• Journal of Applied Biological Chemistry
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• 제59권3호
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• pp.173-178
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• 2016

Phenyllactic acid (PLA), which is a known antimicrobial compound, can be synthesized through the reduction of phenylpyruvic acid (PPA) by lactate dehydrogenase of lactic acid bacteria (LAB). PLA-producing LAB was isolated from coffee beans, and the isolated LAB was identified as Lactobacillus zeae Y44 by 16S rRNA gene sequence analysis. Cell-free supernatant (CFS) from L. zeae Y44 was assessed for both its capability to produce the antimicrobial compound PLA and its antifungal activity against three fungal pathogens (Rhizoctonia solani, Botrytis cinerea, and Colletotrichum aculatum). PLA concentration was found to be 4.21 mM in CFS when L. zeae Y44 was grown in MRS broth containing 5 mM PPA for 12 h. PLA production could be promoted by the supplementation with PPA and phenylalanine (Phe) in the MRS broth, but not affected by 4-hydroxy-phenylpyruvic acid, and inhibited by tyrosine as precursors. Antifungal activity assessment demonstrated that all fungal pathogens were sensitive to 5 % CFS (v/v) of L. zeae Y44 with average growth inhibitions ranging from 27.8 to 50.0 % (p<0.005), in which R. solani was the most sensitive with an inhibition of 50.0 %, followed by B. cinerea and C. aculatum. However, pH modification of CFS to pH 6.5 caused an extreme reduction in their antifungal activity. These results may indicate that the antifungal activity of CFS was caused by acidic compounds like PLA or organic acids rather than proteins or peptides molecules.

• Asian-Australasian Journal of Animal Sciences
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• 제25권6호
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• pp.852-860
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• 2012

An Antarctic bacterial isolate displaying extracellular ${\alpha}$-galactosidic activity was named Paenibacillus sp. LX-20 based on 16S rRNA gene sequence analysis. Optimal activity for the LX-20 ${\alpha}$-galactosidase occurred at pH 6.0-6.5 and $45^{\circ}C$. The enzyme immobilized on the smart polymer Eudragit L-100 retained 70% of its original activity after incubation for 30 min at $50^{\circ}C$, while the free enzyme retained 58% of activity. The enzyme had relatively high specificity for ${\alpha}$-D-galactosides such as p-nitrophenyl-${\alpha}$-galactopyranoside, melibiose, raffinose and stachyose, and was resistant to some proteases such as trypsin, pancreatin and pronase. Enzyme activity was almost completely inhibited by $Ag^+$, $Hg^{2+}$, $Cu^{2+}$, and sodium dodecyl sulfate, but activity was not affected by ${\beta}$-mercaptoethanol or EDTA. LX-20 ${\alpha}$-galactosidase may be potentially useful as an additive for soybean processing in the feed industry.

• Journal of Applied Biological Chemistry
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• 제54권1호
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• pp.1-6
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• 2011

Poly-${\gamma}$-glutamic acid (${\gamma}$-PGA)는 청국장이 발효할 때 생성되는 점질성 물질의 하나로, monomer glutamic acid의 ${\alpha}$-아미노기와 ${\gamma}$-카르복실기 사이의 amide linkage에 의해 결합된 D(-)와 L(-) glutamic acid repeat units로 이루어진 homopolymer이다. 주로 Bacillus sp.에 의해 생산된다. ${\gamma}$-PGA는 수용성, 음이온성, 무독성, 생분해성, 생체적 합성, 식용 등의 다양한 특성을 가지고 있기 때문에 여러 분야에서 응용되고 있다. 본 실험에서 ${\gamma}$-PGA를 생산하는 균주를 우리나라의 전통발효식품인 청국장으로부터 분리하였다. 분리균주의 형태 및 배양학적, 생리학적 특성, API kit 및 16S rRNA 서열을 사용하여 동정한 결과, 분리균주 GS-2는 B. subtilis와 가장 유사하여 B. subtilis GS-2로 명명하였다. 분리 정제된 ${\gamma}$-PGA의 동정은 TLC, HPLC, FTIR 그리고 $^1H$-NMR spectroscopy를 통하여 확인하였다.

• 한국물환경학회지
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• 제36권6호
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• pp.581-591
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• 2020

In this study, two types of reactors were operated to examine the properties of methanol uptake under the high-rate denitrification process. In a sequencing batch reactor, the denitrifying activity was enriched up to 0.80 g-N/g-VSS-day for 72 days. Then, the enriched denitrifying sludge was transferred to a completely stirred tank reactor (CSTR). At the final phase on Day 46-50, the nitrogen removal efficiency was around 100% and the total nitrogen removal rate reached 0.097±0.003 kg-N/㎥-day. During the continuous process, the sludge settling index (SVI30) was stabilized as 118.3 mL/g with the biomass concentration of 1,607 mg/L. The continuous denitrifying process was accelerated by using a sequencing batch reactor (SBR) with a total nitrogen removal rate of 0.403±0.029 kg-N/㎥-day with a high biomass concentration of 8,433 mg-VSS/L. Because the reactor was open to ambient air with the dissolved oxygen range of 0.2-0.5 mg-O2/L, an increased organic carbon requirement of 5.58±0.70 COD/NO3--N was shown for the SBR in comparison to the value of 4.13±0.94 for the test of the same biomass in a completely anaerobic batch reactor. The molecular analysis based on the 16S rRNA gene showed that Methyloversatilis discipulorum and Hyphomicrobium zavarzinii were the responsible denitrifiers with the sole organic carbon source of methanol.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.560-570
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• 2007

The effective and accurate assessment of the total microbial community diversity is one of the primary challenges in modem microbial ecology, especially for the detection and characterization of unculturable populations and populations with a low abundance. Accordingly, this study was undertaken to investigate the diversity of the microbial community during the biodegradation of cis- and trans-dichloroethenes in soil and wastewater enrichment cultures. Community profiling using PCR targeting the l6S rRNA gene and denaturing gradient gel electrophoresis (PCR-DGGE) revealed an alteration in the bacterial community profiles with time. Exposure to cis- and trans-dichloroethenes led to the disappearance of certain genospecies that were initially observed in the untreated samples. A cluster analysis of the bacterial DGGE community profiles at various sampling times during the degradation process indicated that the community profile became stable after day 10 of the enrichment. DNA sequencing and phylogenetic analysis of selected DGGE bands revealed that the genera Acinetobacter, Pseudomonas, Bacillus, Comamonas, and Arthrobacter, plus several other important uncultured bacterial phylotypes, dominated the enrichment cultures. Thus, the identified dominant phylotypes may play an important role in the degradation of cis- and trans-dichloroethenes.

• 생명과학회지
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• 제27권2호
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• pp.202-210
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• 2017

토하젓에서 분리한 박테리오신 생산 균주 중 상대적으로 넓은 항균스펙트럼을 나타내는 1균주를 선발하였고 16S rRNA 유전자 염기서열 분석 결과 B. subtilis E9-1와 거의 일치하는 것으로 동정되었다. B. subtilis E9-1가 생산하는 박테리오신의 물리화학적 특성을 조사하였고, 박테리오신을 정제하였다. 이 박테리오신은 B. cereus KCCM 11204, M. luteus IAM 1056, L. monocytogenes KCCM 40307, E. faecium KCCM 12118 및 S. aureus subsp. aureus KCCM 40050 등에 대해서 항균활성을 나타내었다. pH 2.0~8.0 범위에서는 안정하였으나 8.0 이상에서는 항균활성이 감소하였다. Isopropanol, ethanol 및 methanol 등의 유기용매에서 100%까지, acetone과 acetonitrile에서는 80%까지 항균활성을 유지하였다. 내열성의 경우 $40{\sim}100^{\circ}C$에서 60분까지는 안정하게 항균활성을 보였다. 박테리오신 농도를 증가시키면서 B. cereus, L. monocytogenes, E. faecium 및 S. aureus subsp. aureus 등 시험균 4주의 감수성을 조사한 결과 농도 의존적으로 시험균의 생육이 감소하였고 이중 L. monocytogenes 의 감수성이 가장 높게 나타났다. 박테리오신의 작용양상을 알아본 결과 B. cereus와 L. monocytogenes 배양액에 박테리오신 용액을 첨가한 후 흡광도와 CFU값이 감소하여 bactericidal임을 확인하였다. 식품에 적용 가능성을 알아보기 위해 실험한 결과 3일째부터 박테리오신을 처리하지 않은 대조구에 비해 실험구에서 생균수(CFU/ml)가 감소하였다. 아세톤을 이용한 배양상등액의 농축, superdex peptide HR 10/300 column 이용한 겔여과크로마토그래피, 역상 HPLC로써 박테리오신을 정제하였다. 역상 HPLC를 통해서 정제한 박테리오신의 분자량을 tricine SDS- PAGE로 분석한 결과 약 4 kDa이었고 질량분석법으로 측정한 정확한 분자량은 3347.6 Da로 나타났다.

• 한국환경과학회지
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• 제14권10호
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• pp.955-963
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• 2005

From sludge of S municipal wastewater treatment plant in Busan, Korea, we isolated the denitrifier DN-9 which showed the ability of denitrification under aerobic conditionby the color change and gas formation in liquid culture with Giltay medium. The isolated strain was identified as Pseudomonas sp. DN-9 on the basis of the morphological, physiological, biochemical and nucleotide sequence analysis of l6S rRNA. The isolated strain, Pseudomonas sp. DN-9, has cytochrome $cd_1$, nirS of nitrite reductase. By the co-existance of additional ammonium and nitrate ion, the strain was not affected largely on growth in SL series broth. It seemed the result of denitrification. Although Pseudomonas sp. DN-9 has a good nitrate reduction activity under aerobic condition, the activity is less than Pseudomonas stutzeri in same cultivation condition. However, Escherichia coli had little the activity of aerobic denitrification and Pseudomonas putida showed lower activity of aerobic denitrification than Pseudomonas sp. DN-9 and Pseudomonas stutzeri in this study.

• 한국미생물·생명공학회지
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• 제33권3호
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• pp.200-206
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• 2005

한국 청국장에서 poly-$\gamma$-glutamic acid (PGA)를 대량 생산하는 세균을 분리하였다. 이 세균의 16s ribosomal RNA 서열을 분석한 결과 Bacillus subtilis BFAS, B. subtilis MO4와 B. amyloliquefaciens B128과 99.0, 97.7 그리고 $97.3{\%}$의 상동성을 각각 나타내었다. 따라서 본 분리 균주를 Bacillus sp.로 동정하고 Bacillus sp. YN-1로 명명하였다. PGA 대량생산 을 위해 생산 조건을 검토한 결과 $3{\%}$ glutamic acid, $4{\%}$ fructose를 탄소원으로 첨가하였을 때 최대량의 PGA를 생산하는 것을 알 수 있었다. 또한 PGA 최대 생산량은 최적 배양 조건에서 27 g/l의 양으로 생산되어 본 균주는 PGA 대량 생산에 적합한 세균임을 확인할 수 있었으며 식품 및 화장품 산업에 유용하게 사용할 수 있을 것으로 사료된다.

• 한국환경농학회지
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• 제30권4호
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• pp.424-431
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• 2011

본 연구에서 우리는 광양만의 해수와 표층 퇴적물에서 TBTCl 내성세균의 개체수를 조사하였다. 광양만에서 TBTCl 내성세균의 개체수는 해수에서 $2.5{\times}10^3-3.8{\times}10^3$ cfu/mL 범위였으며, 표층 퇴적물에서 TBTCl 내성세균의 개체수는 $3.2{\times}10^5-9.1{\times}10^5$ cfu/g 범위였다. 광양만에서 TBTCl 내성세균의 종조성은 Vibrio spp. (19.2%)가 가장 높은 우점종으로 나타났고, Bacillus spp. (16.2%), Aeromonas spp. (15.2%), Pseudomonas spp. (13.1%), Klebsiella spp. (11.1%), Alteromonas spp. (9.1%), Pantoea spp. (6.1%), Proteus spp. (3.0%), Listeria spp. (2.0%), unidentified (5.0%)의 순으로 우점하였다. 또한 11개의 대표적인 TBTCl 내성균주는 여러 중금속들(Cd, Cu, Hg 및 Zn)에도 내성을 나타내었다. 이들 중에서 가장 강한 TBTCl 내성을 보이는 T7 균주를 선별하여, API 20NE등을 이용하여 본 균주의 형태학적, 생리학적 및 생화학적 특성들을 조사하였다. T7 균주는 16S rRNA gene 염기서열 분석에 의해 Pantoea 속으로 동정되어 Pantoea sp. T7으로 명명되었다. 또한 본 균주는 $500{\mu}M$의 TBTCl 농도에서도 60시간 배양 후에 정상 균주 성장의 50.7%까지 증식하였다. Pantoea sp. T7의 생물학적 TBTCl 분해활성은 GC-FPD 분석에 의해 측정되었는데, $100{\mu}M$의 TBTCl 농도에서 배양 40시간 후에 TBTCl 제거 효율은 62.7%로 나타났다.

• Corrosion Science and Technology
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• 제18권6호
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• pp.221-227
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• 2019

During the operation, maintenance and decommissioning of nuclear power plant radioactive contaminated waste is produced. This waste is stored in an underground repository 60-100 meters below the surface. The metallic portion of this waste comprises mostly carbon and stainless steel. A long-term field exposure showed high corrosion rates, general corrosion up to 29 ㎛ a^-1 and localized corrosion even higher. High corrosion rate is possible if microbes produce corrosive products, or alter the local microenvironment to favor corrosion. The bacterial and archaeal composition of biofilm formed on the surface of carbon steel was studied using 16S rRNA gene targeting sequencing, followed by phylogenetic analyses of the microbial community. The functional potential of the microbial communities in biofilm was studied by functional gene targeting quantitative PCR. The corrosion rate was calculated from weight loss measurements and the deposits on the surfaces were analyzed with SEM/EDS and XRD. Our results demonstrate that microbial diversity on the surface of carbon steel and their functionality is vast. Our results suggest that in these nutrient poor conditions the role of methanogenic archaea in corrosive biofilm, in addition to sulphate reducing bacteria, could be greater than previously suspected.