• 한국미생물·생명공학회지
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• 제25권5호
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• pp.490-494
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• 1997

A variety of microbial strains isolated from soil were tested for their ability to produce D-tagatose from D-galactose. An organism that can convert D-galactose into D-tagatose was selected and was identified as Enterobacter agglomerans. The cells grown on the induction medium containing 20 g/l arabinose were found to the best conversion potential among different carbohydrates and the conversion yield was about 15% when 20 gll galactose was used. The isolated crystals were obtained from the culture broth after the purification process such as treatment of ion resins, crystallization, and drying. The recovery yield was 70% after the purification. The crystals were identified as D-tagatose by the infrared spectroscopy, HPLC, specific optical rotation, and melting point.

• 한국미생물·생명공학회지
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• 제32권1호
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• pp.52-59
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• 2004

Fructose와 galactose를 배지에 동시에 사용하였을 때 catabolite repression에 의한 PAFS생산성 저해 현상을 극복하기 위해서 본 연구에서는 두 가지 탄소원의 공급량과 유속을 달리하는 유가식 배양으로 PAFS 생산성을 향상시키고자 하였다. 또한 통계적으로 성공률이 매우 높다고 밝혀진 실험방법에 의해 모균주로부터 고생산변이주를 선별하여 생산성이 가장 우수한 것으로 판명된 AP-20 균주를 생물반응기를 이용한 회분식 배양 및 유가식 배양 실험에 이용하였다. 생물반응기에서의 유가식 배양이 회분식 배양에서보다 PAFS생산성이 약 4배 이상 향상되었음을 확인할 수 있었다. 또한 생산균주의 배양생리학적 특성으로서 Pseudomonas aeruginosa는 galactose를 이용해서 세포성장과 이차대사산물 생합성과 관련된 유전자의 발현을 하고 fructose를 이용하여 PAFS를 생합성하는 것으로 추론되며, 너무 느린 탄소원의 공급은 세포성장에 제한요소로 작용하여 이차대사산물의 생합성을 저해하는 것으로 판단되었다. 한편 유가식 배양일지라도 배양 조건에 따라 그 생산성이 뚜렷이 차이가 나는 것으로 관찰되었다 즉 galactos의 초기량이 20g/L이고 fructose 30g/L를 0.032 mL/min의 속도로 공급했을 경우의 PAFS생산량을 100%로 정의했을 때, 초기부터 40 g/L의 galactose가 존재하고 20 g/L의 fructose를 0.032 mL/min의 속도로 공급한 경우에 PAFS생산성이 약 580%향상된 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1659-1669
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• 2020

1,3-α-3,6-anhydro-L-galactosidase (α-neoagarooligosaccharide hydrolase) catalyzes the last step of agar degradation by hydrolyzing neoagarobiose into monomers, D-galactose, and 3,6-anhydro-L-galactose, which is important for the bioindustrial application of algal biomass. Ahg943, from the agarolytic marine bacterium Gayadomonas joobiniege G7, is composed of 423 amino acids (47.96 kDa), including a 22-amino acid signal peptide. It was found to have 67% identity with the α-neoagarooligosaccharide hydrolase ZgAhgA, from Zobellia galactanivorans, but low identity (< 40%) with the other α-neoagarooligosaccharide hydrolases reported. The recombinant Ahg943 (rAhg943, 47.89 kDa), purified from Escherichia coli, was estimated to be a monomer upon gel filtration chromatography, making it quite distinct from other α-neoagarooligosaccharide hydrolases. The rAhg943 hydrolyzed neoagarobiose, neoagarotetraose, and neoagarohexaose into D-galactose, neoagarotriose, and neoagaropentaose, respectively, with a common product, 3,6-anhydro-L-galactose, indicating that it is an exo-acting α-neoagarooligosaccharide hydrolase that releases 3,6-anhydro-L-galactose by hydrolyzing α-1,3 glycosidic bonds from the nonreducing ends of neoagarooligosaccharides. The optimum pH and temperature of Ahg943 activity were 6.0 and 20℃, respectively. In particular, rAhg943 could maintain enzyme activity at 10℃ (71% of the maximum). Complete inhibition of rAhg943 activity by 0.5 mM EDTA was restored and even, remarkably, enhanced by Ca²⁺ ions. rAhg943 activity was at maximum at 0.5 M NaCl and maintained above 73% of the maximum at 3M NaCl. K_m and V_max of rAhg943 toward neoagarobiose were 9.7 mg/ml and 250 μM/min (3 U/mg), respectively. Therefore, Ahg943 is a unique α-neoagarooligosaccharide hydrolase that has cold- and high-salt-adapted features, and possibly exists as a monomer.

• BMB Reports
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• 제32권5호
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• pp.451-455
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• 1999

The concentrations of L-ascorbic acid (AsA, ascorbate, vitamin C) and its biosynthetic and metabolically-related enzymes such as L-galactono-1,4-lactone dehydrogenase (GLDase), ascorbate peroxidase (APX), and ascorbate oxidase (ASO) were investigated in suspension cultures of Scutellaria baicalensis. Cells growing from 4 days after subculture (DAS) to 9 DAS and from 16 DAS to 19 DAS showed a diauxic growth, and then growth rapidly decreased with further culturing. The AsA content slowly increased to 19 DAS, reached a maximum at 21 DAS (ca $120\;{\mu}g/g$ dry cell wt), and then rapidly decreased with further culturing. GLDase and ASO activity were well correlated with the cell growth curve, showing a maximum at 19 DAS, whereas APX activity showed a good correlation with the changes in AsA content, showing a maximum at 21 DAS. The total ascorbate contents (reduced form, AsA, and oxidized form, dehydroascorbate, DHA) were markedly enhanced at 10 DAS when L-galactose and L-galactono-1,4-lactone (25 mM) were added to SH medium supplemented with 20 g/l sucrose at 9 DAS, by 5.5 and 6.8 times, respectively. DHA composed more than 90% of the total ascorbate contents in suspension cultures of S. baicalensis, even though the ratio of reduced to oxidized form slightly varied with cell growth stage. The results indicate that L-galactose and L-galactono-1,4-lactone are effective precursors of AsA in cell cultures of S. baicalensis, and that in vitro cultured cells provide suitable biomaterials for the study of biosynthesis and metabolism of AsA.

• 한국작물학회지
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• 제19권
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• pp.52-58
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• 1975

대두에 함유되어 있는 Stachyose를 소화성당으로 변화시켜 식품으로서의 가치를 제고시킬 목적으로 대두 '평양'품종을 표준발아와 Hypochlorite를 처리한후 발아과정중 종자내에 함유되어있는 Monosaccharides 및 Oligosaccharides의 함량변화를 Thin-Layer Chromatography법으로 실험하였다. 1. Monosaccharides의 함량변화: 표준발아시 전기간중 Fructose가 제일함량이 많았고 Glucose, Galactose순으로 함량이 적었고 시간이 경과함에 따라 점점 감소되었다. Hypochlorite처리시 전기간중 Galactose는 전연 나타나지 않았다. 두 처리간에는 144시간을 제외하고 표준발아시켰을때가 Monosaccharide의 함량이 많았다. 2. Oligosaccharides의 함량변화: Sucrose는 표준발아시 함량은 적으나 전기간중 나타났으며96시간까지는 증가되었다가 약간씩 감소됐다.

• Journal of Microbiology and Biotechnology
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• 제5권4호
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• pp.224-228
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• 1995

Fed-batch fermentations were conducted to produce human lipocortin-I (LC1), a potential anti-inflammatory agent, from recombinant Sacchromyces cerevisiae carrying a galactose-inducible expression system. The cell growth, expression level of LC1, and the plasmid stability were investigated under various LC1 induction modes performed by three different galactose feeding strategies. Galactoe was fed to induce the expression of LCl from the beginning (initial induction) of culture or when the cell concentration reached 120 OD (mid-phase induction) or 300 OD (late induction). Among the three galactose-induction modes tested, the initial induction mode yielded the best result with respect to a final expression level of LC1. Fedbatch fermentation with initial induction mode produced LC1 at a conentration of 220 mg/l, which corresponded to 1.38- and 1.53-fold increases over those produced by mid-phase and late induction modes.

• 한국미생물·생명공학회지
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• 제49권1호
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• pp.88-94
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• 2021

해조류 중 홍조류인 꼬시래기(G. verrucosa)로부터 효모를 이용한 발효를 위해 열산가수분해, 효소당화 및 에탄올 발효수율 향상을 검토하고, 기존의 혼합당의 흡수효율을 높이기 위해 고농도 당 순치를 수행하였다. 열산가수분해는 200 mM 황산(H₂SO₄)을 이용하여 10% (w/v)의 꼬시래기(G. verrucosa)의 슬러리, 130℃의 온도에서 60분 동안 열산가수분해를 수행하였다. 또한 wild type 효모와 고농도 galactose에 순치(adaptive evolution)된 효모를 이용한 발효를 실시한 결과, wild type 효모의 경우 발효 144시간에 8.5 g/l 에탄올 발효로 에탄올수율계수 Y_EtOH = 0.19와 galactose에 순치된 효모의 경우 21.5 g/l 에탄올 발효로 에탄올수율계수 Y_EtOH = 0.50을 나타내었다. 이러한 연구결과는 해양 바이오매스인 해조류로부터 바이오 연료의 효율적인 생산방법을 제공할 수 있을 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1259-1266
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• 2016

Bioethanol was produced from Kappaphycus alvarezii seaweed biomass using separate hydrolysis and fermentation (SHF). Pretreatment was evaluated for 60 min at 121℃ using 12% (w/v) biomass slurry with 364 mM H₂SO₄. Enzymatic saccharification was then carried out at 45℃ for 48 h using Celluclast 1.5 L. Ethanol fermentation with 12% (w/v) K. alvarezii hydrolyzate was performed using the yeasts Saccharomyces cerevisiae KCTC1126, Kluyveromyces marxianus KCTC7150, and Candida lusitaniae ATCC42720 with or without prior adaptation to high concentrations of galactose. When non-adapted S. cerevisiae, K. marxianus, and C. lusitaniae were used, 11.5 g/l, 6.7 g/l, and 6.0 g/l of ethanol were produced, respectively. When adapted S. cerevisiae, K. marxianus, and C. lusitaniae were used, 15.8 g/l, 11.6 g/l, and 13.4 g/l of ethanol were obtained, respectively. The highest ethanol concentration was 15.8 g/l, with Y_EtOH = 0.43 and Y_T% = 84.3%, which was obtained using adapted S. cerevisiae.

• 한국미생물·생명공학회지
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• 제48권1호
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• pp.32-37
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• 2020

We improved on a unified saccharification and fermentation (USF) system for the direct production of ethanol from agarose by increasing total agarase activity. The pGMFα-NGH plasmid harboring the NABH558 gene encoding neoagarobiose hydrolase and the AGAG1 and AGAH71 genes encoding β-agarase was constructed and used to transform Saccharomyces cerevisiae 2805. NABH558 gene transcription level was increased and total agarase activity was increased by 25 to 40% by placing the NABH558 gene expression cassette upstream of the other gene expression cassettes. In the 2805/pGMFα-NGH transformant, three secretory agarases were produced that efficiently degraded agarose to galactose, 3,6-anhydro-L-galactose (AHG), neoagarobiose, and neoagarohexaose. During the united cultivation process, a maximum of 2.36 g/l ethanol from 10 g/l agarose was produced over 120 h.

• Journal of the Korean Wood Science and Technology
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• 제32권1호
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• pp.35-44
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• 2004

표고버섯(Lentinula edodes)의 생장이 매우 좋았던 일본잎갈나무재의 수용성 추출물(water-soluble fraction, WSF)을 분리하여 구성당을 분석한 결과, rhamnose 및 mannose는 거의 없고, glucose도 2.2%로 매우 낮았으며, arabinose가 18.3%, galactose가 75.3%로서 가장 많이 함유되어 있었다. 정제된 추출물의 arabinose와 galactose의 함량비는 1 : 3.4였다. 정제된 WSF를 완전메틸화·가수분해·가스크로마토그래피에 의하여 분석한 결과, β-1,3 결합한 D- galactopyranose가 주쇄를 이루며, 이에 galactose의 C₆위에 측쇄로서 β-1,6 결합한 D-galactose와, β-1,6 결합한 L-arabinose가 존재하며, 전자는 2-3개의 D-galactopyranose가 결합을 하고 있고, 후자는 L-arabinofuranose가 1-2개 중간의 측쇄구조를 이루고, 말단은 L-arabinopyranose로 구성되어 있었다. PDA배지에 WSF첨가로 표고의 균사 생장이 매우 증진되었으며, 2 - 4% 첨가수준에서 균사 생장이 최대였고, 첨가량이 더 많으면 균사의 생장이 오히려 감소되었다. 톱밥배지에서도 PDA 배지에서의 결과와 마찬가지로 WSF첨가로 균사 생장이 증진되었으며, 산림 6호 및 Mok-H의 경우 모두 4% 첨가에서 균사의 생장이 최대로 나타났다. 톱밥배지에 WSF 첨가가 버섯생산량을 증가시켰는바, Mok-H의 경우 무첨가에 비해 약 1.3배, 산림 6호의 경우 1.2배 증수되었다. 버섯균 세포벽의 주성분인 ergosterol 함량변화를 측정한 결과, WSF첨가로 미첨가에 비하여 ergosterol의 함량이 증가하였으며, 균사가 콜로니를 형성하는 초기단계에서는 낮은 ergosterol함량을 나타냈으나 자실체가 형성되는 시기에 급격히 높아지는 결과를 나타냈다. 따라서 배지내의 ergosterol함량이 자실체형성의 주요 예측수단으로 이용될 수 있을 것으로 판단된다.