The Monascus azaphilone (MAz) pigment is a wellknown food colorant that has yellow, orange and red components. The structures of the yellow and orange MAz differ by two hydride reductions, with yellow MAz being the reduced form. Orange MAz can be non-enzymatically converted to red MAz in the presence of amine derivatives. It was previously demonstrated that mppE and mppG are involved in the biosynthesis of yellow and orange MAz, respectively. However, ΔmppE and ΔmppG knockout mutants maintained residual production of yellow and orange MAz, respectively. In this study, we deleted the region encompassing mppD, mppE and mppG in M. purpureus and compared the phenotype of the resulting mutant (ΔmppDEG) with that of an mppD knockout mutant (ΔmppD). It was previously reported that the ΔmppD strain retained the ability to produce MAz but at approximately 10% of the level observed in the wildtype strain. A chemical analysis demonstrated that the ΔmppDEG strain was still capable of producing both yellow and orange MAz, suggesting the presence of minor MAz route(s) not involving mppE or mppG. Unexpectedly, the ΔmppDEG strain was observed to accumulate fast-eluting pigments in a reverse phase high-performance liquid chromatography analysis. A LC-MS analysis identified these pigments as ethanolamine derivatives of red MAz, which had been previously identified in an mppE knockout mutant that produces high amounts of orange MAz.Although the underlying mechanism is largely unknown, this study has yielded an M. purpureus strain that selectively accumulates red MAz.

In this paper, we report numerically calculated results of testing a temperature‐insensitive refractive sensor based on a planar‐type long‐period waveguide grating (LPWG). The LPWG consists of properly chosen polymer materials with an optimized thermo‐optic coefficient for the core layer in a four‐layer waveguide structure. The resonant wavelength shift below the spectral resolution of the conventional optical spectrum analyzer is obtained accurately over a temperature change of ±7.5°C even without any temperature control. The refractive index sensitivity of the proposed grating scheme is about 0.004 per resonant wavelength shift of 0.1 nm for an optimized thermo‐optic coefficient.

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서 론초내열 상용화된 초내열 합금현재까지 상용화된 초내열 합금은 기지 금속의 종류에 따라 Fe기, Ni기, Co기 초내열 합금으로 구분할 수 있다.

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