Phylogenetic identification of lactic acid bacteria isolates and their effects on the fermentation quality of sweet sorghum (Sorghum bicolor) silage

Influence of two sorghum varieties on metabolic factors, microbial community, and flavor component precursors of strong-flavor Baijiu Zaopei

As the primary raw material for Baijiu brewing, sorghum variety exerts an intricate influence on the taste profile of strong-flavor Baijiu. However, how sorghum variety comprehensively affects Baijiu flavor formation through fermentation by microorganisms and metabolites remains largely unknown. Using 16S&ITS rRNA gene sequencing and non-targeted metabolomics, in this study we comprehensively analyzed the changes in microbial communities and metabolites during fermentation of a glutinous and non-glutinous sorghum variety. The results showed that these varieties significantly affected microbial diversity and community structure, and their interactions, among which, there were particularly complex interactions among bacterial communities, while the effects of "functional differentiation" and "community aggregation" of fungal communities were prominent. Furthermore, three bacterial and nine fungal genera were identified as core microorganisms related to changes in glycerophospholipids during fermentation, that led to a change in ester content, ultimately improving Baijiu quality. These findings provide reference for the selection of brewing materials.

Isolation of Lactic Acid Bacteria from Naturally Ensiled Rosa roxburghii Tratt Pomace and Evaluation of Their Ensiling Potential and Antioxidant Properties

This study isolated five acid-producing strains (XQ1 and YZ1-YZ4) from naturally fermented pomace of Rosa roxburghii Tratt (RRT) in Guizhou's karst region. Genetic and phenotypic analyses identified XQ1, YZ2, and YZ4 as Lactobacillus plantarum (L. plantarum), YZ3 as Weissella cibaria, and YZ1 as Bacillus licheniformis. A comparative evaluation with commercial strain AC revealed that XQ1, YZ2, and YZ4 exhibited superior acidification (reaching the stationary phase at 40 h) and tolerance to acidic conditions (pH 3.0), ethanol (6% v/v), bile salts (0.3%), and osmotic stress (6.5% NaCl), along with broad-spectrum antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Shigella dysenteriae, and Pseudomonas aeruginosa. Their cell-free supernatants (CFSs) showed comparable superoxide dismutase activity and total antioxidant capacity (2.54-2.66 FeSO4·7H2O eq mmol/L) to AC (2.68), with DPPH radical scavenging exceeding 50%. YZ3 displayed weaker acid production, tolerance, and limited antimicrobial effects. Safety assessments confirmed non-hemolytic activity and antibiotic susceptibility. In conclusion, the L. plantarum strains XQ1, YZ2, and YZ4 demonstrated strong ensiling potential and remarkable probiotic properties, establishing them as promising indigenous microbial resources for the preservation of RRT pomace and other food products.

Effects of Lactiplantibacillus plantarum on Metabolites and Flavors in Synthetic Microbiota During Baijiu Fermentation

The distinctive flavor and aroma of Chinese baijiu are closely linked to the microorganisms involved in the fermentation process. Lactiplantibacillus plantarum, a dominant species in the fermentation of Chinese baijiu, has become a prominent research focus. In this study, we selected well-characterized pure cultures of microorganisms to construct diverse chassis microflora. The primary objective was to investigate the effects of L. plantarum on the fermentation process of Chinese baijiu and its association with metabolites produced by different chassis microflora. Our results demonstrated that the concentrations of ethyl lactate and other volatile aromatic compounds increased in all fermentation protocols where L. plantarum was added. The addition of L. plantarum also significantly increased the concentration of total organic acids, particularly lactic acid, which rose by 17 to 123 times. Furthermore, L. plantarum helped maintain the stability of ethanol concentration during the middle and late stages of fermentation. Notably, among the three different chassis microbial fermentation protocols involving L. plantarum, the protocol with the highest microbial diversity exhibited a greater capacity to produce lactic acid (1.56 ± 0.19 mg/g), ethanol (5.74 ± 0.47 mg/g), and reducing sugars (6.39 ± 0.31 mg/g). These findings provide valuable insights into the potential of L. plantarum for modulating the flavor of Chinese baijiu.

Suitable fermentation temperature of forage sorghum silage increases greenhouse gas production: Exploring the relationship between temperature, microbial community, and gas production

Silage is an excellent method of feed preservation; however, carbon dioxide, methane and nitrous oxide produced during fermentation are significant sources of agricultural greenhouse gases. Therefore, determining a specific production method is crucial for reducing global warming. The effects of four temperatures (10 °C, 20 °C, 30 °C, and 40 °C) on silage quality, greenhouse gas yield and microbial community composition of forage sorghum were investigated. At 20 °C and 30 °C, the silage has a lower pH value and a higher lactic acid content, resulting in higher silage quality and higher total gas production. In the first five days of ensiling, there was a significant increase in the production of carbon dioxide, methane, and nitrous oxide. After that, the output remained relatively stable, and their production at 20 °C and 30 °C was significantly higher than that at 10 °C and 40 °C. Firmicutes and Proteobacteria were the predominant silage microorganisms at the phylum level. Under the treatment of 20 °C, 30 °C, and 40 °C, Lactobacillus had already dominated on the second day of silage. However, low temperatures under 10 °C slowed down the microbial community succession, allowing, bad microorganisms such as Chryseobacterium, Pantoea and Pseudomonas dominate the fermentation, in the early stage of ensiling, which also resulted in the highest bacterial network complexity. According to random forest and structural equation model analysis, the production of carbon dioxide, methane and nitrous oxide is mainly affected by microorganisms such as Lactobacillus, Klebsiella and Enterobacter, and temperature influences the activity of these microorganisms to mediate gas production in silage. This study helps reveal the relationship between temperature, microbial community and greenhouse gas production during silage fermentation, providing a reference for clean silage fermentation.

Dynamics of fermentation quality, bacterial communities, and fermentation weight loss during fermentation of sweet sorghum silage

BACKGROUND

Sweet sorghum is used mainly as an energy crop and feed crop in arid and semiarid regions, and ensiling is a satisfactory method for preserving high-quality sweet sorghum. The aim of this study was to reveal the dynamics of the fermentation quality, bacterial communities, and fermentation weight loss (FWL) of sweet sorghum silage during fermentation.

METHODS

Sweet sorghum was harvested at the first inflorescence spikelet stage and ensiled without (CK) or with lactic acid bacterial (LAB) additives (L). After ensiling, samples were collected on days 0, 1, 3, 5, 15, 40, and 100 to assess the fermentation quality, bacterial communities, and FWL.

RESULTS

For CK and L, on day 1, the pH was 5.77 and 5.57, respectively, and the lactic acid (LA) was 1.30 and 2.81 g/kg dry matter (DM), respectively. Compared with CK, L had a lower pH and higher LA from days 1 to 5 (P < 0.05), a lower FWL from days 5 to 100 (P < 0.05), and a greater abundance of Lactiplantibacillus from days 1 to 15 (P < 0.05). The main bacterial genera were Leuconostoc and Weissella in CK and Lactiplantibacillus, Leuconostoc, and Weissella in L on day 1; Lactiplantibacillus in all silages from days 3 to 40; and Lactiplantibacillus and Lentilactobacillus in all silages on day 100.

CONCLUSIONS

Sweet sorghum silage fermented relatively slowly during the first day. Moreover, inoculation with LAB accelerated fermentation and optimized bacterial communities during the initial fermentation phase. Inoculation with LAB also reduced the silage FWL, and the LAB succession relay occurred in the silage throughout the fermentation process.

Bioaugmented ensiling of sweet sorghum with Pichia anomala and cellulase and improved enzymatic hydrolysis of silage via ball milling

Sweet sorghum, as a seasonal energy crop, is rich in cellulose and hemicellulose that can be converted into biofuels. This work aims at investigating the effects of synergistic regulation of Pichia anomala and cellulase on ensiling quality and microbial community of sweet sorghum silages as a storage and pretreatment method. Furthermore, the combined pretreatment effects of ensiling and ball milling on sweet sorghum were evaluated by microstructure change and enzymatic hydrolysis. Based on membership function analysis, the combination of P. anomala and cellulase (PA + CE) significantly improved the silage quality by preserving organic components and promoting fermentation characteristics. The bioaugmented ensiling with PA + CE restructured the bacterial community by facilitating Lactobacillus and inhibiting undesired microorganisms by killer activity of P. anomala. The combined bioaugmented ensiling pretreatment with ball milling significantly increased the enzymatic hydrolysis efficiency (EHE) to 71%, accompanied by the increased specific surface area and decreased pore size/crystallinity of sweet sorghum. Moreover, the EHE after combined pretreatment was increased by 1.37 times compared with raw material. Hence, the combined pretreatment was demonstrated as a novel strategy to effectively enhance enzymatic hydrolysis of sweet sorghum.

The improvement of Hovenia acerba-sorghum co-fermentation in terms of microbial diversity, functional ingredients, and volatile flavor components during Baijiu fermentation

The quality of Baijiu was largely affected by raw materials, which determine the flavor and taste. In the present study, organic acids, polyphenols, volatile flavor components and microbial community in Hovenia acerba-sorghum co-fermented Baijiu (JP1) and pure sorghum-fermented Baijiu (JP2) were comprehensively analyzed. Organic acids, polyphenols and volatile flavor components in JP1 were more abundant than JP2. The abundance and diversity of bacteria and fungi in JP1 was higher than that in JP2 in the early stage of fermentation, but presented opposite trend in the middle and late stages. Leuconostoc, Lentilactobacillus and Issatchenkia were dominant genera in JP1. Whereas, Cronobacter, Pediococcus and Saccharomyces occupied the main position in JP2. Lentilactobacillus and Issatchenkia were positively related to most of organic acids and polyphenols. Pseudomonas, Rhodococcus, Cronobacter, Pediococcus, Brucella, Lentilactobacillus, Lactobacillus, Saccharomycopsis, Wickerhamomyces, Aspergillus, Thermomyces and unclassified_f-Dipodascaccae were associated with the main volatile flavor components. The main metabolic pathways in two JPs exhibited the variation trend of first decreasing and then increasing, and the metabolism activity in JP1 were higher than that in JP2. The results demonstrated the introduction of Hovenia acerba improved the functional ingredients and volatile flavor components, which is helpful for the quality promotion of Baijiu. This study identified the key microorganisms and discussed their effect on organic acids, polyphenols and volatile flavor components during the fermentation of Baijiu with different raw materials, providing a scientific basis for the development and production of high-quality Baijiu.

Effect of lactic acid bacteria on the structure and potential function of the microbial community of Nongxiangxing Daqu

OBJECTIVES

The microbial community structure of the saccharifying starter, Nongxiangxing Daqu(Daqu), is a crucial factor in determining Baijiu's quality. Lactic acid bacteria (LAB), are the dominant microorganisms in the Daqu. The present study investigated the effects of LAB on the microbial community structure and its contribution to microbial community function during the fermentation of Daqu.

METHODS

The effect of LAB on the structure and function of the microbial community of Daqu was investigated using high-throughput sequencing technology combined with multivariate statistical analysis.

RESULTS

LAB showed a significant stage-specific evolution pattern during Daqu fermentation. The LEfSe analysis and the random forest learning algorithm identified LAB as vital differential microorganisms during Daqu fermentation. The correlation co-occurrence network showed aggregation of LAB and Daqu microorganisms, indicating LAB's significant position in influencing the microbial community structure, and suggests that LAB showed negative correlations with Bacillus, Saccharopolyspora, and Thermoactinomyces but positive correlations with Issatchenkia, Candida, Acetobacter, and Gluconobacter. The predicted genes of LAB enriched 20 functional pathways during Daqu fermentation, including Biosynthesis of amino acids, Alanine, aspartate and glutamate metabolism, Valine, leucine and isoleucine biosynthesis and Starch and sucrose metabolism, which suggested that LAB had the functions of polysaccharide metabolism and amino acid biosynthesis.

CONCLUSION

LAB are important in determining the composition and function of Daqu microorganisms, and LAB are closely related to the production of nitrogenous flavor substances in Daqu. The study provides a foundation for further exploring the function of LAB and the regulation of Daqu quality.

Effect of isolated lactic acid bacteria on the quality and bacterial diversity of native grass silage

Objective

The objective of this study was to isolate lactic acid bacteria (LAB) from native grasses and naturally fermented silages, determine their identity, and assess their effects on silage quality and bacterial communities of the native grasses of three steppe types fermented for 60 days.

Methods

Among the 58 isolated LAB strains, Limosilactobacillus fermentum (BL1) and Latilactobacillus graminis (BL5) were identified using 16S rRNA sequences. Both strains showed normal growth at 15- 45°C temperature, 3-6.5% NaCl concentration, and pH 4-9. Two isolated LAB strains (labeled L1 and L5) and two commercial additives (Lactiplantibacillus plantarum and Lentilactobacillus buchneri; designated as LP and LB, respectively) were added individually to native grasses of three steppe types (meadow steppe, MS; typical steppe, TS; desert steppe, DS), and measured after 60 d of fermentation. The fresh material (FM) of different steppe types was treated with LAB (1 × 10⁵ colony forming units/g fresh weight) or distilled water (control treatment [CK]).

Results

Compared with CK, the LAB treatment showed favorable effects on all three steppe types, i.e., reduced pH and increased water-soluble carbohydrate content, by modulating the microbiota. The lowest pH was found in the L5 treatment of three steppe types, at the same time, the markedly (p < 0.05) elevated acetic acid (AA) concentration was detected in the L1 and LB treatment. The composition of bacterial community in native grass silage shifted from Pantoea agglomerans and Rosenbergiella nectarea to Lentilactobacillus buchneri at the species level. The abundance of Lentilactobacillus buchneri and Lactiplantibacillus plantarum increased significantly in L1, L5, LP, and LB treatments, respectively, compared with CK (p < 0.05).

Conclusion

In summary, the addition of LAB led to the shifted of microbiota and modified the quality of silage, and L. fermentum and L. graminis improved the performance of native grass silage.

The microbial diversity and flavour metabolism of Chinese strong flavour Baijiu: a review

Strong flavour Baijiu is widely consumed in China and is produced by the fermentation of grains using microbial starters. However, a comprehensive understanding of the diversity and metabolic characteristics of microbial communities involved in the solid-state fermentation of Baijiu is important for determining the relationship between microbial composition, flavour metabolism and understanding Baijiu fermentation conditions. Although studies have examined the metabolic pathways and impact of major processes on flavour compounds in strong flavour Baijiu, aspects of the fermentation process remain unexplored. In this review, methods are discussed for the optimisation of microbial diversity in strong flavour Baijiu and associated effects on the flavour of Baijiu. Recent studies are reviewed on starters (Daqu), fermented grains (Jiupei), and pit mud together with the effects of microbial composition on the quality of strong flavour Baijiu. The challenges of Baijiu research and production are discussed, including the role of the microbial diversity of Daqu and Jiupei in the flavour composition of strong flavour Baijiu. This review contributes to the current understanding of processing strong flavour Baijiu and serves as a reference for screening flavour related microorganisms, which is valuable for improving the quality of strong flavour Baijiu.

Isolation and identification of ligninolytic bacterium (Bacillus cereus) from buffalo (Bubalus bubalis) rumen and its effects on the fermentation quality, nutrient composition, and bacterial community of rape silage

This study aimed to isolate and identify a ligninolytic bacterium from the rumen of buffalo (Bubalus bubalis) and investigate its effects as a silage additive for whole-plant rape. Three lignin-degradation strains were isolated from the buffalo rumen, with AH7-7 being chosen for further experiments. Strain AH7-7, with acid tolerance and a 51.4% survival rate at pH 4, was identified as Bacillus cereus. It exhibited a lignin-degradation rate of 20.5% after being inoculated in a lignin-degrading medium for 8 days. We divided the rape into four groups according to the various additive compositions to examine the fermentation quality, nutritional value, and bacterial community after ensiling: Bc group (inoculated with B. cereus AH7-7 3.0 × 10⁶ CFU g FW^-1), Blac group (inoculated with B. cereus AH7-7 1.0 × 10⁶ CFU g FW^-1, L. plantarum 1.0 × 10⁶ CFU g FW^-1, and L. buchneri 1.0 × 10⁶ CFU g FW^-1), Lac group (inoculated with L. plantarum 1.5 × 10⁶ CFU g FW^-1 and L. buchneri 1.5 × 10⁶ CFU g FW^-1), and Ctrl group (no additives). After 60 days of fermentation, the application of B. cereus AH7-7 was potent in modulating the fermentation quality of silage, especially when combined with L. plantarum and L. buchneri, as indicated by lower dry matter loss and higher contents of crude protein, water-soluble carbohydrate, and lactic acid. Furthermore, treatments with the B. cereus AH7-7 additive decreased the contents of acid detergent lignin, cellulose, and hemicellulose. The B. cereus AH7-7 additive treatments reduced the bacterial diversity and optimized the bacterial community compositions of silage, with an increase in the relative abundance of beneficial Lactobacillus and a decrease in the relative abundance of undesirable Pantoea and Erwinia. Functional prediction revealed that inoculation with B. cereus AH7-7 could increase the cofactors and vitamins metabolism, amino acid metabolism, translation, replication and repair, and nucleotide metabolism, while decreasing the carbohydrate metabolism, membrane transport, and energy metabolism. In brief, B. cereus AH7-7 improved the microbial community, fermentation activity, and ultimately the quality of silage. The ensiling with B. cereus AH7-7, L. plantarum, and L. buchneri combination is an effective and practical strategy to improve the fermentation and nutrition preservation of rape silage.

Effects of Bacillus subtilis or Lentilactobacillus buchneri on aerobic stability, and the microbial community in aerobic exposure of whole plant corn silage

This study aimed to evaluate the effects of Bacillus subtilis or Lentilactobacillus buchneri on the fermentation quality, aerobic stability, and bacterial and fungal communities of whole plant corn silage during aerobic exposure. Whole plant corn was harvested at the wax maturity stage, which chopped to a length of approximately 1 cm, and treated with the following: distilled sterile water control, 2.0 × 10⁵ CFU/g of Lentilactobacillus buchneri (LB) or 2.0 × 10⁵ CFU/g of Bacillus subtilis (BS) for 42 days silage. Then, the samples were exposed to air (23-28^°C) after opening and sampled at 0, 18 and 60 h, to investigate fermentation quality, bacterial and fungal communities, and aerobic stability. Inoculation with LB or BS increased the pH value, acetic acid, and ammonia nitrogen content of silage (P < 0.05), but it was still far below the threshold of inferior silage, the yield of ethanol was reduced (P < 0.05), and satisfactory fermentation quality was achieved. With the extension of the aerobic exposure time, inoculation with LB or BS prolonged the aerobic stabilization time of silage, attenuated the trend of pH increase during aerobic exposure, and increased the residues of lactic acid and acetic acid. The bacterial and fungal alpha diversity indices gradually declined, and the relative abundance of Basidiomycota and Kazachstania gradually increased. The relative abundance of Weissella and unclassified_f_Enterobacteria was higher and the relative abundance of Kazachstania was lower after inoculation with BS compared to the CK group. According to the correlation analysis, Bacillus and Kazachstania are bacteria and fungi that are more closely related to aerobic spoilage and inoculation with LB or BS could inhibit spoilage. The FUNGuild predictive analysis indicated that the higher relative abundance of fungal parasite-undefined saprotroph in the LB or BS groups at AS2, may account for its good aerobic stability. In conclusion, silage inoculated with LB or BS had better fermentation quality and improved aerobic stability by effectively inhibiting the microorganisms that induce aerobic spoilage.

Study on the correlation between microbial communities with physicochemical properties and flavor substances in the Xiasha round of cave-brewed sauce-flavor Baijiu

The Chishui River basin is the main production area of the sauce-flavor Baijiu. Due to the particularity of sauce-flavor Baijiu technology, a large site of workshops needs to be built for brewing and storage. Therefore, used the natural karst caves of Guizhou province to manufacture the sauce-flavor Baijiu, which has enriched the connotation of sauce-flavor Baijiu and saved valuable land resources. In this study, the fermentation grains in the seven stages during the Xiasha round of the cave-brewed sauce-flavor Baijiu (CBSB) were detected using a combination of physicochemical analysis, Headspace solid-phase microextraction gas chromatography-mass detection, and Illumina HiSeq sequencing methods. The results showed Unspecified_Leuconostocaceae, Weissella, Unspecified_Bacillaceae, Saccharomycopsis, Thermomyces, and Unspecified_Phaffomycetaceae were the main bacterial and fungal genera in the stacking fermentation (SF). In the cellar fermentation (CF), the Lactobacillus, Unspecified_Lactobacillaceae, Thermoactinomyces, Saccharomycopsis, Unspecified_Phaffomycetaceae, and Wickerhamomyces were the main bacterial and fungal genera. A total of 72 volatiles were detected in the fermented grains. Linear discriminant analysis Effect Size (LEfSe) identified 23 significantly different volatile metabolites in the fermentation process, including 7 esters, 6 alcohols, 4 acids, 3 phenols, 1 hydrocarbon, and 2 other compounds. Redundancy analysis was used to explore the correlation between dominant microbial genera and physicochemical properties. Starch was the main physicochemical property affecting microbial succession in the SF. Acidity, moisture, and reducing sugar were the main driving factors of microbial succession in the CF. The Pearson correlation coefficient revealed the correlation between dominant microbial genera and significantly different volatile flavor substances. A total of 18 dominant microbial genera were associated with significantly different volatile metabolites, Lactobacillus, Weissella, Wickerhamomyces, and Aspergillus were shown to play crucial roles in metabolite synthesis. On this basis, a metabolic map of the dominant microbial genera was established. This study provides a theoretical basis for the production and quality control of sauce-flavor Baijiu brewed in natural karst caves and lays a foundation for studying the link between flavor formation and microorganisms.

Effects of Isolated LAB on Chemical Composition, Fermentation Quality and Bacterial Community of Stipa grandis Silage

This study aimed to screen and identify lactic acid bacteria (LAB) strains from the Stipa grandis and naturally fermented silage, and assess their effects on the silage quality and bacterial community of Stipa grandis after 60 days of the fermentation process. A total of 38 LAB were isolated, and strains ZX301 and YX34 were identified as Lactiplantibacillus plantarum and Pediococcus pentosaceus using 16S rRNA sequences; they can normally grow at 10−30 °C, with a tolerance of pH and NaCl from 3.5 to 8.0 and 3 to 6.5%, respectively. Subsequently, the two isolated LAB and one commercial additive (Lactiplantibacillus plantarum) were added to Stipa grandis for ensiling for 60 days and recorded as the ZX301, YX34, and P treatments. The addition of LAB was added at 1 × 105 colony-forming unit/g of fresh weight, and the same amount of distilled water was sprayed to serve as a control treatment (CK). Compared to the CK treatment, the ZX301 and YX34 treatments exhibited a positive effect on pH reduction. The water-soluble carbohydrate content was significantly (p < 0.05) increased in ZX301, YX34, and P treatments than in CK treatment. At the genus level, the bacterial community in Stipa grandis silage involves a shift from Pantoea to Lactiplantibacillus. Compared to the CK treatment, the ZX301, YX34, and P treatments significantly (p < 0.05) increase the abundance of Pediococcus and Lactiplantibacillus, respectively. Consequently, the results indicated that the addition of LAB reconstructed microbiota and influenced silage quality. The strain ZX301 could improve the ensiling performance in Stipa grandis silage.

Fermentation weight loss, fermentation quality, and bacterial community of ensiling of sweet sorghum with lactic acid bacteria at different silo densities

Sweet sorghum is an important forage in arid and semi-arid climatic regions. This study aimed to reveal the fermentation weight loss (FWL), fermentation quality, and bacterial community of ensiling of sweet sorghum with lactic acid bacteria LAB; (Lactiplantibacillus plantarum and Lentilactobacillus buchneri) at different silo densities. For this study, sweet sorghum was harvested at the first spikelet of inflorescence stage and ensiled without or with LAB (CK or L) in polyethylene laboratory-scale silos (diameter, 20 cm; height, 30 cm) at densities of 650 (CK_650 and L_650), 700 (CK_700 and L_700), and 750 kg/m3 (CK_750 and L_750), respectively. The FWL, fermentation quality, microbial counts, and bacterial community of the silage were assessed after 100 days of ensiling. L_750 had a lower FWL than CK_650, _700, and _750 after 100 days of ensiling (P &lt; 0.005), and the FWL was affected by silo density and inoculating LAB (P &lt; 0.005). All silages had low pH (&lt;4.0) and ammonia nitrogen content (&lt;50 g/kg total nitrogen) and did not contain propionic and butyric acids; moreover, inoculating LAB increased lactic and acetic acids (P &lt; 0.005). Bacterial communities in inoculated and uninoculated silages were clustered together, respectively, and clearly separated from each other. The total abundance of Lactiplantibacillus and Lentilactobacillus in fresh forage was &lt;1%. Lactiplantibacillus had the highest abundance in all silages (from 71.39 to 93.27%), followed by Lentilactobacillus (from 3.59 to 27.63%). Inoculating LAB increased the abundance of Lentilactobacillus in each silo density (P &lt; 0.005) and decreased Lactiplantibacillus in the silage in densities of 700 and 750 kg/m3 (P &lt; 0.005); moreover, increasing silo density decreased Lactiplantibacillus abundance and increased Lentilactobacillus abundance in inoculated silages (P &lt; 0.005). Overall, sweet sorghum silage showed satisfactory fermentation quality, with a density of no &lt;650 kg/m3, and inoculating LAB improved fermentation quality and reduced FWL. Lactiplantibacillus and Lentilactobacillus presented as minor taxa in fresh sweet sorghum and dominated the bacterial community of all silages. Inoculating LAB was the main factor affecting the bacterial community of sweet sorghum silage. Moreover, inoculating LAB and increasing silo density can contribute to the decreasing Lactiplantibacillus abundance and increasing Lentilactobacillus abundance.

Evaluating the Effect of Forage Rape (Brassica napus) Ensiling Kinetics on Degradability and Milk Performance as Non-conventional Forage for Dairy Buffalo

The recent increase in demand for animal protein sources has led to the urgency to introduce non-conventional feed sources and opened the space to study feed management and its effects on animal productivity. Forage rape (Brassica napus L.) is a high-quality forage crop with a remarkable nutritional value and productive and fast growth capacity; however, studies on processing methods are limited. This study evaluates the effect of an ensiling process on rape silage quality kinetics, in situ degradability, and milk responses in dairy buffaloes. Firstly, the whole-plant forage rape was ensiled, and silage samples were collected 30, 60, and 90 days after ensiling to determine pH, evaluation of sensory characteristics, and chemical composition. Then, samples were taken for further chemical analysis at days 30, 60, and 90. After that, the degradability of the dry matter (DM) and crude protein (CP) of the silage was evaluated by an in situ degradability experiment using three fistulated buffalos (550 ± 20 kg body weight, 4.7 ± 0.76 years). Finally, whole-plant rape silage (after 60 days) was included in a 10, 20, and 30% of DM dairy buffalo diet in the lactating buffalo ration. The results showed that silage pH did not change significantly during the ensiling process (p > 0.05); however, the silage achieved the optimal comprehensive sensory characteristic score from days 30 to 60. There was also a significant change in neutral detergent fiber (NDF) content and acid detergent fiber content, which decreased significantly (p = 0.001 and p < 0.001, respectively). Ensiling of the whole-plant rape significantly reduced effective DM degradability (p < 0.05) without altering CP degradability (p > 0.05). Furthermore, the inclusion of forage rape silage linearly (p = 0.03) increased milk fat and protein contents and did not affect milk yield, lactose, and urea nitrogen contents in raw buffalo milk. In conclusion, whole-plant rape silage could significantly maintain the optimal ether extract (EE) protein content without affecting CP degradability, in addition to improving milk fat and milk protein. Therefore, ensiling may be an efficient method of forage rape utilization, and forage rape silage can be recommended as a good forage source for dairy buffaloes.

Flavor mystery of Chinese traditional fermented baijiu: The great contribution of ester compounds

Chinese traditional fermented baijiu is a famous alcoholic beverage with unique flavor. Despite its consumption for millennia, the flavor mystery behind baijiu is still unclear. Studies indicate that esters are the most important flavor substances, and bring health benefits. However, the aroma contribution and formation mechanism of esters still need to be clarified to reveal the flavor profile of baijiu. This review systematically summarizes all the 510 esters and finds 9 ethyl esters contribute greatly to the flavor of baijiu. The 508 different microbial species that have been identified affect the synthesis of esters through fatty acid and amino acid metabolism. The determination of minimum functional microbial groups and the analysis of their metabolic characteristics are crucial to reveal the mechanism of formation of baijiu flavor, and ensure the reproducible formation of flavor substances.

Silage Fermentation on Sweet Sorghum Whole Plant for Fen-Flavor Baijiu

The technology for producing bioethanol from sweet sorghum stalks by solid-state fermentation has developed rapidly in recent years, and has many similarities with traditional Chinese liquor production. However, the product from sweet sorghum stalks was lacking in volatile flavors, and the level of harmful contents were uncertain, therefore it could not be sold as liquor. In this study, the protein, fat, and tannin in the clusters and leaves of sweet sorghum were utilized to increase the content of flavor compounds in the ethanol product through the anaerobic fermentation of Saccharomyces cerevisiae. Meanwhile, the silage fermentation method was used to extend the preservation time of the raw materials and to further enhance the flavors of Fen-flavor liquor, with ethyl acetate as the characteristic flavor. The effects of different feedstock groups on ethyl acetate, ethyl lactate, methanol, acetaldehyde, acetal, fusel oil, total acid, and total ester were evaluated by analyzing the chemical composition of different parts of sweet sorghum and determined by gas chromatograph. The effect of different fermentation periods on the volatile flavor of sweet sorghum Baijiu was evaluated. The yield of the characteristic volatile flavor was increased by the extension of the fermentation time. Sweet sorghum Baijiu with a high ester content can be used as a flavoring liquor, blended with liquor with a shorter fermentation period to prepare the finished Fen-flavor Baijiu, conforming to the Chinese national standard for sale.

Effects of Ferulic Acid Esterase-Producing Lactic Acid Bacteria and Storage Temperature on the Fermentation Quality, In Vitro Digestibility and Phenolic Acid Extraction Yields of Sorghum (Sorghum bicolor L.) Silage

Two lactic acid bacteria (LAB) strains with different ferulic acid esterase (FAE) activities were isolated: Lactobacillus farciminis (LF18) and Lactobacillus plantarum (LP23). The effects of these strains on the fermentation quality, in vitro digestibility and phenolic acid extraction yields of sorghum (Sorghum bicolor L.) silage were studied at 20, 30 and 40 °C. Sorghum was ensiled with no additive (control), LF18 or LP23 for 45 days. At 40 °C, the lactic acid content decreased, whereas the ammonia nitrogen (NH₃-N) content significantly increased (p < 0.05). At all three temperatures, the inoculants significantly improved the lactic acid contents and reduced the NH₃-N contents (p < 0.05). Neither LP23 nor LF18 significantly improved the digestibility of sorghum silages (p > 0.05). The LP23 group exhibited higher phenolic acid extraction yields at 30 °C (p < 0.05), and the corresponding yields of the LF18 and control groups were improved at 40 °C (p < 0.05). FAE-producing LABs might partially ameliorate the negative effects of high temperature and improve the fermentation quality of sorghum silage. The screened FAE-producing LABs could be candidate strains for preserving sorghum silage at high temperature, and some further insights into the relationship between FAE-producing LABs and ensiling temperatures were obtained.