Microbial community structure, co-occurrence network and fermentation characteristics of woody plant silage

Cooperation of Lactoplantibacillus plantarum and polyethylene microplastics facilitated the disappearance of tetracycline during anaerobic fermentation of whole plant maize

In agricultural production systems, the harm of both antibiotics and microplastics (MPs) to human health has been an important and continuously concerned issue. A small bagged silage production system was designed to investigate the effects of Lactoplantibacillus plantarum, polyethylene (PE) -MPs and their mixture on the silage fermentation and chemical composition of Tetracycline (TET) -contaminated whole plant maize. In addition, the bacterial community of silage samples was analyzed by using next generation genome sequencing technology. The formation of an extremely acidic environment (pH < 3.8) by ensiling effectively promoted the degradation of tetracycline (about 12.36 ng/ml), with PE-MPs particles also cleaved from 100 μm to 10 μm (in diameter) after 60 days of anaerobic storage. The PE-MPs physically adsorbed TET through its special pore structure and interacted with silage fermentation-dominated microorganisms including Lacticaseibacillus with relative abundances of 33-95 %, where the combination of PE-MPs and L. plantarum degrades tetracycline to 7.05 ng/ml. The PE-MPs inclusion enhanced the fermentation function of Lacticaseibacillus and stabilized the pH, ammonia nitrogen and other chemical indices of silage mass. Importantly, the co-occurrence of PE-MPs sustained also the dominance of desirable Lacticaseibacillus at late stage of ensiling with TET-contaminated maize. Therefore, the combination of PE-MPs and L. plantarum counteracted undesirable silage fermentation from TET contamination, reduced hypothetically the risks to animal and even human health by unappreciated use of antibiotics in agricultural production system.

Effects of tannin-tolerant lactic acid bacteria in combination with tannic acid on the fermentation quality, protease activity and bacterial community of stylo silage

BACKGROUND

Proteolysis during ensiling primarily occurs due to undesirable microbial and plant protease activities, which reduce the protein supply to ruminant livestock and cause a series of environmental problems. The objective of this study was to investigate the effects of the tannin-tolerant lactic acid bacterium strain Lactiplantibacillus plantarum 4 (LABLP4) in combination with tannic acid (TA) on protein preservation in stylo (Stylosanthes guianensis) silage. The stylos were either ensiled without additives (control) or treated with LABLP4 (106 colony-forming units per gram of fresh matter), 1% (fresh matter basis) TA, 2% TA, LABLP4 + 1% TA and LABLP4 + 2% TA. Fermentation quality, protein composition, protease activity and bacterial diversity were determined at 3, 7, 14 and 31 days of ensiling.

RESULTS

The combination of LABLP4 and TA decreased the pH, coliform bacteria count, non-protein nitrogen, ammonia-nitrogen (NH3-N) content and protease activities (P < 0.05) and increased the true protein content (P < 0.05) compared to the control. LABLP4 + TA led to a lower pH and NH3-N content than LABLP4 or TA alone (P < 0.05). On the last day (31 days) of ensiling, LABLP4 + TA increased the relative abundances of Firmicutes and Lactiplantibacillus (P < 0.05), except for the LABLP4 treatment, and decreased the relative abundance of Actinobacteria (P < 0.05).

CONCLUSION

The combination of tannin-tolerant LABLP4 and TA effectively improved the fermentation quality of stylo silage and reduced protein degradation by altering the bacterial community structure. © 2024 Society of Chemical Industry.

Producing high-quality and safe whole-plant quinoa silage through selecting variety and harvest time

The great potential of whole-plant quinoa (WPQ) as a forage crop has been recognized in recent years. In this study, we investigated the effects of variety and harvest time on the fermentation characteristics, bacterial community, and hygienic quality of WPQ silage. Five varieties (Hongxin, Mengli1, SL577, SL2860, SL923) were grown across five separate experimental fields, with harvest occurring after 90 days (H1), 105 days (H2), or 120 days (H3). The samples were ensiled to evaluate their fermentation characteristics and bacterial composition. Hygienic quality was assessed using the Tax4fun2 and BugBase tools for potential pathogenicity and antimicrobial resistance prediction. The variety significantly influenced (P < 0.05) all fermentation variables (including pH, lactic acid, acetic acid, propionic acid, ethanol, and ammonia nitrogen), while harvest time affected pH and the contents of acetic acid, propionic acid, and NH3-N (P < 0.05). An interaction between variety and harvest time was detected (P < 0.05) for all fermentation variables. Based on the flieg' score index, silage quality increased for Mengli1 (5.20-54.8), SL577 (36.7-71.5), and SL923 (34.9-77.0) with delayed harvest time, while silage quality decreased for Hongxin (52.1-41.4) and SL2860 (78.4-63.6). Compared to other silages, Hongxin silages exhibited greater differences in bacterial community composition between harvest times (indicated by higher PERMANOVA R2-value). Tax4fun2 and BugBase analyses revealed that delaying harvest time significantly increased (P < 0.05) the relative abundances of pathogenic and antibiotic-resistant KEGG pathways ("Infectious disease: bacterial invasion" and "Drug resistance") and harmful microbes associated with potential pathogenicity and antimicrobial resistance in Hongxin silages. This study highlights the importance of variety and harvest time in producing high-quality, safe WPQ silage, which is beneficial for ensuring the safety in our food supply chain.

Exploring the influence of moisture stress on microbial-driven organic acid synthesis in potato waste fermentation

Anaerobic fermentation of potato leaves and stems for organic acid synthesis, serving as food additives, faces impediments due to misconceptions about the effects of moisture stress on the acid-synthesizing microbiome. An ingenious method, avoiding interference from microbiome and nutrient integrations, was employed in the present study. Results showed that increasing the moisture level from 60 % to 75 % significantly improved lactic acid (182.64 %), acetic acid (163.55 %), propionic acid (1960.43 %), nonprotein nitrogen, free amino acid and ammonia levels but reduced pH value and water-soluble carbohydrate and hemicellulose levels. Microbiologically, the high-moisture groups enriched Lactiplantibacillus, Levilactobacillus and Enterobacter, upregulated glycolysis, nitrogen, pyruvate and propanoate metabolisms, and activated genes for acid-producing and ammonia-forming enzymes. Notably, Lactiplantibacillus and Enterobacter prevailed in glycolysis and nitrogen metabolism, respectively, and Levilactobacillus was more prominent in pyruvate and propanoate metabolism under high-moisture conditions. Collectively, a moisture level of 75 % benefited organic acid synthesis from potato waste via anaerobic fermentation.

Formation of high-quality mixed silage from paper mulberry and wheat bran driven by the characteristics of the microbial community

Paper mulberry (Broussonetia papyrifera) is a high-quality silage protein feed material that can help address feed shortages and support livestock development. Although some studies have investigated the relationships between microbial communities and silage quality, these relationships and the underlying community assembly processes remain complex, requiring further research to clarify them. Additionally, limited research has explored the relationship between microbial community fermentation functions and silage quality. In this study, we aimed to explore B. papyrifera and wheat bran mixed silage quality driven by the characteristics of the microbial community. After 50 days of silage fermentation, high-quality and low-quality samples were selected from every mixing ratio (90:10, 80:20, and 65:35). The silage chemical composition, lignocellulose degradation enzyme activity, microbial community composition, and potential functions were used to explore the relevance between silage quality and the characteristics of the microbial community. The contents of hemicellulose, neutral detergent fiber, pH, and the activities of endoglucanase and exoglucanase were significantly affected by mixing ratios and silage quality grade. There were higher crude protein content, lignocellulose degrading enzyme activity, and lower pH, lignin, and acid detergent fiber in the mixing of 65:35 (BP65%) samples. The PERMANOVA results showed that mixing ratios had significant impacts on microbial community composition and bacterial fermentation functions. There was a higher bacterial diversity, lower fungal diversity, and better functional potentials for fermentation and lignocellulose degradation in BP65% high-quality silage. The dominant genera were Lactobacillus, Cladosporium, and Wallemia in all samples. The relative abundance of Clostridium, Rhodococcus, Turicibacter, Ralstonia, and Burkholderia was significantly higher in BP65% high-quality samples. There was a higher abundance of Wallemia in the BP65% samples than in other mixing ratios samples. Notably, silage quality showed a close relationship with Lactobacillus, Turicibacter, Romboutsia, Wallemia, and Pichia. In summary, 65:35 was a suitable mixing ratio for B. papyrifera and wheat bran silage, but high-quality silage still required the participation of multiple specific rare microbial taxa. The higher bacterial diversity and specific microbial taxa abundance could be critical for improving B. papyrifera silage quality. We expect that our findings will provide new insights into silage quality driven by the characteristics of the microbial community.

Effect of Lactiplantibacillus and sea buckthorn pomace on the fermentation quality and microbial community of paper mulberry silage

Background

Paper mulberry is a promising alternative fodder source due to its high protein and the abundance of active components. However, paper mulberry often faces susceptibility to contamination during silage fermentation, and there is a need to improve the quality of silage fermentation of paper mulberry through exotic additives. Sea buckthorn pomace (BP) is a feed additive containing antimicrobial and antioxidant substances that help to enhance silage fermentation. Therefore, the objective of this study was to evaluate the effects of BP and Lactiplantibacillus as additives on silage fermentation and bacterial community of paper mulberry.

Results

The results showed that BP and Lactiplantibacillus significantly reduced the pH and ammonium nitrogen content of paper mulberry silage (P < 0.05) and significantly increased the content of lactic acid and acetic acid (P < 0.05), resulting in more residual water-soluble carbohydrate and crude protein contents and less fiber content relative to the control. The key microorganisms in paper mulberry silage fermentation are Lactiplantibacillus pentosus and Weissella cibaria. Among these, Lactiplantibacillus favored a rapid increase in Lactiplantibacillus pentosus abundance during the pre-silage fermentation period, whereas BP favored the promotion of Lactiplantibacillus pentosus growth, resulting in higher contents of lactic and acetic acid than those of the control.

Conclusions

Simultaneously adding Lactiplantibacillus and BP can effectively improve the quality of paper mulberry silage and increase the abundance of beneficial microorganisms in paper mulberry silage.

Microbial network and fermentation modulation of Napier grass and sugarcane top silage in southern Africa

IMPORTANCE

Feed shortage in the tropics is a major constraint to the production of livestock products such as milk and meat. In order to effectively utilize of local feed resources, the selected lactic acid bacteria (LAB) strain was used to prepare Napier grass and sugarcane top silage. The results showed that the two silages inoculated with LAB formed a co-occurrence microbial network dominated by Lactiplantibacillus during the fermentation process, regulated the microbial community structure and metabolic pathways, and improved the silage fermentation quality. This is of great significance for alleviating feed shortage and promoting sustainable production of livestock.

In vitro antibacterial effects of Broussonetia papyrifera leaf extract and its anti-colitis in DSS-treated mice

Recently, the hybrid Broussonetia papyrifera (BP) has been extensively cultivated and predominantly utilized in ruminants because of its high protein and bioactive compound content. In the present study, the effects of an ethanolic extract of BP leaves (BPE, 200 mg/kg) on mitigating 2% dextran sodium sulfate (DSS)-induced intestinal inflammation in mice were evaluated. BPE is rich in flavonoids, polyphenols, and polysaccharides, and displays potent antioxidant and antibacterial activities against pathogenic strains such as Clostridium perfringens, Salmonella Typhimurium, and Salmonella enterica subsp. enterica in vitro. In a mouse study, oral administration of DSS resulted in weight loss, incidence of diarrhea, enlargement of the liver and spleen, impaired colonic morphology, downregulation of both gene and protein expression related to intestinal antioxidant (Nrf2) and barrier function (ZO-1), decreased diversity of colonic microbiota, and 218 differentially altered colonic metabolites; however, co-treatment with BPE did not restore these modified aspects except for the liver index and colonic bacterial diversity. The singular treatment with BPE did not manifest evident side effects in normal mice but induced a mild occurrence of diarrhea and a notable alteration in the colonic metabolite profile. Moreover, a single BPE administration augmented the abundance of the commensal beneficial bacteria Faecalibaculum and Akkermansia genera. Overall, the extract of BP leaves did not demonstrate the anticipated effectiveness in alleviating DSS-induced intestinal inflammation.

Alfalfa as a vegetable source of β-carotene: The change mechanism of β-carotene during fermentation

The objectives of this study were to explore the β-carotene-producing bacteria and ascertain the main factors affecting β-carotene content via investigating the effects of various additives on β-carotene content, bacterial community succession, and quality of fermented alfalfa, using single-molecule real-time (SMRT) sequencing technology. Fresh alfalfa was fermented without (CON) or with squalene (SQ), the combination of Lactobacillus plantarum and cellulase (LPEN), and the combination of SQ and LPEN (SQLPEN) for 3, 45, and 90 d. The results showed that relative to the fresh alfalfa, extensive β-carotene loss in all groups occurred in the early fermentation phase (3 d) since epiphytic Pantoea agglomerans with the ability to produce β-carotene disappeared and β-carotene was oxidized by lipoxygenase and peroxidase. With the prolonged fermentation days, β-carotene content in all groups increased due to bacterial community succession in the middle and late phases of fermentation (45 and 90 d). The species L. parabuchneri, L. kunkeei, and L. kullabergensis (r = 0.591, 0.366, 0.341, orderly) had positive correlations with β-carotene content (P < 0.05). Bacterial functional potential prediction showed that species L. kunkeei, L. helsingborgensis, and L. kullabergensis had positive (r = 0.478, 0.765, 0.601) correlations with C10-C20 isoprenoid biosynthesis (P < 0.01), and L. helsingborgensis and L. kullabergensis had positive (r = 0.805, 0.522) correlations with β-carotene biosynthesis (P < 0.01). Additionally, the pH and propionic acid (r = -0.567, -0.504) had negative correlations with β-carotene content (P < 0.01). The CON group was preserved well after 90 d, LPEN and SQLPEN further improved fermentation quality. In conclusion, certain Lactobacillus had the potential for β-carotene biosynthesis, and high pH and propionic acid content were the unbenefited factors for β-carotene retention in fermented alfalfa.

Silage preparation and sustainable livestock production of natural woody plant

As the global population increases and the economy grows rapidly, the demand for livestock products such as meat, egg and milk continue to increase. The shortage of feed in livestock production is a worldwide problem restricting the development of the animal industry. Natural woody plants are widely distributed and have a huge biomass yield. The fresh leaves and branches of some woody plants are rich in nutrients such as proteins, amino acids, vitamins and minerals and can be used to produce storage feed such as silage for livestock. Therefore, the development and utilization of natural woody plants for clean fermented feed is important for the sustainable production of livestock product. This paper presents a comprehensive review of the research progress, current status and development prospects of forageable natural woody plant feed resources. The nutritional composition and uses of natural woody plants, the main factors affecting the fermentation of woody plant silage and the interaction mechanism between microbial co-occurrence network and secondary metabolite are reviewed. Various preparation technologies for clean fermentation of woody plant silage were summarized comprehensively, which provided a sustainable production mode for improving the production efficiency of livestock and producing high-quality livestock product. Therefore, woody plants play an increasingly important role as a potential natural feed resource in alleviating feed shortage and promoting sustainable development of livestock product.

Microbial assemblages in water hyacinth silages with different initial moistures

Making silage is a green process to use the fast-growing water hyacinth (Eichhornia crassipes) biomass. However, the high moisture (∼95%) of the water hyacinth is the biggest challenge to making silage while its effects on fermentation processes are less studied. In this study, water hyacinths silage with different initial moistures were conducted to investigate the fermentation microbial communities and their roles on the silage qualities. Results show that both silages with 70% (S70) and 90% (S90) of initial moistures achieved the target of silage fermentation, however, their microbial processes were significantly different. Their succession directions of microbial communities were different: Plant cells in S70 were destroyed by the air-dry treatment, thus there were more soluble carbohydrates, which helped the inoculated fermentative bacteria become dominant (Lactobacillus spp. > 69%) and produce abundant lactic acid; In contrast, stochastic succession became dominant over time in S90 (NST = 0.79), in which Lactobacillus spp. and Clostridium spp. produced butyric that also obviously decreased the pH and promoted the fermentation process. Different microbial succession led to different metabolic patterns: S70 had stronger starch and sucrose metabolisms while S90 had stronger amino acid and nitrogen metabolisms. Consequently, S70 had higher lactic acid, crude protein and lower ammonia nitrogen and S90 had higher in vitro digestibility of dry matter and higher relative feeding value. Moreover, the variance partitioning analysis indicated that moisture could only explain less information (5.9%) of the microbial assemblage than pH value (41.4%). Therefore, the colonization of acid-producing bacteria and establishment of acidic environment were suggested as the key on the silage fermentation no matter how much is the initial moisture. This work can provide a basis for the future preparation of high-moisture raw biomasses for silage.

Cellulase-lactic acid bacteria synergy action regulates silage fermentation of woody plant

BACKGROUND

Feed shortage is an important factor limiting livestock production in the world. To effectively utilize natural woody plant resources, we used wilting and microbial additives to prepare an anaerobic fermentation feed of mulberry, and used PacBio single-molecule real-time (SMRT) sequencing technology to analyse the "enzyme-bacteria synergy" and fermentation mechanism.

RESULTS

The fresh branches and leaves of mulberry have high levels of moisture and nutrients, and also contain a diverse range of epiphytic microorganisms. After ensiling, the microbial diversity decreased markedly, and the dominant bacteria rapidly shifted from Gram-negative Proteobacteria to Gram-positive Firmicutes. Lactic acid bacteria (LAB) emerged as the dominant microbial population, resulting in increased in the proportion of the carbohydrate metabolism and decreased in the proportion of the amino acid and "global and overview map" (GOM) metabolism categories. The combination of cellulase and LAB exhibited a synergistic effect, through which cellulases such as glycanase, pectinase, and carboxymethyl cellulase decomposed cellulose and hemicellulose into sugars. LAB converted these sugars into lactic acid through the glycolytic pathway, thereby improving the microbial community structure, metabolism and fermentation quality of mulberry silage. The GOM, carbohydrate metabolism, and amino acid metabolism were the main microbial metabolic categories during ensiling. The presence of LAB had an important effect on the microbial community and metabolic pathways during silage fermentation. A "co-occurrence microbial network" formed with LAB, effectively inhibiting the growth of harmful microorganisms, and dominating the anaerobic fermentation process.

CONCLUSIONS

In summary, PacBio SMRT was used to accurately analyse the microbial network information and regulatory mechanism of anaerobic fermentation, which provided a scientific basis for the study of woody silage fermentation theory. This study reveals for the first time the main principle of the enzyme-bacteria synergy in a woody silage fermentation system, which provides technical support for the development and utilization of woody feed resources, and achieves sustainable livestock production.

Dry matter content and inoculant alter the metabolome and bacterial community of alfalfa ensiled at high temperature

Alfalfa silage fermentation quality, metabolome, bacterial interactions, and successions as well as their predicted metabolic pathways were explored under different dry matter contents (DM) and lactic acid bacteria (LAB) inoculations. Silages were prepared from alfalfa with DM contents of 304 (LDM) and 433 (HDM) g/kg fresh weight and inoculated with Lactiplantibacillus plantarum (L. plantarum, LP), Pediococcus pentosaceus (P. pentosaceus, PP), or sterile water (control). The silages were stored at a simulated hot climate condition (35°C) and sampled at 0, 7, 14, 30, and 60 days of fermentation. The results revealed that HDM significantly improved the alfalfa silage quality and altered microbial community composition. The GC-TOF-MS analysis discovered 200 metabolites in both LDM and HDM alfalfa silage, mainly consisting of amino acids, carbohydrates, fatty acids, and alcohols. Compared with LP and control, PP-inoculated silages had increased concentrations of lactic acid (P < 0.05) and essential amino acids (threonine and tryptophan) as well as decreased pH, putrescine content, and amino acid metabolism. However, alfalfa silage inoculated with LP had higher proteolytic activities than control and PP-inoculated silage, as revealed by a higher concentration of ammonia nitrogen (NH₃-N), and also upregulated amino acid and energy metabolism. HDM content and P. pentosaceus inoculation significantly altered the composition of alfalfa silage microbiota from 7 to 60 days of ensiling. Conclusively, these results indicated that inoculation with PP exhibited great potential in enhancing the fermentation of silage with LDM and HDM via altering the microbiome and metabolome of the ensiled alfalfa, which could help in understanding and improving the ensiling practices under hot climate conditions. KEY POINTS: • HDM improved fermentation quality and declined putrescine content of alfalfa silage • P. pentosaceus inoculation enhanced the fermentation quality of alfalfa silage • P. pentosaceus is an ideal inoculant for alfalfa silage under high temperature.

Soil properties and silage quality in response to oat and pea seeding ratios and harvest stage on the Qinghai-Tibetan Plateau

Livestock intensification improves production efficiency and enhances the demand for quality forage to feed ruminants. Novel combinations of forage plants, especially including Gramineae and Leguminous plants, benefit both ruminant animals and contribute to a sustainable environment. This study explored an oat-pea mixed seeding strategy as an approach to improving silage quality. Before ensialing, lactic acid bacteria (Lactobacillus plantarum and Lactobacillus brucelli) were added to forage from five different mixed seeding proportions of oats (O) and peas (P) (10:0, 8:2, 7:3, 5:5, and 0:10 oat to pea ratio) at two harvesting periods (the early flowering stage and the milk ripening stage for the oats). The results showed that mixed seeding changed the soil quality parameters. Moreover, the silage from the O5P5 (5:5 oat to pea ratio) group showed the lowest pH values (4.16) and highest LA contents (7.74% DM) after ensiling for 7d (p &lt; 0.05) in early flowering stage. Also, the O5P5 group increased the number of tillers/branches and produced silage with the highest CP content (13.14–14.06) after ensiling for 7d in early flowering stage and both 7d and 30d in early flowering stage and milk ripening stage (p &lt; 0.05). In conclusion, this study found that the selection of oat-pea mixed seeding as O5P5 and harvesting at the milk ripening stage of oat is recommended as a desirable oat-pea mixed seeding strategy for producing high quality silage.

Patterns of biogenic amine during broad bean paste fermentation: microbial diversity and functionality via Bacillus bioaugmentation

BACKGROUND

Broad bean paste is a high nitrogen and high salt traditional Chinese condiment, which triggers biosynthesis of nitrogen hazards like biogenic amines (BAs). Mechanisms of association and applied research of functional safety and community assembly within multiple-microbial fermentation are currently lacking. Here, bioaugmentation was performed based on the profiles of BAs accumulation and microbial succession to evaluate the functional variation within broad bean paste fermentation.

RESULTS

Putrescine, spermine, and spermidine were the main BAs during traditional broad bean paste fermentation. Staphylococcus, Streptococcus, Lactococcus, Lactobacillus, Leuconostoc, and Bacillus were the predominant bacteria, whereas Aspergillus and Zygosaccharomyces dominated in fungal species, and community structure shifted upon salt exposure. PICRUSt software uncovered that Bacillus contributed significantly (>1%) to the amine oxidase gene family. Bacillus amyloliquefaciens 1-G6 and Bacillus licheniformis 2-B3 were screened to perform the bioaugmentation of broad bean paste, which achieved a 29% and 16% BA decrease respectively. Interaction network analysis showed that Cronobacter and Lactobacillus were significantly negatively correlated with Bacillus (ρ = -0.829 and ρ = -0.714, respectively, P < 0.05) in the B. amyloliquefaciens 1-G6 group, and Staphylococcus and Buttiauxella were inhibited by Bacillus (ρ = -0.657 and ρ = -0.543, respectively, P < 0.05) in the B. licheniformis 2-B3 group.

CONCLUSION

The synergism of amine oxidase activity and microbial interactions led to the decline of BAs. Thus, this study improves our understanding of the underlying mechanisms of microbial succession and functional variation to further facilitate the optimization of the fermented food industry.

Effect of different regions on fermentation profiles, microbial communities, and their metabolomic pathways and properties in Italian ryegrass silage

Introduction

Italian ryegrass is less studied in northern China due to high-quality forage grass has not been fully utilized. Full utilization of high-quality forage grass helps to alleviate the shortage of forage grass in winter and spring season and guarantee stable development of livestock production. Consequently, this study was aimed to evaluate the effects of different regions in northern China on the fermentative products, bacterial community compositions, and metabolic pathways and metabolites of Italian ryegrass silage.

Methods

The Italian ryegrass was harvested from three regions (Ordos-WK; Hohhot-AK; Ulanqab-SYK) and ensiled for 60 days. Single molecule real-time (SMRT) sequencing and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) were used to analyze bacterial communities and metabolites, respectively.

Results

After 60 d of fermentation, the SYK group had the lowest pH (4.67), the highest lactic acid contents (95.02 g/kg DM) and largest lactic acid bacteria populations (6.66 log₁₀ cfu/g FM) among the treatment groups. In addition, the SYK group had the highest abundance of Lactiplantibacillus plantarum (63.98%). In SYK group, isoquinoline alkaloid biosynthesis was the significantly enriched (p < 0.05) and high-impact value (0.0225) metabolic pathway. In AK group, tryptophan metabolism the was the significantly enriched (p < 0.001) and high-impact value (0.1387) metabolic pathway. In WK group, citrate cycle (TCA cycle) was the significantly enriched (p < 0.001) and high-impact value (0.1174) metabolic pathway. Further, Lactiplantibacillus plantarum was positively correlated with cinnamic acid, tetranor 12-HETE, D-Mannitol, (2S)-2-amino-4-methylpentanoic acid L-Leucine, guanine, isoleucyl-aspartate and 3,4-Dihydroxyphenyl propanoate, but negatively correlated with isocitrate and D-mannose.

Discussion

In conclusion, this study can improve our understanding of the ensiling microbiology and metabolomics in different regions to further regulate the fermentation products and promote livestock production.

Anaerobic fermentation featuring wheat bran and rice bran realizes the clean transformation of Chinese cabbage waste into livestock feed

Rapid aerobic decomposition and a high cost/benefit ratio restrain the transformation of Chinese cabbage waste into livestock feed. Herein, anaerobically co-fermenting Chinese cabbage waste with wheat bran and rice bran at different dry matter levels (250, 300, 350 g/kg fresh weight) was employed to achieve the effective and feasible clean transformation of Chinese cabbage waste, and the related microbiological mechanisms were revealed by high-throughput sequencing technology. The bran treatments caused an increase in pH value (4.75-77.25%) and free amino acid content (12.09-152.66%), but a reduction in lactic acid concentration (54.58-77.25%) and coliform bacteria counts (15.91-20.27%). In addition, the wheat bran treatment improved the levels of short-chain fatty acids, nonprotein nitrogen, water-soluble carbohydrates and antioxidant activity and reduced the ammonia nitrogen contents. In contrast, the rice bran treatment decreased the levels of acetic acid, water-soluble carbohydrates, nonprotein nitrogen, ammonia nitrogen, and antioxidant activities. Microbiologically, the bran treatments stimulated Pediococcus, Lactobacillus, Enterobacter, and Weissella but inhibited Lactococcus and Leuconostoc, which were the primary organic acid producers reflected by the redundancy analysis. In addition, Chinese cabbage waste fermented with wheat bran at 350 g/kg fresh weight or with rice bran at 300 g/kg fresh weight increased the scale and complexity of bacteriome, promoted commensalism or mutualism and upregulated the global metabolism pathways, including carbohydrate and amino acid metabolisms. Furthermore, the bran treatments resulted in an increase in bacterial communities that were facultatively anaerobic, biofilm-formed, Gram-negative, potentially pathogenic and stress-tolerant. Collectively, the bran treatments inhibited effluent formation and protein degradation and improved nutrient preservation but reduced organic acid production during the anaerobic fermentation, which is linked to the variations in the bacteriome, indicating that the constructed fermentation system should be further optimized.

Effects of Acremonium cellulase and heat-resistant lactic acid bacteria on lignocellulose degradation, fermentation quality, and microbial community structure of hybrid elephant grass silage in humid and hot areas

To better evaluate the effects of Acremonium cellulase (AC) and previously screened heat-resistant Lactobacillus plantarum 149 (LP149) on lignocellulose degradation, fermentation quality, and microbial community during ensiling in humid and hot areas, this study used a small-scale fermentation system to prepare hybrid elephant grass silage at 30 and 45°C, respectively. Compared to control and commercial inoculant Lactobacillus plantarum (LP), the addition of AC or strain LP149 decreased the contents of neutral detergent fiber, acid detergent fiber, and cellulose and increased the contents of glucose, fructose, and sucrose during fermentation. Furthermore, AC and LP149 treatments altered the microbial communities' structure during ensiling. AC treatment provided more substrate for microbial fermentation, resulting in an increase in bacterial alpha diversity. LP149 treatment increased the Lactobacillus abundance and optimized the bacterial community compositions. In addition, AC and LP149 treatments had higher (P < 0.05) lactic acid and acetic acid contents and lower (P < 0.05) pH, butyric acid, and NH3-N levels compared to the control. These results indicated that AC and strain LP149 are promising silage additives that can promote lignocellulose degradation and improve the fermentation quality of hybrid elephant grass in humid and hot areas.

Microbial Community, Co-Occurrence Network Relationship and Fermentation Lignocellulose Characteristics of Broussonetia papyrifera Ensiled with Wheat Bran

Broussonetia papyrifera has a high lignocellulose content leading to poor palatability and low digestion rate of ruminants. Thus, dynamic profiles of fermentation lignocellulose characteristics, microbial community structure, potential function, and interspecific relationships of B. papyrifera mixing with wheat bran in different ratios: 100:0 (BP100), 90:10 (BP90), 80:20 (BP80), and 65:35 (BP65) were investigated on ensiling days 5, 15, 30, and 50. The results showed that adding bran increased the degradation rate of hemicellulose, neutral detergent fiber, and the activities of filter paper cellulase, endoglucanase, acid protease, and neutral protease, especially in the ratio of 65:35. Lactobacillus, Pediococcus, and Weissella genus bacteria were the dominant genera in silage fermentation, and Pediococcus and Weissella genus bacteria regulated the process of silage fermentation. Compared with monospecific B. papyrifera silage, adding bran significantly increased the abundance of Weissella sp., and improved bacterial fermentation potential in BP65 (p < 0.05). Distance-based redundancy analysis showed that lactic acid bacteria (LAB) were significantly positive correlated with most lignocellulose content and degrading enzymes activities, while Monascus sp. and Syncephalastrum sp. were opposite (p < 0.05). Co-occurrence network analysis indicated that there were significant differences in microbial networks among different mixing ratios of B. papyrifera silage prepared with bran. There was a more complex, highly diverse and less competitive co-occurrence network in BP65, which was helpful to silage fermentation. In conclusion, B. papyrifera ensiled with bran improved the microbial community structure and the interspecific relationship and reduced the content of lignocellulose.

Addition of Organic Acids and Lactobacillus acidophilus to the Leguminous Forage Chamaecrista rotundifolia Improved the Quality and Decreased Harmful Bacteria of the Silage

This study aimed to investigate the effects of citric acid, malic acid, and Lactobacillus acidophilus (L) on fermentation parameters and the microbial community of leguminous Chamaecrista rotundifolia silage. Fresh C. rotundifolia was treated without any additive (CK), or with L (106 CFU/g fresh weight), different levels (0.1, 0.3, 0.5, and 1% fresh weight) of organic acid (malic or citric acid), and the combinations of L and the different levels of organic acids for 30, 45, and 60 days of ensiling. The effects of malic acid and citric acid were similar during the ensiling process. Treatment with either citric or malic acid and also when combined with L inhibited crude protein degradation, lowered pH and ammonia nitrogen, and increased lactic acid concentration and dry matter content (p < 0.05). The neutral detergent fiber and acid detergent fiber increased initially and then decreased with fermentation time in all treatments (p < 0.05). Increasing the level of organic acid positively affected the chemical composition of C. rotundifolia silage. In addition, the addition of 1% organic acid increased the relative abundance of Lactobacillus, while the relative abundances of Clostridium and Enterobacter decreased at 60 days (p < 0.05). Moreover, both organic acids and combined additives increased (p < 0.05) the relative abundance of Cyanobacteria at 60 days of fermentation. We concluded that adding malic acid, citric acid, and L combined with an organic acid could improve the quality of C. rotundifolia silage and increase the relative abundance of beneficial bacteria. The addition of organic acid at a level of 1% was the most effective.

Gamma-ray irradiation and microbiota transplantation to separate the effects of chemical and microbial diurnal variations on the fermentation characteristics and bacterial community of Napier grass silage

BACKGROUND

To investigate the contributions of chemical and microbial diurnal variations in fermentation characteristics and bacterial community of Napier grass silage, gamma-ray irradiated Napier grass harvested at 07.00 h (AM), 12.00 h (M) and 17.00 h (PM) was inoculated with the microbiota derived from Napier grass harvested at AM, M and PM in a 3 (irradiated forage: AM_G , M_G and PM_G ) × 3 (microbiota: AM_M , M_M and PM_M ) design and then ensiled for 14 and 60 days.

RESULTS

Napier grass harvested at various times had different chemical compositions and epiphytic microbiota prior to ensiling. For silages inoculated with the same microbiota, the pH values, residual water soluble carbohydrates and dry matter contents increased, and lactic acid, acetic acid, propionic acid, butyric acid, ethanol and volatile fatty acids contents decreased in PM_G and M_G silages compared to AM_G silages. M_M and PM_M inoculum promoted lactic acid fermentation as indicated by higher lactic acid contents and lactic/acetic acid ratios in M_M and PM_M -inculated silages compared to those in AM_M -inoculated silages after 60 days of ensiling. During ensiling, epiphytic microbiota affected the Chao1 index, operational taxonomic units (OTUs) number and Shannon index, as well as the abundances, of more than half of the top 10 abundant genera, whereas chemical composition did not affect any of the bacterial diversity and richness indices and only showed significant impacts on the abundances of two genera.

CONCLUSION

The results indicated that chemical diurnal variation exerted an influence mainly on the extent of fermentation, whereas microbial diurnal variation affected more the bacterial community and fermentation types during Napier grass ensiling. © 2022 Society of Chemical Industry.

Time of Day for Harvest Affects the Fermentation Parameters, Bacterial Community, and Metabolic Characteristics of Sorghum-Sudangrass Hybrid Silage

To characterize the effects of time of day for harvest on the fermentation parameters, bacterial community, and metabolic characteristics of sorghum-sudangrass hybrid (SSG) silage, SSG (vegetative stage) harvested at 7:00 (AM), 12:00 (M), and 17:00 (PM) on three sunny days were ensiled for 1, 3, 7, 14, 30, and 60 days. Compared to AM silage, M and PM silages were characterized by delayed fermentation, unnormal lower final pH, and lower acetic acid production. In addition, PM silage contained higher residual water-soluble carbohydrates than other silages. After 60 days of ensiling, AM silage was dominated by Lactobacillus, whereas the bacterial communities of M and PM silages were complex and mainly composed of bacteria such as Delftia, Methylobacterium-Methylorubrum, Enhydrobacter, Acinetobacter, and Bacillus. The harvest time affected a wide range of metabolic pathways including "Metabolism" and "Cellular Processes" and "Organismal Systems" in SSG silage. Particularly, at the late stage of ensiling M silage exhibited highest relative abundances of amino acid metabolisms including "glycine, serine, and threonine metabolism," "phenylalanine metabolism," and lowest relative abundances of "lysine biosynthesis." These results suggest that the time of day for harvest could affect the fermentation parameters, bacterial community, and metabolic characteristics of SSG silage. Better SSG silage characteristics could be achieved through morning harvest. IMPORTANCE Ensiling is a common way for preserving green forages worldwide. Silage fermentation quality can vary greatly depending on the chemical and microbial characteristics of forage crop being ensiled. It is well documented that forages exhibit considerable variations in chemical composition and epiphytic microbiota during daylight. However, the effects of the time of day for harvest on silage fermentation is less investigated. Our results demonstrate that the time of day for harvest could affect the fermentation parameters, bacterial community, and metabolic characteristics of SSG hybrid silage. Harvesting SSG late in the day delayed fermentation process, lowered acetic acid production and final pH, and increased the residual water-soluble carbohydrates content in silage. Moreover, the delayed harvest time increased the relative abundances of bacteria such as Delftia, Methylobacterium-Methylorubrum, Acinetobacter, Enhydrobacter, and Bacillus, and amino acid metabolisms at the late stage of SSG ensiling. This study highlights the importance of diurnal changes in forage to fermentation characteristics, providing a strategy to improve silage quality through optimizing the harvest time.

Characterization of Lactic Acid Bacteria Isolated from Banana and Its Application in Silage Fermentation of Defective Banana

To effectively utilize banana by-products, we prepared silage with defective bananas using screened lactic acid bacteria (LAB), sucrose, and tannase as additives. Eleven strains of LAB were isolated from the fruits and flowers of defective bananas, all of which were Gram-positive and catalase-negative bacteria that produced lactic acid from glucose. Among these LAB, homofermentative strain CG1 was selected as the most suitable silage additive due to its high lactic acid production and good growth in a low pH environment. Based on its physiological and biochemical properties and 16S rRNA gene sequence analysis, strain CG1 was identified as Lactiplantibacillus plantarum. Defective bananas contain 74.8−76.3% moisture, 7.2−8.2% crude protein, 5.9−6.5% ether extract, and 25.3−27.8% neutral detergent fibre on a dry matter basis. After 45 d of fermentation, the silage of deficient bananas treated with LAB or sucrose alone improved fermentation quality, with significantly (p < 0.05) lower pH and higher lactic acid contents than the control. The combination of LAB and sucrose had a synergistic effect on the fermentation quality of silage. The tannase-treated silage significantly (p < 0.05) decreased the tannin content, while the combination of tannase and LAB in silage not only decreased (p < 0.05) the tannin content, but also improved the fermentation quality. The study confirmed that defective bananas are rich in nutrients, can prepare good quality silage, and have good potential as a feed source for livestock.

The Potential of Pre-fermented Juice or Lactobacillus Inoculants to Improve the Fermentation Quality of Mixed Silage of Agro-Residue and Lucerne

The objective of this study was to determine the effect of pre-fermented juice, Lactobacillus plantarum, and L. buchneri on chemical composition, fermentation, aerobic stability, dynamics of microbial community, and metabolic pathway of a mixture of lucerne, wheat bran (WB), and rice straw (RS). All mixtures were ensiled for 1, 3, 5, 7, 15, 30, and 45 days after treatment with uninoculated (control, C); L. plantarum [LP, 1 × 106 cfu/g of fresh weight (FW)]; L. buchneri (LB, 1 × 106 cfu/g of FW); LP + LB (LPB, 1 × 106 cfu/g of FW of each inoculant); and pre-fermented juice (J; 2 × 106 cfu/g of FW). Four lactic acid bacteria (LAB) species from three genera were cultured from the pre-fermented juice, with W. cibaria being dominant. The inoculants increased lactic acid (LA), decreased pH and ammonia nitrogen (AN) compared to C silage at earlier stages of ensiling, and high dry matter (DM) and water-soluble carbohydrate (WSC) content in inoculated silages. Adding LPB increased the abundance of L. plantarum, L. paralimentarius, and L. nodensis, resulting in the lowest pH. Pre-fermented juice enriched W. cibaria, L. sakei, L. parabrevis, Pseudomonas putida, and Stenotrophomonas maltophilia, mainly enhanced accumulation of acetic acid (AA) and LA, and decreased pH, crude protein losses, AN, and hemicellulose contents. L. buchneri and L. brevis had a high abundance in LB-treated and J silages, respectively, inhibited undesirable bacteria, and improved aerobic stability with more than 16 days. In addition, the metabolic pathways changed with time and L. buchneri inoculants promoted global metabolism. In conclusion, inoculations altered bacterial succession and metabolic pathways in silage; LB and pre-fermented juice enhanced ensiling by promoting pH reductions, enhancing concentrations of LA and AA, and extending aerobic stability more than 16 days.

Hybrid Broussonetia papyrifera Fermented Feed Can Play a Role Through Flavonoid Extracts to Increase Milk Production and Milk Fatty Acid Synthesis in Dairy Goats

In order to explore the effect of hybrid Broussonetia papyrifera fermented feed on milk production and milk quality of dairy goats, and to compare with alfalfa hay, three dairy goat diets were designed based on the principle of equal energy and equal protein. The goats in the control group were fed a basic TMR diet (CG group), and the other two groups were supplemented with 10% alfalfa hay (AH group) and 10% hybrid B. papyrifera fermented feed (BP group). The results showed that the dry matter intake and milk production of BP group increased significantly. The total amount of amino acids and the content of each amino acid in the milk of AH group and BP group were lower than those of CG group. The content of saturated fatty acids in the milk of BP group decreased while the content of unsaturated fatty acids increased. The contents of prolactin, estrogen and progesterone in BP goat serum were generally higher than those of AH goat and CG goat. Subsequently, this study separated and cultured mammary epithelial cells from breast tissue, and added flavone extracted from the leaves of hybrid B. papyrifera and alfalfa to their culture medium for comparison, which is one of their important bioactive components. The results showed that low-dose alfalfa flavone (AH) and hybrid B. papyrifera flavone (BP) can increase cell viability. They also can increase the accumulation of intracellular triglyceride and the formation of lipid droplets. Both AH flavone and BP flavone significantly up-regulated the expression of genes related to milk fat synthesis, including genes related to fatty acid de novo synthesis (ACACA, FASN, and SCD1), long-chain fatty acid activation and transport related genes (ACSL1), and genes related to transcription regulation (SREBP1). The three genes related to triglyceride synthesis (DGAT1, DGAT2, and GPAM) were all significantly increased by BP flavone. Both AH flavone and BP flavone significantly increased the protein expression of progesterone receptor and estrogen receptor in mammary epithelial cells but had no effect on prolactin receptor.

Fermentation Profiles, Bacterial Community Compositions, and Their Predicted Functional Characteristics of Grass Silage in Response to Epiphytic Microbiota on Legume Forages

This study aimed to investigate the effect of epiphytic microbiota from alfalfa and red clover on the fermentative products, bacterial community compositions, and their predicted functional characteristics in Italian ryegrass silage. By microbiota transplantation and γ-ray irradiation sterilization, the irradiated Italian ryegrass was treated as follows: (1) sterile distilled water (STIR); (2) epiphytic microbiota on Italian ryegrass (IRIR); (3) epiphytic microbiota on alfalfa (IRAL); and (4) epiphytic microbiota on red clover (IRRC). The irradiated Italian ryegrass was ensiled for 1, 3, 7, 15, 30, and 60 days. STIR had similar chemical components with fresh Italian ryegrass. IRAL had higher lactic acid concentrations [64.0 g/kg dry matter (DM)] than IRIR (22.3 g/kg DM) and IRRC (49.4 g/kg DM) on day 3. IRRC had the lowest lactic acid concentrations (59.7 g/kg DM) and the highest pH (4.64), acetic acid (60.4 g/kg DM), ethanol (20.4 g/kg DM), and ammonia nitrogen (82.6 g/kg DM) concentrations and Enterobacteriaceae [9.51 log10 cfu/g fresh weight (FW)] populations among treatments on day 60. On days 3 and 60, Lactobacillus was dominant in both IRIR (42.2%; 72.7%) and IRAL (29.7%; 91.6%), while Hafnia-Obesumbacterium was predominant in IRRC (85.2%; 48.9%). IRIR and IRAL had lower abundances of "Membrane transport" than IRRC on day 3. IRIR and IRAL had lower abundances of phosphotransacetylase and putative ATP-binding cassette transporter and higher abundances of arginine deiminase on day 3. IRAL had the highest abundance of fructokinase on day 3. Overall, inoculating epiphytic microbiota from different legume forages changed the fermentative products, bacterial community compositions, and their predicted functional characteristics in Italian ryegrass silage. The microbial factors that result in the differences in fermentative profiles between legume forage and grass were revealed. Knowledge regarding the effect of epiphytic microbiota could provide more insights into the improvement of silage quality.

Addition of Lactic Acid Bacteria Can Promote the Quality and Feeding Value of Broussonetia papyrifera (Paper Mulberry) Silage

In this study, the influence of two lactic acid bacteria (LAB) strains [Lactobacillus rhamnosus BDy (LR-BDy) and Lactobacillus buchneri TSy (LB-TSy)] selected from Southwest China on the fermentation characteristics and in vitro gas production of Broussonetia papyrifera (paper mulberry) silage were experimentally explored. The experimental groups were a control group (C), an LB-TSy treatment (LB), an LR-BDy treatment (LR), and an LR-BDy + LB-TSy hybrid group (LR × LB). After the LAB were added, the pH value of paper mulberry silage significantly declined (p < 0.05), and the crude protein content was effectively preserved (p < 0.05). However, no significant changes were found in the levels of neutral detergent fiber, acid detergent fiber, and crude ash (p > 0.05). The lactic acid content in paper mulberry silage was evidently increased (p < 0.05). The in vitro gas production in the LR at 36, 48, and 72 h were markedly higher than that in the other treatments (p < 0.05). Owing to the addition of LAB, the microbial diversity in paper mulberry silage was reduced, while the relative bacterial abundance of Lactobacillus was enhanced. Hence, the addition of LAB selected from the warm and humid region in Southwest China can improve the quality of paper mulberry silage and elevate its feeding value in this region.