Enhancement of yellow pigments production via high CaCl2 stress fermentation of Monascus purpureus.

Monascus pigments (MPs) are a kind of natural ingredient fermented by Monascus spp., which contains three types of pigments: red, orange, and yellow ones. Monascus yellow pigments have a restricted yield and cannot meet industrial application. The method and mechanism of CaCl2 improving yellow pigments production by liquid fermentation of Monascus purpureus M8 were studied in order to overcome the low yield of yellow pigments produced by liquid fermentation. Changes in physiological and biochemical indicators explained the effects of CaCl2 on the production of Monascus yellow pigments from solid fermentation. The intracellular yellow pigments, orange pigments, and red pigments increased by 156.08%, 43.76%, and 42.73%, respectively, with 60 g/l CaCl2 addition to culture medium. The amount of red and orange pigments reduced, while the proportion of yellow pigments increased and the relative peak area of intracellular yellow pigments accounted for a dominant 98.2%, according to thin layer chromatography and high performance liquid chromatography analyses. Furthermore, the influence of CaCl2 extended to the modulation of pigments synthesis-related gene expression in M8 strain. This modulation led to a pronounced upregulation in the expression of the yellow pigments synthesis-related gene, mppE, signifying a pivotal role played by CaCl2 in orchestrating the intricate machinery behind yellow pigments biosynthesis.

A facile and scalable patterning approach for ultrastretchable liquid metal features.

Liquid metals represent an attractive class of compliant conductors featuring metallic conductivity and inherent deformability. The widespread implementation of liquid metal conductors in stretchable electronics is currently hindered by the lack of a facile patterning approach. In this study, we introduce a facile and scalable patterning approach to create liquid metal features on an elastomer substrate. A screen-printed Ag nanoflake pattern is employed as a template for the subsequent selective coating of a liquid metal layer. The as-prepared liquid metal conductors show a bulk-level conductivity of ∼2.7 × 104 S cm-1, an ultrahigh stretchability of up to 700% tensile strain, and excellent electromechanical durability. The practical suitability is demonstrated by the successful fabrication of an ultradeformable ribbon cable and a smart sensing glove. The efficient and economical access to ultrastretchable liquid metal features may open up a broad range of emerging applications in soft electronic devices and systems.

Transcriptional regulation contributes more to Monascus pigments diversity in different strains than to DNA sequence variation.

Monascus azaphilone pigments, including red, orange, and yellow, are world-famous food colorants. However, the pigments produced by different Monascus species vary in yields and compositions. The underlying mechanism is unclear. In this study, four wild-type Monascus strains, namely M. anka M7, M. purpureus M9, M. ruber C100, and M. aurantiacus M15, were selected as research objects according to the diversification of their pigments fermented in the same mediums and conditions. Twenty-three 3 kbp segments (300 bp overlap with adjacent segments) of the pigment gene cluster were amplified, sequenced, and assembled into the DNA sequences of the clusters. The DNA sequences of pigment biosynthetic gene clusters of the four strains showed 99.94% similarity according to the results of multiple alignment. The expression levels of 17 pigment biosynthetic genes of four strains were determined by using real-time quantitative PCR. The transcriptional regulation contributed more than the DNA sequence variation in Monascus pigments metabolism. Our result gives insight into the study of Monascus pigment biosynthesis.