• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.228-232
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• 2003

Lovastatin produced by Aspergillus terreus via polyketide pathway is a secondary metabolite with high anti-hypercholesterolemic activity. In this paper we are going to present effective strain development strategies for lovastatin production by comparing the productivity of the mutants obtained through traditional rational screening process and protoplast fusion method. Mutants resistant against various antibiotics and/or antimetabolites showed significantly higher lovastatin productivity than the corresponding mother strains, demonstrating that rational screening method was very efficient in selecting high yielding producers. Recombinant fusants obtained using protoplast fusion between high producers were observed to have very different morphology and physiology as represented by the production and secretion of lovastatin, as well as cell growth pattern. In parallel with the strain development, optimization process for the production medium was carried out in order to find optimal concentrations of the medium components using such a powerful statistical method as response surface method (RSM). It was concluded that not only the optimum production medium but also good morphological characteristics of the high-yielding producers led to higher lovastatin production.

• Journal of Microbiology and Biotechnology
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• 제6권6호
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• pp.482-486
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• 1996

Batch fermentations of lactic acid were performed with Lactobacillus casei to investigate the effect of pH on cell growth and production of lactic acid and by-products. Maximum productivity of lactic acid increased with increasing pH from 5.0 to 6.5, and the extent of D-lactate production was different at each pH. Acetate and D-lactate concentrations increased even after the complete consumption of glucose in the medium. While a pH range of 6.0-6.5 was optimal for cell growth and lactic acid production, superior results were achieved at pH 6.0 when both maximum lactic acid productivity and minimum by-product formation were considered.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1226-1231
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• 2014

The rare actinomycete Pseudonocardia autotrophica was previously shown to produce a solubility-improved toxicity-reduced novel polyene compound named $\underline{N}ystatin$-like $\underline{P}seudonocardia$ $\underline{P}olyene$ (NPP). The low productivity of NPP in P. autotrophica implies that its biosynthetic pathway is tightly regulated. In this study, $wblA_{pau}$ was isolated and identified as a novel negative regulatory gene for NPP production in P. autotrophica, which showed approximately 49% amino acid identity with a global antibiotic down-regulatory gene, wblA, identified from various Streptomycetes species. Although no significant difference in NPP production was observed between P. autotrophica harboring empty vector and the S. coelicolor wblA under its native promoter, approximately 12% less NPP was produced in P. autotrophica expressing the wblA gene under the strong constitutive $ermE^*$ promoter. Furthermore, disruption of the $wblA_{pau}$ gene from P. autotrophica resulted in an approximately 80% increase in NPP productivity. These results strongly suggest that identification and inactivation of the global antibiotic down-regulatory gene wblA ortholog are a critical strategy for improving secondary metabolite overproduction in not only Streptomyces but also non-Streptomyces rare actinomycete species.

• 한국미생물·생명공학회지
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• 제35권1호
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• pp.26-29
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• 2007

Tautomycetin(TMC)은 국내 토양에서 분리된 방선균(Streptomyces sp. CK4412)로부터 생합성 되는 항진균성 2차 대사산물로서, Cyclosporin및 FK506과 같은 기존의 면역억제제보다 작용 메카니즘 및 효능이 훨씬 탁월한 선형의 폴리케타이드계 면역억제 화합물이다. 고체배지의 pH변화와 TMC생산성과의 상관관계를 규명하기 위하여, 방선균 CK4412를 다양한 pH조건에서 배양하면서 항진균 활성 및 TMC생산량을 비교분석 하였다. 고체배지의 pH를 산성조건(pH 4-5)으로 유지하여 방선균 CK4412 균주를 배양할 경우, 중성 pH 조건에서 배양한 경우보다 훨씬 탁월한 항진균 활성 및 TMC생산성이 관찰되었다. 본 연구결과는 대표적인 방선균 S. coelicolor에서 입증된 pH-shock게 의한 2차대사산물의 생산성 증대효과가 대사산물의 특성과 균주가 전혀 다른 TMC 생산균주 CK4412에서도 관찰됨을 입증함으로써, pH조절에 의한 다양한 종류의 방선균 유래 유용 생리활성물질의 생산성 증대 전략을 제시하고 있다.

• Journal of Microbiology
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• 제39권4호
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• pp.305-313
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• 2001

The spr D gene encoding Strptomyces griseus protease D(SGPD); a chymotrypsin-like proteae, was cloned from Strptomyces griseus IFO13350 and sequence. Most of the amino-acid sequence deduced from the nucleotide sequence is idential to that Strptomyces griseus IMRU3499 except that one amino acid has been deleted and Trp 369 has been substituted into Cys369 in the SGPD from S. griseus IFO13350 without affecting the protease activity. The spr D gene was overexpressed in Streptomyce liv-idans TK24 as a heterologous host. Various media with different compositions were also used to max-imize the productivity of SGPD inthe heterologous host. The SGPD productivity was best when the transformant S. lividans TK24 was cultivated in R2YE medium. The relative chymotrypsin activity of the culture broth measured with an artificial chromogenic substrate, N-scuccinyl-ala-ala-pro-phe-p-nitroanilide, was 16 units/ml. A high level of SGPD was also produced in YEME and SAAM medial but it was relatively lower that in R2YE medium and negligible amounts of SGPD were produced in GYE, GAE and Benedict media. The growth of S. lividans reacted the maximum level of cell mass at days 3 and 4 of the culture, but SGPD production started in the stationary phase of cell growth and kept increase in till the 10$^{th}$ day of culture in R2YE and YEME medium, but in GYE media the productivity reached maximum level at 8days of cultivation. The introduction of the spr D gene into S. lividans TK24 triggered biosyntheis of the pigmented antibiotic , actinorhodin, which implies some protease may paly a very improtant role in secondary-metabolite formation in sStreptomyces.

• 원예과학기술지
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• 제18권4호
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• pp.499-502
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• 2000

의성 지역에서 재배하기 적합한 국내 한지형 마늘을 선발하고자 '의성', '예천', '단양', '정선' 및 '용인' 등 한지형 마늘 5종을 공시하여 생육특성과 수량성을 조사하였고, 난지형 마늘의 재배 적합성을 검증하기 위해 '남도' 마늘을 동시에 공시하였다. 국내 지방 재배종 마늘의 생장특성은 생태형에 따라 차이를 보여 난지형인 '남도'가 초기생장과 숙기가 빨랐던 반면, 한지형 지방종간에는 뚜렷한 차이가 없었다. 추대 현상에 있어서는 '정선'과 '용인'이 추대율이 낮았고 불완전 추대가 많았던 반면, '예천'과 '의성'은 추대율이 높고 '의성'은 2차생장률이 낮았다. 의성지방에서 재배된 한지형 마늘 중에 '예천'의 수량이 높았으며 생장 최성기에 타 품종에 비하여 작물생장률도 높았다. 의성 지역에서 재배된 '정선', '용인' 및 '단양'은 '의성'에 비하여 생산성이 낮은 것으로 평가되었다.

• Journal of Microbiology and Biotechnology
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• 제31권12호
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• pp.1624-1631
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• 2021

Prodigiosin as a high-valued compound, which is a microbial secondary metabolite, has the potential for antioxidant and anticancer effects. However, the large-scale production of functionally active Hahella chejuensis-derived prodigiosin by fermentation in a cost-effective manner has yet to be achieved. In the present study, we established carbon source-optimized medium conditions, as well as a procedure for producing prodigiosin by fermentation by culturing H. chejuensis using 10 L and 200 L bioreactors. Our results showed that prodigiosin productivity using 250 ml flasks was higher in the presence of glucose than other carbon sources, including mannose, sucrose, galactose, and fructose, and could be scaled up to 10 L and 200 L batches. Productivity in the glucose (2.5 g/l) culture while maintaining the medium at pH 6.89 during 10 days of cultivation in the 200 L bioreactor was measured and increased more than productivity in the basal culture medium in the absence of glucose. Prodigiosin production from 10 L and 200 L fermentation cultures of H. chejuensis was confirmed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) analyses for more accurate identification. Finally, the anticancer activity of crude extracted prodigiosin against human cancerous leukemia THP-1 cells was evaluated and confirmed at various concentrations. Conclusively, we demonstrate that culture conditions for H. chejuensis using a bioreactor with various parameters and ethanol-based extraction procedures were optimized to mass-produce the marine bacterium-derived high purity prodigiosin associated with anti-cancer activity.

• Journal of Plant Biotechnology
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• 제30권4호
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• pp.387-397
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• 2003

During the first half of twentieth century, even though the importance of non-calorie essential micronutrients of 13 vitamins and 17 minerals has been known to alleviate nutritional disorder; the primary objective of agriculture and plant breeding programs has been to increase the productivity and seed yields, and macronutrients of proteins, fats, and carbohydrates made up the bulk of foodstuff which were used primarily as an energy source. In the last decade it has been found that non-essential micronutrients encompass a vast group of phytochemicals including antioxidants that are not strictly required in the diet but when present at sufficient levels work as health-promoting chemicals. Nowadays agricultural crops are grown for health rather than for food or fiber, and modifying the nutritional compositions of plant foods has become an urgent health issue. To ensure an adequate intake of essential vitamins and minerals, and to increase the consumption of health-promoting phytochemicals, the researches on plant secondary metabolism have been made. The attempt to improve nutritional quality of crops has been blocked by a lack of basic knowledge of plant metabolism. The advent of genomics era enabled new approaches to make crossing regardless of species, family, or phylum barriers, and the accumulation in our basic knowledge on plant secondary metabolism during the coming decade would be tremendous. As the major staple crops contain insufficient amount of many micronutrients, fortification strategy will be a necessary practice. Elevated intake of specific vitamins, C, E, and $\beta$-carotene, mineral selenium, antioxidants, and phytochemicals significantly reduces the risk of chronic disease such as cancer, cardiovascular disorder, diabetis, and other degenerative disease associated with aging. As the attempt to improve the nutritional quality of crops requires the basic knowledges on plant metabolism, plant biochemistry, human physiology, and food chemistry, strong interdisplinary collaboration among plant biotechnologists, human nutritionists, and food scientists will be needed. Inhibition of cancer, cardiovascular disease, and other degenerative disorder may be the biggest goal facing nutritional plant breeders. But the assumption that simply increasing dietary level of any compound will necessarily improve human health is a dangerous idea because many plant secondary products and dietary contaminants have paradoxical (hermetic) effects. Before biotechnical manipulation is undertaken to elevate or reduce any individual constituent of crops, the contribution of the micronutrient to human health must first be investigated.

• 멤브레인
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• 제22권6호
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• pp.395-403
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• 2012

분리막에 대한 지속적인 성장과 더불어 나노섬유 분리막은 현재 기체, 수처리, 에너지 등 다양한 분야에서 활발히 연구가 진행되고 있다. 나노섬유를 제조하는 방법에는 연신(drawing), 템플레이트 합성(template synthesis), 상분리(phase separation), 자가조립(self-assembly), 전기방사(electrospinning)법이 있으며, 특히, 전기방사법은 다른 제법들에 비해 높은 생산성과 생산비용이 낮은 장점이 있다. 또한, 재료의 선택성이 용이하며, 높은 비표면적과 기능기 추가가 용이하다. 분리막에 있어서 나노섬유의 적용은, 이차전지분야에서 기존의 PP, PE 혹은 PE/PP 격리막 위에 나노섬유를 도포함으로써 고온에서 안정성과 고출력을 가진 분리막을 개발할 수 있으며, 수처리 분야에서는 나노섬유 사이에 항균성 물질 등 다양한 첨가제를 추가하여 고기능성 분리막을 개발할 수 있다. 따라서 나노섬유 분리막은 에너지 분야에서 수처리 분야에 이르기까지 다양한 용도에 활용가능하며, 다양한 기능성의 발현으로 고부가 가치가 기대된다.

• 한국미생물·생명공학회지
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• 제50권4호
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• pp.488-500
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• 2022

Most fungal infections by opportunistic yeast pathogens such as Candida spp. are the major causes of morbidity and mortality in patients with lowered immune. Previous studies have reported that some strains of Candida secret secondary metabolites play an important role in the decreasing of immunity in the infected patient. In this study, 110 Candida spp. were isolated from different clinical specimens from Baghdad hospitals. Candida isolates were identified by conventional methods, they were processed for Candida speciation on CHROMagar. The results of identification were confirmed by internal transcribed spacer (ITS) sequencing. Phylogenetic trees were analyzed with reference strains deposited in GenBank. Antifungal susceptibility testing was evaluated by the disc diffusion method and performed as recommended by the Clinical and Laboratory Standard Institute (CLSI) M44-A document. Candida isolates investigated produce secondary metabolites gliotoxin with HPLC technique and quantification. Out of 110 Candida isolates, C. albicans (66.36%) was the most frequent isolate, followed by the isolates of C. tropicalis (10.9%) and C. glabrata (6.36%) respectively. Concerning the antifungal susceptibility test, Candida isolates showed a high level of susceptibility to Miconazole (70.9%), Itraconazole (68.2%), and Nystatine (64.5%). The ability of obtained isolates of Candida spp. to produce gliotoxin on RPMI medium was investigated, only 28 isolates had the ability to secret this toxin in culture filtrates. The highest concentrations were detected in C. albicans (1.048 ㎍/ml). Gliotoxin productivity of other Candida species was significantly lower. The retention time for gliotoxin was approximately 5.08 min.