• Korean Journal of Food Science and Technology
• /
• v.32 no.2
• /
• pp.284-290
• /
• 2000

A marine bacterium Bacillus cereus ASK202 showing a high agar degrading activity, was incubated in the culture medium containing agar. After incubation for 30 hr, the productivity of agarase in the culture broth reached to maximum value (160.8 units/L). As the results of TLC and HPLC analysis, agarooligosaccharides (degrees of polymerization 2, 4 and 6) were produced from the hydrolysis of agar by using the crude agarase. Physical and chemical properties of agarooligosaccharides were compared with the manufactured products of other oligosaccharides (fructooligosaccharide; isomaltooligosaccharide; maltotetraoligosaccharide) and agarooligosaccharides showed higher viscosity, higher contents of oligosaccharides, higher stability at low pH's and higher temperatures, and lower sweetness than other oligosaccharides.

• Proceedings of the Korean Society of Life Science Conference
• /
• 2006.09a
• /
• pp.61.2-61.2
• /
• 2006

• Journal of Food Hygiene and Safety
• /
• v.15 no.4
• /
• pp.277-281
• /
• 2000

Agar, one of the most abundant marine products has not been utilized extensively because of low level of processing technology in Korea. This research was carried out to improve the utilization of agar and consequent increase in profit. Antibacterial activity of agarooligosaccharides were evaluated against bacteria causing putrefaction and flood poisoning. Addition of 0.4% agarooligosaccharides showed antibacterial activity toward Staphylococcus aureus and Escherichia coli O157:H7; furthermore, autoclave treatment of agarooligosaccharides solution enhanced the antibacterial activity. Agarooligosaccharides showed high stability against the pH change. Addition of amino acid(alanine, lysine, glycine, phenylalanine) in agarooligosaccharides solution enhanced antibacterial activity in E. coli O157:H7, Streptococcus mutans and Staphylococcus aureus.

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

• Journal of Microbiology and Biotechnology
• /
• v.24 no.12
• /
• pp.1622-1628
• /
• 2014

DagA, a ${\beta}$-agarase, was produced by cultivating a recombinant Streptomyces lividans in a glucose medium or a mixed-sugar medium simulating microalgae hydrolysate. The optimum composition of the glucose medium was identified as 25 g/l glucose, 10 g/l yeast extract, and $5g/l\;MgCl_2{\cdot}6H_2O$. With this, a DagA activity of 7.26 U/ml could be obtained. When a mixed-sugar medium containing 25 g/l of sugars was used, a DagA activity of 4.81 U/ml was obtained with very low substrate utilization efficiency owing to the catabolic repression of glucose against the other sugars. When glucose and galactose were removed from the medium, an unexpectedly high DagA activity of about 8.7 U/ml was obtained, even though a smaller amount of sugars was used. It is recommended for better substrate utilization and process economics that glucose and galactose be eliminated from the medium, by being consumed by some other useful applications, before the production of DagA.

• Journal of Life Science
• /
• v.13 no.4
• /
• pp.516-521
• /
• 2003

Optimal conditions of protoplast isolation from the seaweed Prophyra pseudolinearis have been described. The P. pseudolinearis is one of indigenous and dominant Porphyra species in the East Sea region. Protoplasts have been released by enzymatic treatment of 2% agarase and 2% hemicellulase in 25mM MES buffer, pH 6.0 containing 0.5 M sorbitol. The protoplasts could be fused with neutral red-stained protoplasts of P. okamurae by the addition of polyethylene glycol 8000 solution.

• Microbiology and Biotechnology Letters
• /
• v.40 no.1
• /
• pp.1-9
• /
• 2012

This study's aim was to isolate microorganisms producing agarase with a high activity, with possible applications in improving the performance of the pretreatment processes for bioethanol production. Marine algaes were collected from the south coast of Korea, from which three kinds of microorganisms were isolated. After a 4-day culture of these strains at $25^{\circ}C$, crude enzymes were obtained from culture supernatant or cell-free extract by ammonium sulfate precipitation and membrane dialysis. Agarase activity was observed in these crude enzymes. Notably higher specific activity was observed in the crude enzyme obtained from the culture supernatant rather than that from the cell-free extract. This indicates that a secreted enzyme has a much greater activity than a cellular enzyme. Crude enzymes from the GNUM08122 strain were inferred to have ${\alpha}$-agarase activity because release of p-nitrophenol was observed, possibly due to the cleavage of p-nitrophenyl-${\alpha}$-D-galactopyranoside. The 16S rRNA sequence of GNUM08122 showed a close relationship to Pseudoalteromonas issachenkonii KMM 3549 (99.8%) and Pseudoalteromonas tetraodonis IMA 14160 (99.7%), which led us to assign it to the genus Pseudoalteromonas. Biochemical and physiological study revealed that this strain can grow well at $40^{\circ}C$ under a wide range of pH (pH 4~8) in high-salt conditions (10% NaCl).

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

• 한국생물공학회:학술대회논문집
• /
• 2005.04a
• /
• pp.315-315
• /
• 2005

• Proceedings of the Korean Society of Life Science Conference
• /
• 2005.09a
• /
• pp.61-61
• /
• 2005