• Journal of environmental and Sanitary engineering
• /
• v.16 no.4
• /
• pp.1-8
• /
• 2001

We have previously demonstrated that sodium molybdate(Mo) improved lead-intoxicated status by enhancing the metabolism of mao-inositol-related phospholipids in sciatic nerves isolated from rats. In this study, in order to address the reduction mechanism of Mo for lead toxicity, effects of Mo on cystidine-diglyceride transferase, phosphatidylinositol kinase, and phosphatidyl inositol-4-phosphate kinase, involved in mao-inositol metabolism of nerve, were investigated in vivo and in vitro. Mo significantly increased the activities of cystidine- diglyceride transferase and phosphatidylinositol kinase in lead-intoxicated rat, and the pattern of increase was dose-dependent manner. However, Mo did not affect the activity of phosp- hatidylinositiol-4-phosphate kinase in normal and lead-intoxicated rats. We also found that Mo affected the activities of phopholipid metabolism-related enzymes not by the indirect manner such as activation of another metabolic pathway but by the direct manner. These results suggest that the improvement mechanism of Mo for lead-intoxicated status might be a normalization of the activities of phospholipid metabolism-related enzymes in sciatic nerve.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2002.05b
• /
• pp.209-212
• /
• 2002

The heavy use of petroleum products in modern livings has brought ubiquitous environmental contaminants of aromatic compounds, which persist in aquatic and geo-environment without the substantial degradation. The persistence and accumulation of the aromatic compounds, which include xylene, phenol, toluene, phthalate, and so on are known to cause serious problems in our environments. Some of soil and aquatic microorganisms facilitate their growth by degrading aromatic compounds and utilizing degrading products as growth substrates, the biodegradation helps the reentry of carbons of aromatic compounds, preventing their accumulation in our environments. The metabolic studies on the degradation of aromatic compounds by microoganlsms were extensively carried out along with their genetic studies. A Rhodococcus sp. isolated in activated sludges has shown the excellent ability to grow on phenol as a sole carbon source. In the present study investigated a gene encoding phenol-degrading enzymes from a Rhodococcus sp.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.119.1-119
• /
• 2003

The glyoxysomal nature of microbodies was determined in Botryosphaeria dothidea hyphae based on morphology and in situ enzyme characteristics by transmission electron microscopy and cytochemistry. Bound by a single membrane, microbodies had a homogeneous matrix and varied in size ranging from 200 to 400 m in diameter. Microbodies had crystalline inclusion(s) which consisted of parallel arrays of fine tubules in their matrices. Microbodies and lipid globules were frequently placed in close association with each other, forming microbody-lipid globule complexes in hyphae. The cytochemical activities of catalase and malate synthase were localized in matrices of microbodies, showing intense electron-density of the organelle. In addition, the immunogold labeling detected the presence of catalase in multivesicular bodies and hyphal cell walls as well as in matrices and crystalline inclusions of microbodies, supporting the enzyme secretion through cell walls. Meanwhile, isocitrate Iyase was localized only in matrices of microbodies. These results suggest that microbodies, particularly complexed with lipid globules, in the fungal hyphae are functionally defined as glyoxysomes, where glyoxysomal enzymes are biochemically active for the glyoxylate cycle to be a metabolic pathway in gluconeogenesis. (Mycology and Fugus Diseases)

• Genomics & Informatics
• /
• v.14 no.4
• /
• pp.222-229
• /
• 2016

Kimchi is a traditional Korean food prepared by fermenting vegetables, such as Chinese cabbage and radishes, which are seasoned with various ingredients, including red pepper powder, garlic, ginger, green onion, fermented seafood (Jeotgal), and salt. The various unique microorganisms and bioactive components in kimchi show antioxidant activity and have been associated with an enhanced immune response, as well as anti-cancer and anti-diabetic effects. Red pepper inhibits decay due to microorganisms and prevents food from spoiling. The vast amount of biological information generated by academic and industrial research groups is reflected in a rapidly growing body of scientific literature and expanding data resources. However, the genome, biological pathway, and related disease data are insufficient to explain the health benefits of kimchi because of the varied and heterogeneous data types. Therefore, we have constructed an appropriate semantic data model based on an integrated food knowledge database and analyzed the functional and biological processes associated with kimchi in silico. This complex semantic network of several entities and connections was generalized to answer complex questions, and we demonstrated how specific disease pathways are related to kimchi consumption.

• Microbiology and Biotechnology Letters
• /
• v.24 no.4
• /
• pp.385-392
• /
• 1996

Bacillus stearotheymophilus, a potent xylanolytic bacterium isolated from soil, was tested for the strain's strategies of pentose utilization and the evidence of substrate preferences. The strain metabolized glucose, xylose, ribose, maltose, cellobiose, sucrose, arabinose and xylitol. The efficacy of the sugars as a carbon and energy source in this strain was of the order named above. The organism, however, could not grow on glycerol as a sole growth substrate. During cultivation on a mixture of glucose and xylose or arabinose, the major hydrolytic products of xylan, B. stearothermophilus displayed classical diauxic growth in which glucose was utilized during the first phase. On the other hand, the pentose utilization was prevented immediately upon addition of glucose. Cellobiose was preferred over xylose or arabinose. In contrast, maltose and pentose were co-utilized, and also no preference on between xylose and arabinose. Enzymatic studies indicated that B. stearothermophilus possessed constitutive hexokinase, a key enzyme of the glucose metabolic system. While, the production of $^{D}$-xylose isomerase, $^{D}$-xylulokinase and $^{D}$-arabinose isomerase essential for pentose phosphate pathway were induced by xylose, xylan, and xylitol but repressed by glucose. Taken together, the results suggested that the sequential utilization of B. stearothermophilus would be mediated by catabolite regulatory mechanisms such as catabolite inhibition or inducer exclusion.

• Proceedings of the Korean Society for Bioinformatics Conference
• /
• 2003.10a
• /
• pp.210-219
• /
• 2003

오페론(operon)은 보통 미생물에서 다수의 인접한 유전자들로 구성된 그룹으로 하나의 유전자처럼 공통된 프로모터에 의해 전사되는 단위이다. 오페론을 구성하는 유전자들은 기능적으로 서로 유사하거나 같은 물질대사경로(metabolic pathway) 상에 존재하는 특징을 지니기 때문에 이들은 중요한 의미를 가지며, 미생물 유전체 분석에서 오페론을 구성하는 유전자들을 예측하는 것은 상당히 중요하다. 오페론을 예측하는 이전 연구들로는 이미 알려진 오페론의 특징인 유전자간 거리나 오페론을 구성하는 평균 유전자 개수 등을 이용하는 방법, 마이크로어레이 발현 실험을 이용한 방법, 전유전체(whole genome)들 간의 보존된 유전자 집합(conserved gene cluster)을 이용한 방법 그리고 물질대사경로를 이용한 방법 등이 있다. 본 논문에서는 COG 기능(function) 거리, 유전자 간의 거리, 코돈 사용빈도(codon usage) 그리고COG 기능 거리와 유전자간 거리를 같이 적용한 방법을 이용하여 오페론 예측을 위한 전처리 모델을 생성하였다 전처리 모델을 E. coli 전유전체에 적용해본 결과, 알려진 오페론들의 약 90%가 이를 포함하였다. 따라서 본 논문에서 제시한 전처리 모델은, 추후 오페론 예측을 위한 좋은 도구로 활용할 수 있을 것이다.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.10
• /
• pp.1127-1134
• /
• 2009

Escherichia coli excretes acetate during aerobic growth on glycolytic carbon sources, which has been explained as an overflow metabolism when the carbon flux into the cell exceeds the capacity of central metabolic pathways. Nonacetogenic growth of E. coli on gluconeogenic carbon sources like succinate or in carbon-limited slow growth conditions is believed an evidence for the explanation. However, we found that a strain defected in the acs (acetyl Co-A synthetase) gene, the product of which is involved in scavenging acetate, accumulated acetate even in succinate medium and in carbon-limited low growth rate condition, where as its isogenic parental strain did not. The acs promoter was inducible in noncatabolite repression condition, whereas the expression of the ackA-pta operon encoding acetate kinase and phosphotransacetylase for acetate synthesis was constitutive. Results in this study suggest that E. coli excretes and scavenges acetate simultaneously in the carbon-limited low growth condition and in nonacetogenic carbon source, and the activity of the acetate consumption pathway directly affects the accumulation level of acetate in the culture broth.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.8
• /
• pp.1174-1179
• /
• 2006

The wild-type Corynebacterium glutamicum ATIC 13032 and Corynebacterium glutamicum ATTC 13032 lysC S301Y, exhibiting a deregulated aspartokinase, were compared concerning growth, lysine production, and intracellular carbon fluxes. Both strains differ by only one single nucleotide over the whole genome. In comparison to the wild-type, the mutant showed significant production of lysine with a molar yield of 0.087 mol (mol glucose$^{-1}$) whereas the biomass yield was reduced. The deregulation of aspartokinase further led to a global rearrangement of carbon flux throughout the whole central metabolism. This involved an increased flux through the pentose phosphate pathway (PPP) and an increased flux through anaplerosis. Because of this, the mutant revealed an enhanced supply of NADPH and oxaloacetate required for lysine biosynthesis. Additionally, the lumped flux through phosphoenolpyruvate carboxykinase and malic enzyme, withdrawing oxaloacetate back to the glycolysis and therefore detrimental for lysine production, was increased. The reason for this might be a contribution of malic enzyme to NADPH supply in the mutant in the mutant. The observed complex changes are remarkable, because they are due to the minimum genetic modification possible, the exchange of only one single nucleotide.

• Microbiology and Biotechnology Letters
• /
• v.37 no.4
• /
• pp.306-315
• /
• 2009

Due to the depleting petroleum reserve, recurring energy crisis, and global warming, it is necessary to study the development of white biotech-based aromatic chemical feedstock from renewable biomass for replacing petroleum-based one. In particular, the production of aromatic intermediates and derivatives in biosynthetic pathway of aromatic amino acids from glucose might be replaced by the production of petrochemical-based aromatic chemical feedstock including benzene-derived aromatic compounds. In this review, I briefly described the production technology for hydroquinone, catechol, adipic acid, shikimic acid, gallic acid, pyrogallol, vanillin, p-hydroxycinnamic acid, p-hydroxystyrene, p-hydroxybenzoic acid, indigo, and indole 3-acetic acid using metabolic engineering, bioconversion, and chemical process. The problems and possible solutions regarding development of production technology for competitive white biotech-based aromatic compounds were also discussed.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.5
• /
• pp.719-723
• /
• 2013

Nitrification in wastewater treatment emits a significant amount of nitrous oxide ($N_2O$), which is one of the major greenhouse gases. However, the actual mechanism or metabolic pathway is still largely unknown. Selective nitrification inhibitors were used to determine the nitrification steps responsible for $N_2O$ emission with activated sludge and enriched nitrifiers. Allylthiourea (86 ${\mu}M$) completely inhibited ammonia oxidation and $N_2O$ emission both in activated sludge and enriched nitrifiers. Sodium azide (24 ${\mu}M$) selectively inhibited nitrite oxidation and it led to more $N_2O$ emission than the control experiment both in activated sludge and enriched nitrifiers. The inhibition tests showed that $N_2O$ emission was mainly related to the activity of ammonia oxidizers in aerobic condition, and the inhibition of ammonia monooxygenase completely blocked $N_2O$ emission. On the other hand, $N_2O$ emission increased significantly as the nitrogen flux from nitrite to nitrate was blocked by the selective inhibition of nitrite oxidation.