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Introduction: Fengxiangxing Huairang Daqu (FHD) is one of the major types of Daqu in China. However, the relationship between the microbial community structure at different stages, the changes in the sensory characteristics, fermentation characteristics, volatiles, the most critical process point, and the quality formation of FHD is not clear. Methods: Based on microscopic characterization, PacBio SMRT sequencing, and HS-SPME-GC-MS volatile metabolite analysis revealed the relationship between FHD quality formation and the dynamics of Qupi. Results: The results showed that the 12th day of the culture was the most critical process point, highlighting the most significant differences in microbial community structure, sensory characteristics, fermentation characteristics, and flavor substances. Bacillus licheniformis (43.25%), Saccharopolyspora rectivirgula (35.05%), Thermoascus aurantiacus (76.51%), Aspergillus amstelodami (10.81%), and Saccharomycopsis fibuligera (8.88%) were the dominant species in FHD. S. fibuligera, A. amstelodami, and T. aurantiacus were associated with the snow-white color of the FHD epidermis, the yellow color of the interior, and the gray-white color, respectively. The abundance of T. aurantiacus, A. amstelodami, B. licheniformis, and S. rectivirgula was positively associated with the esterifying power and liquefying power of FHD. The abundance of T. aurantiacus and A. amstelodami was positively correlated with the saccharifying power of FHD. The abundance of S. fibuligera was positively related to the fermenting power of FHD. A total of 248 volatiles were detected in Qupi, mainly including alcohols, esters, aldehydes, and ketones. Of them, eleven volatiles had a significant effect on the flavor of Qupi, such as 1-butanol-3-methyl-, hydrazinecarboxamide, ethanol, phenylethyl alcohol, ethyl acetate, 2-octanone, 1-octen-3-ol, formic acid-hexyl ester, (E)-2-octen-1-ol, ethyl hexanoate, and 2(3H)-furanone-dihydro-5-pentyl-. The abundance of B. licheniformis, S. rectivirgula, T. aurantiacus, and S. fibuligera was positively correlated with the alcohols, aromatic compounds, and phenols in FHD. The abundance of S. fibuligera was positively correlated with the acids, esters, and hydrocarbons in FHD. Discussion: These results indicate important theoretical basis and technical support for controllable adjustment of FHD microbial community structure, stable control of FHD quality, and precise, effective, and large-scale guidance of FHD production. [ABSTRACT FROM AUTHOR]

Background: Jinmudan (JMD) is a high-aroma variety widely cultivated in China. The current study primarily focuses on the key volatile metabolites in JMD black and oolong teas, and investigates the impact of processing technologies on the aroma quality of JMD tea. However, few studies have explored the suitability of JMD for producing a certain type of tea or the characteristic quality differences among various JMD teas using multivariate statistical analysis methods., Results: The principal volatile metabolites contributing to the floral quality of JMD tea are linalool, geraniol, indole and phenethyl alcohol. In JMD black tea (BT), the key volatile metabolites include methyl salicylate, geraniol, (E)-β-ocimene and phenethyl alcohol. In JMD oolong tea (OT), the key volatile metabolites include indole, linalyl valerate and phenethyl alcohol. In JMD yellow tea (YT), the key volatile metabolites include methyl salicylate, geraniol and terpinolene. In JMD white tea (WT), the key volatile metabolites include methyl salicylate, geraniol and terpinolene. In JMD green tea (GT), the key volatile metabolites include (E)-β-ocimene, indole and geraniol. Comparative analysis and KEGG pathway enrichment analysis revealed that flavonoid biosynthesis is the primary metabolic pathway responsible for the taste differences among various tea types. GT exhibited higher levels of phloretin, dihydromyricetin and galangin. The contents of vitexin, tricetin in YT were relatively higher. The contents of aromadendrin and naringenin in BT were higher, while OT contained higher levels of kaempferol. Additionally, WT showed higher contents of 3-O-acetylpinobanksin and 3,5,7-pinobanksin., Conclusion: This study explained the reasons for the quality differences of different JMD tea and provided a reliable theoretical basis for the adaptability of JMD tea. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

Chrysanthemum indicum var. aromaticum (CIA) is an endemic plant that occurs only in the high mountain areas of the Shennongjia Forest District in China. The whole plant, in particular the flowers of CIA, have intense fragrance, making it a novel resource plant for agricultural, medicinal, and industrial applications. However, the volatile metabolite emissions in relation to CIA flower development and the molecular mechanisms underlying the generation of floral scent remain poorly understood. Here, integrative metabolome and transcriptome analyses were performed to investigate floral scent-related volatile compounds and genes in CIA flowers at three different developmental stages. A total of 370 volatile metabolites, mainly terpenoids and esters, were identified, of which 89 key differential metabolites exhibited variable emitting profiles during flower development. Transcriptome analysis further identified 8,945 differentially expressed genes (DEGs) between these samples derived from different flower developmental stages and KEGG enrichment analyses showed that 45, 93, and 101 candidate DEGs associated with the biosynthesis of phenylpropanoids, esters, and terpenes, respectively. Interestingly, significant DEGs involved into the volatile terpenes are only present in the MEP and its downstream pathways, including those genes encoding ISPE, ISPG, FPPS, GPPS, GERD, ND and TPS14 enzymes. Further analysis showed that 20 transcription factors from MYB, bHLH, AP2/EFR, and WRKY families were potentially key regulators affecting the expressions of floral scent-related genes during the CIA flower development. These findings provide insights into the molecular basis of plant floral scent metabolite biosynthesis and serve as an important data resources for molecular breeding and utilization of CIA plants in the future. [ABSTRACT FROM AUTHOR]

Salted fermented chili pepper (SFCP) is a fermented vegetable with unique flavors, and its flavors vary in different regions of China. However, in-depth investigations of its microbial community and their relationship to the volatile metabolites are scarce. Our work investigated the microbial community and volatile metabolites in 14 SFCP samples from nine regions around China by both culture-dependent and high-throughput sequencing methods. Five samples were dominated by Lactobacillus , Weissella , and Pediococcus, whereas nine of the samples were dominated by Pseudomonas and Enterobacter microbes. Two types of sufficient-fermentation and slight-fermentation were suggested based on the microbial community and water activity (a w). Three samples from Guizhou province were included in the sufficient-fermentation type with a w > 0.75 and culturable lactic acid bacteria, whereas the other 11 samples were intergrated into the slight-fermentation type with a w ≤ 0.75 and unculturable lactic acid bacteria. The Lactobacillaceae , comprised of unclassified Lactobacillaceae , Lactobacillus , and Pediococcus , positively correlated with the characteristic flavor formation. The sufficient-fermentation type showed enriched in valencene, 2-methyl-naphthalene, pentadecanoic acid 3-methylbutyl ester, and acetic acid hexyl ester, generating wood, floral and fruit flavors. These findings help us to select the appropriate functional bacteria for high-quality SFCP. • Analyzed microbial community's diversity of salted fermented chili pepper in China. • Sufficient-fermentation and slight-fermentation associated with the a w. • Two types of samples based on fermentation degree in salted fermented chili peppers. • Lactic acid bacteria positively correlated with the flavor formation. [ABSTRACT FROM AUTHOR]

Nongxiangxing Baijiu is a liquor widely consumed in China and whose flavor vary considerably depending on the production area. Daqu is a common fermentation starter for Baijiu production and significantly affects the flavor of Nongxiangxing Baijiu. The present study aimed to evaluate differences in the structure and potential functions of the microbial communities, as well as in volatile metabolites of Nongxiangxing daqu samples obtained from different production areas. A total of 36 different microorganisms were found in daqu from five production areas in China. Saccharopolyspora , Pantoea , Pediococcuss , Thermomyces , Issatchenkia , and Saccharomycopsis could be considered as biomarkers to discriminate daqu origin based on production area. Moreover, 41 differential metabolites were found based on PLS-DA analysis. Co-occurrence network analysis indicated that the abundance of most differential microorganisms was significantly correlated with changes in differential volatile metabolites in daqu. Function prediction of microbial communities and pathway enrichment analysis of differential metabolites further revealed differences in the functions of daqu samples from different production areas, especially related to amino acid metabolism, fatty acid metabolism, and carbon metabolism. Collectively, the results described herein provide a theoretical basis for the understanding of differences in the flavor of Nongxiangxing Baijiu from distinct production areas. • The differences in production areas lead to six biomarkers among d aqu. • Saccharomyces and Mucorales caused the difference in volatile flavors in daqu. • Lactococcus inhibit the production of alcohols and esters during daqu fermentation. [ABSTRACT FROM AUTHOR]

Abstract: The fungal genus Muscodor was erected on the basis of Muscodor albus, an endophytic fungus originally isolated from Cinnamomum zeylanicum. It produces a mixture of volatile organic compounds (VOCs) with antimicrobial activity that can be used as mycofumigants. The genus currently comprises five species. Here we describe the isolation and characterization of a new species of Muscodor on the basis of five endophytic fungal strains from leaves of Actinidia chinensis, Pseudotaxus chienii and an unidentified broad leaf tree in the Fengyangshan Nature Reserve, Zhejiang Province, Southeast of China. They exhibit white colonies on potato dextrose agar (PDA) media, rope-like mycelial strands, but did not sporulate. The optimum growth temperature is 25°C. The results of a phylogenetic analysis based on four loci (ITS1–5.8S–ITS2, 28S rRNA, rpb2 and tub1) are consistent with the hypothesis that these five strains belong to a single taxon. All five strains also produce volatile chemical components with antimicrobial activity in vitro, which were different from those previously described for other Muscodor species. [ABSTRACT FROM AUTHOR]

Differences between the old and young pit mud in a pit cellar enlarged differences in Zaopei (ZP) fermentation to varying degrees, ultimately affecting the aromatic quality of the Baijiu that is produced. The whole fermentation process could be divided into two phases, namely phase I (0_15 days) and phase II (25_40 days) based on the dynamics of the diversity of microbial communities. Starch and reducing sugar in phase I were used more rapidly by microflora, leading to a higher ethanol production in ZP within an old pit mud (OZP) and a higher acidity in ZP within a new pit mud (NZP), and resulting in different microbial succession patterns therein. Lactobacillus became the dominant bacteria more rapidly in OZP but maintained its abundance in NZP. Monascus and Trichosporon were the unique dominant functional fungi observed in the phase II of OZP. Two bacterial and six fungal genera were identified as core functional microorganisms linked to the variations in volatile metabolites during the fermentation process, ultimately resulting in a higher ester content in OZP and improved liquor quality. This study demonstrated the effect of new and old pit muds on ZP fermentation, and its findings can guide the future artificial regulation of NZP., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The mud cellar creates a unique microenvironment for the fermentation of strong-flavor baijiu (SFB). Recent research and long-term practice have highlighted the key roles of microbes inhabiting pit mud in the formation of SFB's characteristic flavor. A positive correlation between the quality of SFB and cellar age was extracted from practice; however, the evolutionary patterns of pit mud microbiome and driving factors remain unclear. Here, based on the variation regularity analysis of microbial community structure and metabolites of samples from cellars of different ages (∼30/100/300 years), we further investigated the effects of lactate and acetate (main microbial metabolites in fermented grains) on modulating the pit mud microbiome. Esters (50.3% to 64.5%) dominated the volatile compounds identified in pit mud, and contents of the four typical acids (lactate, hexanoate, acetate, and butyrate) increased with cellar age. Bacteria (9.5 to 10.4 log 10 [lg] copies/g) and archaea (8.3 to 9.1 lg copies/g) mainly constituted pit mud microbiota, respectively dominated by Clostridia (39.7% to 81.2%) and Methanomicrobia (32.8% to 92.9%). An upward trend with cellar age characterized the relative and absolute abundance of the most predominant bacterial and archaeal genera, Caproiciproducens and Methanosarcina . Correlation analysis revealed significantly ( P  < 0.05) positive relationships between the two genera and major metabolites. Anaerobic fermentation with acetate and lactate as carbon sources enhanced the enrichment of Clostridia , and furthermore, the relative abundance of Caproiciproducens (40.9%) significantly increased after 15-day fed-batch fermentation with lactate compared with the initial pit mud (0.22%). This work presents a directional evolutionary pattern of pit mud microbial consortia and provides an alternative way to accelerate the enrichment of functional microbes. IMPORTANCE The solid-state anaerobic fermentation in a mud cellar is the most typical feature of strong-flavor baijiu (SFB). Metabolites produced by microbes inhabiting pit mud are crucial to create the unique flavor of SFB. Accordingly, craftspeople have always highlighted the importance of the pit mud microbiome and concluded by centuries of practice that the production rate of high-quality baijiu increases with cellar age. To deepen the understanding of the pit mud microbiome, we determined the microbial community and metabolites of different-aged pit mud, inferred the main functional groups, and explored the forces driving the microbial community evolution through metagenomic, metabolomic, and multivariate statistical analyses. The results showed that the microbial consortia of pit mud presented a regular and directional evolutionary pattern under the impact of continuous batch-to-batch brewing activities. This work provides insight into the key roles of the pit mud microbiome in SFB production and supports the production optimization of high-quality pit mud.

Dajiang, or naturally fermented soybean paste, has a unique flavor that is influenced by the resident microflora. However, the association between flavor and the core microbiota is unclear. Recent advances in RNA sequencing have identified genes that are actively expressed in complex microbial communities. To this end, we analyzed the time-dependent changes in the microbiota and the metabolite profiles of Dajiang using metatranscriptome sequencing, HS-SPME-GC-MS and amino acid analysis identified 10 volatile compounds that contribute to the development of soybean paste flavor. Further analysis of the correlation between the active microorganisms and the physicochemical characteristics and flavor substances in soybean paste indicated that Lactobacillus and Tetragenococcus were the core genera affecting chromaticity and flavor. These microorganisms produce enzymes that catalyze a series of metabolic pathways that generate flavor substances. Our findings provide new insights into the role of the microbiota in the development of flavor in fermented foods., (Copyright © 2020 Elsevier Ltd. All rights reserved.)