• 생명과학회지
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• 제22권11호
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• pp.1545-1551
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• 2012

이전 연구에서 저자들이 Glycoside hydrolase family 50 (GH-50)과 GH-118 ${\beta}$-agarase들의 발현과 특성을 보고한 Agarivorans sp. JA-1 균주로부터 신규의 GH-16 ${\beta}$-agarase를 보고하고자 한다. 본 유전자는 1,362 염기쌍으로 구성되어 있으며, 453 아미노산 잔기로 구성된 49,830 Da의 단백질을 암호화한다. 본 효소는 Pseudoalteromonas sp. CY24 유래의 GH-16 ${\beta}$-agarase와 98%의 염기서열 상동성과 99%의 아미노산서열 상동성을 나타냈다. 신호서열을 제외한 429 아미노산으로 구성된 성숙단백질에 해당하는 유전자를 E. coli BL21 (DE3) 세포에서 재조합 발현시킨 후, 친화성 크로마토그래피로 효소를 정제하였다. 정제된 효소는 $40^{\circ}C$와 pH 5.0에서 67.6 U/mg의 최적 활성을 보였다. 아가로스를 기질로 한 효소분해산물의 박막크로마토그래피 분석결과, neoagarohexaose와 neoagarotetraose가 주산물로 생산되는 것을 알 수 있었다. 본 효소는 기능성 한천올리고당의 산업적 생산에 활용 가능할 것으로 기대된다.

• 미생물학회지
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• 제52권1호
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• pp.40-48
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• 2016

본 연구는 식물성플랑크톤의 대량증식 조절과 관련된 해양성 살조능이 있는 박테리아의 분리와 유해조류에 대한 분리 균주의 살조능 특성에 주로 초점을 맞추고 있다. 해수 표면에서 자연적으로 발생하는 유해조류번성(HAB)은 전세계적으로 많은 환경문제를 일으키고 있다. 본 연구에서는 유해조류 성장을 억제하는 능력을 가진 40개의 박테리아 균주를 마산만, 진해만, 돌섬, 거제도, 통영 앞바다에서 분리하였다. 분리된 균주들은 다양한 유해조류인 Cochlodinium polykrikoides, Chattonella marina, Skeletonema costatum, Heterosigma akashiwo, Heterocapsa triquetra, Prorocentrum minimum, Scrippsiella trochoidea에 대한 살조특성을 추가로 조사하였다. 살조균주의 선별은 이중층 아가배지와 현미경 계수법을 이용하여 진행하였고 Pseudomonas, Vibrio, Bacillus, Pseudoalteromonas, Ruegeria, Joostella, Marinomonas, Stakelama, Porphyrobacter, Albirhodobacter의 속들에 속하는 균주들이었다. 가장 중요한 유해조류인 Co. polykrikoides에 대한 가장 강력한 살조능은 10% 배양상등액으로 6시간 처리했을 때 94%를 보이는 균주였다. 이 연구를 통해 살조효과를 보이는 새로운 속으로 Marinomonas sp. M Jin 1-8, Stakelama sp. ZB Yeonmyeong 1-11 & 1-13, Porphyrobacter sp. M Yeonmyeong 2-22, Albirhodobacter sp. 6-R Jin 6-1를 새롭게 찾았다. 결론적으로 이들 해양박테리아를 이용하면 식물성플랑크톤 번성을 제어하는데 중요한 역할을 할 것으로 예상된다.

• Journal of Microbiology
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• 제41권3호
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• pp.183-188
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• 2003

We isolated and cultured bacteria that inhabited marine biofilms, and identified them by phylogenetic analysis using 16S rDNA sequences. In the marine environment, biofilms cover most subtidal and intertidal solid surfaces such as rocks, ships, loops, marine animals, and algae. The bacteria in most biofilms are embedded in extracellular polymeric substances that comprise mainly of exopolysaccharides. The exopolysaccharides are excreted from multiple bacterial species; therefore, biofilms are a good source for screening exopolysaccharide-producing bacteria. Thirty-one strains were cultured, and a total of 17 unique strains were identified. Phylogenetic analysis using 16S rDNA sequences indicated that the 17 strains belonged to ${\alpha}$-Proteobacteria (Ochrobactrum anthropi, Paracoccus carotinifaciens); ${\gamma}$-Proteobacteria (Pseudoalteromonas agarovorans, P. piscicida, Pseudomonas aeruginosa, Shewanella baltica, Vibrio parahaemolyticus, V. pomeroyi); CFB group bacteria (Cytophaga latercula, Tenacibaculum mesophilum); high GC, Gram-positive bacteria (Arthrobacter nicotianae, Brevibacterium casei, B. epidermidis, Tsukamurella inchonensis); and low GC, Gram-positive bacteria (Bacillus macroides, Staphylococcus haemolyticus, S. warneri).

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권5호
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• pp.414-419
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• 2006

When the alginate lyase gene (aly) from Pseudoalteromonas elyakovii was expressed in E. coli, most of the gene product was organized as aggregated insoluble particles known as inclusion bodies. To examine the effects of chaperones on soluble and nonaggregated form of alginate lyase in E. coli, we constructed plasm ids designed to permit the coexpression of aly and the DnaK/DnaJ/GrpE or GroEL/ES chaperones. The results indicate that coexpression of aly with the DnaK/DnaJ/GrpE chaperone together had a marked effect on the yield alginate lyase as a soluble and active form of the enzyme. It is speculated this result occurs through facilitation of the correct folding of the protein. The optimal concentration of L-arabinose required for the induction of the DnaK/DnaJ/GrpE chaperone was found to be 0.05mg/mL. An analysis of the protein bands on SDS-PAGE gel indicated that at least 37% of total alginate lyase was produced in the soluble fraction when the DnaK/DnaJ/GrpE chaperone was coexpressed.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.777-782
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• 2004

The arylsulfatase gene (astA, 984 bp ORF) from the P. carrageenovora genome was amplified by PCR and subcloned into the pET21a vector. When the constructed plasmid pAST-A1 (6.4 kb) was introduced into E. coli BL21(DE3), the transformant on the LB plate containing IPTG showed a hydrolyzing activity for 4-methylumbelliferyl sulfate and p-nitrophenyl sulfate. The highest arylsulfatase activity (2.1 unit/ml) was obtained at 10 mM IPTG. Most arylsulfatase activity was found in the cell lysate, whereas no significant activity was detected in the culture supernatant. The molecular weight of the recombinant enzyme was estimated to be 33.1 kDa by SDS-PAGE. After the reaction of agar with arylsulfatase for 12 h at $40^{\circ}C$, the gel strength of the agar increased by 2-fold, and 73% of the sulfate in the agar had been removed. This result suggests that arylsulfatase expressed in E. coli could be useful in the production of electrophoretic grade agarose.

• 환경생물
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• 제37권4호
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• pp.592-599
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• 2019

Ostrea denselamellosa and Eriocheir japonica samples were collected from the Seomjin River in 2019 as part of the "Research of Host-Associated Bacteria" research program. Almost 200 bacterial strains were isolated from the O. denselamellosa and E. japonica samples and subsequently identified by 16S rRNA gene sequencing. Among the bacterial isolates, ten strains possessed greater than 98.7% sequence similarity with published bacterial species that had not previously been recorded in Korea. These species were phylogenetically diverse, belonging to three phyla, four classes, seven orders, and eight genera. At the genus and class level, the previously unrecorded species belonged to Pseudoalteromonas, Aliivibrio, Rheinheimera, Leucothrix, and Shewanella of the class Gamma-proteobacteria, Olleya of the class Flavobacteriia, Algoriphagus of the class Cytophagia, and Lactococcus of the class Bacilli. The previously unrecorded species were further characterized by examining their Gram staining, colony and cell morphology, biochemical properties, and phylogenetic positions.

• 한국환경과학회지
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• 제21권10호
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• pp.1187-1193
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• 2012

The aim of this research is to enhance the bottom environment of Geoje fish farm that has been severely contaminated. Treatment of microbial agent and/or calcium oxide significantly changed that environment: in ignition loss, either treatment (25% or 21%) showed better than mixed treatment (13.2%). In COD, the oxygen releasing agent or mixed treatment reduced the index by more than 20%. In T-P and T-N, the effects of $CaO_2$ on them were overwhelming (50% or more) meanwhile that of the microbial agent on them was less than 20%. Also, $CaO_2$ influenced on the microbial flora: Desulfobvibrio thermophilus, a sulfate reducing bacterium decreased in number, considering the increase of pH and rise of redox potential. In contrast, Pseudomonas sp., Pseudoalteromonas sp., Pseudomonas aeruginosa were remarkably dominant over other species with mixed treatment as a PCA analysis confirmed it.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1692-1697
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• 2012

We report a glycoside hydrolase (GH)-118 ${\beta}$-agarase from a strain of Agarivorans, in which we previously reported recombinant expression and characterization of the GH-50 ${\beta}$-agarase. The GH comprised an open reading frame of 1,437 base pairs, which encoded a protein of 52,580 daltons consisting of 478 amino acid residues. Assessment of the entire sequence showed that the enzyme had 97% nucleotide and 99% amino acid sequence similarities to those of GH-118 ${\beta}$-agarase from Pseudoalteromonas sp. CY24, which belongs to a different order within the same class. The gene corresponding to a mature protein of 440 amino acids was inserted, recombinantly expressed in Escherichia coli, and purified to homogeneity with affinity chromatography. It had maximal activity at $35^{\circ}C$ and pH 7.0 and had 208.1 units/mg in the presence of 300 mM NaCl and 1 mM $CaCl_2$. More than 80% activity was maintained after 2 h exposure to $35^{\circ}C$; however, < 40% activity remained at $45^{\circ}C$. The enzyme hydrolyzed agarose to yield neoagarooctaose as the main product. This enzyme could be useful for industrial production of functional neoagarooligosaccharides.

• Journal of Species Research
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• 제11권3호
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• pp.143-154
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• 2022

To obtain unrecorded bacterial species in Korea, various marine samples were collected from Jeollanam-do Province, Korea in 2021. After plating the samples on marine agar and marine R2A agar, and incubating aerobically and anaerobically, approximately 1200 bacterial strains were isolated and identified using 16S rRNA gene sequences. A total of 30 strains showed ≥98.7% 16S rRNA gene sequence similarity with validly published bacterial species but not reported in Korea, indicating that they are unrecorded bacterial species in Korea. The unrecorded bacterial strains belonged to 4 phyla, 7 classes, 13 orders, 19 families, and 22 genera, which were assigned to Azospirllium, Loktanella, and Pseudovibrio of the class Alphaproteobacteria; Grimontia, Halomonas, Marinobacter, Microbulbifer, Photobacterium, Pseudoalteromonas, Pseudidiomarina, Ferrimonas, Shewanella, Simiduia, Thalassotalea, and Vibrio of the class Gammaproteobacteria; Priestia and Enterococcus of the class Bacilli; Persicobacter of the class Cytophagia; Aureivirga of the class Flavobacteriia; Propionigenium and Psychrilyobacter of the class Fusobacteriia; and Tepidibacter of the class Clostridia. The details of the unreported species including Gram reaction, colony and cell morphology, biochemical characteristics, and phylogenetic position are also provided in the description of the strains.

• 한국환경농학회지
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• 제42권3호
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• pp.169-176
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• 2023

The emergence and spread of antibiotic-resistant bacteria have been increasing with anthropogenic contamination. Understanding the prevalence and distribution of these resistant bacteria in environments is crucial for effectively managing anthropogenic pollutants. Lake Gyeongpo in the Gangwon Province of South Korea is known for its diverse ecological features and human interactions. The lake is exposed to pollutants from nonpoint sources, including urban areas, agricultural practices, and recreational activities, which can introduce antibiotics and foster antibiotic resistance in bacteria. The present study investigates Lake Gyeongpo as a potential reservoir for antibiotic-resistant bacteria in a natural ecosystem. A total of 203 bacterial isolates were collected from six sampling locations in Lake Gyeongpo during May, July, and November 2022. Most isolates were taxonomically identified as Pseudoalteromonas, Bacillus, Shewanella, and Vibrio spp.; their abundance showed a spatiotemporal distribution. An antibiotic susceptibility test was conducted on 75 isolates using the disk diffusion method with six drugs according to the CLSI guideline; 42 isolates were resistant to one or more antibiotics. Among these, 15 isolates were identified as multidrug resistant bacteria. This finding suggests the potential anthropogenic impact on Lake Gyeongpo and provides valuable insights into the dissemination of antibiotic resistance caused by anthropogenic pollutants.