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Featured researches published by Yi-Joon Kim.
Bioresource Technology | 2011
Do Young Kim; Su-Jin Ham; Hyun Ju Lee; Han-Young Cho; Ji-Hoon Kim; Yi-Joon Kim; Dong-Ha Shin; Young Ha Rhee; Kwang-Hee Son; Ho-Yong Park
The gene (1272-bp) encoding a β-1,4-mannanase from a gut bacterium of Eisenia fetida, Cellulosimicrobium sp. strain HY-13 was cloned and expressed in Escherichia coli. The recombinant β-1,4-mannanase (rManH) was approximately 44.0 kDa and has a catalytic GH5 domain that is 65% identical to that of the Micromonospora sp. β-1,4-mannosidase. The enzyme exhibited the highest catalytic activity toward mannans at 50 °C and pH 6.0. rManH displayed a high specific activity of 14,711 and 8498 IU mg⁻¹ towards ivory nut mannan and locust bean gum, respectively; however it could not degrade the structurally unrelated polysaccharides, mannobiose, or p-nitrophenyl sugar derivatives. rManH was strongly bound to ivory nut mannan, Avicel, chitosan, and chitin but did not attach to curdlan, insoluble oat spelt xylan, lignin, or poly(3-hydroxybutyrate). The superior biocatalytic properties of rManH suggest that the enzyme can be exploited as an effective additive in the animal feed industry.
Enzyme and Microbial Technology | 2011
Do Young Kim; Su-Jin Ham; Hyun Ju Lee; Yi-Joon Kim; Dong-Ha Shin; Young Ha Rhee; Kwang-Hee Son; Ho-Yong Park
A xylanolytic gut bacterium isolated from Eisenia fetida, Cellulosimicrobium sp. strain HY-13, produced an extracellular glycoside hydrolase capable of efficiently degrading mannose-based substrates such as locust bean gum, guar gum, mannotetraose, and mannopentaose. The purified mannan-degrading enzyme (ManK, 34,926 Da) from strain HY-13 was found to have an N-terminal amino acid sequence of DEATTDGLHVVDD, which has not yet been identified. Under the optimized reaction conditions of 50°C and pH 7.0, ManK exhibited extraordinary high specific activities of 7109 IU/mg and 5158 IU/mg toward locust bean gum and guar gum, respectively, while the enzyme showed no effect on sugars substituted with p-nitrophenol and various non-mannose carbohydrates. Thin layer chromatography revealed that the enzyme degraded locust bean gum to mannobiose and mannotetraose. No detectable amount of mannose was produced from hydrolytic reactions with the substrates. ManK strongly attached to Avicel, β-cyclodextrin, lignin, and poly(3-hydroxybutyrate) granules, but not bound to chitin, chitosan, curdlan, or insoluble oat spelt xylan. The aforementioned characteristics of ManK suggest that it is a unique endo-β-1,4-mannanase without additional carbohydrolase activities, which differentiates it from other well-known carbohydrolases.
Entomological Research | 2011
Zhen Ji; Do Young Kim; Han-Young Cho; Yi-Joon Kim; Dong-Ha Shin; Kwang-Hee Son; Ho-Yong Park
Metarhizium anisopliae HY‐2, an entomopathogenic fungus isolated from pest cadaver in South Korea, is applicable as a potent bio‐pesticide because of its insecticidal activity to Adoretus tenuimaculatus. Here we report this strain varied in its ability to grow under different nutritional and environmental factors. Temperature at 28°C and pH from 6 to 7 were obtained the best‐fit environmental requirements. Insect pupa and tryptone were found the optimal nitrogen sources for both mycelial growth and sporulation. The strain reached the most suitable effects at the carbon‐to‐nitrogen ratio from 10:1 to 20:1 when the carbon concentration was 4 g/ml provided by glucose and nitrogen supplied by tryptone. Additionally, strain HY‐2 produced an extracellular chitinase at a relatively high level (21.1 mU/ml) when cultivated for 20 days on a medium supplemented with colloidal chitin (1%) and insect pupa (0.5%), indicating that synthesis of chitinase is subject to induction by certain substrate.
Entomological Research | 2011
Do Young Kim; Han-Young Cho; Hyo Jeong Kim; Yi-Joon Kim; Dong-Ha Shin; Kwang-Hee Son; Ho-Yong Park
Invertebrates including insects are heterotrophic organisms and widely distributed in ecosystems. Due to their superior ability to digest various types of plant biomass taken as foods, some herbivorous invertebrates have attracted a great deal of industrial attention because such organisms include diverse cellulolytic and hemicellulolytic symbionts in their gut. Recent studies have shown that some of gut microorganisms of herbivores possess one or more extracellular fibrolytic enzymes with unique functions, which can be exploited as useful biocatalysts in various bioindustrial fields. Specifically, microbial hemicellulases with favorable biocatalytic activities are expected to be used for the development of excellent animal feed additives, production of prebiotics such as xylo‐ and mannooligosaccharides, and pretreatment of lignocellulosic biomass for the preparation of fermentable sugars. Here, we review our recent studies accomplished on several hemicellulolytic bacteria isolated from the guts of invertebrates and their glycoside hydrolases such as endo‐β‐1,4‐xylanases and endo‐β‐1,4‐mannanases.
한국생물공학회 학술대회 | 2013
Bo-Hyun Kim; Soo-Wan Nam; Yeon-Hee Kim; Yi-Joon Kim; Kwang-Hee Son; Ho-Yong Park
한국응용곤충학회 학술발표회 | 2012
Han-Young Cho; Zhen Ji; Do Young Kim; Yi-Joon Kim; Dong-Ha Shin; Kwang-Hee Son; Ho-Yong Park
한국생물공학회 학술대회 | 2012
Min-Ji Kim; Bo-Hyun Kim; Soo-Wan Nam; Yi-Joon Kim; Kwang-Hee Son; Ho-Yong Park; Yeon-Hee Kim
한국응용곤충학회 학술발표회 | 2011
Yi-Joon Kim; Do Young Kim; Han-Young Cho; Dong-Ha Shin; Kwang-Hee Son; Ho-Yong Park
한국응용곤충학회 학술발표회 | 2011
Zhen Ji; Do Young Kim; Han-Young Cho; Yi-Joon Kim; Dong-Ha Shin; Kwang-Hee Son; Ho-Yong Park
한국응용곤충학회 학술발표회 | 2011
Do Young Kim; Hyun Ju Lee; Han-Young Cho; Yi-Joon Kim; Dong-Ha Shin; Kwang-Hee Son; Ho-Yong Park