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•The microbial ecosystem of Chinese liquor cellar was studied as a whole.•Significantly distinctive microbial communities were identified in jiupei and pit mud.•The metabolic ...contribution in organic acid synthesis of jiupei and pit mud microbiota was explored.•Acetate and lactate accumulated in jiupei were further converted to butyrate and hexanoate by pit mud microbiota.•Synergistic cooperation within jiupei and pit mud microbiota drives baijiu’s typical flavor formation.
Mud cellars have long been used as anaerobic bioreactors for the fermentation of Chinese strong-flavor Baijiu, where starchy raw materials (mainly sorghum) are metabolized to ethanol and various flavor compounds by multi-species microorganisms. Jiupei (fermented grains) and pit mud are two spatially linked microbial habitats in the mud cellar, yet their metabolic division of labor remains unclear. Here, we investigated the changes in environmental variables (e.g., temperature, oxygen, pH), key metabolites (e.g., ethanol, organic acids) and microbial communities in jiupei and pit mud during fermentation. Jiupei (low pH, high ethanol) and pit mud (neutral pH) provided two habitats with distinctly different environmental conditions for microbial growth. Lactic acid accumulated in jiupei, while butyric and hexanoic acids were mainly produced by microbes inhabiting the pit mud. Biomass analysis using quantitative real-time PCR showed that bacteria dominated the microbial consortia during fermentation, moreover cluster and principal coordinate analysis (PCoA) analysis showed that the bacterial communities of jiupei and pit mud were significantly divergent. The bacterial community diversity of jiupei decreased significantly during the fermentation process, and was relatively stable in pit mud. Lactobacillus dominated the jiupei bacterial community, and its relative abundance reached 98.0% at the end of fermentation. Clostridia (relative abundance: 42.9–85.5%) was the most abundant bacteria in pit mud, mainly distributed in the genus Hydrogenispora (5.3–68.4%). Fungal communities of jiupei and pit mud showed a similar succession pattern, and Kazachstania, Aspergillus and Thermoascus were the predominant genera. PICRUSt analysis demonstrated that enzymes participating in the biosynthesis of acetic and lactic acid were mainly enriched in jiupei samples, while the bacterial community in the pit mud displayed greater potential for butyric and hexanoic acid synthesis. Assays from an in vitro simulated fermentation further validated the roles of jiupei microbiota in acetic and lactic acid production, and these acids were subsequently metabolized to butyric and hexanoic acid by the pit mud microbiota. This work has demonstrated the synergistic cooperation between the microbial communities of jiupei and pit mud for the representative flavor formation of strong-flavor Baijiu.
Humans have mastered high-salinity fermentation techniques for bean-based fermented product preparation over thousands of years. High salinity was used to select the functional microbiota and ...conducted food fermentation production with unique flavor. Although a high-salinity environment is beneficial for suppressing harmful microbes in the open fermentation environment, the fermentation efficiency of functional microbes is partially inhibited. Therefore, application of defined starter cultures for reduced-salt fermentation in a sterile environment is an alternative approach to improve the fermentation efficiency of bean-based fermented foods and guide the transformation of traditional industry. However, the assembly and function of self-organized microbiota in an open fermentation environment are still unclear. This study provides a comprehensive understanding of microbial function and the mechanism of community succession in a high-salinity environment during the fermentation of broad bean paste so as to reconstruct the microbial community and realize efficient fermentation of broad bean paste in a sterile environment.
ABSTRACT
Humans have used high salinity for the production of bean-based fermented foods over thousands of years. Although high salinity can inhibit the growth of harmful microbes and select functional microbiota in an open environment, it also affects fermentation efficiency of bean-based fermented foods and has a negative impact on people’s health. Therefore, it is imperative to develop novel defined starter cultures for reduced-salt fermentation in a sterile environment. Here, we explored the microbial assembly and function in the fermentation of traditional Chinese broad bean paste with 12% salinity. The results revealed that the salinity and microbial interactions together drove the dynamic of community and pointed out that five dominant genera (
Staphylococcus
,
Bacillus
,
Weissella
,
Aspergillus
, and
Zygosaccharomyces
) may play different key roles in different fermentation stages. Then, core species were isolated from broad bean paste, and their salinity tolerance, interactions, and metabolic characteristics were evaluated. The results provided an opportunity to validate
in situ
predictions through
in vitro
dissection of microbial assembly and function. Last, we reconstructed the synthetic microbial community with five strains (
Aspergillus oryzae
,
Bacillus subtilis
,
Staphylococcus gallinarum
,
Weissella confusa
, and
Zygosaccharomyces rouxii
) under different salinities and realized efficient fermentation of broad bean paste for 6 weeks in a sterile environment with 6% salinity. In general, this work provided a bottom-up approach for the development of a simplified microbial community model with desired functions to improve the fermentation efficiency of bean-based fermented foods by deconstructing and reconstructing the microbial structure and function.
IMPORTANCE
Humans have mastered high-salinity fermentation techniques for bean-based fermented product preparation over thousands of years. High salinity was used to select the functional microbiota and conducted food fermentation production with unique flavor. Although a high-salinity environment is beneficial for suppressing harmful microbes in the open fermentation environment, the fermentation efficiency of functional microbes is partially inhibited. Therefore, application of defined starter cultures for reduced-salt fermentation in a sterile environment is an alternative approach to improve the fermentation efficiency of bean-based fermented foods and guide the transformation of traditional industry. However, the assembly and function of self-organized microbiota in an open fermentation environment are still unclear. This study provides a comprehensive understanding of microbial function and the mechanism of community succession in a high-salinity environment during the fermentation of broad bean paste so as to reconstruct the microbial community and realize efficient fermentation of broad bean paste in a sterile environment.
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•The profiles of microbiome and metabolome were explored during the whole fermentation of Zhenjiang aromatic vinegar.•Positive correlations were identified between fungi and lots of ...flavor metabolites.•Sealed fermentation promoted the accumulation of various flavor compounds.•Jiuqu and seed pei provided microorganisms to initiate starch saccharification and acetic acid fermentation, respectively.•Maiqu was mainly the donor of enzymes in alcohol fermentation.
Microbial ecosystems of fermented foods are largely interfered by human activities in myriad ways. The aim of this study was to illuminate the impacts of various starters and environmental variables on the fermentation process of Zhenjiang aromatic vinegar (ZAV), one of the four representative cereal vinegars in China. The effects of environmental variables (e.g., ethanol, total acidity, temperature) and starters (e.g., jiuqu, maiqu, seed pei) on the profiles of microbiome and metabolome (e.g., organic acids, amino acids and volatiles) during fermentation process of ZAV were analyzed. Amongst the four fermentation stages, acetic acid fermentation was the main stage for the accumulation of flavor substances, and subsequently, the contents of acids (mainly acetic, lactic and citric acids) and volatile metabolites (e.g., 2,3-butanedione, acetoin, etc.) continued to enrich in sealed fermentation stage. Principal coordinate analysis (PCoA) and analysis of similarities (ANOSIM) showed that the fungal and bacterial community structures of four fermentation stages were significantly different. As for bacterial community, the dominant OTUs with average relative abundance over 10% in at least one fermentation stage were assigned to the genera Acetilactobacillus, Acetobacter, Acinetobacter, Aeromonas, Lactobacillus, and Pseudomonas. The dominant fungal populations in each fermentation stage were obviously divergent, including Wickerhamomyces, Saccharomyces, Alternaria, Fusarium, etc. SourceTracker analysis demonstrated that jiuqu and seed pei provided microorganisms to initiate starch saccharification and acetic acid fermentation stages, respectively, and maiqu was mainly the donor of enzymes in alcohol fermentation. Spearman correlation coefficients revealed positive relationships between fungal community and various flavor metabolites, indicating the essential role of fungi in the flavor formation of ZAV. This study systematically reveals the effects of fermentation starters and environmental variables on vinegar production and deepens the understanding of the traditional production craft.
Bridge deck link slabs prepared using Basalt Fiber Reinforced Polymer (BFRP) bar‐reinforced ecological high‐ductility cementitious composites (Eco‐HDCC) were applied as substitutes for steel ...expansion joints in Malin Bridge. Theoretical calculations and numerical simulations were combined to develop a design method. The total length and debond length of the link slabs were assumed based on the bridge information, and the reinforcement ratio of the BFRP bar was calculated using the maximum crack width limit. Then, the flexural capacity of the link slabs was evaluated. A preliminary reinforcement program using eight reinforcement ratios and different bar diameters was developed. In addition, the maximum stresses, strains, and deflections of the link slabs were validated through Abaqus finite element analysis. The simulation results of the reinforcement programs with minor reinforcement ratios are similar. The maximum stresses, strains, and deflections of the link slab materials are significantly lower than the design ultimate capacities of the materials, implying that the eight reinforcement programs are feasible. Because the thickness of the link slabs is within the range of 80–120 mm, a small‐diameter bar is preferable. Furthermore, BFRP bars with diameters of 10–14 mm are suitable along the driving direction, whereas BFRP bars with diameters of 10 mm are recommended along the direction perpendicular to the driving direction. A detailed design method flowchart for bridge deck link slabs was constructed to serve as a guideline for engineers.
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•Aged Baijiu was rich in acids, long-chain ethyl esters, pyrazines and terpenes.•More even composition was driven by attaining equilibrium state of esterification.•Evenness index and ...reaction quotient (Qc) of esterification are age-indicative.•41 age-related features were selected out using 5 ranking algorithms and 3 models.•Model using 41 key-features as input could accurately predict age group of Baijiu.
The aged Chinese liquor, Baijiu, is highly valued for its superior organoleptic qualities. However, since age-authentication method and aging-mechanism elucidation of Baijiu is still in the exploratory stage, high-quality aged Baijiu is often replaced by lower-quality, less-aged product with fraudulent mislabeling. Authentic high-quality strong-flavor Baijiu was analyzed by gas chromatography-mass spectrometry. Total esters decreased with aging, while acids, alcohols, aldehydes, ketones, terpenes, pyrazines increased. Although concentrations of partial compounds showed non-monotonic profiling during aging, a close positive linear correlation (R2 = 0.7012) of Baijiu Evenness index (0.55–0.59) with aging time was observed, indicating a more balanced composition in aged Baijiu. The reaction quotient (Qc) of each esterification, calculated by the corresponding reactant and product concentration, approached to the corresponding thermodynamic equilibrium constant Kc. This result demonstrated that the spontaneous transformation driven by thermodynamics explained part of the aging compositional profiling. Furthermore, an aging-related feature selection and an age-authentication method were established based on three models combined with five ranking algorithms. Forty-one key features, including thirty-six compound concentrations, four esterification Qc values and the Evenness index were selected out. The age-authentication based on neural network using forty-one input features accurately predicted the age group of Baijiu samples (F1 = 100 %). These findings have deepened understanding of the Baijiu aging mechanism and provided a novel, effective approach for age-authentication of Baijiu and other liquors.
Female fig (Ficus carica L.) fruit are characterized by a major increase in volume and sugar content during the final week of development. A detailed developmental analysis of water and dry matter ...accumulation during these final days indicated a temporal separation between the increase in volume due to increasing water content and a subsequent sharp increase in sugar content during a few days. The results present fig as an extreme example of sugar import and accumulation, with calculated import rates that are one order of magnitude higher than those of other sugar‐accumulating sweet fruit species. To shed light on the metabolic changes occurring during this period, we followed the expression pattern of 80 genes encoding sugar metabolism enzymes and sugar transporter proteins identified in fig fruit. A parallel comparison with male fig fruits, which do not accumulate sugar during ripening, highlighted the genes specifically related to sugar accumulation. Tissue‐specific analysis indicated that the expression of genes involved in sugar metabolism and transport undergoes a global transition.
As the saccharifying and fermentative agent, medium-temperature Daqu (MT-Daqu) plays an irreplaceable role in the production of strong-flavor Baijiu. Numerous studies have focused on the microbial ...community structure and potential functional microorganisms, however, little is known about the succession of active microbial community and the formation mechanism of community function during MT-Daqu fermentation. In this study, we presented an integrated analysis of metagenomics, metatranscriptomics, and metabonomics covering the whole fermentation process of MT-Daqu to reveal the active microorganisms and their participations in metabolic networks. The results showed that dynamic of metabolites were time-specific, and the metabolites and co-expressed active unigenes were further classified into four clusters according to their accumulation patterns, with members within each cluster displaying a uniform and clear pattern of abundance across fermentation. Based on KEGG enrichment analysis in co-expression clusters and succession of active microbial community, we revealed that Limosilactobacillus, Staphylococcus, Pichia, Rhizopus, and Lichtheimia were metabolically active members at the early stage, and their metabolic activities were conducive to releasing abundant energy to drive multiple basal metabolisms such as carbohydrates and amino acids. Thereafter, during the high temperature period and at the end of fermentation, multiple heat-resistant filamentous fungi were transcriptionally active populations, and they acted as both the saccharifying agents and flavor compound producers, especially aromatic compounds, suggesting their crucial contribution to enzymatic activity and aroma of mature MT-Daqu. Our findings revealed the succession and metabolic functions of the active microbial community, providing a deeper understanding of their contribution to MT-Daqu ecosystem.
•The accumulation of metabolites during fermentation was time-specific and staged.•Metabolites and active genes exhibited consistent and clear abundance patterns.•Fungi gradually replaced bacteria as the active species during fermentation.•Lactobacillales, Mucorales, and Pichia initially cooperated in the hydrolyses.•Filamentous fungi contributed to form flavor substances under thermal conditions.
Imbalances in gut microbiota composition are linked to hypertension, host metabolic abnormalities, systemic inflammation, and other conditions. In the present study, we examined the changes of gut ...microbiota in women with early-onset preeclampsia (PE) and in normotensive, uncomplicated pregnant women during late pregnancy and at 1 and 6 weeks postpartum.
Gut microbiota profiles of women with PE and healthy pregnant women in the third trimester and at 1 and 6 weeks postpartum were assessed by 16S rRNA gene amplicon sequencing. Plasma levels of interleukin-6 (IL-6), intestinal fatty acid-binding protein (I-FABP), zonulin, and lipopolysaccharide (LPS) were measured in the third trimesters.
At the genus level, 8 bacterial genera were significantly enriched in the antepartum samples of PE patients compared to healthy controls, of which
, and
represented the major variances in PE microbiomes. Conversely, 5 genera, including
, and
, were significantly depleted in antepartum PE samples. Maternal blood pressure and liver enzyme levels were positively correlated to the PE-enriched genera such as
, and
, while the fetal features (e.g., Apgar score and newborn birth weight) were positively correlated with PE-depleted genera and negatively correlated with PE-enriched genera. Moreover, maternal blood IL-6 level was positively associated with gut
and
, whereas LPS level was negatively associated with
. In terms of postpartum women, both the gut microbial composition and the PE-associated microbial alterations were highly consistent with those of the antepartum women.
PE diagnosed in the third trimester of pregnancy is associated with a disrupted gut microbiota composition compared with uncomplicated pregnant women, which are associated with maternal clinical features (blood pressure level and liver dysfunction) and newborn birth weight. Moreover, these antepartum alterations in gut microbiota persisted 6 weeks postpartum.
Characterized by an excessively increased uric acid (UA) level in serum, hyperuricemia induces gout and also poses a great threat to renal and cardiovascular systems. It is urgent and meaningful to ...perform early warning by noninvasive diagnosis, thus conducing to blockage of disease aggravation. Here, guanidinocalix5arene (GC5A) is successfully identified from the self‐built macrocyclic library to specifically monitor UA from urine by the indicator displacement assay. UA is strongly bound to GC5A at micromolar‐level, while simultaneously excluding fluorescein (Fl) from the GC5A·Fl complex in the “switch‐on” mode. This method successfully differentiates patients with hyperuricemia from volunteers except for those with kidney dysfunction and targets a volunteer at high risk of hyperuricemia. In order to meet the trend from hospital‐centered to individual‐centered testing, visual detection of UA is studied through a smartphone equipped with a color‐scanning feature, whose adaptability and feasibility are demonstrated in sensing UA from authentic urine, leading to a promising method in family‐centered healthcare style. A high‐throughput and visual detection method is provided here for alarming hyperuricemic by noninvasive diagnosis.
A noninvasive and individual‐centered method is accomplished for monitoring uric acid (UA) in urine by executing indicator displacement assay, which successfully differentiates hyperuricemia patients from volunteers and targets a volunteer at high risk of hyperuricemia. To fit the family‐centered healthcare style, optical supramolecular sensing of UA is achieved by reading G value of images acquired with a portable smartphone.
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•LABs (Weissella, Lactobacillus, and Pediococcus) were dominant bacteria around day 2.•Thermotolerant/thermophilic taxa exhibited the highest proportion after day 6.•A metabolic ...network of core microbes involved in flavor development was constructed.•Potential populations responsible for the production of lytic enzymes were revealed.•Lactic acid and bio-heat produced by microbes could promote the microbiota shift.
As a widely used Asian starter culture, the quality of daqu can significantly affect the organoleptic characteristics of the final products, yet the microbial metabolic network involved in flavor development remains unclear. This study aims to investigate that network based on the dynamics of physicochemical properties, microbial community, and volatile compounds in medium-temperature daqu (MT-daqu) during spontaneous fermentation. Analyses using the metagenomic data set facilitated the gene repertoire overview of this ecosystem, indicating that Lactobacillales (mainly Weissella, Lactobacillus, and Pediococcus), Mucorales (mainly Lichtheimia), and Eurotiales (mainly Aspergillus, Rasamsonia and Byssochlamys) were the potential predominant populations successively responsible for the production of lytic enzymes and flavor precursors/compounds in MT-daqu. Flavor-relevant pathways were found to exist in multiple species, but only bacteria showed the potential to participate in butane-2,3-diol (e.g. Weissella, Lactobacillus, and Staphylococcus) and butanoate (Thermoactinomyces) metabolism, and only fungi were potentially involved in biosynthesis of guaiacol (Byssochlamys) and 4-vinylguaiacol (Aspergillus). Furthermore, a combined analysis revealed that the acidic thermal environment present in early phases was mainly due to the catabolic activities of Lactobacillales and Lichtheimia, which could contribute to the effective self-domestication of microbiota. The study helps elucidate the different metabolic roles of microorganisms and disclose the formation mechanism of daqu’s partial functions, namely providing various aromatic substances/precursors and enzymes.
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