• 생명과학회지
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• 제23권6호
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• pp.796-803
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• 2013

전통막걸리들에서 순수분리한 효모균주 5종을 이용하여 각각 막걸리를 제조하면서 발효 시일에 따른 막걸리의 물성 변화와 PCR-DGGE를 이용하여 미생물 군집구조 변화를 조사하였다. 막걸리의 pH는 0일째 pH 6에서 발효 2일째 pH 3 정도의 큰 감소를 보였고 이후 큰 변화가 없었다. 발효일별로는 차이를 보였지만(ANOVA, p<0.001) 균주별로는 차이가 없었다(p=0.60). 산도는 0.19~1.04% 범위였으며 발효 2일째부터 증가하였고 발효일자별(p<0.001) 및 균주별(p=0.006) 모두 차이가 있었다. C 균주의 산도 증가가 가장 컸으며 S 균주의 산도 증가가 가장 적었다. 아미노태 질소는 S 균주가 8일째 0.442%로 높은 값을 보였지만 다른 균주들은 모두 0.150% 이하를 나타내었다. 발효일자별(p=0.4558) 및 균주별(p=0.3513) 모두 큰 차이를 보이지 않았다. 당도는 빵효모균주인 C가 발효 4일 째부터 다른 균주들에 비해 높았고 발효일자별(p<0.0001) 및 균주별(p=0.007) 모두 유의미한 차이를 보였다. 알코올 함량은 모든 효모균주에서 발효 2일째 10%의 급격한 증가를 보였으며 그 이후에 큰 차이가 없었다. 발효일자별(p<0.0001)로는 차이를 보였지만 균주별로는 차이는 없는 것으로 나타났다(p=0.1464). DGGE 밴드로 검출된 우점세균은 산성물질을 생산하며 기능성을 보이는 Lactobacillus fermentum와 Pediococcus pentosaceus였고, 우점진균은 Saccharomyces cerevisiae였는데 이는 효모균주 첨가에 의한 결과로 판단된다.

• 대한환경공학회지
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• 제28권2호
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• pp.165-172
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• 2006

생물학적 인 제거공정에서 인 제거 효율에 따른 인제거관련 미생물을 포함하는 슬러지 미생물상의 변화를 분석하기 위하여 2개의 반응조(SBR)에 각기 다른 탄소원(초산나트륨, 포도당)을 주입하여 작동시켰다. 초산나트륨을 주입한 SBR1에서는 반응 100일 후, 유출수에서 $PO_4-P$가 3.92 mg/L 검출되었고(제거효율 60.8%) 이때의 미생물상은 ${\beta}$-subclass proteobacteria(39.67%)와 인제거미생물인 PAO(45.10%)가 우점하는 양상을 보인 반면, 포도당을 주입한 SBR 2에서는 $PO_4-P$가 8.3 mg/L 검출되었으며(제거효율 17%), ${\gamma}$-subclass proteobacteria(23.89%)가 우점하였고 PAO는 21.42%를 차지할 뿐이었다. DGGE결과에서도 ${\beta}$-subclass proteobacteria가 SBR1에서 우점하였다. 그러나 수온이 증가할수록 ${\beta}$-subclass proteobacteria and PAOs의 비율이 감소하였고 GAOs는 증가하였다. 그러므로 생물학적인 인제거공정에서 수온과 영양원의 상태 등 환경인자들이 인제거 미생물과 인제거를 저해하는 미생물의 우점도에 영향을 미친다고 할 수 있다.

• 미생물학회지
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• 제45권2호
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• pp.140-147
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• 2009

경기도 김포 지역과 인천 서구 지역공단 주변에 위치한 소하천의 저니(sediment)에서 난분해성 염소화합물인 PCE (tetrachloroethylene)의 혐기성 탈염소화 능력이 있는 군집을 선별하고, 탈염소화에 관여하는 미생물을 탐색하였다. 혐기성 탈염소화 능력을 조사하기 위해 전자공여체로 lactate를 사용하여 혐기성 회분식 실험을 실시하였으며, 탈염소화 능력을 가진 군집을 선별하였다. 선발된 미생물군집은 분자생물학적 기법인 16S rRNA gene의 Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) 기법과 탈염소화 미생물을 선택적으로 탐색할 수 있는 species-specific primer를 이용하여 분석하였다. 총 16개의 시료 중에서 접종 8주 만에 3개의 시료에서 ethene까지 탈염소화시켰으며, 4개의 시료에서 cis-1,2-dichloroethene (cis-DCE)까지 탈염소화시켰다. 또한, 16S rRNA gene을 이용한 PCR-DGGE와 탈염소화 species-specific primer를 이용하여 분석한 결과, PCE 탈염소화 시료 내에는 Dehalococcoides sp.와 Geobacter sp.가 주로 존재하였으며, Dehalobacter sp.도 일부 시료에서 검출되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권8호
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• pp.1088-1097
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• 2014

The study aimed to investigate the effects of gynosaponin on in vitro methanogenesis under different forage-concentrate ratios (F:C ratios). Experiment was conducted with two kinds of F:C ratios (F:C = 7:3 and F:C = 3:7) and gynosaponin addition (0 mg and 16 mg) in a $2{\times}2$ double factorial design. In the presence of gynosaponin, methane production and acetate concentration were significantly decreased, whereas concentration of propionate tended to be increased resulting in a significant reduction (p<0.05) of acetate:propionate ratio (A:P ratio), in high-forage substrate. Gynosaponin treatment increased (p<0.05) the butyrate concentration in both F:C ratios. Denaturing gradient gel electrophoresis (DGGE) analysis showed there was no apparent shift in the composition of total bacteria, protozoa and methanogens after treated by gynosaponin under both F:C ratios. The real-time polymerase chain reaction (PCR) analysis indicated that variable F:C ratios significantly affected the abundances of Fibrobacter succinogenes, Rumninococcus flavefaciens, total fungi and counts of protozoa (p<0.05), but did not affect the mcrA gene copies of methanogens and abundance of total bacteria. Counts of protozoa and abundance of F.succinogenes were decreased significantly (p<0.05), whereas mcrA gene copies of methanogens were decreased slightly (p<0.10) in high-forage substrate after treated by gynosaponin. However, gynosaponin treatment under high-concentrate level did not affect the methanogenesis, fermentation characteristics and tested microbes. Accordingly, overall results suggested that gynosaponin supplementation reduced the in vitro methanogenesis and improved rumen fermentation under highforage condition by changing the abundances of related rumen microbes.

• 신재생에너지
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• 제16권1호
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• pp.58-67
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• 2020

Microbial electrosynthesis has recently been considered a potentially sustainable biotechnology for converting carbon dioxide (CO₂) into valuable biochemicals. In this study, bioelectrochemical acetate production from CO₂ was studied in an H-type two-chambered reactor system with an anaerobic microbial consortium. Metal-rich mud flat was used as the inoculum and incubated electrochemically for 90 days under a cathode potential of -1.1 V (vs. Ag/AgCl). Four consecutive batch cultivations resulted in a high acetate concentration and productivity of 93 mmol/L and 7.35 mmol/L/day, respectively. The maximal coulombic efficiency (rate of recovered acetate from supplied electrons) was estimated to be 64%. Cyclic voltammetry showed a characteristic reduction peak at -0.2~-0.4 V, implying reductive acetate generation on the cathode electrode. Furthermore, several electroactive acetate-producing microorganisms were identified based on denaturing- gradient-gel-electrophoresis (DGGE) and 16S rRNA sequence analyses. These results suggest that the mud flat can be used effectively as a microbial source for bioelectrochemical CO₂ conversion.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.1005-1012
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• 2020

Acid mine drainage (AMD) has been a serious environmental issue that threatens soil and aquatic ecosystems. In this study, an acid-tolerant sulfate-reducing bacterium, strain S4, was isolated from the mud of an AMD storage pond in Vietnam via enrichment in anoxic mineral medium at pH 5. Comparative analyses of sequences of the 16S rRNA gene and dsrB gene involved in sulfate reduction revealed that the isolate belonged to the genus Desulfovibrio, and is most closely related to Desulfovibrio oxamicus (with 99% homology in 16S rDNA sequence and 98% homology in dsrB gene sequence). Denaturing gradient gel electrophoresis (DGGE) analyses of dsrB gene showed that strain S4 represented one of the two most abundant groups developed in the enrichment culture. Notably, strain S4 was capable of reducing sulfate in low pH environments (from 2 and above), and resistance to extremely high concentration of heavy metals (Fe 3,000 mg/l, Zn 100 mg/l, Cu 100 mg/l). In a batch incubation experiment in synthetic AMD with pH 3.5, strain S4 showed strong effects in facilitating growth of a neutrophilic, metal sensitive Desulfovibrio sp. strain SR4H, which was not capable of growing alone in such an environment. Thus, it is postulated that under extreme conditions such as an AMD environment, acid- and metal-tolerant sulfate-reducing bacteria (SRB)-like strain S4 would facilitate the growth of other widely distributed SRB by starting to reduce sulfate at low pH, thus increasing pH and lowering the metal concentration in the environment. Owing to such unique physiological characteristics, strain S4 shows great potential for application in sustainable remediation of AMD.

• Journal of Microbiology and Biotechnology
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• 제22권9호
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• pp.1193-1201
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• 2012

The analysis and quantification of ammonia-oxidizing bacteria (AOB) is crucial, as they initiate the biological removal of ammonia-nitrogen from sewage. Previous methods for analyzing the microbial community structure, which involve the plating of samples or culture media over agar plates, have been inadequate because many microorganisms found in a sewage plant are unculturable. In this study, to exclusively detect AOB, the analysis was carried out via denaturing gradient gel electrophoresis using a primer specific to the amoA gene, which is one of the functional genes known as ammonia monooxygenase. An AOB consortium (S1 sample) that could oxidize an unprecedented 100% of ammonia in 24 h was obtained from sewage sludge. In addition, real-time PCR was used to quantify the AOB. Results of the microbial community analysis in terms of carbon utilization ability of samples showed that the aeration tank water sample (S2), influent water sample (S3), and effluent water sample (S4) used all the 31 substrates considered, whereas the AOB consortium (S1) used only Tween 80, D-galacturonic acid, itaconic acid, D-malic acid, and $_L$-serine after 192 h. The largest concentration of AOB was detected in S1 ($7.6{\times}10^6copies/{\mu}l$), followed by S2 ($3.2{\times}10^6copies/{\mu}l$), S4 ($2.8{\times}10^6copies/{\mu}l$), and S3 ($2.4{\times}10^6copies/{\mu}l$).

• Journal of Dairy Science and Biotechnology
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• 제31권2호
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• pp.171-177
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• 2013

The dairy industry has consistently grown via the expansion of dairy-based food categories. Dairy product consumption is stable since the nutrient composition in dairy products is ideal for human health. However, dairy products are highly susceptible to food-borne pathogens. Controlling the safety of dairy products is thus important when considering the nutrient-rich matrix of this food category. Currently, immunoassays or molecular biology techniques have been used to evaluate the safety of dairy products in Korea. These methods are based on the detection of proteins and thus have low reproducibility and sensitivity. Recent techniques to detect food-borne pathogens have focused on genetic analyses. Rapid detection methods for food-borne pathogens in milk and dairy products using polymerase chain reaction (PCR) techniques, such as conventional PCR, real-time PCR, repetitive sequence-based (rep)-PCR, PCR-denaturing gradient gel electrophoresis (DGGE), and digital PCR, are reviewed in this article. The aim of this review was to contribute knowledge of the relationship between microflora and the quality of dairy products. This study will also assist in the immediate monitoring of food-borne pathogens in milk and dairy products when an outbreak related to this food category occurs.

• 한국수소및신에너지학회논문집
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• 제19권5호
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• pp.410-416
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• 2008

합성 및 두부 제조 폐수로부터 혐기 세균 복합체를 이용하여 수소를 생산하였다. 수소생산 혐기 세균 복합체는 하수처리장 농축 소화조에서 발생하는 슬러지를 $90^{\circ}C$에서 20분간 열처리하여 얻었다. 혐기 세균 복합체는 $37^{\circ}C$ 회분식 운전조건에서 1% (w/v) 포도당 함유 PYG (peptone-yeast extract-glucose) 배지로부터 1.15 L-$H_2$/g-균체건조량의 수소를 생산할 수 있었고, 이때 주요 유기산으로 15 mM acetate와 32 mM butyrate가 생성되었다. 같은 발효조건에서 1.4% 전분과 0.07% 환원당을 포함하는 두부 제조 폐수로부터 1.76 L $H_2$/L-두부제조폐수의 수소를 발생하였다. 이와 같은 결과로 부터 포도당과 두부 제조 폐수로부터 혐기세균 복합체에 의한 수소생산 효율은 각각 1.9과 0.9 mol $H_2$/mol 포도당을 나타내었다. 반연속운전(HRT, 12 시간)시 합성폐수를 이용하여 60일 이상 안정적으로 수소를 생산할 수 있었고, 이 때 혐기 세균 복합체는 1.3-2.0 L $H_2$/L-배양액을 발생하였다. PCR-DGGE(polymer chain reaction-denaturing gradient gel electrophoresis) 분석결과, 반응기 내 세균 복합체의 주요 미생물은 Clostridium 종이었다. 본 연구는 적절한 열처리를 통해 혐기 소화조 슬러지로부터 고활성 수소생산 세균 복합체를 얻을 수 있으며, 이들 세균 복합체를 이용하여 합성 및 두부제조 폐수로부터 효율적인 수소생산이 가능하다는 것을 나타내고 있다.

• Journal of Microbiology and Biotechnology
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• 제24권7호
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• pp.879-887
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• 2014

Bacteria that mediate the anaerobic oxidation of ammonium (anammox) have been detected in natural ecosystems, as well as various wastewater treatment systems. In this study, sludge from a particular landfill leachate anaerobic treatment system was selected as the incubation seed for anammox microorganism enrichment owing to its possible anammox activity. Transmission electron microscopy observation, denaturing gradient gel electrophoresis analysis, and cloning/sequencing techniques were applied to identify the diversity of anammox microorganisms throughout the incubation. During the early stage of operation, the diversity of anammox microorganisms was similar to the original complex microbes in the seed sludge. However, as incubation time increased, the anammox microorganism diversity within the system that was originally dominated by Candidatus (Ca.) Brocadia sp. was replaced by Ca. Anammoxoglobus propionicus. The domination of Ca. Anammoxoglobus propionicus produced a stable removal of ammonia (70 mg-N/l) and nitrite (90 mg-N/l), and the total nitrogen removal efficiency was maintained at nearly 95%. The fluorescence in situ hybridization results showed that Ca. Anammoxoglobus propionicus was successfully enriched from $1.8{\pm}0.6%$ initially to $65{\pm}5%$ after 481 days of operation. Therefore, the present results demonstrated the feasibility of enriching Ca. Anammoxoglobus propionicus from leachate sludge, even though the original cell count was extremely low. Application of this seldom found anammox organism could offer an alternative to current ammonia-nitrogen treatment.