Search Results (3)

We investigated the dynamic changes in volatile aroma compound profiles (types and concentrations) and associated gene expression patterns in both the peel and pulp tissues of apples during fruit maturation. This study aimed to elucidate the metabolic regulatory mechanisms underlying volatile aroma biosynthesis in Malus domestica “Ningqiu” apples, thereby providing theoretical support for the comprehensive utilization of aroma resources. Our methodological framework integrated headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS), ultra-high-performance liquid chromatography–orbitrap mass spectrometry (UHPLC-OE-MS), and Illumina high-throughput sequencing to generate comprehensive metabolomic and transcriptomic profiles of peel and pulp tissues. Critical differential aroma compound classes were identified, including esters, aldehydes, alcohols, terpenoids, and ketones, with their metabolic pathways systematically mapped through KEGG functional annotation. Our findings revealed substantial transcriptomic and metabolomic divergence across carotenoid, terpenoid, and fatty acid metabolic pathways. Integrative analysis of multi-omics data revealed 26 and 31 putative biologically significant hub genes in peel and pulp tissues, respectively, putatively associated with the observed metabolic signatures. Among these, five core genes—farnesyl diphosphate synthase (FDPS1.X1), alcohol acyltransferases (AAT1 and AAT3), alcohol dehydrogenase (ADH3), and carotenoid cleavage dioxygenase (CCD3)—were recognized as shared regulatory determinants between both tissue types. Furthermore, terpene synthase (TPS7) emerged as a peel-specific regulatory factor, while hydroperoxide lyase (HPL2), alcohol dehydrogenases (ADH2 and ADH4), and alcohol acyltransferase (AAT2) were identified as pulp-exclusive modulators of metabolic differentiation. The experimental findings provide foundational insights into the molecular basis of aroma profile variation in Malus domestica “Ningqiu” and establish a functional genomics framework for precision breeding initiatives targeting fruit quality optimization through transcriptional regulatory network manipulation. Full article

In order to reveal the fermentation microflora and fermentation metabolites of traditional mung bean sour liquid (MBSL) in Luoyang area, China, this experiment was sampled from four administrative districts of Luoyang, and volatile metabolites and non-targeted metabolites were detected and analyzed by HS-SPME-GC-MS and LC-MS, and bacterial and fungal sequencing were analyzed by Illumina MiSeq high-throughput sequencing technology. And the correlation between microorganisms and metabolites was conducted. The results showed that 42 volatiles were detected in four MBSL samples named Jianxi (JX), Liujia (Liu), LiJia (LJ), Majia (MJ), with 11 identical volatile flavor subtances, and the highest content of esters was found in JX, Liu, and LJ, and the highest content of acids was found in MJ. A total of 1703 non-targeted metabolites were identified, and there were more types of amino acids, carbohydrates, fatty acids and their complexes, flavonoids, carbonyl compounds, and organic acids, accounting for 40.93%. High-throughput sequencing results showed that there were nine bacterial and fungal genera with an average abundance of more than 1%, and the dominant genera mainly belonged to lactic acid bacteria and yeast. The composition of dominant genera was different in different workshop samples, and the abundance of fungal genera differed greatly. Among the volatile substances, Methyleugenol, a volatile component, was related to more bacteria, and ketones and hydrocarbons may be more closely associated with bacteria. Acetic acid and Oxalic acid may be more closely related to fungi, while some esters were more closely related to both fungal and bacterial genera. For non-target metabolites, amino acid and alcohol metabolites may be more influenced by bacteria, and organic acids and flavonoids may be more influenced by fungi. Full article

The effects of microwave (MW) pretreatment were investigated by six anaerobic digesters operated under thermophilic and mesophilic conditions at high organic loading rates (4.9–5.7 g volatile solids/L/d). The experiments and analyses were mainly designed to reveal the impact of MW pretreatment and digester temperatures on the process stability and microbial community structure by correlating the composition of microbial populations with volatile fatty acid (VFA) concentrations. A slight shift from biogas production (with a reasonable methane content) to VFA accumulation was observed in the thermophilic digesters, especially in the MW-irradiated reactors. Microbial population structure was assessed using a high-throughput sequencing of 16S rRNA gene on the MiSeq platform. Microbial community structure was slightly affected by different MW pretreatment conditions, while substantially affected by the digester temperature. The phylum Bacteroidetes proliferated in the MW-irradiated mesophilic digesters by resisting high-temperature MW (at 160 °C). Hydrogenotrophic methanogenesis (mostly the genus of Methanothermobacter) was found to be a key route of methane production in the thermophilic digesters, whereas aceticlastic methanogenesis (mostly the genus of Methanosaeta) was the main pathway in the mesophilic digesters. Full article