• Computers and Concrete
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• 제14권4호
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• pp.419-444
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• 2014

In this study experimental result of a total of eight SCC and FRSCC slabs with the same cross-section were monitored for up to 240 days to measure the time-dependent development of cracking and deformations under service loads are presented. For this purpose, four SCC mixes are considered in the test program. This study aimed to compare SCC and FRSCC experimental results with conventional concrete experimental results. The steel strains within the high moment regions, the concrete surface strains at the tensile steel level, deflection at the mid-span, crack widths and crack spacing were recorded throughout the testing period. Experimental results show that hybrid fibre reinforced SCC slabs demonstrated minimum instantaneous and time-dependent crack widths and steel fibre reinforced SCC slabs presented minimum final deflection.

• 미생물학회지
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• 제27권2호
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• pp.98-107
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• 1989

Trichoderma koningii ATCC26113으로부터 얻어진 영양요구성 돌연변이주간의 종내 원형질체 융합을 시도하여 생성된 융합체의 유전자형을 완전평판배상에서 분석하였다. 생성된 융합체 중 모균고 다른 독립영양형 균주에서 섬유소 분해능이 증진된 융합체를 얻었으며 이들이 이배체(혹은 이수체)임을 확인하였다. 또한 이들 이배체(혹은 이수체)의 독립영양청 잡종의 원형 질체 융합을 통하여 유전자의 교환 및 재조합에 의하여 자연분리되므로써 형성됨을 확인하였다.

• Journal of Microbiology
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• 제34권4호
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• pp.327-333
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• 1996

Yeast, like many other microbes, encounters large variations in ambient pH in their natural environments. Microorganisms capable of growing over a wide pH range require a versatile, efficient pH homeostatic mechanism protecting intracellular processes against extremes of pH. In several organisms, fusions to the bacterial lacZ gene have been extremely useful for the identification of genes expressed at different time during the life cycle or under different growth conditions. In this study, using the lacZ gene screening system, we surveyed a large number of yeast strains with lacZ insertion to identify genes regulated by pH. A yeast genomic library was constructed and inserted with lacZ by a shuttle mutagenesis procedure. The yeast transformants were individually picked up with a toothpick, replica-plated, and grown in alkaline pH medium. Among the 35,000 colonies screened, 10 candidate strains were identified initially by the $\beta$-gal assay. We finally confirmed two yeast strains carrying the genes whose expression are strictly dependent on pH of growth medium. One of the fusions showing a 10-fold induction in expression level in response to alkali pH was selected and further characterized. The pH-regulated gene was cloned by inverse PCR and a partial sequence of the gene was determined. Identification and characterization of the gene is currently under investigation.

• 한국토양비료학회지
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• 제45권1호
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• pp.51-58
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• 2012

Salinity is one of the most relevant abiotic factor limiting crop yield and its net primary productivity. In addition, salinity induces an increased stress ethylene synthesis in plants which, in turn, exacerbate the responses to the stressor. Bacterial single or co-inoculation effect was tested using previously characterized plant growth promoting (PGP) bacteria Brevibacterium iodinum RS16 and Methylobacterium oryzae CBMB20 on maize and sorghum-sudan grass hybrid under different concentrations of NaCl. Non-inoculated maize and sorghum-sudangrass hybrid showed 33.4% and 20.0% reduction in seed germination under highest NaCl (150 mM) level tested. However, under the same NaCl concentration, co-inoculation with B. iodinum RS16 and M. oryzae CBMB20 PGP strains increased the seed germination in maize (16.7%) and sorghum-sudangrass hybrid (4.4%). In Gnotobiotic growth pouch experiments conducted for maize and sorghum-sudangrass hybrid, co-inoculation of PGP B. iodinum RS16 and M. oryzae CBMB20 mitigated the salinity stress and promoted root length by 22.9% and 29.7%, respectively. Thus the results of this study could help in development of potential bioinoculants that may be suitable for crop production under saline conditions.

• 한국버섯학회지
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• 제2권2호
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• pp.109-113
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• 2004

큰느타리버섯은 식용 및 약용으로 쓰이는 부가가치가 높은 버섯으로서 한국 고유의 육성품종 개발이 절실하다. 이에 새로운 큰느타리버섯 품종을 육성하고자 시중에 고가로 판매되고 있는 ASI 2547균주의 단포자를 분리하고 22개의 수집균주와 Di-Mon 교배를 실시하여 꺽쇠연결체를 가진 253균주중에서 자실체를 형성하는 19균주를 선발하여 그 중에서 형태적으로 다양한 7균주를 선택하여 RAPD로 분석한 결과 Hybrid H6 균주가 형태학적으로는 양친과 유사하나 유전자 증폭산물은 재조합된 교배체임이 확인되었다. 따라서 Di-Mon 교배법이 분자생물학적 동정과 결합됨으로서 손쉽고 빠른 교배법으로 새로운 균주육성에 사용할 수 있으리라 사료된다.

• International Journal of Industrial Entomology and Biomaterials
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• 제29권2호
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• pp.198-206
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• 2014

The olive fly Bactrocera oleae (Rossi) is the key pest for olive cultivation worldwide. Substantial effort has been invested in the development of the sterile insect technique (SIT) to control this pest. One of the limitations to develop SIT technology for olive fruit fly is the low ability of wild females to lay eggs in other medium than olive fruits, and their slow adaptation to oviposition in artificial substrates. In the present study, fruit grapes were used as an alternative egg collection medium to harvest eggs and young larvae from freshly colonized wild strains originating from France, Italy, Spain and Croatia. The larvae were allowed to develop into the fruits until the second instar, before they were extracted out and further reared on a standard artificial diet. Furthermore, F1 to F4 female flies were alternatively offered wax bottles to oviposit. Finally, the performance of hybrid strains created from crosses between wild and long colonised flies was assessed. The results showed that females of all 4 wild strains readily oviposited eggs in grapes and from the F2 generation onward, females from all strains were adapted to laying eggs in wax bottles. No difference was observed in eggs and pupae production among all strains tested. The findings are discussed for their implications on SIT application against olive fruit fly.

• 한국균학회지
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• 제49권3호
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• pp.405-412
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• 2021

복령은 한국, 일본, 중국을 포함한 동북아시아 지역에서 사용되어 왔던 중요한 약용버섯이다. 복령은내부색깔을기준으로적복령과백복령으로구분하며, 일반적으로 백복령이 농가에서 재배되고 있다. 본 연구에서는 2가지 재배 복령과 3가지 야생 복령을 이용하여 이원교배를 통해 만들어진 균주로부터 톱밥배지에서 균핵을 형성하는 균주를 선발하려고 하였다. 단포자는 PDA 배지에서 만들어진 복령의 자실체로부터 분리하였다. 분리된 교잡균주 338개 중 39개가 소나무 톱밥배지에서 3개월 동안 배양하는 과정에서 백색 또는 황색의 균핵을 형성하였다. 톱밥배지를 이용한 균핵 형성 균주의 선발은 매우 간단하고 쉬운 방법이며 본 논문에서 처음으로 제시하는 것이다. 그리고 선발된 균주는 향후 새로운 품종을 개발하고자 야외실험을 시도할 계획이다.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.207-212
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• 2016

PacBio's long-read sequencing technologies can be successfully used for a complete bacterial genome assembly using recently developed non-hybrid assemblers in the absence of second-generation, high-quality short reads. However, standardized procedures that take into account multiple pre-existing second-generation sequencing platforms are scarce. In addition to Illumina HiSeq and Ion Torrent PGM-based genome sequencing results derived from previous studies, we generated further sequencing data, including from the PacBio RS II platform, and applied various bioinformatics tools to obtain complete genome assemblies for five bacterial strains. Our approach revealed that the hierarchical genome assembly process (HGAP) non-hybrid assembler resulted in nearly complete assemblies at a moderate coverage of ~75x, but that different versions produced non-compatible results requiring post processing. The other two platforms further improved the PacBio assembly through scaffolding and a final error correction.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.60-60
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• 2015

Hybrid histidine kinase is a part of two-component system that is required for various stress responses and pathogenesis of pathogenic fungi. In the present study, Tco1, a homologue of human pathogen Cryptococcus neoformans Tco1 encoding a hybrid histidine kinase, was identified in corn smut pathogen Ustilago maydis by bioinformatic analysis. To explore the role of Tco1 in the virulence of U. maydis, mutants in which the tco1 gene was partially deleted were constructed by allelic exchange. The U. maydis tco1 mutants did show unaltered growth rate on axenic medium but were unable to produce conjugation tubes and develop fuzzy filaments, resulting in impaired mating of compatible strains. The expression levels of prf1, pra1, and mfa1 which are involved in the pheromone pathway significantly decreased in the tco1 mutants. In inoculation tests to host, the tco1 mutants showed significantly reduced ability in the production of anthocyanin pigments and tumor development on maize leaves. Overall, the combined results indicated that Tco1 plays important roles in sexual development and virulence of U. maydis by regulating the expression of the genes involved in the pheromone pathway.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2002년도 학술발표대회
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• pp.18-25
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• 2002

The pikromycin biosynthetic system in Streptomyces venezuleae is unique for its ability to produce two groups of antibiotics that include the 12-membered ring macrolides methymycin and neomethymycin, and the 14-membered ring macrolides narbomycin and pikromycin. The metabolic pathway also contains two post polyketide-modification enzymes, a glycosyltransferase and P450 hydroxylase that have unusually broad substrate specificities. In order to explore further the substrate flexibility of these enzymes a series of hybrid polyketide synthases were constructed and their metabolic products characterized. The plasmid-based replacement of the multifunctional protein subunits of the pikromycin PKS in S. venezuelae by the corresponding subunits from heterologous modular PKSs resulted in recombinant strains that produce both 12- and 14-membered ring macrolactones with predicted structural alterations. In all cases, novel macrolactones were produced and further modified by the DesVII glycosyltransferase and PikC hydroxylase leading to biologically active macrolide structures. These results demonstrate that hybrid PKSs in S. venezuelae can produce a multiplicity of new macrolactones that are modified further by the highly flexible DesVII glycosyltransferase and PikC hydroxylase tailoring enzymes. This work demonstrates the unique capacity of the S. venezuelae pikromycin pathway to expand the toolbox of combinatorial biosynthesis and to accelerate the creation of novel biologically active natural products. The polyketide backbone of rifamycin B is assembled through successive condensation and ${\beta}$-carbonyl processing of the extender units by the modular rifamycin PKS. The eighth module, in the RifD protein, contains nonfunctional DH domain and functional KR domain, which specify the reduction of the ${\beta}$-carbonyl group resulting in the C-21 bydroxyl of rifamycin B. A four amino acid substitution and one amino acid deletion were introduced in the putative NADPH binding motif in the proposed KR domain encoded by rifD. This strategy of mutation was based on the amino acid sequences of the corresponding motif of the KR domain of module 3 in the RifA protein, which is believed dysfunctional, so as to introduce a minimum alteration and retain the reading frame intact, yet ensure loss of function. The resulting strain produces linear polyketides, from tetraketide to octaketide, which are also produced by a rifD disrupted mutant as a consequence of premature termination of polyketide assembly. Much of the structural diversity within the polyketide superfamily of natural products is due to the ability of PKSs to vary the reduction level of every other alternate carbon atom in the backbone. Thus, the ability to introduce heterologous reductive segments such as ketoreductase (KR), dehydratase (DH), and enoylreductase (ER) into modules that naturally lack these activities would increase the power of the combinatorial biosynthetic toolbox. The dehydratase domain of module 7 of the rifamycin PKS, which is predicted to be nonfunctional in view of the sequence of the apparent active site, was replaced with its functional homolog from module 7 of rapamycin-producing polyketide synthase. The resulting mutant strain behaved like a rifC disrupted mutant, i.e., it accumulated the heptaketide intermediate and its precursors. This result points out a major difficulty we have encountered with all the Amycolatopsis mediterranei strain containing hybrid polyketide synthases: all the engineered strains prepared so far accumulate a plethora of products derived from the polyketide chain assembly intermediates as major products instead of just analogs of rifamycin B or its ansamycin precursors.