• Journal of Microbiology and Biotechnology
• /
• 제19권3호
• /
• pp.299-306
• /
• 2009

Dissolved oxygen (DO) has a significant effect on the molecular weight of hyaluronic acid (HA) during the fermentation of Streptococcus zooepidemicus. Therefore, to further investigate the effect of DO on the yield and molecular weight of HA, this study compared the metabolic flux distribution of S. zooepidemicus under aerobic conditions at various DO levels. The metabolic flux analysis demonstrated that the HA synthesis pathway, considered a dependent network, was little affected by the DO level. In contrast, the fluxes of lactate and acetate were greatly influenced, and more ATP was generated concomitant with acetate at a high DO level. Furthermore, the has gene expression and HA synthase activity were both repressed under anaerobic conditions, yet not obviously affected under aerobic conditions at various DO levels. Therefore, it was concluded that the HA molecular weight would seem to depend on the concomitant effect of the generation of ATP and reactive oxygen species. It is expected that this work will contribute to a better understanding of the effect of the DO level on the mechanism of the elongation of HA chains.

• Molecules and Cells
• /
• 제40권2호
• /
• pp.123-132
• /
• 2017

Insulin signaling is coordinated by insulin receptor substrates (IRSs). Many insulin responses, especially for blood glucose metabolism, are mediated primarily through Irs-1 and Irs-2. Irs-1 knockout mice show growth retardation and insulin signaling defects, which can be compensated by other IRSs in vivo; however, the underlying mechanism is not clear. Here, we presented an Irs-1 truncated mutated mouse ($Irs-1^{-/-}$) with growth retardation and subcutaneous adipocyte atrophy. $Irs-1^{-/-}$ mice exhibited mild insulin resistance, as demonstrated by the insulin tolerance test. Phosphatidylinositol 3-kinase (PI3K) activity and phosphorylated Protein Kinase B (PKB/AKT) expression were elevated in liver, skeletal muscle, and subcutaneous adipocytes in Irs-1 deficiency. In addition, the expression of IRS-2 and its phosphorylated version were clearly elevated in liver and skeletal muscle. With miRNA microarray analysis, we found miR-33 was down-regulated in bone marrow stromal cells (BMSCs) of $Irs-1^{-/-}$ mice, while its target gene Irs-2 was up-regulated in vitro studies. In addition, miR-33 was down-regulated in the presence of Irs-1 and which was up-regulated in fasting status. What's more, miR-33 restored its expression in re-feeding status. Meanwhile, miR-33 levels decreased and Irs-2 levels increased in liver, skeletal muscle, and subcutaneous adipocytes of $Irs-1^{-/-}$ mice. In primary cultured liver cells transfected with an miR-33 inhibitor, the expression of IRS-2, PI3K, and phosphorylated-AKT (p-AKT) increased while the opposite results were observed in the presence of an miR-33 mimic. Therefore, decreased miR-33 levels can up-regulate IRS-2 expression, which appears to compensate for the defects of the insulin signaling pathway in Irs-1 deficient mice.

• Journal of Microbiology and Biotechnology
• /
• 제34권6호
• /
• pp.1214-1221
• /
• 2024

The accumulating evidence substantiates the indispensable role of gut microbiota in modulating the pathogenesis of type 2 diabetes. Uncovering the intricacies of the mechanism is imperative in aiding disease control efforts. Revealing key bacterial species, their metabolites and/or metabolic pathways from the vast array of gut microorganisms can significantly contribute to precise treatment of the disease. With a high prevalence of type 2 diabetes in Inner Mongolia, China, we recruited volunteers from among the Mongolian population to investigate the relationship between gut microbiota and the disease. Fecal samples were collected from the Volunteers of Mongolia with Type 2 Diabetes group and a Control group, and detected by metagenomic analysis and untargeted metabolomics analysis. The findings suggest that Firmicutes and Bacteroidetes phyla are the predominant gut microorganisms that exert significant influence on the pathogenesis of type 2 diabetes in the Mongolian population. In the disease group, despite an increase in the quantity of most gut microbial metabolic enzymes, there was a concomitant weakening of gut metabolic function, suggesting that the gut microbiota may be in a compensatory state during the disease stage. β-Tocotrienol may serve as a pivotal gut metabolite produced by gut microorganisms and a potential biomarker for type 2 diabetes. The metabolic biosynthesis pathways of ubiquinone and other terpenoid quinones could be the crucial mechanism through which the gut microbiota regulates type 2 diabetes. Additionally, certain Clostridium gut species may play a pivotal role in the progression of the disease.

• Journal of Microbiology and Biotechnology
• /
• 제30권12호
• /
• pp.1937-1943
• /
• 2020

Although classical metabolic engineering strategies have succeeded in developing microbial strains capable of producing desired bioproducts, metabolic imbalance resulting from extensive genetic manipulation often leads to decreased productivity. Thus, abiotic strategies for improving microbial production performance can be an alternative to overcome drawbacks arising from intensive metabolic engineering. Herein, we report a promising abiotic method for enhancing lycopene production by UV-C irradiation using a radiation-resistant ΔcrtLm/crtB+dxs+ Deinococcus radiodurans R1 strain. First, the onset of UV irradiation was determined through analysis of the expression of 11 genes mainly involved in the carotenoid biosynthetic pathway in the ΔcrtLm/crtB+dxs+ D. radiodurans R1 strain. Second, the effects of different UV wavelengths (UV-A, UV-B, and UV-C) on lycopene production were investigated. UV-C irradiation induced the highest production, resulting in a 69.9% increase in lycopene content [64.2 ± 3.2 mg/g dry cell weight (DCW)]. Extended UV-C irradiation further enhanced lycopene content up to 73.9 ± 2.3 mg/g DCW, a 95.5% increase compared to production without UV-C irradiation (37.8 ± 0.7 mg/g DCW).

• 생명과학회지
• /
• 제34권7호
• /
• pp.465-475
• /
• 2024

Lactiplantibacillus plantarum K9은 굼벵이에서 분리된 다양한 생리활성물질에 기인하여 프로바이오틱스 균주로 활용 가능한 유산균이다. L. plantarum K9 유전체 분석결과로써 박테리아 염색체와 3 plasmid가 존재하는 것으로 나타났다. L. plantarum K9의 핵심 대사경로 분석 결과 해당과정, 오탄당대사(pentose phosphate pathway)는 정상적으로 수행되는 것으로 나타났다. 그러나 포도당신생합성과 ED pathway의 핵심 효소인 fructose-1,6-bisphosphatase (EC: 3.1.3.11)와 6-phosphogluconate dehydratase (EC: 4.2.1.12) / 2-keto-de- oxy-6-phosphogluconate (KDPG) aldolase (EC: 4.2.1.55)가 각각 결여되어 있기 때문에 포도당신생합성과 ED pathway는 수행하지 못하는 것으로 제의된다. 또한, TCA 회로에서 fumarate 및 malate를 형성하는 일부 효소만 존재하는 반면에 나머지 TCA 회로에 연관되는 효소들이 모두 결여되어 있었기 때문에 TCA 회로는 진행되지 못하는 것으로 추정되었다. 산화적 전자전달계는 NADH dehydrogenase complex I과 cytochrome reductase complex IV에 해당하는 요소들을 보유하고 있기 때문에 class IIB 타입(bd-type)의 전자전달시스템을 수행할 것으로 예측되었다. 종합적으로, L. plantarum K9은 lactic acid 동형발효를 수행하며, 포도당신생합성 및 오탄당대사가 가능하며, class IIB 타입(bd-type) 산화적 전자전달시스템에 의해 에너지 대사를 수행하는 것으로 제의된다. 따라서, L. plantarum K9은 다른 유산균주에 비교하여 lactic acid 생성량이 비교적 높아 생리활성도가 우수할 것으로 제의된다. 다른 한편으로, L. plantarum K9은 산화적 전자전달이 가능한 것으로 추정되어 산소에 대한 내성이 높아서 배양 특성이 양호하여 프로바이틱스로써 활용가능성이 높은 것으로 제의된다.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 2004년도 Annual Meeting BioExibition International Symposium
• /
• pp.60-61
• /
• 2004

Metabolic engineering is now a well established discipline, used extensively to determine and execute rational strategies of strain development to improve the performance of micro-organisms employed in industrial fermentations. The basic principle of this approach is that performance of the microbial catalyst should be adequately characterised metabolically so as to clearlyidentify the metabolic network constraints, thereby identifying the most probable targets for genetic engineering and the extent to which improvements can be realistically achieved. In order to harness correctly this potential, it is clear that the physiological analysis of each strain studied needs to be undertaken under conditions as close as possible to the physico-chemical environment in which the strain evolves within the full-scale process. Furthermore, this analysis needs to be undertaken throughoutthe entire fermentation so as to take into account the changing environment in an essentially dynamic situation in which metabolic stress is accentuated by the microbial activity itself, leading to increasingly important stress response at a metabolic level. All too often these industrial fermentation constraints are overlooked, leading to identification of targets whose validity within the industrial context is at best limited. Thus the conceptual error is linked to experimental design rather than inadequate methodology. New tools are becoming available which open up new possibilities in metabolic engineering and the characterisation of complex metabolic networks. Traditionally metabolic analysis was targeted towards pre-identified genes and their corresponding enzymatic activities within pre-selected metabolic pathways. Those pathways not included at the onset were intrinsically removed from the network giving a fundamentally localised vision of pathway functionality. New tools from genome research extend this reductive approach so as to include the global characteristics of a given biological model which can now be seen as an integrated functional unit rather than a specific sub-group of biochemical reactions, thereby facilitating the resolution of complexnetworks whose exact composition cannot be estimated at the onset. This global overview of whole cell physiology enables new targets to be identified which would classically not have been suspected previously. Of course, as with all powerful analytical tools, post-genomic technology must be used carefully so as to avoid expensive errors. This is not always the case and the data obtained need to be examined carefully to avoid embarking on the study of artefacts due to poor understanding of cell biology. These basic developments and the underlying concepts will be illustrated with examples from the author's laboratory concerning the industrial production of commodity chemicals using a number of industrially important bacteria. The different levels of possibleinvestigation and the extent to which the data can be extrapolated will be highlighted together with the extent to which realistic yield targets can be attained. Genetic engineering strategies and the performance of the resulting strains will be examined within the context of the prevailing experimental conditions encountered in the industrial fermentor. Examples used will include the production of amino acids, vitamins and polysaccharides. In each case metabolic constraints can be identified and the extent to which performance can be enhanced predicted

• The Korean Journal of Physiology and Pharmacology
• /
• 제28권4호
• /
• pp.361-377
• /
• 2024

The dried rattan stem of the Fibraurea Recisa Pierre plant contains the active ingredient known as fibrauretine (FN). Although it greatly affects Alzheimer's disease (AD), the mechanism of their effects still remains unclear. Proteomics and transcriptomics analysis methods were used in this study to determine the mechanism of FN in the treatment of AD. AD model is used through bilateral hippocampal injection of Aβ_1-40. After successful modeling, FN was given for 30 days. The results showed that FN could improve the cognitive dysfunction of AD model rats, reduce the expression of AE and P-Tau, increase the content of acetylcholine and reduce the activity of acetylcholinesterase. The Kyoto Encyclopedia of Genes and Genomes enriched differentially expressed genes and proteins are involved in signaling pathways including metabolic pathway, AD, pathway in cancer, PI3K-AKT signaling pathway, and cAMP signaling pathway. Transcriptomics and proteomics sequencing resulted in 19 differentially expressed genes and proteins. Finally, in contrast to the model group, after FN treatment, the protein expressions and genes associated with the PI3K-AKT pathway were significantly improved in RT-qPCR and Western blot and assays. This is consistent with the findings of transcriptomic and proteomic analyses. Our study found that, FN may improve some symptoms of AD model rats through PI3K-AKT signaling pathway.

• KSBB Journal
• /
• 제22권1호
• /
• pp.62-65
• /
• 2007

대사 공학을 이용한 생산 균주 개발의 핵심 기술은 원하는 대사산물을 과량으로 얻기 위하여 기존의 대사회로에서 제거, 증폭, 변경을 시켜야 할 유전자를 선정하는 것이다. 대사조절 분석 기법은 대사 흐름이 특정 효소의 활성에 따라 어떻게 변하는지를 예측하는 기술이다. 본 논문에서는 대장균의 threonine 생합성 효소 반응 kinetic model과 대사조절 분석 기법을 이용하여 threonine 생합성 flux를 가장 효과적으로 증가시키기 위하여 활성 증가가 필요한 효소가 aspartate semialdehyde dehyogenase라는 것을 밝혔다. 이러한 결과를 확인하기 위하여 asd가 과발현된 vector와 threonine 생합성 경로의 다른 효소인 aspartate kinase를 coding하는 thrA를 과발현 시키는 vector를 제작하여 threonine 생산 균주인 TF5015에 형질전환하여 threonine 농도를 측정하였다. Flask 배양결과 대사조절 분석 기법으로 확인된 유전자 asd를 과발현시킬 경우가 생합성 경로의 다른 유전자를 과발현시킨 경우보다 더 높은 threonine 농도의 증가를 보였다. 이러한 연구 결과들은 효소 반응 kinetic model과 대사조절 분석 기법을 이용하여 원하는 product를 효율적으로 생산할 수 있는 생산 균주를 제작할 수 있게 할 것이다.

• Genomics & Informatics
• /
• 제9권4호
• /
• pp.143-151
• /
• 2011

In this study, we propose a novel, intuitive method of constructing an expression quantitative trait (eQT) network that is related to the metabolic syndrome using LOD scores and peak loci for selected eQTs, based on the concept of gene-gene interactions. We selected 49 eQTs that were related to insulin resistance. A variance component linkage analysis was performed to explore the expression loci of each of the eQTs. The linkage peak loci were investigated, and the "support zone" was defined within boundaries of an LOD score of 0.5 from the peak. If one gene was located within the "support zone" of the peak loci for the eQT of another gene, the relationship was considered as a potential "directed causal pathway" from the former to the latter gene. SNP markers under the linkage peaks or within the support zone were searched for in the database to identify the genes at the loci. Two groups of gene networks were formed separately around the genes IRS2 and UGCGL2. The findings indicated evidence of networks between genes that were related to the metabolic syndrome. The use of linkage analysis enabled the construction of directed causal networks. This methodology showed that characterizing and locating eQTs can provide an effective means of constructing a genetic network.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2005년도 생물공학의 동향(XVII)
• /
• pp.71-72
• /
• 2005