• 한국식품저장유통학회지
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• 제30권1호
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• pp.132-145
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• 2023

본 연구에서는 식품 원료로 이용이 허가된 Acetobacter pasteurianus SRCM101388을 사용하여 바이오매스 고농도배양을 위한 최적화 연구를 실시하였다. SRCM101388의 최적 배양온도와 pH 조건은 각각 28℃와 pH 6.0으로 나타났다. 배지조건을 확립하기 위하여 Plackett-Burman design을 실시한 결과, glucose, sucrose, yeast extract가 biomass 증가에 가장 높은 효과를 보였다. Glucose, sucrose, yeast extract의 최적농도를 알아보기 위하여 central composite design을 실시하였으며, 최적농도는 glucose 10.73 g/L, sucrose 3.98 g/L, yeast extract 18.73 g/L로 나타났다. Plackett-Burman design에서 biomass 증가에 영향이 있는 기타 미량원소에 대한 최적농도를 조사한 결과, ammonium sulfate 1 g/L, magnesium sulfate 0.5 g/L, sodium phosphate monobasic 2 g/L, sodium phosphate dibasic 2 g/L로 나타났으며, 최종 최적화된 배지 제조 시 pH는 6.10으로 최적 pH 조건과도 일치하였다. 최적화된 배지 3.5 L를 함유한 5 L jar fermenter에서의 배양결과, SRCM101388은 DO가 낮은 rpm에서 DO 감소가 더 빠르게 나타났다. 최대 생균수는 150 rpm, 0.5 vvm, pH 6.0, 28℃ 조건에서 18시간 배양 시 2.53± 0.12×10⁹ CFU/mL로 나타났다.

• 한국환경보건학회지
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• 제15권1호
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• pp.89-96
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• 1989

An aerated submerged biofilm reactor is the reactor in which influent organic substrates are aerobically oxidized by suspended biomass and attached biomass of biofilm grown on the surface of submerged media. The objective of this study was to investigate the effect of aeration intensity on microbial characteristics and treatment efficiency in submerged biofilm process. In the organic loading rate (4.3kg BOD/$m^{3} \cdot day$), biofilm thickness (420-780$\mu$m) and attached biomass(1.79-2.94mg/cm$^{2}$) increased as the aeration intensity increased (2-8m$^{3}$ air/$m^{2} \cdot hr$), but biofilm density decreased (42.25-37.69mg/cm$^{3}$). The minimum aeration intensity for prevention of deposited biomass was 2m$^{3}$ air/$m^{2} \cdot hr$. The minimum dissolved oxygen of 2.5mg/l had to be maintained for improved efficiency.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.843-853
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• 2014

In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil.

• Journal of Microbiology
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• 제42권4호
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• pp.267-277
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• 2004

Effects of elevated $CO_2$ on soil microorganisms are known to be mediated by various interactions with plants, for which such effects are relatively poorly documented. In this review, we summarize and syn­thesize results from studies assessing impacts of elevated $CO_2$ on soil ecosystems, focusing primarily on plants and a variety the of microbial processes. The processes considered include changes in microbial biomass of C and N, microbial number, respiration rates, organic matter decomposition, soil enzyme activities, microbial community composition, and functional groups of bacteria mediating trace gas emission such as methane and nitrous oxide. Elevated $CO_2$ in atmosphere may enhance certain micro­bial processes such as $CH_4$ emission from wetlands due to enhanced carbon supply from plants. How­ever, responses of extracellular enzyme activities and microbial community structure are still controversy, because interferences with other factors such as the types of plants, nutrient availabilitial in soil, soil types, analysis methods, and types of $CO_2$ fumigation systems are not fully understood.

• 한국토양비료학회지
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• 제46권6호
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• pp.487-493
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• 2013

The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.

• Environmental Engineering Research
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• 제19권1호
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• pp.91-99
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• 2014

Ordinary heterotrophic organism (OHO) active biomass plays key roles in biological wastewater treatment processes. However, due to the lack of measurement techniques, the OHO active biomass exists hypothetically within the design and simulation of biological wastewater treatment processes. This research was purposed to develop a quick and easy quantifying technique for the OHO active biomass applying a modified batch aerobic growth test. Two nitrification-denitrification activated sludge systems, with 10- and 20-day sludge ages, were operated to provide well-cultured mixed liquor to the batch tests. A steady state design model was firstly applied to quantify the "theoretical" OHO active biomass concentration of the two parent systems. The mixed liquor from the parent systems was then inoculated to a batch growth test and a batch digestion test to estimate the "measured" OHO active biomass concentration in the mixed liquor. The measured OHO active biomass concentrations with the batch growth test and the batch digestion test were compared to the theoretical concentrations of the parent system. The measured concentrations with the batch growth test were generally smaller than the theoretical concentrations. However, the measured concentrations with the batch aerobic digestion tests showed a good correlation to the theoretical concentrations. Thus, a different microbial growth condition (i.e., a higher food/biomass ratio) in the batch growth test, compared to the parent system or the batch digestion test, was found to cause underestimation of the OHO active biomass concentrations.

• 한국물환경학회지
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• 제16권4호
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• pp.523-532
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• 2000

The purpose of this study was to investigate the effects of the hydraulic retention time (HRT) and organic loading rate (OLR) on microbial characteristics and treatment efficiency in sewage treatment using aerated submerged biological filter (ASBF) reactor. This reactor combines biodegradation of organic substrates by fixed biomass with a physical separation of biomass by filtration in a single reactor. Both simulated wastewater and domestic wastewater were used as feed solutions. The experimental conditions were a temperature of 17 to $27^{\circ}C$, a hydraulic retention time of 1 to 9hr, an organic loading rate of 0.47 to $3.84kg\;BOD/m^3{\cdot}day$ in ASBF reactor. This equipment could obtain a stable effluent quality in spite of high variation of influent loading rate. Total biomass concentration. biofilm thickness and biofilm mass increased an exponential function according to the increasing OLR. The relationships between water content and biofilm density were in inverse proportion. The percentage of backwash water to influent flow was almost 9%. The separation efficiency of biomass was the percentage of 91 to 92 in ASBF reactor. The sludge production rates in feed solutions of simulated wastewater and domestic wastewater were 0.14~0.26 kg VSS/kg BODrem, 0.43~0.48 kg VSS/kg BODrem, respectively.

• Environmental Engineering Research
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• 제14권1호
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• pp.19-25
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• 2009

In this study, total bacteria, enteric members of the $\gamma$-proteobacteria, and microbial communities in seawater were analyzed as indirect indicators for quantifying biofouling. Biomass in seawater can significantly affect feed water pretreatment and membrane biofouling of reverse osmosis desalination processes. The purpose of this paper is to investigate microbiological quantity and quality of seawater at the potential intake of a desalination plant. For this analysis, the total direct cell count (TDC) using 4'-6-diamidino-2-phenylindole (DAPI)-staining and DNA-based real-time PCR were used to quantify the total bacteria and relative content of enteric members of $\gamma$-proteobacteria in seawater, respectively. In addition, microbial communities were examined using 16S rRNA gene cloning and bacterial isolation to identify the most abundant bacteria for a further biofouling study. The experimental results of this study identified about $10^6$ cells/mL of (total) bacteria, $10^5$ 16S rRNA gene copies/mL of enteric $\gamma$-proteobacteria, and the presence of more than 20 groups of bacteria.

• 한국토양비료학회지
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• 제45권5호
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• pp.792-797
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• 2012

경남지역 논토양의 글로말린 함량과 미생물 특성과의 관계를 분석하기 위하여 2011년에 20개소를 선정하여 분석한 결과는 다음과 같다. 토양 글로말린 함량은 토양 유기물 함량 (r=0.595, p<0.01) 및 탈수소효소 활성 (r=0.663, p<0.01)과 정의상관 관계를 나타냈다. 또한, 글로말린 함량은 미생물 생체 탄소 함량 (r=0.710, p<0.001) 및 총 세균군집 (r=0.616, p<0.01)과 정의상관을 보였다. 그리고 글로말린 함량은 그람음성 세균의 군집 (r=0.561, p<0.05) 및 cy19:0/18:$1{\omega}7c$ (r=0.487, p<0.05)와 정의상관 관계를 나타냈다. 따라서 논토양에서 글로말린 함량은 지속가능한 친환경농업을 위해 토양 건강성의 지표로 활용할 수 있을 것으로 생각된다.

• 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.