A High-Throughput Method Based on Microculture Technology for Screening of High-Yield Strains of Tylosin-Producing Streptomyces fradiae

Yao Zhiming,Fan Jingyan,Dai Jun,Yu Chen,Zeng Han,Li Qingzhi,Hu Wei,Yan Chaoyue,Hao Meilin,Li Haotian,Li Shuo,Liu Jie,Huang Qi,Li Lu,Zhou Rui 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.6

Tylosin is a potent veterinary macrolide antibiotic produced by the fermentation of Streptomyces fradiae; however, it is necessary to modify S. fradiae strains to improve tylosin production. In this study, we established a high-throughput, 24-well plate screening method for identifying S. fradiae strains that produce increased yields of tylosin. Additionally, we constructed mutant libraries of S. fradiae via ultraviolet (UV) irradiation and/or sodium nitrite mutagenesis. A primary screening of the libraries in 24-well plates and UV spectrophotometry identified S. fradiae mutants producing increased yields of tylosin. Mutants with tylosin yield 10% higher than the wild-type strain were inoculated into shake flasks, and the tylosin concentrations produced were determined by highperformance liquid chromatography (HPLC). Joint (UV irradiation and sodium nitrite) mutagenesis resulted in higher yields of mutants with enhanced tylosin production. Finally, 10 mutants showing higher tylosin yield were re-screened in shake flasks. The yield of tylosin A by strains UN-C183 (6767.64 ± 82.43 μg/ml) and UN-C137 (6889.72 ± 70.25 μg/ml) was significantly higher than that of the wild-type strain (6617.99 ± 22.67 μg/ml). These mutant strains will form the basis for further strain breeding in tylosin production.

Bioactive Compounds / Food Microbiology : Improvement of FK506 Production in the High-Yielding Strain Streptomyces sp. RM7011 by Engineering the Supply of Allylmalonyl-CoA Through a Combination of Genetic and Chemical Approach

( Sang Joon Mo ),( Sung Kwon Lee ),( Ying Yu Jin ),( Joo Won Suh ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.2

FK506, a widely used immunosuppressant, is a 23-membered polyketide macrolide that is produced by several Streptomyces species. FK506 high-yielding strain Streptomyces sp. RM7011 was developed from the discovered Streptomyces sp. KCCM 11116P by random mutagenesis in our previous study. The results of transcript expression analysis showed that the transcription levels of tcsA, B, C, and D were increased in Streptomyces sp. RM7011 by 2.1-, 3.1-, 3.3-, and 4.1- fold, respectively, compared with Streptomyces sp. KCCM 11116P. The overexpression of tcsABCD g enes in Streptomyces sp. RM7011 gave rise to approximately 2.5-fold (238.1 μg/ml) increase in the level of FK506 production compared with that of Streptomyces sp. RM7011. When vinyl pentanoate was added into the culture broth of Streptomyces sp. RM7011, the level of FK506 production was approximately 2.2-fold (207.7 μg/ml) higher than that of the unsupplemented fermentation. Furthermore, supplementing the culture broth of Streptomyces sp. RM7011 expressing tcsABCD genes with vinyl pentanoate resulted in an additional 1.7-fold improvement in the FK506 titer (498.1 μg/ml) compared with that observed under nonsupplemented condition. Overall, the level of FK506 production was increased approximately 5.2-fold by engineering the supply of allylmalonyl-CoA in the high-yielding strain Streptomyces sp. RM7011, using a combination of overexpressing tcs ABCD genes and adding vinyl pentanoate, as compared with Streptomyces sp. RM7011 (95.3 μg/ml). Moreover, among the three precursors analyzed, pentanoate was the most effective precursor, supporting the highest titer of FK506 in the FK506 high-yielding strain Streptomyces sp. RM7011.

Taylor Impact Test시 고속 카메라 영상을 사용한 폴리머 재료의 동적 거동 해석

박성택(Sung-Taek Park),박정수(Jung-Soo Park),신형섭(Hyung-Seop Shin),최준홍(Joon-Hong Choi),김정태(Jeong-Tae Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

To evaluate dynamic material properties of metallic materials at high-strain-rate. several one-dimensional models using recovered projectiles by Taylor Impact tests have been developed. However, for polymeric materials, the models can not be used as developed because polymers show significant elastic and anelastic deformation. This limitation could be released by incorporating the high-speed photography technique with Taylor impact tests in the range of impact velocity from 150 to 350 m/s. A series of photographs made it possible to depict the deformation pattern and to measure instantaneous diameter along the projectile length. In addition, it gave a relationship between the deformation length and the elapsed time which make possible to calculate a strain rate at an instant of deformation. The strain rate dependance of the dynamic yield stress in thermoplastic materials of PE, PC and PEEK can be determined by rod impact test in the strain-rate range of 10³~10⁴ sec?¹.

Enhancement of strain-rate sensitivity and shear yield strength of a magnesium alloy processed by high-pressure torsion

Choi, In-Chul,Lee, Dong-Hyun,Ahn, Byungmin,Durst, Karsten,Kawasaki, Megumi,Langdon, Terence G.,Jang, Jae-il Elsevier 2015 Scripta materialia Vol.94 No.-

<P>A Mg–Zn–Zr alloy was processed by high-pressure torsion for up to 2 turns at room temperature to produce significant grain refinement together with enhanced plasticity and strength. Measurements were performed to determine the strain-rate sensitivity, shear yield strength and activation volume as a function of the processing conditions. The results suggest there is a significant contribution from grain boundary sliding to the flow process and the onset of plasticity is associated with heterogeneous dislocation nucleation.</P>

Taylor 봉 충격시험을 통한 고 변형률속도하 금속재료의 동적변형거동 평가

배경오(Kyung Oh Bae),신형섭(Hyung Seop Shin) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.9

최근 기계 시스템의 고속화가 진행됨에 따라 구조물 및 기계부품의 신뢰성 및 안전성 확보 측면에서, 충격하중하에서 구조용 재료의 동적변형거동에 대한 평가가 필요하다. 그러나 10<SUP>4</SUP> s<SUP>-1</SUP>를 넘는 고 변형률속도에서 실험적 기법을 사용한 구조용 재료의 변형거동의 파악은 용이하지 않은 실정이다. 본 연구에서는, 고 변형률속도역에서 금속재료의 동적변형거동을 조사하기 위해 Taylor 봉 충격시험을 실시하였다. 또한 고속영상촬영 시스템을 사용하여 Taylor 봉 충격시험 동안 변형거동을 관찰하였다. Taylor 봉 충격시, 경과시간에 따른 변형과정을 AUTODYN 상용 S/W를 사용한 수치해석을 수행하여 실험결과와 비교하여 고 변형률속도역에서 거동을 평가하였다. To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10<SUP>4</SUP> s<SUP>-1</SUP>. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

Effect of Strain Aging on Tensile Behavior and Properties of API X60, X70, and X80 Pipeline Steels

Sang‑In Lee,Seung‑Yong Lee,Seok Gyu Lee,Hwan Gyo Jung,Byoungchul Hwang 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6

The effect of strain aging on tensile behavior and properties of API X60, X70, and X80 pipeline steels was investigated inthis study. The API X60, X70, and X80 pipeline steels were fabricated by varying alloying elements and thermomechanicalprocessing conditions. Although all the steels exhibited complex microstructure consisting of polygonal ferrite (PF), acicularferrite, granular bainite (GB), bainitic ferrite (BF), and secondary phases, they had different fractions of microstructuresdepending on the alloying elements and thermomechanical processing conditions. The tensile test results revealed that yieldingbehavior steadily changed from continuous-type to discontinuous-type as aging temperature increases after 1% pre-strain. After pre-strain and thermal aging treatment in all the steels, the yield and tensile strengths, and yield ratio were increased,while the uniform elongation and work hardening exponent were decreased. In the case of the X80 steel, particularly, thedecrease in uniform elongation was relatively small due to many mobile dislocations in PF, and the increase in yield ratiowas the lowest because a large amount of harder microstructures such as GB, BF, and coarse secondary phases effectivelyenhanced work hardening.