• KSBB Journal
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• v.11 no.5
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• pp.593-599
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• 1996

The strain which produces agar degrading enzyme was isolated from chiton(Liolophura japonica). The strain was identified as Cytophaga sp. through its morphological, physiological, and biological characteristics. For the production of agar degrading enzyme, 0.3% nutrient broth, 0.2% yeast extract and 0.5% agar was used as nitrogen and carbon source, respectively. The optimal initial pH, NaCl and temperature for the agar degrading activity of Cytophaga sp. were 7.0, 2.0% and $30{\pm}2^{\circ}C$, respectively. Agar degrading activity of enzyme obtained from Cytophaga sp. was increased until the incubation of 96hrs, but after 96hrs, the activity was decreased.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.324-330
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• 2014

A marine bacterial strain producing agar-degrading enzymes was isolated from a mud flat in Jeboo-do (Korea) using a selective artificial sea water (ASW) agar plate containing agar as the sole carbon source. The isolate, designated as SH-1, was gram-negative, aerobic, and motile with single polar flagellum. 16S rRNA gene sequence similarity analysis showed the isolate SH-1 had the highest homology (96.5%) to marine bacterium Neiella marina J221. Cells could grow at $28-37^{\circ}C$ but not at $42^{\circ}C$, and the agarase activity of the cell culture supernatant was higher when grown at $28^{\circ}C$ than when grown at $37^{\circ}C$. Cells could grow when concentrations of 1-5% (w/v) NaCl were added to the growth media with the best growth observed at 3% NaCl, and the agardegrading enzyme activity of the cell culture supernatant was best when grown at 3% NaCl-containing growth media under the conditions we examined. The crude enzyme prepared from 48-h culture broth of strain SH-1 exhibited an optimum pH and temperature for agar-degrading activity at 7.0 and $40^{\circ}C$, respectively. Zymogram analysis of the crude supernatant and cell extract showed that strain SH-1 produced at least 3 agar-degrading enzymes with molecular weights of 15, 35, and 52 KD. Thinlayer chromatography (TLC) analysis also suggested that HS-1 produces ${\beta}$-agarase to degrade agarose to neoagarooligosaccharides.

• Journal of Life Science
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• v.22 no.2
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• pp.259-265
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• 2012

A bacterial strain, CK214, exhibiting high motility on an LB agar (1.5%, w/v) surface was isolated from the environment. The formation of unusual agar shrinking around colonies on agar plates was observed. The strain grew on minimal media containing pure agar as a sole carbon source. The cell-free culture supernatant of CK214 generated a reduced form of sugar in the in vitro reaction with the use of pure agar as a substrate, suggesting the secretion of an agar-degrading enzyme. The CK214 strain showed swarming motility on the solid media containing a wide range of concentrations of agar (0.5, 1.0, 1.5, 2.0% w/v). Various tests, including Gram staining, API analysis, and phylogenetic analysis based on 16S rDNA sequences identified that the CK214 strain was a G(+) rod-shaped bacterium grouped in genus Paenibacillus. Electron microscopic analysis demonstrated that the P. CK214 strain is peritrichously flagellated. Through transposon random mutagenesis, several agar-degrading activity defective mutants (ADMs) were generated. These mutants will be used in the future experimentation for the study of the correlation between agar-degrading activity and motility.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.36-48
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• 2010

An agar-degrading Agarivorans sp. AG17 strain was isolated from the red seaweed Grateloupia filicina collected from Jeju Island. A beta-agarase gene from Agarivorans sp. AG17 was cloned and designated as agrA. agrA has a 2,985 bp coding region encoding 995 amino acids and was classified into the glycoside hydrolase family (GHF)-50. Predicted molecular mass of the mature protein was 105 kDa. His-tagged agrA was overexpressed in Escherichia coli and purified as a fusion protein. The enzyme showed 158.8 unit/mg specific activity (optimum temperature at $65^{\circ}C$ and pH 5.5 in acetate buffer) with unique biochemical properties (high thermal and pH stabilities). Enzyme produced neoagarohexaose, neoagarotetraose and neoagarobiose by degrading agar, and hydrolyzed neoagaro-oligosaccharides were biologically active. Hence the purified enzyme has potential for use in industrial applications such as the development of cosmetics and pharmaceuticals.

• Journal of Animal Science and Technology
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• v.57 no.7
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• pp.23.1-23.6
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• 2015

Cellulose degrading bacteria from koala faeces were isolated using caboxymethylcellulose-Congo red agar, screened in vitro for different hydrolytic enzyme activities and phylogenetically characterized using molecular tools. Bacillus sp. and Pseudomonas sp. were the most prominent bacteria from koala faeces. The isolates demonstrated good xylanase, amylase, lipase, protease, tannase and lignin peroxidase activities apart from endoglucanase activity. Furthermore many isolates grew in the presence of phenanthrene, indicating their probable application for bioremediation. Potential isolates can be exploited further for industrial enzyme production or in bioremediation of contaminated sites.

• Journal of Life Science
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• v.32 no.10
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• pp.778-783
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• 2022

This study isolated a new agarase-producing bacterium and characterized its agarase. A new agar-degrading strain was isolated from the seashore of Namhae in Gyeongnam province, Korea, and was purely cultured using the Marine Agar 2216 media. The isolated bacterium was identified as Simiduia sp. SH-2 after 16S rRNA gene sequencing. The crude agarase was obtained from the culture medium of the Simiduia sp. SH-2 strain, and the agar-degrading activity was measured. The highest level of activity of the Simiduia sp. SH-2-derived agar-degrading enzyme was 625 U/l. Agar degradation activity was most significant at 40℃ and pH 7.0. Compared to the activity at 40℃, the relative activity was 31% at 20℃ and 71% at 30℃. Compared to the activity at pH 7.0, the relative activity was 94% and 89% at pH 6.0 and pH 8.0, respectively. Residual activity was greater than 96% after exposure to 20℃ and 30℃ for 2 hr and more than 49% after exposure to 40℃ for 2 hr. Simiduia sp. SH-2 was identified as a strain producing β-agarase that creates neoagarooligosaccharides, such as neoagarotetraose and neoagarohexaose. Therefore, the Simiduia sp. SH-2 strain and its β-agarase are expected to be useful functional material producers in the food, cosmetic, and pharmaceutical industries.

• KSBB Journal
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• v.13 no.3
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• pp.320-324
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• 1998

Agar degrading enzyme-agarase-was purified from the culture fluid of Cytophaga so/ ACLJ-18, by acetone precipitation, DEAE-Cellulose, Sephadex G-100 and CM-Sephadex C25 column chromatographies. The molecular weight of purified agarase was estimated to be 24,700 dalton by SDS-polyacrylamide gel electrophoresis. The optimum pH and temperature for agarase activity were 7.0 and 40$^{\circ}C$, respectively. this agarase was stable in the pH range of 6.5 - 8.0 and 40$^{\circ}C$, and required 0.35M NaCl for optimum activity. And this agarase was inhibited by metal ions such as Ba2+, Cu2+, Co2+, Mn2+, Hg2+, Zn2+, and showed specificity on agar.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.818-821
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• 2011

An agar-degrading bacterium was isolated from the guts of spiny turban shells. It was identified as a Pseudoalteromonas species and named Pseudoalteromonas sp. JYBCL 1. The viscosity of the inoculated agar medium decreased by more than 60% after 20 h cultivation. The agarase produced by the isolate had optimal activities at $35^{\circ}C$ and pH 7. The enzyme had extremely strong resistance to ionic stress compared with other known agarases. Its molecular mass was estimated at about 60 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The agarase could saccharify Gelidium amansii directly, with an efficiency about half that compared with agar saccharification.

• Journal of Microbiology and Biotechnology
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• v.29 no.2
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• pp.235-243
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• 2019

A special eosinophilic agarase exo-type ${\beta}$-agarase gene, AgaDL6, was cloned from a marine agar-degrading bacterium, Flammeovirga sp. HQM9. The gene comprised 1,383-bp nucleotides encoding a putative agarase AgaDL6 of 461 amino acids with a calculated molecular mass of 52.8 kDa. Sequence analysis revealed a ${\beta}$-agarase domain that belongs to the glycoside hydrolase family (GH) 16 and a carbohydrate-binding module (CBM_4_9) unique to agarases. AgaDL6 was heterologously expressed in Escherichia coli BL21 (DE3). Enzyme activity analysis of the purified protein showed that the optimal temperature and pH of AgaDL6 were $50^{\circ}C$ and 3.0, respectively. AgaDL6 showed thermal stability by retaining more than 98% of activity after incubation for 2 h at $50^{\circ}C$, a feature quite different from other agarases. AgaDL6 also exhibited outstanding acid stability, retaining 100% of activity after incubation for 24 h at pH 2.0 to 5.0, a property distinct from other agarases. This is the first agarase characterized to have such high acid stability. In addition, we observed no obvious stimulation or inhibition of AgaDL6 in the presence of various metal ions and denaturants. AgaDL6 is an exo-type ${\beta}$-1,4 agarase that cleaved agarose into neoagarotetraose and neoagarohexaose as the final products. These characteristics make AgaDL6 a potentially valuable enzyme in the cosmetic, food, and pharmaceutical industries.

• Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.186-191
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• 2011

An agar-degrading enzyme-producing strain was isolated from seawater. The isolate was identified as Microbulbifer sp. SD-1 by 16S rRNA sequencing analysis. The optimal pH and temperature for growth were 6.0 and $30^{\circ}C$, respectively, and growth was possible at pH 9.0 and $60^{\circ}C$. The isolate required 5% NaCl for optimal growth and showed 45% growth activity without NaCl. Agar concentrations of 0-0.4% in the medium did not affect growth. Thin-layer chromatography analysis revealed that this strain could degrade agar into a monosaccharide and oligosaccharide, which may have industrial applications.