• 한국미생물·생명공학회지
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• 제20권6호
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• pp.668-676
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• 1992

Alcaligenes eutrophus에 의한 poly-Beta-hydroxybuty-rate(PHB) 생산을 최적화하기 위해서 1단계에서는 성장을 최대화하고, 2단계에서는 생산을 최대화하는 이단 유가식 배양을 채택하였다. 성장단계에서 탄소원과 질소원의 최적농도는 회분식 배양 모델로부터 결정되었는데, 각기 16.64g/l와 0.54g/l이었다. 생산단계에서 질소원의 경우, 유가식 배양실험을 통해 0.07g/l가 최적인 것으로 나타났다. 탄소원의 최적농도는 모사로부터 결정되었고 이때 최적 전환시간도 함께 결정되었다. 생산공정의 제어를 위하여 시간지연을 고려한 적응비례 되먹임제어를 이용한 결과, 탄소원 농도 및 질소원농도를 최적의 상태로 유지시킬 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.71-77
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• 2010

The time, yield, and related genes expression of PHB accumulation of Acidiphilium cryptum DX1-1 were investigated under four different initial C/N ratios, 1.2, 2.4, 7.5, and 24. The results of time and yield of poly-$\beta$-hydroxybutyrate (PHB) accumulation show that the initial C/N ratio of 2.4 was optimum for strain DX1-1 to accumulate PHB, but both higher and lower initial C/N ratios did not favor that process. Based on the genome of Acidiphilium cryptum JF-5, 13 PHB accumulation related genes in strain JF-5 were chosen and successfully cloned from strain DX1-1. The differential expressions of the 13 functional genes, in different C/N ratios as cited above, were then studied by real-time PCR. The results show that all the 13 genes were most upregulated when the initial C/N ratio was 2.4, and among which the gene Acry_3030 encoding poly-$\beta$-hydroxybutyrate polymerase and Aery_0626 encoding acetyl-CoA synthetase were much more upregulated than the other genes, which proved that they play the most important role for PHB accumulation, and acetate is the main initial substance for PHB accumulation for strain DX1-1. Potential regulatory motifs analysis showed that the genes related to PHB accumulation are regulated by different promoters and that the motif had weak similarity to the model promoters, suggesting that PHB metabolism in Acidiphilium cryptum may be mediated by a different mechanism.

• 미생물학회지
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• 제27권1호
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• pp.63-69
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• 1989

흙으로부터 에탄올을 이용하여 성장하는 분홍색 통성 에단올 자화세율을 분리하여 Methylobacteriu~η sp. strain SY 1이라 명명하였다. 이 세균은 그람음성세균으호 약간 굽은 간균이고 한쪽 끝에 달련 한개의 편모로 운동하였다. 세균의 군략은 매끈 하고 밝은 분홍맺을 띄우며 정성이 높았다. 이 세균이 지니는 DNA의 G+C 함량은 약 66%로 나타났다. 이 제균은 칠대호가 성으호 catalase와 oxidase 활성을 나타내었고, carotenoid 색소와 poly-$\beta$-hydroxy butyrate를 가지고 있었다. 이 세균은 또 한 세가지 종류의 큰 plasmid DNA (45,000, 38,500, 23,000)을 가졌으며, $30^{\circ}C$와 pH7.0에서 0.5%(v/v)의 에탄올을 이용 하여 빼른 성장을 하였다($t_{d}$=6.5시간), 이 세균은 메탄올은 울온 여러까지 종듀의 당, 유기산, 아미노산, 아민 및 알코올을 이용하여 성장할 수 있었고, 메탄올은 serine pathway를 통하여 이 세균의 세포 구성물질로 전환됨을 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.1115-1119
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• 2005

The photoheterotrophic $H_2$ production of Rhodobacter sphaeroides was significantly increased through disruption of the genes coding for uptake hydrogenase and poly-${\beta}$-hydroxybutyrate (PHB) synthase (Lee et al., Appl. Microbiol. Biotechnol. 60: 147-153, 2002). In this work, we further removed the B800-850 light-harvesting (LH) complex from the strain and found an increase in $H_2$ production at the light-saturating cell growth (${\ge}10$ Watts $[W]/m^2$). Neither the mutant nor the wild-type produced more $H_2$ at the brighter light. Accordingly, light does not appear to be limited for the $H_2$ production by the presence of B800-850. However, increase in the level of the spectral complexes resulted in decrease of $H_2$ production. Thus, although the B875 is essential for light harvesting, the consumption of cellular energy for the synthesis of B800-850 and the surplus LH complexes may reduce the energy flow into the $H_2$ production of R. sphaeroides.

• 생명과학회지
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• 제8권5호
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• pp.526-531
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• 1998

In this study, the composition and characteristics of poly-$\beta$-hydroxybutyrate (PHB) biosynthesized by Actinobacillus sp. EL-9 are investigated. PHB produced by Actinobacillus sp. EL-9 was identified as the homopolymer of 3-hydroxy-butyric acid (PHB) by infrared spectroscopy and nuclear magnetic resonance spectroscopy analysis. The melting tem-perature (T$_{m}$), and crystallization temperature(T$_{c}$) of PHB was 169.7$^{\circ}C$ and 69.13$^{\circ}C$, respectively. The viscosity on he basis of Brookfield viscometer was 6.01 ㎗/g. The viscosity-average molecular weight estimated by Mark-Ho-wink-Sakurada equation was 1.08$\times$10$^{6}$ ($\pm$3,000).00).

• 식물병과 농업
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• 제5권2호
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• pp.69-76
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• 1999

Acidovorax avenae subsp. avenae is the causal pathogen of several hosts including oats corn foxtail millet wheatgrass sugarcane and rice. The pathogen is a seedborne pathogen of rice and known to occur widely in rice growing countries. The pathogen cause inhibition of germination brown stripe on the leaf curling of the leaf sheath and abnormal elongation of the mesocotyl of irce. Bacterial colonies grow slowly and are convex circular and creamy with tan to brown center. The causal baterium is Gram-negative and rod shape with a single polar flagellum Nonfluorescence poly-$\beta$-hydroxybutyrate accumulation and precipitate formation around the colony on the medium are useful in the differentiation of this bacterium from other subspecies of A. avenae as well as nonfluorescent bacteria pathogenic to rice. This bacterium has belonged to the genus of Psdeudomonas but recently was transferred to the new genus Acidovorax on the basis of bacteriological and molecular biological data. However the difference of biochemical characteristics protein profile of the cell and host range among strains should be more clarified. To develop an effective control strategy for this disease understanding of detailed life cycle of the disease ritical environmental factors affecting disease development on each host and relationship to grain discoloration of rice are prerequisite. Although the affected area has been world-widely reported there is on recent progress on the understanding of the bacteriological and ecological characteristics of the causal bacterium and control means of the disease.

• Journal of Microbiology
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• 제44권2호
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• pp.171-176
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• 2006

A strictly aerobic, non-motile, ovoid-shaped Alphaproteobacteria, designated strain $JC2049^T$ was isolated from a tidal flat sediment sample. The results of 16S rRNA gene sequence analysis indicated that this isolate belonged to the genus Thalassobius, with a sequence similarity of 96.9-97.3% to other valid Thalassobius spp. The cells required 1-7% NaCl for growth (optimum 2%) and accumulated $poly-\beta-hydroxybutyrate$. Nitrite was reduced to nitrogen, but nitrate was not reduced to nitrite. No genetic potential for aerobic anoxygenic photosynthesis was detected. The primary isoprenoid quinone (Ubiquinone-10), predominant cellular fatty acids $(C_{18:1}{\omega}7c,\;11\;methyl\;C_{18:1}\omega7c\;and\;C_{16:0})$ and DNA G+C content (61 mol %) were all consistent with the assignment of this isolate to the genus Thalassobius. Several phenotypic characteristics clearly distinguished our isolate from other Thalassobius species. The degree of genomic relatedness between strain $JC2049^T$ and other Thalassobius species was in a range of 20-43 %. The polyphasic data presented in this study indicates that our isolate should be classified as a novel species within the genus Thalassobius. The name Thalassobius aestuarii sp. novo is therefore proposed for this isolate; the type strain is $JC2049^T(=IMSNU\;14011^T=KCTC\;12049^T=DSM\;15283^T)$.

• Journal of Microbiology and Biotechnology
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• 제25권2호
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• pp.152-161
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• 2015

CodY is a highly conserved protein in low G+C gram-positive bacteria that regulates genes involved in sporulation and stationary-phase adaptation. Bacillus thuringiensis is a grampositive bacterium that forms spores and parasporal crystals during the stationary phase. To our knowledge, the regulatory mechanism of CodY in B. thuringiensis is unknown. To study the function of CodY protein in B. thuringiensis, BMB171codY^- was constructed in a BMB171 strain. A shuttle vector containing the ORF of cry1Ac10 was transformed into BMB171 and BMB171codY^-, named BMB171cry1Ac and BMB171codY^-cry1Ac, respectively. Some morphological and physiological changes of codY mutant BMB171codY^-cry1Ac were observed. A comparative proteomic analysis was conducted for both BMB171codY^-cry1Ac and BMB171cry1Ac through two-dimensional gel electrophoresis and MALDI-TOF-MS/MS analysis. The results showed that the proteins regulated by CodY are involved in microbial metabolism, including branched-chain amino acid metabolism, carbohydrate metabolism, fatty acid metabolism, and energy metabolism. Furthermore, we found CodY to be involved in sporulation, biosynthesis of poly-β-hydroxybutyrate, growth, genetic competence, and translation. According to the analysis of differentially expressed proteins, and physiological characterization of the codY mutant, we performed bacterial one-hybrid and electrophoretic mobility shift assay experiments and confirmed the direct regulation of genes by CodY, specifically those involved in metabolism of branched-chain amino acids, ribosomal recycling factor FRR, and the late competence protein ComER. Our data establish the foundation for in-depth study of the regulation of CodY in B. thuringiensis, and also offer a potential biocatalyst for functions of CodY in other bacteria.

• 한국토양비료학회지
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• 제45권4호
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• pp.572-581
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• 2012

In this study, we compared growth pattern, floc yield, Exo-polysaccharides (EPS) production, Poly-${\beta}$-hydroxybutyrate (PHB) accumulation, resistance to osmotic and acid stress in Methylobacterium strains CBMB20, CBMB27, CBMB35, and CBMB110. Modified high C:N ratio medium denoted as HCN-AMS medium was used with a C:N ratio of 30:1. The HCN-AMS medium favored increased growth in all the studied strains. All Methylobacterium strains tested positive for EPS production and showed positive fluorescence with calcoflour stain. Elevated levels of EPS production from 4.2 to 75.0% was observed in HCN-AMS medium. Accumulation of PHB in HCN-AMS medium increased by 3.8, 36.7, and 12.0% in strains CBMB27, CBMB35, and CBMB110 respectively. Among the abiotic stresses, osmotic stress-induced growth inhibition of Methylobacterium strains was found to be lowered when grown in HCN-AMS medium. Likewise, growth inhibition due to acid stress at pH 5.0 was lower for strains grown in HCN-AMS medium compared to growth in AMS medium. Enhanced survivability under stress conditions may be attributed to the high EPS and PHB production at increased carbon concentration in the growth medium.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.5-10
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• 2009

A freshwater bacterium, designated $IMCC1713^T$, was isolated from a highly eutrophic artificial pond. Cells of the strain were Gram-negative, chemoheterotrophic, poly-$\beta$-hydroxybutyrate granule containing and obligately aerobic short rods that were motile with a single polar flagellum. The 16S rRNA gene sequence similarity analysis showed that the novel strain was most closely related to the species Roseateles depolymerans (96.3%), Mitsuaria chitosanitabida (96.2%), Ideonella dechloratans (96.2%), and Pelomonas saccharophila (96.1%) in the Sphaerotilus-Leptothrix group within the order Burkholderiales. Phylogenetic trees based on 16S rRNA gene sequences indicated that the isolate formed an independent monophyletic clade within the order Burkholderiales. The relatively low DNA G+C content (57.4mol%), together with several phenotypic characteristics, differentiated the novel strain from other members of the Sphaerotilus-Leptothrix group. From the taxonomic data, therefore, the strain should be classified as a novel genus and species, for which the name Inhella inkyongensis gen. nov., sp. nov. is proposed. The type strain of the proposed species is strain $IMCC1713^T$ (=KCTC $12791^T$=NBRC $103252^T$=CCUG $54308^T$).