• 한국미생물·생명공학회지
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• 제33권3호
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• pp.215-221
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• 2005

Hexane을 유일 탄소원으로 첨가한 무기염 배지에서 hexane 생분해 속도와 비성장속도를 구하였고, $^{14}C-hexane$을 이용하여 무기화(mineralization) 정도를 측정하였다. 또한, 16S rDNA PCR-DGGE 분석기법을 활용하여 consortium의 미생물 군집 특성을 조사하였다. Consortium CH의 최대 비성장속도 (${\mu}_{max}$)값은 $0.2\;h^{-1}$이고, 최대 hexane 분해속도 ($V_{max}$)와 포화상수 ($K_{s}$)는 각각 460 ${\mu}mol{\cdot}g-DCW^{-1}{\cdot}h^{-1}$ 및 25.87mM 이었다. Consortium CH는 $^{14}C-hexane$의 약 $49.1\%$를 무기화하였고, $43.6{\%}$의 $^{14}C-hexane$는 biomass를 증가시키는데 사용하였다. DGGE band로부터 얻은 clone들은 유류, biphenyl, PCE 및 폐가스 등과 같은 오염물질 분해능을 가진 세균들과 유사성이 가장 높았다. 본 연구에서 얻은 hexane 생분해용 consortium은 향후 hexane 제거용 생물학적 시스템을 개발하는데 유용하게 활용될 수 있다.

• Journal of Microbiology and Biotechnology
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• 제18권8호
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• pp.1459-1469
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• 2008

Using a rotating biological contactor modified with a sequencing bath reactor system (SBRBC) designed and operated to remove phosphate and nitrogen [58], the microbial community structure of the biofilm from the SBRBC system was characterized based on the extracellular polymeric substance (EPS) constituents, electron microscopy, and molecular techniques. Protein and carbohydrate were identified as the major EPS constituents at three different biofilm thicknesses, where the amount of EPS and bacterial cell number were highest in the initial thickness of 0-100${\mu}m$. However, the percent of carbohydrate in the total amount of EPS decreased by about 11.23%, whereas the percent of protein increased by about 11.15% as the biofilm grew. Thus, an abundant quantity of EPS and cell mass, as well as a specific quality of EPS were apparently needed to attach to the substratum in the first step of the biofilm growth. A FISH analysis revealed that the dominant phylogenetic group was $\beta$- and $\gamma$-Proteobacteria, where a significant subclass of Proteobacteria for removing phosphate and/or nitrate was found within a biofilm thickness of 0-250${\mu}m$. In addition, 16S rDNA clone libraries revealed that Klebsiella sp. and Citrobacter sp. were most dominant within the initial biofilm thickness of 0-250${\mu}m$, whereas sulfur-oxidizing bacteria, such as Beggiatoa sp. and Thiothrix sp., were detected in a biofilm thickness over 250${\mu}m$. The results of the bacterial community structure analysis using molecular techniques agreed with the results of the morphological structure based on scanning electron microscopy. Therefore, the overall results indicated that coliform bacteria participated in the nitrate and phosphorus removal when using the SBRBC system. Moreover, the structure of the biofilm was also found to be related to the EPS constituents, as well as the nitrogen and phosphate removal efficiency. Consequently, since this is the first identification of the bacterial community and structure of the biofilm from an RBC simultaneously removing nitrogen and phosphate from domestic wastewater, and it is hoped that the present results may provide a foundation for understanding nitrate and phosphate removal by an RBC system.

• Journal of Microbiology and Biotechnology
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• 제18권4호
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• pp.711-717
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• 2008

To speed up the conversion of rice straw into feeds in a low-temperature region, a start culture used for ensiling rice straw at low temperature was selected by continuous enrichment cultivation. During the selection, the microbial source for enrichment was rice straw and soil from two places in Northeast China. Lab-scale rice straw fermentation at $10^{\circ}C$ verified, compared with the commercial inoculant, that the selected start culture lowered the pH of the fermented rice straw more rapidly and produced more lactic acid. The results from denatured gradient gel eletrophoresis showed that the selected start culture could colonize into the rice straw fermentation system. To analyze the composition of the culture, a 16S rRNA gene clone library was constructed. Sequencing results showed that the culture mainly consisted of two bacterial species. One (A) belonged to Lactobacillus and another (B) belonged to Leuconostoc. To make clear the roles of composition microbes in the fermented system, quantitative PCR was used. For species A, the DNA mass increased continuously until sixteen days of the fermentation, which occupied 65%. For species B, the DNA mass amounted to 5.5% at six days of the fermentation, which was the maximum relative value during the fermentation. To the authors' best knowledge, this is the first report on ensiling rice straw with a selected starter at low temperature and investigation of the fermented characteristics.

• Journal of Microbiology and Biotechnology
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• 제29권4호
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• pp.527-537
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• 2019

Three types of meongge (Halocynthia roretzi) jeotgal (MJ) were prepared with 3 different types of salts (12%, w/v): purified salt (PS), solar salt aged for 3 years (SS), and bamboo salt that had been recrystalized 3 times (BS). One set of MJ was fermented with starters, Bacillus subtilis JS2 and Tetragenococcus halophilus BS1-37 (each 6 log CFU/g), and another set without starters for 42 days at $10^{\circ}C$. The LAB count of the SSMJ (non-starter) was highest at day 28 (2.30 log CFU/g). The pH of the PSMJ and SSMJ was 5.72-5.77 at day 0, and 5.40-5.50 at day 42. BSMJ showed higher pH and lower titratable acidities than other samples. Amino-type nitrogen (ANN) increased continuously, and SSMJ showed higher values than other samples from day 14. Bacterial species of non-starter MJ were examined by culture independent method. Clone libraries of 16S rRNA genes were constructed in Escherichia coli from total DNA from non-starter MJ samples at day 0, 14, and 28. Thirty clones per each sample were randomly selected and DNA sequences were analyzed. Variovorax sp., uncultured bacterium, and Acidovorax sp. were the most dominant group at day 0, 14, and 28, respectively. Lactobacillus sakei and Streptococcus sp. were the next dominant group in SSMJ at day 28. A Streptococcus sp. was detected from PSMJ at day 28. Sensory evaluation for MJ samples at day 28 showed that SSMJ got higher overall acceptability scores. These results showed that solar salt can cause desirable changes in the microbial community of fermented foods, thereby positively affecting their overall quality.

• 미생물학회지
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• 제49권2호
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• pp.156-164
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• 2013

방선균은 의약, 농업 및 식품 생산 등에 유용하게 사용되는 이차대사물질을 생산하는 미생물 자원으로 자연환경 내에서 많은 생물들과 긴밀한 상호작용을 유지하고 있다. 본 연구에서는 장수풍뎅이 유충의 분변에 존재하는 방선균의 다양성과 기능성을 조사하기 위해서 비배양적 접근과 배양적 방법으로 실험을 수행하였다. 먼저 시료로부터 직접 추출한 community DNA에서 방선균-특이 primer를 이용하여 방선균의 16S rRNA 유전자를 PCR로 증폭, 클로닝한 후에 각 clone에 삽입된 염기서열을 분석하였다. 총 37개의 염기서열을 얻었으며 계통분류학적 분석을 수행한 결과, 15속 24종으로 분류되었다. 아울러 53개의 방선균 균주를 장수풍뎅이 유충 분변으로부터 분리하였다. 형태학적 특징을 비교하여 최종적으로 27개의 균주를 선발하여 다양성, 항균활성 및 생화학적 특징을 검정하였다. 분리된 균주들은 4속 14종으로 분류되었으며, 24균주(89%)는 Streptomyces 속으로 분류되었다. 대다수의 균주들이 식물병원성 곰팡이와 그람양성 세균에 대해 길항 효과를 보였다. 또한 많은 균주들이 셀룰로오스와 카제인을 분해하는 생화학적 특징을 보였다. 본 연구를 통해, 장수풍뎅이 유충의 분변 시료로부터 다양한 방선균이 분리될 수 있으며, 분리된 균주들은 다양한 항균효과 및 효소활성을 지니고 있다는 것을 확인하였다. 결론적으로 본 연구는 장수풍뎅이와 같은 곤충의 장과 분변은 다양한 방선균의 서식처이며, 이곳에서 유용한 생리활성 물질을 발견할 수 있다는 것을 제시한다.

• 대한환경공학회지
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• 제31권10호
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• pp.919-926
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• 2009

혐기성 암모늄 산화공정을 안정화시키기 전에 많은 양의 식종 미생물 투여가 필요하므로 혐기성 암모늄 산화균의 농후배양은 실규모의 혐기성 암모늄 산화 반응기를 운영할 때 필수적인 과정이다. 본 연구에서는 활성슬러지 미생물을 식종한 연속 회분식 반응기를 이용하여 혐기성 암모늄 산화균을 농후배양하고, 미생물 군집구조의 변화를 관찰하여 농후배양 결과를 검증하였다. 혐기성 암모늄 산화균의 농후배양은 70일간 시행되었고, 농후배양 후 활성시험에서 $NH_4\;^+$와 $NO_2\;^-$의 기질제거효율이 각각 98.5%와 90.7%로 관찰되어 혐기성 암모늄 산화균의 배양이 성공적으로 수행된 것으로 판단되었다. 계통분류학적 분지도 작성 결과, 다양하였던 Planctomycetes 문(phylum)의 미생물 군집구조가 농후배양 이후에 현저하게 단순해졌다는 것이 밝혀졌다. 농후배양 이후 발견된 36개의 clone들 모두가 혐기성 암모늄 산화균이었으며, Candidatus Brocadia (36%) 와 Candidatus Anammoxoglobus (64%) 속(genus)에 속하였다. RTQ-PCR (real-time quantitative PCR)을 통해 혐기성 암모늄 산화균을 정량한 결과, 혐기성 암모늄 산화 상향류식 연속 배양기에서 1년 이상 선택 배양된 붉은색 혐기성암모늄 산화 입상 슬러지에 비해 혐기성 암모늄 산화균의 16S rDNA 농도가 74.8%인 것으로 나타났다. 상기의 분자생물학적 분석을 통해 70일간 농후배양된 활성슬러지가 혐기성 암모늄 산화 실용화 공정의 접종 미생물로 활용 가능할 것으로 판단되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권1호
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• pp.50-57
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• 2015

This study was conducted to investigate the effect of soybean meal (SM) and soluble starch (SS) on biogenic amine production and microbial diversity using in vitro ruminal fermentation. Treatments comprised of incubation of 2 g of mixture (expressed as 10 parts) containing different ratios of SM to SS as: 0:0, 10:0, 7:3, 5:5, 3:7, or 0:10. In vitro ruminal fermentation parameters were determined at 0, 12, 24, and 48 h of incubation while the biogenic amine and microbial diversity were determined at 48 h of incubation. Treatment with highest proportion of SM had higher (p<0.05) gas production than those with higher proportions of SS. Samples with higher proportion of SS resulted in lower pH than those with higher proportion of SM after 48 h of incubation. The largest change in $NH_3$-N concentration from 0 to 48 h was observed on all SM while the smallest was observed on exclusive SS. Similarly, exclusive SS had the lowest $NH_3$-N concentration among all groups after 24 h of incubation. Increasing methane ($CH_4$) concentrations were observed with time, and $CH_4$ concentrations were higher (p<0.05) with greater proportions of SM than SS. Balanced proportion of SM and SS had the highest (p<0.05) total volatile fatty acid (TVFA) while propionate was found highest in higher proportion of SS. Moreover, biogenic amine (BA) was higher (p<0.05) in samples containing greater proportions of SM. Histamines, amine index and total amines were highest in exclusive SM followed in sequence mixtures with increasing proportion of SS (and lowered proportion of SM) at 48 h of incubation. Nine dominant bands were identified by denaturing gradient gel electrophoresis (DGGE) and their identity ranged from 87% to 100% which were mostly isolated from rumen and feces. Bands R2 (uncultured bacterium clone RB-5E1) and R4 (uncultured rumen bacterium clone L7A_C10) bands were found in samples with higher proportions of SM while R3 (uncultured Firmicutes bacterium clone NI_52), R7 (Selenomonas sp. MCB2), R8 (Selenomonas ruminantium gene) and R9 (Selenomonas ruminantium strain LongY6) were found in samples with higher proportions of SS. Different feed ratios affect rumen fermentation in terms of pH, $NH_3$-N, $CH_4$, BA, volatile fatty acid and other metabolite concentrations and microbial diversity. Balanced protein and carbohydrate ratios are needed for rumen fermentation.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.952-964
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• 2005

The diesel-degrading activities of biofilms sampled from petroleum-contaminated groundwaters in urban subway drainage systems were examined in liquid cultures, and the microbial populations of the biofilms were characterized by denaturing gel gradient electrophoresis (DGGE) and 16S rDNA sequence analysis. Biofilm samples derived from two sites (19 K and 20 K) at subway Station N and Station I could degrade around $80\%$ of applied diesel within 20 and 40 days, respectively, at $15^{\circ}C$, and these results were strongly correlated with the growth patterns of the biofilms. The closest phylogenetic neighbor of a dominant component in the 19 K biofilm was Thiothrix fructosivorans strain Q ($100\%$ similarity). Four dominant strains in the 20 K biofilm were closely related to Thiothrix fructosivorans strain Q ($100\%$ similarity), Thiothrix sp. CC-5 ($100\%$ similarity), Sphaerotilus sp. IF14 ($99\%$ similarity), and Cytophaga-Flexibacter-Bacterioides (CFB) group bacterium RW262 ($98\%$ similarity). Three dominant members in the Station I biofilms were very similar to uncultured Cytophagales clone CRE-PA82 ($91\%$ similarity), Pseudomonas sp. WDL5 ($97\%$ similarity), and uncultured CFB group bacterium LCK-64 ($94\%$ similarity). The microbial components of the biofilms differed depending on the sampling site. This is the first report on the isolation of clones highly similar to Thiothrix fructosivorans and Thiothrix sp. from biofilms in petroleum-polluted groundwaters, and the first evidence that these organisms may play major roles in petroleum degradation and/or biofilm-development.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.994-1001
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• 2001

An easier way of understanding the BNR system was proposed from the study on substrate, nutrient removal tendency, microbial community and its metabolic function by applying the municipal settled sewage. During the anaerobic period, the phosphorus release rate per VFACOD we varied depending on the phosphorus content in the sludge. When the phosphorus content in the sludge was $6\%$ VSS, according to influent VFACOD, the phosphorus release rate and PHA production were $0.35 gPO_4P/gVFACOD$ and 1.0 gPHA/gVFACOD, respectively. The $NO_3N$ requirement for the phosphorus uptake as an electron acceptor was about $0.5 gNO_3N/gPO_4P_{uptake}$ based on the proposed equation with PHA, biomass, production, and the concentration of phosphorus release/uptake. Bacterial-community analysis of the sludge, as determined by FISH and 16SrDNA characterization FISH, revealed that the beta-subclass proteobacteria were the most abundant group ($27.9\%$ of the proteobacteria-specific probe EUB338), and it was likely that representative of the beta-subclass played key roles in activated sludge. The next dominant group found was the gamma-protebacteria ($15.4\%$ of probe EUB338). 16S rDNA clone library analysis showed that the members of${\beta}$- and ${\gamma}$-proteobacteria were also the most abundant groups, and $21.5\%$ (PN2 and PN4) and $15.4\%$ (PN1 and PN5) of total clones were the genera of denitrifying bacteria and PAO, respectively. Prediction of the microbial community composition was made with phosphorus content (Pv, $\%$ P/VSS) in wasted sludge and profiles of COD, PHA, $PO_4P,\;and\;NO_3N$ in an anaerobic-anoxic SBR unit. Generally, the predicted microbial composition based upon metabolic function, i.e., as measured by stoichiometry, is fairly similar to that measure by the unculturable dependent method. In this study, a proposal was made on he microbial community composition that was more easily approached to analyze the reactor behavior.