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KMID : 0613820180280091056
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Journal of Life Science
2018 Volume.28 No. 9 p.1056 ~ p.1061
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Isolation of Agarivorans sp. KC-1 and Characterization of Its Thermotolerant β-Agarase
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Min Kyung-Cheol
Lee Chang-Eun
Lee Dong-Geun
Lee Sang-Hyeon
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Abstract
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This article reports an agar-degrading marine bacterium and characterizes its agarase. The agar-degrading marine bacterium, KC-1, was isolated from seawater on the shores of Sacheon, in Gyeongnam province, Korea, using Marine Broth 2216 agar medium. To identify the agar-degrading bacterium as Agarivorans sp. KC-1, phylogenetic analysis based on the 16S rRNA gene sequence was used. An extracellular agarase was prepared from a culture medium of Agarivorans sp. KC-1, and used for the characterization of enzyme. The relative activities at 20, 30, 40, 50, 60, and 70℃ were 65, 91, 96, 100, 77, and 35%, respectively. The relative activities at pH 5, 6, 7, and 8 were 93, 100, 87, and 82%, respectively. The extracellular agarase showed maximum activity (254 units/l) at pH 6.0 and 50℃ in 20 mM of Tris- HCl buffer. The agarase activity was maintained at 90% or more until 2 hr exposure at 20℃, 30℃and 40℃, but it was found that the activity decreased sharply from 60℃. A zymogram analysis showed that Agarivorans sp. KC-1 produced 3 agar-degrading enzymes that had molecular weights of 130, 80, and 69 kDa. A thin layer chromatography analysis suggested that Agarivorans sp. KC-1 produced extracellular β-agarases as it hydrolyzed agarose to produce neoagarooligosaccharides, including neoagarohexaose (21.6%), neoagarotetraose (32.2%), and neoagarobiose (46.2%). These results suggest that Agarivorans sp. KC-1 and its thermotolerant β-agarase would be useful for the production of neoagarooligosaccharides that inhibit bacterial growth and delay starch degradation.
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KEYWORD
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Agarivorans sp. KC-1, β-agarase, marine bacterium, neoagarooligosaccharides, zymogram
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