Search

Abstract [Objective] The aim is to provide micromorphological data for their identification by studying the leaves of Artemisia stolonifera and Artemisia argyi. [Methods] Digital camera, optical microscope, and scanning electron microscope were used to study the characteristics of leaf veins, leaf surfaces, and powder. [Results] (1) Under strong light background, only the veins at all levels of A . stolonifera leaves could be clearly observed. (2) Glandular trichomes were only distributed on the lower surface of the leaves of A . argyi, and there were a large number of glandular trichomes on both the upper and lower surfaces of A . argyi leaves. (3) Similar to A . argyi leaves, the lower surface of A . stolonifera leaves was also densely covered with T-shaped non-glandular trichomes. There were two types of apical cells: One was a long spindle-shaped and curved apical cell, with an average length about 1 450 μm (Type-Ⅰ); the other type of apical cell was long and thin, and flat and twisted, with an average length of approximately 2 800 μm (Type-Ⅱ). (4) There were fewer calcium oxalate cluster crystals in the mesophyll tissue of A . stolonifera leaves, with a maximum of only 10 μm. [Conclusion] Results show that the micromorphological characteristics of the leaf veins and the presence or absence of glandular trichomes on the upper surface of the leaves of A . stolonifera and A . argyi can be used for rapid identification of the two leaves.

Chitosan can be used as an active antibacterial agent or film-forming substrate in foods, and has become a powerful substitute for synthetic plastic polymers because of its good biodegradability, film-forming capacity and antibacterial activity. However, chitosan films have several limitations such as poor water solubility and weak mechanical properties, which limit its application in antibacterial food packaging materials to a certain degree. The safety of applying the antibacterial activity of chitosan in foods has attracted much attention in recent years. In order to provide new ideas for further development and utilization of chitosan-based antibacterial composite materials, this paper expounds the antibacterial mechanism of chitosan and the methods to improve its antibacterial performance, and summarizes the current status of the application of chitosan-polysaccharide, protein or lipid composite films in food preservation.

Complete synthetic minimal media for Zygosaccharomyces rouxii growth were designed for high temperature (40 ℃, HTS) and high salt stress (18% NaCl, HSS) in this study, and the difference in the nutritional requirements of Z. rouxii cells under long-term adverse environmental conditions was analyzed. The differences in the metabolism and gene expression of organic acids, amino acids and sugars during the period from the growth adaptation stage to the early logarithmic stage were highlighted between HSS and HTS conditions. The results showed that Z. rouxii cells exposed to HSS needed more exogenous amino acids, vitamin and amino acid supplementation alleviated HTS-induced damage in yeast cells. The adversity transcription gene MSN4 and the hypertonic regulatory protein gene HOG1 responded to high salt, while the heat shock regulatory protein gene HSF1 and the superoxide dismutase gene SOD1 responded to high temperature. In summary, different strategies for organic acid, amino acid and sugar metabolism were adopted by Z. rouxii in response to HSS and HTS. This study deepens the understanding of the mechanism of temperature tolerance in salt-tolerant Z. rouxii, which will contribute to the development of new brewing yeast cells with tolerance to both high salt and temperature.

Bioactive peptides are small protein molecules with specific physiological activity. The efficient separation and purification of bioactive peptides contributes to the full exertion of bioactive peptides and research on their structure-activity relationship. However, the separation process is difficult and tedious. In view of this, researchers have developed mixed-mode chromatography (MMC) to separate and purify bioactive peptides by virtue of the differences in their properties such as hydrophilic, hydrophobic and charge characteristics, which exerts multiple retention mechanisms through the multifunctional stationary phases and the adjustable mobile phases. MMC has the advantages of controllable stationary phase, specific recognition and high efficiency. The development of MMC stationary phases and their application in the separation of bioactive peptides are summarized in this paper in order to provide a reference for the efficient utilization of bioactive peptides.