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Phosphatidylcholine (PC), phosphatidyl ethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositol (PI) are the four major phospholipids in Antarctic krill. In this study, the composition of these phospholipids was analyzed by hydrophilic interaction ultra-high performance liquid chromatography-tandem mass spectrometry (HILIC-UPLC-MS/MS) after purification by solid-phase extraction (SPE) using titania-coated fibrous silica (TiO2/KCC-1) nanoparticles, which had been prepared in our laboratory. The results showed that under the optimal conditions, 291 phospholipids including 75 PCs, 120 PEs, 54 PIs and 42 PSs were detected, which were nearly twice as many as those detected by a previously reported method. Phospholipids containing monounsaturated and polyunsaturated fatty acid chains accounted for 54.73% and 26.17% of the total phospholipids, respectively. PC (40:6) (41.63%), PE (36:0) (39.77%), PI (38:3) (80.05%), and PS (36:1) (81.62%) were found to be the most abundant in the four phospholipids. Multivariate statistical analysis showed significant differences in the types of phospholipids before and after SPE treatment. TiO2/KCC-1 nanoparticles exhibited a significant enrichment capacity for phospholipids, especially PC (18:0/18:0), PE (16:0/18:1), and PI (16:0/18:2). The detection limit was 0.05 μg/g for PC, PE and PS, and 0.01 μg/g for PI. The relative standard deviations (RSDs) for the four major phospholipids were in the range of 0.89% to 5.05%, and the recoveries were 87%–112%. This method demonstrated high specificity, extraction efficiency, sensitivity, precision and accuracy. Therefore, it has broad application prospects for the extraction, purification, and analysis of phospholipids in biological samples.

Ophiocordyceps sinensis is a widely known medicinal entomogenous fungus, which parasitizes the soil-borne larva of Thitarodes (Hepialidae, Lepidoptera) distributed in the Qinghai–Tibetan Plateau and its adjacent areas. Previous research has involved artificial cultivation of Chinese cordyceps (the fungus-caterpillar complex), but it is difficult to achieve large-scale cultivation because the coupling relation between the crucial microbes and their hosts is not quite clear. To clarify the influence of the internal microbial community on the occurrence of Chinese cordyceps, in this study, the unfertilized eggs of Thitarodes of different sampling sites were chosen to analyze the bacterial and fungal communities via 16S rRNA and ITS sequencing for the first time. The results showed that for bacteria, 348 genera (dominant genera include Wolbachia, Spiroplasma, Carnobacterium, Sphingobium, and Acinetobacter) belonging to 26 phyla (dominant phyla include Proteobacteria, Firmicutes, Tenericutes, Actinobacteria, Acidobacteria, and Bacteroidetes), 58 classes, 84 orders, and 120 families were identified from 1294 operational taxonomic units (OTUs). The dominant bacterial genus (Spiroplasma) may be an important bacterial factor promoting the occurrence of Chinese cordyceps. For fungi, 289 genera, mainly including Aureobasidium, Candida, and Cryptococcus, were identified, and they belonged to 5 phyla (Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota, and Zygomycota), 26 classes, 82 orders, and 165 families. Eight bacterial OTUs and 12 fungal OTUs were shared among all of the detected samples and were considered as core species. Among them, Wolbachia, Spiroplasma, Carnobacterium, Aureobasidium, and Phoma may play important roles in helping the host larva to digest foods, adapt to extreme environments, or resist pathogens. On the other hand, the external (soil) microbial community was synchronously and comparatively analyzed. Comparative analysis revealed that external microbial factors might play a more significant role in the occurrence of Chinese cordyceps, owing to the significant differences revealed by α-diversity and β-diversity analyses among different groups. In summary, the results of this study may contribute to the large-scale cultivation of Chinese cordyceps. [ABSTRACT FROM AUTHOR]