>$1.0{\mu}m$) and HNF (>$10{\mu}m$) cells were observed in eutrophic lakes. The bacterial community was dominated by the ${\beta}$-Proteohacteria group, which accounted for 27% of total DAPI counts. Ciliate communities were largely composed of Oligotrichida. Positive correlations between bacteria and protists, as well as between nanoflagellates (both heterotrophic and autotrophic) and ciliates, suggest that concentrations of food sources may be important in determining the abundance of protists in the studied lakes.

• 생태와환경
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• 제39권3호통권117호
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• pp.378-389
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• 2006

본 연구는 2005년 4월부터 12월까지 팔당댐과 경안천에서 박테리아와 원생생물 생물량과 개체크기의 계절적 변화와 이에 영향을 미치는 요인들에 대하여 분석하였다. 조사기간 동안 박테리아의 밀도는 팔당댐과 경안천에서 각각 $2.8{\sim}64.6\;{\times}\;10^6$, $6.1{\sim}43.3\;{\times}\;10^6\;cells\;{\cdot}\;mL^{-1}$로서 두 지점에서 비슷한 분포를 보였고, 수온이 높은 여름동안에도 증가하지 않았다. 원생생물의 총생물량은 팔당호 ($12{\sim}73\;{\mu}gC\;{\cdot}\;L^{-1}$)에 비해 경안천 ($26{\sim}169\;{\mu}gC\;{\cdot}\;L^{-1}$)에서 훨씬 높았으며, 평균 세포크기도 경안천에서 크게 나타났다. 원생생물의 총생물량 중에서 HNAN이 전반적으로 가장 큰 비중을 차지하였으나, 팔당댐에서 4, 10, 11월에 경안천에서 6월에는 섬모충류의 비중이 가장 컸다. PNAN은 상대적으로 매우 낮은 생물량을 보였으나 봄과 가을동안에는 높게 나타났다. HNAN은 두 지점에서 모두 3{\sim}7\;{\mu}m$ 크기의 작은 개체들이 우점하였다. HNAN 평균 세포의 크기는 영양염의 농도가 훨씬 높았던 경안천에서 더 크게 나타났다. 섬모충의 세포당 평균 크기는 여름 동안에 작았다. 팔당댐에서 HNAN 생물량은 Chl-a 농도와 상관성이 있었으며, 또한 섬모충류의 생물량과 관련이 높게 나타나 HNAN의 증가가 섬모충류의 높은 생물량으로 연결된 것으로 판단되었다. 경안천에서 PNAN과 HNAN은 Chl-a 농도와 높은 상관성을 보였고, PNAN의 생물량이 증가할수록 HNAN의 생물량도 증가하였다. 섬모충류의 생물량은 다른 생물보다는 영양염 (TN, TP)과 입자성 물질(SS)과 높은 상관성을 보였다. 또한 두 지점 모두에서 원생생물의 생물량은 박테리아 생물량과 밀접한 관계를 보였고, 섬모충류는 박테리아 뿐만 아니라 편모류의 생물량과도 밀접한 관계가 있는 것으로 나타났다. 팔당호 생태계에서 본 연구의 결과가 보여준 microbial loop 구성요인들의 높은 생물량과 이들 간의 밀접한 상관관계는 팔당호 생태계 플랑크톤 먹이망 내에서 microbial loop를 통한 먹이망 기능이 중요함을 시사한다.

• Journal of Forest and Environmental Science
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• 제30권2호
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• pp.179-188
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• 2014

This research reports the effects of shifting cultivation on soil environment collecting samples from 0-5 cm soil depth from five locations viz. at Burburichhara, Maichchari, Longadu, Sukurchhari and Muralipara in Rangamati district of Chittagong Hill Tracts (CHTs). Soil analyses showed that fungal and bacterial population, microbial respiration and active microbial biomass, maximum water holding capacity, conductivity and moisture contents were significantly (at least $p{\leq}0.05$) lower in shifting cultivated soil compared to adjacent mixed tree plantations at all the sites. On an average in soils of 5 different shifting cultivated lands fungal population was $1.33{\times}10^5$ CFU/g dry soil and bacterial population $1.80{\times}10^7$ CFU/g dry soil and in mixed plantations fungal population was $1.70{\times}10^5$ and bacterial population $2.51{\times}10^7$ CFU/g dry soil. Organic matter and exchangeable Ca and Mg contents were significantly (at least $p{\leq}0.05$) lower and bulk density significantly (at least $p{\leq}0.05$) higher in shifting cultivated land in most of the locations compared to adjacent mixed tree plantations. Ratios of microbial respiration and organic carbon as well as active microbial biomass and organic carbon were distinctly lower and pH higher at 3 locations in shifting cultivated soils compared to mixed plantations. Findings of various soil properties, therefore, suggest that shifting cultivation has deteriorating effects on soil environment.

• Ocean and Polar Research
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• 제35권4호
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• pp.415-425
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• 2013

In order to understand phytoplankton and bacterial distribution in tropical coral reef ecosystems in relation to the mangrove community, their biomass and activities were measured in the sea waters of the Chuuk and the Kosrae lagoons located in Micronesia. Chlorophyll a and bacterial abundance showed maximal values in the seawater near the mangrove forests, and then steeply decreased as the distance increased from the mangrove forests, indicating that environmental conditions for these microorganisms changed greatly in lagoon waters. Together with chlorophyll a, abundance of Synechococcus and phototrophic picoeukaryotes and a variety of indicator pigments for dinoflagellates, diatoms, green algae and cryptophytes also showed similar spatial distribution patterns, suggesting that phytoplankton assemblages respond to the environmental gradient by changing community compositions. In addition, primary production and bacterial production were also highest in the bay surrounded by mangrove forest and lowest outside of the lagoon. These results suggest that mangrove waters play an important role in energy production and nutrient cycling in tropical coasts, undoubtedly receiving large inputs of organic matter from shore vegetation such as mangroves. However, the steep decrease of biomass and production of phytoplankton and heterotrophic bacteria within a short distance from the bay to the level of oligotrophic waters indicates that the effect of mangrove waters does not extend far away.

• 대한환경공학회지
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• 제33권5호
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• pp.314-324
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• 2011

하수를 이용해서 배양된 조류는 바이오디젤 생산에 유용한 자원이다. 그러나 실제 하수에서 조류의 영양염류 신진대사와 하수 세균과의 상호작용에 관한 연구는 미흡하다. 본 연구에서는 하수로 배양되는 대표적 조류균주인 Ankistrodesmus gracilis SAG 278-2에 의한 하수 내 질소, 인 제거 거동을 평가하였고, 조류와 상호작용하는 하수 내의 세균 군집을 분석하였다. 하수 슬러지 세균 군집과 비교하였을 때, 조류-세균 복합 군집은 하수 내보다 높은 영양염류 제거를 보였다. 16S rRNA 유전자 분석 결과, 조류-세균 군집에서 조류가 성장함에 따라 Unclassified Alcaligenaceae 세균이 선택적으로 우점됨을 알 수 있었고, 조류에 의해서 선택적으로 우점화된 하수세균은 자연 수질 환경에서 조류와 공생적으로 상호작용 하는 것으로 알려진 Alcaligenes faecalis subsp. 5659-H와 계통학적으로 가까운 것으로 밝혀졌다. 본 연구의 결과, 하수 내의 높은 영양염류 제거를 보이는 조류-세균 복합 군집에서의 조류의 성장 및 신진대사가 특정 세균의 분포에 영향을 주는 것을 알 수 있었다.

• 한국해양학회지
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• 제28권2호
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• pp.107-113
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• 1993

하구 혼합이 활발한 만경.동진강하구에서 박테리아와 일차생산자와의 상호 관계 의 특징에 대해, 그리고 이러한 관계의 특징이 일차생산자의 군집구조와 어떠한 관련 이 있는가에 대해 1990년 7월에서 1991년 10월 동안 4회에 걸친 측정자료를 분석하였 다. 연구기간 동안 엽록소와 생산량만이 의미있는 관계 ($r^2$>0.36, p<0.02) 를 나타내어, 본 연구해역에서 일차생산자의 생물량에 관련된 과정이 박테리아의 생산 량과 관련이 있었으며를 시사하였다. 그러나 유광대내의 박테리아 생산량은 일차생산 량은 매우 적은 부분(평균2.6%)을 차지하여, 두 변수 사이에 uncouplin이 존재함을 시 사하였다. 이러한 uncoupling은 동물플랑크톤의 먹이인 식물플랑크톤이 주로 개체 크 기가 크고 사슬을 형성하는 규조류로 구성되어 있는 먹이사슬 구조에 기인하는 것으로 추측된다.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1221-1228
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• 2005

Carbon electrode was applied to a wastewater treatment system as biofilm media. The spatial distribution of heterotrophic bacteria in aerobic wastewater biofilm grown on carbon electrode was investigated by scanning electron microscopy, atomic force microscopy, and biomass measurement. Five volts of electric oxidation and reduction potential were charged to the carbon anode and cathode of the bioelectrochemical system, respectively, but were not charged to electrodes of a conventional system. To correlate the biofilm architecture of bacterial populations with their activity, the bacterial treatment efficiency of organic carbons was measured in the bioelectrochemical system and compared with that in the conventional system. In the SEM image, the biofilm on the anodic medium of the bioelectrochemical system looked intact and active; however, that on the carbon medium of the conventional system appeared to be shrinking or damaging. In the AFM image, the thickness of biofilm formed on the carbon medium was about two times of those on the anodic medium. The bacterial treatment efficiency of organic carbons in the bioelectrochemical system was about 1.5 times higher than that in the conventional system. Some denitrifying bacteria can metabolically oxidize $H_{2}$, coupled to reduction of $NO_{3}^{-}\;to\;N_{2}$. $H_{2}$ was produced from the cathode in the bioelectrochemical system by electrolysis of water but was not so in the conventional system. The denitrification efficiency was less than $22\%$ in the conventional system and more than $77\%$ in the bioelectrochemical system. From these results, we found that the electrochemical coupling reactions between aerobic and anaerobic reactors may be a useful tool for improvement of wastewater treatment and denitrification efficiency, without special manipulations such as bacterial growth condition control, C/N ratio (the ratio of carbon to nitrogen) control, MLSS returning, or biofilm refreshing.

• 한국해양학회지
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• 제26권3호
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• pp.255-261
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• 1991

중앙 북부 태평양의 두 개의 해산(Horizon guyot와 Magellan rise) 상의 수층에서 박테리아의 생체량과 생산력이 1987년 3월에 조사되었다. 이 기간에 관찰된 표층수의 박테 리아 개체수는 (0.9-2.3$\times$10/SUP 8/l/SUP -1/) 빈영양 해역에서 보고 된 박테리아의 개체수에 비해 낮은 값은 나타냈다. 또한 mesopelagic zone 의 박테리아 개체수도 (대 개 < 5$\times$10/SUP 7/l/SUP -1/) 다른 아열대 지역에서 보고 된 것보다 훨씬 낮았다. 표층수에서의 박테리아 생산력(20-466 ng C l/SUP -1/ d/SUP -1/)또한 다른 빈영양 해 역과 비교시 낮았다. 그러나 표층수의 박테리아 생산력을 이 지역에서 발표된 일차 생 산력과 비교한 경우, 유기물의 이용에 있어서 박테리아의 역할이 중요한 것으로 추정 되었다. 이 연구에서 보고 된 박테리아 생산력의 공간적 분포에 대한 자료는 충분하진 않으나, 매우 빈영양인 수서 환경에서 소규모 그리고 대규모적 공간상의 박테리아 생 산력 분포에 대한 연구의 필요성을 제시하고 있다.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.585-591
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• 2014

To evaluate the potential utility of pretreatment of raw biomass with a complex microbial system, we investigated the degradation of rice straw by BMC-9, a lignocellulose decomposition strain obtained from a biogas slurry compost environment. The degradation characteristics and corresponding changes in the bacterial community were assessed. The results showed that rapid degradation occurred from day 0 to day 9, with a peak total biomass bacterium concentration of $3.3{\times}10^8$ copies/ml on day 1. The pH of the fermentation broth declined initially and then increased, and the mass of rice straw decreased steadily. The highest concentrations of volatile fatty acid contents (0.291 mg/l lactic acid, 0.31 mg/l formic acid, 1.93 mg/l acetic acid, and 0.73 mg/l propionic acid) as well as the highest xylanse activity (1.79 U/ml) and carboxymethyl cellulase activity (0.37 U/ml) occurred on day 9. The greatest diversity among the microbial community also occurred on day 9, with the presence of bacteria belonging to Clostridium sp., Bacillus sp., and Geobacillus sp. Together, our results indicate that BMC-9 has a strong ability to rapidly degrade the lignocelluloses of rice straw under relatively inexpensive conditions, and the optimum fermentation time is 9 days.