Eurotium cristatum as the dominant fungi species of Fuzhuan brick tea in China, can produce multitudinous secondary metabolites (SMs) with various bioactivities. Polyketides are a very important class of SMs found in E. cristatum and have gained extensive attention in recent years due to their remarkable diversity of structures and multiple functions. Therefore, it is necessary to explore the polyketides produced by E. cristatum at the genomic level to enhance its application value. In this paper, 12 polyketide synthase (PKS) genes were found in the whole genome of E. cristatum E1 isolated from Fuzhuan brick tea. In addition, the qRT-PCR results further demonstrated that these genes were expressed. Moreover, metabolic analysis demonstrated E. cristatum E1 can produce a variety of polyketides, including citreorosein, emodin, physcion, isoaspergin, dihydroauroglaucin, iso-dihydroauroglaucin, aspergin, flavoglaucin and auroglaucin. Furthermore, based on genomic analysis, the putative secondary metabolites clusters for emodin and flavoglaucin were proposed. The results reported here will lay a good basis for systematically mining SMs resources of E. cristatum and broadening its application fields.

Lotus roots are widely consumed vegetables because of their great taste and abundant nutrients, but their quality varies with the environments and cultivar. This study systematically compared farinose (Elian No. 5) and crisp (Elian No. 6) lotus root cultivars from three geographical origins. Pasting and texture characteristics verified that Elian No. 5 possessed lower hardness and lower ability to withstand shear stress and heating during cooking compared with Elian No. 6. Untargeted metabolite profiling was first performed using ultrahigh-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) combined with a Zeno trap. In total, 188 metabolites were identified based on the matching chemistry database. Multivariate analysis demonstrated that lotus roots from different cultivars and origins could be adequately distinguished. Sixty-one differential metabolites were identified among three Elian No. 5 samples, and 28 were identified among three Elian No. 6 samples. Isoscopoletin, scopoletin, and paprazine were the most differential metabolites between Elian No. 5 and Elian No. 6. These results can inform future research on the discrimination and utilization of lotus roots.

Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are the core components that mediate vesicle fusion, and they play an important role in secondary metabolism of filamentous fungi. However, in Monascus spp., one of the traditional medicinal and edible filamentous fungi, the members and function of SNAREs remain unknown. Here, twenty SNAREs in M. ruber M7 were systematically identified based on the gene structure, amino acid structure and phylogenetic analysis and were classified into four subfamilies. We also compared the expression profiles of twenty MrSNAREs in M. ruber M7 and its deletion mutants, ΔmrpigA and ΔpksCT, which could not produce Monascus pigment and citrinin, respectively. The results indicated that these MrSNAREs showed distinct expression patterns in the three strains. Compared to M. ruber M7, the expression levels of Mrtlg2, Mrbet1, Mrgos1 and Mrsec22 remained higher in ΔmrpigA but lower in ΔpksCT, which could be reason to consider them as potential candidate genes involved in secondary metabolism for further functional characterization. Further, the significant upregulation of Mrpep12 and Mrvtil in ΔpksCT is worthy of attention for further research. Our results provide systematic identification and expression profiling of the SNARE family in Monascus and imply that the functions of MrSNAREs are specific to different secondary metabolic processes.

Lotus sprouts are a widely consumed aquatic vegetable, yet their quality remains poorly characterized. This study integrated physicochemical analysis, volatile flavor profiling, and metabolomics to evaluate quality differences among three lotus sprout cultivars, as well as different parts and grades. The apical portions had significantly higher contents of protein, total phenolics, and γ-aminobutyric acid than the stem portions. A total of 46 volatile compounds were identified by headspace solid-phase micro-extraction combined with gas chromatography–mass spectrophotometry (HS-SPME-GC-MS), and the abundance of 2,4-di-tert-butylphenol and 1-octen-3-ol was further confirmed using standards. Untargeted metabolomics identified 335 compounds, with sugars, polyphenols, and amino acids being the most abundant categories. Differentially accumulated metabolites between parts and cultivars were significantly enriched in glutathione metabolism, flavonoid biosynthesis, and amino acid metabolism. Notably, the two Baiyuzan cultivars generally accumulated higher levels of beneficial metabolites than Wuzhi No. 2, whereas the stem portion of the higher-grade Wuzhi No. 2 showed lower accumulation of sucrose and paprazine. Quantitative analysis of eight alkaloids using external standard calibration curves indicated that nuciferine was the most abundant alkaloid (13.3 to 31.1 μg/g). Collectively, this study provides a foundational framework for evaluating the metabolite profiles and application potential of lotus sprouts.