Dynamics of microbial community and fermentation quality during ensiling of sterile and nonsterile alfalfa with or without Lactobacillus plantarum inoculant

Effects of selenium enrichment on fermentation characteristics, selenium content and microbial community of alfalfa silage

BACKGROUND

Selenium is essential for livestock and human health. The traditional way of adding selenium to livestock diets has limitations, and there is a growing trend to provide livestock with a safe and efficient source of selenium through selenium-enriched pasture. Therefore, this study was conducted to investigate the effects of selenium enrichment on fermentation characteristics, selenium content, selenium morphology, microbial community and in vitro digestion of silage alfalfa by using unenriched (CK) and selenium-enriched (Se) alfalfa as raw material for silage.

RESULTS

In this study, selenium enrichment significantly increased crude protein, soluble carbohydrate, total selenium, and organic selenium contents of alfalfa silage fresh and post-silage samples, and it significantly decreased neutral detergent fiber and acid detergent fiber contents (p < 0.05). Selenium enrichment altered the form of selenium in plants, mainly in the form of SeMet and SeMeCys, which were significantly higher than that of CK (p < 0.05). Selenium enrichment could significantly increase the lactic acid content, reduce the pH value, change the diversity of bacterial community, promote the growth of beneficial bacteria such as Lactiplantibacillus and inhibit the growth of harmful bacteria such as Pantoea, so as to improve the fermentation quality of silage. The in vitro digestibility of dry matter (IVDMD), in vitro digestibility of acid detergent fibers (IVADFD) and in vitro digestibility of acid detergent fibers (IVNDFD) of silage after selenium enrichment were significantly higher than those of CK (p < 0.05).

CONCLUSION

This study showed that the presence of selenium could regulate the structure of the alfalfa silage bacterial community and improve alfalfa silage fermentation quality. Selenium enrichment measures can change the morphology of selenium in alfalfa silage products, thus promoting the conversion of organic selenium.

Utilisation of Lactiplantibacillus plantarum and propionic acid to improve silage quality of amaranth before and after wilting: fermentation quality, microbial communities, and their metabolic pathway

Objective

The aim of this study was to investigate the effects of Lactiplantibacillus plantarum (L. plantarum) and propionic acid (PA) on fermentation characteristics and microbial community of amaranth (Amaranthus hypochondriaus) silage with different moisture contents.

Methods

Amaranth was harvested at maturity stage and prepared for ensiling. There were two moisture content gradients (80%: AhG, 70%: AhS; fresh material: FM) and three treatments (control: CK, L. plantarum: LP, propionic acid: PA) set up, and silages were opened after 60 d of ensiling.

Results

The results showed that the addition of L. plantarum and PA increased lactic acid (LA) content and decreased pH of amaranth after fermentation. In particular, the addition of PA significantly increased crude protein content (p < 0.05). LA content was higher in wilted silage than in high-moisture silage, and it was higher with the addition of L. plantarum and PA (p < 0.05). The dominant species of AhGLP, AhSCK, AhSLP and AhSPA were mainly L. plantarum, Lentilactobacillus buchneri and Levilactobacillus brevis. The dominant species in AhGCK include Enterobacter cloacae, and Xanthomonas oryzae was dominated in AhGPA, which affected fermentation quality. L. plantarum and PA acted synergistically after ensiling to accelerate the succession of dominant species from gram-negative to gram-positive bacteria, forming a symbiotic microbial network centred on lactic acid bacteria. Both wilting and additive silage preparation methods increased the degree of dominance of global and overview maps and carbohydrate metabolism, and decreased the degree of dominance of amino acid metabolism categories.

Conclusion

In conclusion, the addition of L. plantarum to silage can effectively improve the fermentation characteristics of amaranth, increase the diversity of bacterial communities, and regulate the microbial community and its functional metabolic pathways to achieve the desired fermentation effect.

Insights into the phage community structure and potential function in silage fermentation

The virus that infects bacteria known as phage, plays a crucial role in the biogeochemical cycling of nutrients. However, the community structure and potential functions of phages in silage fermentation remain largely unexplored. In this study, we utilized viral metagenomics (viromics) to investigate the types, lifestyles, functions, and nutrient utilization patterns of phages in silage. Our findings indicated a high prevalence of annotated phages belonging to Caudovirales and Geplafuvirales, as well as unclassified phages in silage. The predominant host types for these phages were Campylobacterales and Enterobacterales. Virulent phages dominated the silage environment due to their broader range of hosts and enhanced survival capabilities. All identified phages present in silage were found to be non-pathogenic. Although temperate and virulent phages carried distinct genes associated with nutrient cycling processes, the shared genes (prsA) involved in carbon metabolism underscore the potential significance of phages in regulating carbon metabolism in silage. Overall, our findings provide a valuable foundation for further exploring the complex interactions between phages and microorganisms in regulating silage fermentation quality.

Effects of Dried Tea Residues of Different Processing Techniques on the Nutritional Parameters, Fermentation Quality, and Bacterial Structure of Silaged Alfalfa

The effects of dried tea residues on the nutritional parameters and fermentation quality, microbial community, and in vitro digestibility of alfalfa silage were investigated. In this study, dried tea residues generated from five different processing techniques (green tea, G; black tea, B; white tea, W; Pu'er raw tea, Z; Pu'er ripe tea, D) were added at two addition levels (5% and 10% fresh weight (FW)) to alfalfa and fermented for 90 days. The results showed that the tea residues increased the crude protein (CP) content (Z10: 23.85%), true protein nitrogen (TPN) content, DPPH, and ABST radical scavenging capacity, total antioxidant capacity (T-AOC), and in vitro dry matter digestibility (IVDMD) of the alfalfa silage. Moreover, the pH, ammonia-N (NH3-N) content, and acetic acid (AA) content decreased (p < 0.05). The effects of tea residues were promoted on these indicators with increasing tea residue addition. In addition, this study revealed that the influence of dried tea residues on the nutritional quality of alfalfa silage was greater than that on fermentation quality. Based on the nutrient composition, the addition of B or G to alfalfa silage can improve its silage quality, and these tea byproducts have the potential to be used as silage additives.

Effects of lactic acid bacteria inoculants on the nutrient composition, fermentation quality, and microbial diversity of whole-plant soybean-corn mixed silage

The mixture of whole-plant soybean and whole-plant corn silage (WPSCS) is nutrient balanced and is also a promising roughage for ruminants. However, few studies have investigated the changes in bacterial community succession in WPSCS inoculated with homofermentative and heterofermentative lactic acid bacteria (LAB) and whether WPSCS inoculated with LAB can improve fermentation quality by reducing nutrient losses. This study investigated the effect of Lactobacillus plantarum (L. plantarum) or Lactobacillus buchneri (L. buchneri) on the fermentation quality, aerobic stability, and bacterial community of WPSCS. A 40:60 ratio of whole-plant soybean corn was inoculated without (CK) or with L. plantarum (LP), L. buchneri (LB), and a mixture of LP and LB (LPB), and fermented for 14, 28, and 56 days, followed by 7 days of aerobic exposure. The 56-day silage results indicated that the dry matter content of the LP and LB groups reached 37.36 and 36.67%, respectively, which was much greater than that of the CK group (36.05%). The pH values of the LP, LB, and LPB groups were significantly lower than those of the CK group (p < 0.05). The ammoniacal nitrogen content of LB was significantly lower than that of the other three groups (p < 0.05), and the ammoniacal nitrogen content of LP and LPB was significantly lower than that of CK (p < 0.05). The acetic acid content and aerobic stability of the LB group were significantly greater than those of the CK, LP, and LPB groups (p < 0.05). High-throughput sequencing revealed a dominant bacteria shift from Proteobacteria in fresh forage to Firmicutes in silage at the phylum level. Lactobacillus remained the dominant genus in all silage. Linear discriminant analysis effect size (LEFSe) analysis identified Lactobacillus as relatively abundant in LP-treated silage and Weissella in LB-treated groups. The results of KEGG pathway analysis of the 16S rRNA gene of the silage microbial flora showed that the abundance of genes related to amino acid metabolism in the LP, LB, and LPB groups was lower than that in the CK group (p < 0.05). In conclusion, LAB application can improve the fermentation quality and nutritional value of WPSCS by regulating the succession of microbial communities and metabolic pathways during ensiling. Concurrently, the LB inoculant showed the potential to improve the aerobic stability of WPSCS.

Epiphytic microbiota source stimulates the fermentation profile and bacterial community of alfalfa-corn mixed silage

The epiphytic microbiota source on plants plays a crucial role in the production of high-quality silage. To gain a better understanding of its contribution, the microbiota of alfalfa (M1C0), corn (M0C1) and the resulting mixture (M1C1) was applied in alfalfa-corn mixed silage production system. M1C0 decreased ammonia-N levels in terms of total nitrogen (57.59-118.23 g/kg TN) and pH (3.59-4.40) values (p < 0.01), which increased lactic acid (33.73-61.89 g/kg DM) content (p < 0.01). Consequently, this resulted in higher residual water-soluble carbohydrate (29.13-41.76 g/kg DM) and crude protein (152.54-167.91 g/kg DM) contents, as well as lower NDF (427.27 g/kg DM) and ADF (269.53 g/kg DM) contents in the silage compared to M1C1- and M0C1-treated samples. Moreover, M1C0 silage showed significantly higher bacterial alpha diversity indices (p < 0.05), including the number of observed species and Chao1 and Shannon diversity indices, at the later stages of ensiling. Lactobacillus, Kosakonia and Enterobacter were the dominant bacterial species in silages, with a relative abundance of >80%. However, the abundance of Lactobacillus amylovorus in M0C1- and M1C1-treated silage increased (p < 0.01) in the late stages of ensiling. These findings confirmed that the epiphytic microbiota source exerts competitive effects during anaerobic storage of alfalfa-corn mixed silage.

Effect of additive cellulase on fermentation quality of whole-plant corn silage ensiling by a Bacillus inoculant and dynamic microbial community analysis

Whole-plant corn silage (WPCS) has been widely used as the main roughage for ruminant, which promoted the utilization of corn stover for animal feed production. However, rigid cell wall structure of corn stover limits the fiber digestion and nutrients adsorption of WPCS. This study investigated the effect of adding cellulase on improving the fermentation quality of WPCS ensiling with a Bacillus complex inoculant. With the Bacillus (BA), the lactic acid accumulation in the WPCS was significantly higher than that in control (CK). The additive cellulase (BC) increased the lactic acid content to the highest of 8.2% DW at 60 days, which was significantly higher than that in the CK and BA groups, and it reduced the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents from 42.5 to 31.7% DW and 28.4 to 20.3% DW, respectively, which were significantly lower than that in the CK and BA groups. The crude protein and starch were not obviously lost. Dynamic microbial community analysis showed that the Bacillus inoculant promoted the lactic acid bacteria (LAB) fermentation, because higher abundance of Lactobacillus as the dominant bacteria was observed in BA group. Although the addition of cellulase slowed the Lactobacillus fermentation, it increased the bacterial community, where potential lignocellulolytic microorganisms and more functional enzymes were observed, thus leading to the significant degradation of NDF and ADF. The results revealed the mechanism behind the degradation of NDF and ADF in corn stover, and also suggested the potential of cellulase for improving the nutritional quality of WPCS.

Physicochemical characteristics and microbial community succession during oat silage prepared without or with Lactiplantibacillus plantarum or Lentilactobacillus buchneri

IMPORTANCE

Ensiled whole-plant oats are an important feedstuff for ruminants in large parts of the world. Oat silage is rich in dietary fibers, minerals, vitamins, and phytochemicals beneficial to animal health. The fermentation of oat silage is a complex biochemical process that includes interactions between various microorganisms. The activity of many microbes in silage may cause an extensive breakdown of nutrition and lead to undesirable fermentation. Moreover, it is difficult to make high-quality oat silage because the number of epiphytic lactic acid bacterium microflora was lower than the requirement. Understanding the complex microbial community during the fermentation process and its relationship with community functions is therefore important in the context of developing improved fermentation biotechnology systems. These results suggested that the addition of Lactobacillus plantarum or Lactobacillus buchneri regulated the ensiling performance and microbial community in oat silage by shaping the metabolic pathways.

From air to airway: Dynamics and risk of inhalable bacteria in municipal solid waste treatment systems

Municipal solid waste treatment (MSWT) system emits a cocktail of microorganisms that jeopardize environmental and public health. However, the dynamics and risks of airborne microbiota associated with MSWT are poorly understood. Here, we analyzed the bacterial community of inhalable air particulates (PM10, n = 71) and the potentially exposed on-site workers' throat swabs (n = 30) along with waste treatment chain in Shanghai, the largest city of China. Overall, the airborne bacteria varied largely in composition and abundance during the treatment (P < 0.05), especially in winter. Compared to the air conditions, MSWT-sources that contributed to 15 ∼ 70% of airborne bacteria more heavily influenced the PM10-laden bacterial communities (PLS-SEM, β = 0.40, P < 0.05). Moreover, our year-span analysis found PM10 as an important media spreading pathogens (104 ∼ 108 copies/day) into on-site workers. The machine-learning identified Lactobacillus and Streptococcus as pharynx-niched featured biomarker in summer and Rhodococcus and Capnocytophaga in winter (RandomForest, ntree = 500, mtry = 10, cross = 10, OOB = 0%), which closely related to their airborne counterparts (Procrustes test, P < 0.05), suggesting that MSWT a dynamic hotspot of airborne bacteria with the pronounced inhalable risks to the neighboring communities.

Comprehensive profiling of the metabolome in corn silage inoculated with or without Lactiplantibacillus plantarum using different untargeted metabolomics analyses

Silage fermentation is a complicated biochemical process involving interactions between microbes and metabolites. However, the overall metabolome feature of ensiled forage and its response to lactic acid bacteria inoculation is poorly understood. Hence, in this study metabolome profiles of whole-plant corn silage inoculated with or without Lactiplantibacillus plantarum were characterised via solid-phase microextraction/gas chromatography/mass spectrometry (SPME-GC-MS), gas chromatography/time-of-flight mass spectrometry (GC-TOF-MS), and Liquid chromatography/Q Exactive HFX mass spectrometry (LC-QE-MS/MS) analysis. There were 2087 identified metabolites including 1143 reliably identified metabolites in fresh and ensiled whole-plant corn. After ensiling, the increased metabolites in whole-plant corn were mainly composed of organic acids, volatile organic compounds (VOC), benzene and substituted derivatives, carboxylic acids and derivatives, fatty acyls, flavonoids, indoles and derivatives, organooxygen compounds (including amines and amides), phenols, pyridines and derivatives, and steroids and steroid derivatives, which includes neurotransmitters and metabolites with aromatic, antioxidant, anti-inflammatory, and antimicrobial activities. Phenylacetaldehyde was the most abundant aromatic metabolite after ensiling. L-isoleucine and oxoproline were the major free amino acids in silage. Ensiling markedly increased the relative abundances of 3-phenyllactic acid, chrysoeriol, 6-O-acetylaustroinulin, acetylcholine, γ-aminobutyric acid, pyridoxine, and alpha-linoleic acid. Inoculation with L. plantarum remarkably changed silage VOC composition, and essential amino acids, 3-phenyllactic acid, and cinnamaldehyde compared with untreated silage. The present study does not only provide a deeper insight into metabolites of the ensiled whole-plant corn but also reveals metabolites with specific biological functions that could be much helpful in screening novel lactic acid bacteria to well ensile forages. Inoculation with L. plantarum significantly affects the metabolome in ensiled whole-plant corn.

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.

Ensiling hybrid Pennisetum with lactic acid bacteria or organic acids improved the fermentation quality and bacterial community

The aim of this study was to compare the effect of different additives on nutritional quality, fermentation variables and microbial diversity of hybrid Pennisetum silages. A control (CK - no additives) and seven treatments were tested, namely, Lactiplantibacillus plantarum (LP), Lentilactobacillus buchneri (LB), propionic acid (PA), calcium propionate (CAP), LP + LB; LP + PA and LP + CAP. In comparison with CK, all treatments increased the contents of crude protein and lactic acid, decreased the content of butyric acid, and altered the bacterial communities of the silage. Except for the CAP and LP + CAP treatments, the additives decreased pH and the ammonia nitrogen:total nitrogen (NH₃-N:TN) ratio. The results of principal component analysis revealed that the PA, LP + PA and LP + LB treatments ranked as the top three silages. The PA and LP + PA treatments exhibited higher water-soluble carbohydrate content, but lower pH, and NH₃-N:TN ratio than the other treatments. With the PA and LP + PA treatments, the relative abundances of Lactobacillus and Enterobacter decreased, and of Proteobacteria and Delftia increased, while the carbohydrate metabolism of the microorganisms improved. The LP and LB treatments reduced the Shannon and Simpson diversities. In the beta diversity, PA and LP + PA separated from the other treatments, indicating that there were differences in the composition of bacterial species. The relative abundance of Lactobacillus increased in the LP and LB treatments and of Leucanostoc and Weissella increased in the CAP and LP + CAP treatments. In summary, the addition of L. plantarum, L. buchneri, propionic acid, calcium propionate, and their combinations improved fermentation quality, inhibited harmful bacteria and conserved the nutrients of hybrid Pennisetum.

Boosting the Antioxidant Potential of Polymeric Proanthocyanidins in Litchi (Litchi chinensis Sonn.) Pericarp via Biotransformation of Utilizing Lactobacillus Plantarum

In order to enhance the efficient utilization of polymeric proanthocyanidins from litchi pericarp, a process for transforming litchis' polymeric proanthocyanidins (LPPCs) by using Lactobacilli has been established for products with highly antioxidative properties. Lactobacillus plantarum was selected to enhance the transformation effect. The transformation rate of LPPCs reached 78.36%. The content of litchis' oligomeric proanthocyanidins (LOPCs) in the products achieved 302.84 μg grape seed proanthocyanidins (GPS)/mg DW, while that of total phenols was 1077.93 gallic acid equivalents (GAE) μg/mg DW. Seven kinds of substances have been identified in the products by using the HPLC-QTOF-MS/MS method, among which 4-hydroxycinnamic acid, 3,4-dihydroxy-cinnamic acid, and proanthocyanidin A2 were major components. The in vitro antioxidative activity of the products after transformation was significantly (p < 0.05) higher than those of LOPCs and LPPCs. The scavenging activity of the transformed products for DPPH free radicals was 1.71 times that of LOPCs. The rate of inhibiting conjugated diene hydroperoxides (CD-POV) was 2.0 times that of LPPCs. The scavenging activity of the products for ABTS free radicals was 11.5 times that of LPPCs. The ORAC value of the products was 4.13 times that of LPPCs. In general, this study realizes the transformation of polymeric proanthocyanidins into high-activity small-molecule substances.

The metabolome and bacterial composition of high-moisture Italian ryegrass silage inoculated with lactic acid bacteria during ensiling

BACKGROUND

With its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects of Lactobacillus buchneri TSy1-3 (HE), Lactobacillus rhamnosus BDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling.

RESULTS

The results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance of Lactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared with Lactobacillus buchneri TSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway.

CONCLUSIONS

Overall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.

Investigation on Fermentation Characteristics and Microbial Communities of Wheat Straw Silage with Different Proportion Artemisia argyi

Mycotoxins, secondary metabolites of fungi, are a major obstacle to the utilization of animal feed for various reasons. Wheat straw (WS) is hollow, and miscellaneous bacteria can easy attach to its surface; the secondary fermentation frequency after silage is high, and there is a risk of mycotoxin poisoning. In this study, a storage fermentation process was used to preserve and enhance fermentation quality in WS through the addition of Artemisia argyi (AA), which is an effective method to use WS resources and enhance aerobic stability. The storage fermentation of WS treated with AA had lower pH and mycotoxin (AFB1 and DON) values than the control due to rapid changes in microbial counts, especially in the 60% AA groups. Meanwhile, the addition of 60% AA improved anaerobic fermentation profiles, showing higher lactic acid contents, leading to increased efficiency of lactic acid fermentation. A background microbial dynamic study indicated that the addition of 60% AA improved the fermentation and aerobic exposure processes, decreased microbial richness, enriched Lactobacillus abundance, and reduced Enterobacter and Aspergillus abundances. In conclusion, 60% AA treatment could improve the quality by increase fermentation quality and improve the aerobic stability of WS silage by enhancing the dominance of desirable Lactobacillus, inhibiting the growth of undesirable microorganisms, especially fungi, and reducing the content of mycotoxins.

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.

Characterization of mycotoxins and microbial community in whole-plant corn ensiled in different silo types during aerobic exposure

Silage can be contaminated with mycotoxins and accidental fungi after aerobic exposure. The study assessed the effects of bunker silos (BS), round bales (RB), and silage bags (SB) on the nutritional characteristics, fermentation quality, aerobic stability, mycotoxin levels and microbial communities of whole-plant corn silage (WPCS). After 90 days of fermentation, silages were opened and sampled at 0, 1, 3, 5, 7, and 9 days of exposure. SB group conserved higher lactic acid and dry matter contents and a lower pH value than other groups after 9 days of exposure (p &lt; 0.05). The SB group showed the longest aerobic stability (202 h) among all silages (p &lt; 0.05). The concentrations of aflatoxin B1, trichothecenes and fumonisin B1 were significantly lower in SB after 9 days of exposure (p &lt; 0.05). Acetobacter became the dominant bacteria in BS and RB groups after 5 days of exposure. However, Lactobacillus still dominated the bacterial community in SB group. Acetobacter was positively correlated with pH, acetic acid content, and ammonia-N content (p &lt; 0.05). Lactobacillus was positively correlated with Kazachstania and Candida abundances (p &lt; 0.01) but negatively correlated with Fusarium abundance (p &lt; 0.05). Considering the feed value and food safety of silage in the feeding process, silage bags are recommended for WPCS according to the observed nutritional quality, fermentation index and mycotoxin content.

The Effect of Lactiplantibacillus plantarum ZZU203, Cellulase-Producing Bacillus methylotrophicus, and Their Combinations on Alfalfa Silage Quality and Bacterial Community

This study assessed the effects of Lactiplantibacillus plantarum (ZZU203), cellulase-producing Bacillus methylotrophicus (CB), or their combination (ZZU203_CB) on the fermentation parameters of alfalfa after 10 and 60 days of ensiling. Additionally, the bacterial community compositions were analyzed using absolute quantification 16S-seq (AQS). The results showed that CB silage displayed a higher lactic acid (LA) concentration at 10 d, a higher abundance of Lactobacillus, and lower abundance of Pediococcus, Enterococcus, and Weissella than those in the control (CK) silage. Compared with CK silage, the ZZU203 silage increased LA concentration, fructose and rhamnose concentrations, and the abundance of Lactobacillus, and decreased pH value, ammoniacal nitrogen, acetic acid, neutral detergent fiber and acid detergent fiber concentrations, and the abundance of Pediococcus, Enterococcus, Weissella, Hafnia, and Garciella after 60 days of ensiling. In addition, ZZU203 and ZZU203_CB silage had a similar silage quality and bacterial community, while the inoculation of ZZU203_CB significantly promoted LA accumulation and the numbers of Lactobacillus at 10 d compared with ZZU203 silage. Therefore, ZZU203 or a combination of ZZU203 and CB can be used as potential silage additives to improve the silage quality of alfalfa.

Fermentation Properties and Bacterial Community Composition of Mixed Silage of Mulberry Leaves and Smooth Bromegrass with and without Lactobacillus plantarum Inoculation

To evaluate the fermentation properties and bacterial community composition of mulberry leaves when ensiled with smooth bromegrass, and the effects of Lactobacillus plantarum inoculation on the mixed silage of mulberry leaves and smooth bromegrass, mulberry leaves were mixed with smooth bromegrass at ratios of 100:0, 90:10, 80:20, 70:30 and 60:40, and ensiled for 60 d with and without L. plantarum inoculant. The results showed that the sole fermentation of mulberry leaves failed to achieve optimum fermentation quality. Silage with a mulberry leaf ratio of 80% performed better fermentation quality compared with other non-inoculated groups, indicated by lower pH value, adequate lactic acid accumulation, and enriched proportion of Lactobacillus in the bacterial community. L. plantarum inoculation dramatically improved fermentation quality of mulberry leaf silage compared with the non-inoculated control. However, the fermentation quality of the inoculated silage decreased along with the reduction in the ratio of mulberry leaves. In conclusion, L. plantarum inoculation has the capability to improve the silage quality of mulberry leaves. Combined ensiling with smooth bromegrass could also aid in improving silage quality of mulberry leaves, with the optimum ratio of mulberry leaves being 80%.

Natural fermentation quality, bacteria, and functional profiles of three cuttings of alfalfa silage in a year in Inner Mongolia, China

Alfalfa is harvested two or three times a year in central and western Inner Mongolia, China. However, the variations in bacterial communities as affected by wilting and ensiling, and the ensiling characteristics of alfalfa among the different cuttings, are not fully understood. To enable a more complete evaluation, alfalfa was harvested three times a year. At each time of cutting, alfalfa was harvested at early bloom, wilted for 6 h, and then ensiled in polyethylene bags for 60 days. The bacterial communities and nutritional components of fresh alfalfa(F), wilted alfalfa(W) and ensiled alfalfa(S), and the fermentation quality and functional profile of bacterial communities of the three cuttings alfalfa silage, were then analyzed. Functional characteristics of silage bacterial communities were evaluated according to the Kyoto Encyclopedia of Genes and Genomes. The results showed that all nutritional components, fermentation quality, bacterial communities, carbohydrate, amino acid metabolism and key enzymes of bacterial communities were influenced by cutting time. The species richness of F increased from the first cutting to the third cutting; it was not changed by wilting, but was decreased by ensiling. At phylum level, Proteobacteria were more predominant than other bacteria, followed by Firmicutes (0.063–21.39%) in F and W in the first and second cuttings. Firmicutes (96.66–99.79%) were more predominant than other bacteria, followed by Proteobacteria (0.13–3.19%) in S in the first and second cuttings. Proteobacteria, however, predominated over all other bacteria in F, W, or S in the third cutting. The third-cutting silage showed the highest levels of dry matter, pH and butyric acid (p &lt; 0.05). Higher levels of pH and butyric acid were positively correlated with the most predominant genus in silage, and with Rosenbergiella and Pantoea. The third-cutting silage had the lowest fermentation quality as Proteobacteria were more predominant. This suggested that, compared with the first and second cutting, the third cutting is more likely to result in poorly preserved silage in the region studied.

Effects of Bacillus coagulans and Lactobacillus plantarum on the Fermentation Characteristics, Microbial Community, and Functional Shifts during Alfalfa Silage Fermentation

This study aimed to investigate the potential of Bacillus coagulans (BC) as an inoculant in alfalfa silage fermentation. Fresh alfalfa was harvested at a dry matter (DM) content of 329.60 g/kg fresh weight (FW), and inoculated without (CON) or with BC (1 × 10⁶ CFU/g FW), Lactobacillus plantarum (LP, 1 × 10⁶ CFU/g FW), and their combinations (LP+BC, 1 × 10⁶ CFU/g FW, respectively). Samples were taken at 3, 7, 14, 30, and 60 d, with three replicates for each. The prolonged ensiling period resulted in a decrease in pH values and an increase in lactic acid (LA) concentrations in alfalfa silages. After 60 d of fermentation, the application of BC and LP decreased the pH values and increased LA concentrations in treated silages, especially when their combination was applied. Application of BC preserved more water-soluble carbohydrates (WSC), and further application of BC increased WSC in LP+BC-treated silage compared to LP-treated silage. There was no significant difference in the crude protein (CP) content between the CON and treated silages, however, the BC and LP treatments reduced the ammonia nitrogen (NH₃-N) concentration, especially when their combination was applied. Additionally, the BC and LP-treated silages had lower neutral detergent fiber (NDF) and acid detergent fiber (ADF) when compared to the CON silage (p < 0.001). Inoculants also increased Lactobacillus abundance and decreased Enterococcus abundance after 60 d of fermentation. Spearman's rank correlation analysis revealed a positive correlation between LA concentration and Lactobacillus abundance. It was noteworthy that LP, BC, and their combination increased the relative abundances of carbohydrate metabolism, energy metabolism, cofactors, and vitamin metabolism, decreasing the relative abundances of amino acid metabolism and drug resistance: antimicrobial. Therefore, the inclusion of BC increased the fermentation quality of alfalfa silage, with the optimal combination being LP+BC. According to the findings, BC could be considered a viable bioresource for improving fermentation quality.

Influence of Cellulase or Lactiplantibacillus plantarum on the Ensiling Performance and Bacterial Community in Mixed Silage of Alfalfa and Leymus chinensis

The objective of this study was to evaluate the effects of Lactiplantibacillus plantarum or cellulase on the fermentation characteristics and bacterial community of mixed alfalfa (Medicago sativa L., AF) and Leymus chinensis (LC) silage. The harvested alfalfa and Leymus chinensis were cut into 1-2 cm lengths by a crop chopper and they were thoroughly mixed at a ratio of 3/2 (wet weight). The mixtures were treated with no addition (CON), Lactiplantibacillus plantarum (LP, 1 × 10⁶ cfu/g fresh material), cellulase (CE, 7.5 × 10² U/kg fresh material) and their combination (LPCE). The forages were packed into triplicate vacuum-sealed, polyethylene bags per treatment and ensiled for 1, 3, 5, 7 and 30 d at room temperature (17-25 °C). Compared to the CON groups, all the additives increased the lactic acid content and decreased the pH and ammonia nitrogen content over the ensiling period. In comparison to the other groups, higher water-soluble carbohydrate contents were discovered in the CE-inoculated silages. Compared to the CON groups, the treatment with LPCE retained the crude protein content and reduced the acid detergent fiber content. The principal coordinate analysis based on the unweighted UniFrac distance showed that individuals in the AF, LC, CON and LPCE treatment could be significantly separated from each other. At the genus level, the bacterial community in the mixed silage involves a shift from Cyanobacteria_unclassified to Lactobacillus. Lactobacillus dominated in all the treatments until the end of the silage, but when added with Lactiplantibacillus plantarum, it was more effective in inhibiting undesirable microorganisms, such as Enterobacter, while reducing microbial diversity. By changing the bacterial community structure after applying Lactiplantibacillus plantarum and cellulase, the mixed silages quality could be further improved. During ensiling, the metabolism of the nucleotide and carbohydrate were enhanced whereas the metabolism of the amino acid, energy, cofactors and vitamins were hindered. In conclusion, the relative abundance of Lactobacillus in the mixed silage increased with the addition of Lactiplantibacillus plantarum and cellulase, which also improved the fermentation quality.

The effects of native lactic acid bacteria on the microbiome, fermentation profile, and nutritive value of Napier grass silage prepared with different legume ratios

Mixing grass with legumes before ensiling is beneficial for improving dry matter and crude protein yield, but additional information is needed to balance nutrient content and fermentation quality. In this study, the microbial community, fermentation characteristics, and nutrient content of Napier grass mixed with alfalfa at different proportions were assessed. Tested proportions included: 100:0 (M0), 70:30 (M3), 50:50 (M5), 30:70 (M7), and 0:100 (MF). Treatments included: (CK) sterilized deionized water; (IN) selected lactic acid bacteria: Lactobacillus plantarum CGMCC 23166 and Lacticaseibacillus rhamnosus CGMCC 18233 (1.5 × 10⁵ cfu/g of fresh weight for each inoculant); and (CO) commercial lactic acid bacteria: L. plantarum (1 × 10⁵ cfu/g of fresh weight). All mixtures were ensiled for 60 days. Data analysis was used as a completely randomized design with a 5-by-3 factorial arrangement of treatments. The results showed that with increasing alfalfa mixing ratio, dry matter, and crude protein increased, while neutral detergent fiber and acid detergent fiber decreased both before and after ensiling (p < 0.05), which was not influenced by fermentation. Inoculation with IN and CO decreased pH and increased the lactic acid content compared to CK (p < 0.05), especially in silages M7 and MF. The highest Shannon index (6.24) and Simpson index (0.93) were observed in the MF silage CK treatment (p < 0.05). The relative abundance of Lactiplantibacillus decreased with increasing alfalfa mixing ratio, while the abundance of Lactiplantibacillus was significantly higher in the IN-treated group than in other treatment groups (p < 0.05). A higher alfalfa mixing ratio improved the nutrient value, but also made fermentation more difficult. Inoculants improved the fermentation quality by increasing the abundance of Lactiplantibacillus. In conclusion, the groups M3 and M5 achieved the optimal balance of nutrients and fermentation. If a higher proportion of alfalfa needs to be used, it is recommended to use inoculants to ensure sufficient fermentation.

The effect of biochar on nitrogen availability and bacterial community in farmland

Purpose

Nitrification and denitrification in soil are key components of the global nitrogen cycle. This study was conducted to investigate the effect of biochar application on soil nitrogen and bacterial diversity.

Methods

Pot experiments were conducted to investigate the effects of different biochar-based rates 0% (CK), 0.5% (BC1), 1.0% (BC2), 2.0% (BC3), and 4.0% (BC4) on soil nutrient and bacterial community diversity and composition.

Results

The results indicate that the total nitrogen (TN) and ammonium nitrogen (AN) contents in the soil increased by 4.7–32.3% and 8.3–101.5%, respectively. The microbial biomass nitrogen (MBN) content increased with increased amounts of biochar rate. The application of biochar also significantly changed the soil bacterial community composition. The copy number of 16S marker gene of related enzymes to the nitrification process in BC2 was reduced by 20.1%. However, the gene expressions of nitric oxide reductase and nitrous oxide reductase in BC3 increased by 16.4% and 16.0%, respectively, compared to those in CK. AN, nitrate nitrogen (NN), and NN/TN were the main factors affecting the structure of the soil bacterial community. In addition, the expressions of nitrite reductase, hydroxylamine, and nitric oxide reductase (cytochrome c) were also significantly correlated.

Conclusion

Therefore, the applied biochar improved soil nitrogen availability and which ultimately resulted in an environmental risk decrease by soil nitrogen release inhibition.

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.

Lactobacillus plantarum and propionic acid improve the fermentation quality of high-moisture amaranth silage by altering the microbial community composition

Objective

The objective of this study was to determine the effect of Lactobacillus plantarum (L. plantarum) and propionic acid (PA) on the microbial community and fermentation performance of high-moisture amaranth silage.

Methods

Amaranth silages were rown without addition (AhGCK) as a control and with L. plantarum JYLP-002 (AhGLP) or propionic acid (AhGPA) and then were opened after 60 days of ensiling to determine the microbial community and fermentation quality.

Results

Crude protein (CP) content, lactic acid (LA) content, and lactic acid bacteria (LAB) counts were significantly higher in AhGLP and AhGPA compared with those in AhGCK (p < 0.05). In contrast, pH, acetic acid (AA) content, and yeast and aerobic bacteria counts were significantly lower in AhGLP and AhGPA compared with those in AhGCK (p < 0.05). In addition, propionic acid (PA) levels were markedly higher in AhGPA (p < 0.05). In terms of microbial communities, the silage in the additive groups showed an increased relative abundance of Lactiplantibacillus plantarum and Lentilactobacillus buchneri and a reduced relative abundance of Enterobacter cloacae and Clostridium tyrobutyricum. The abundance of Xanthomonas oryzae was significantly increased in AhGPA, but completely inhibited in the silage supplemented with L. plantarum. Spearman's correlation analysis revealed that Lentilactobacillus buchneri and Levilactobacillus brevis were positively associated with LA and negatively associated with pH. Conversely, Clostridium tyrobutyricum and Enterobacter cloacae were negatively associated with LA, but positively associated with pH and AA content. AA content was inversely correlated with Lentilactobacillus buchneri. Functional prediction analysis showed that LAB dominated the three groups of silage and the silages containing additives had improved carbohydrate and amino acid metabolism compared with the control silage; in particular, the AhGLP group had more heterotypic fermentation processes and a richer metabolic pathway. Furthermore, the epiphytic Lactiplantibacillus plantarum and Lentilactobacillus buchneri could inhibit the reproductive activity of undesirable microorganisms to a certain extent, thus slowing the spoilage process of the silage.

Conclusion

In conclusion, L. plantarum can improve fermentation characteristics by modulating the microbial community attached to high-moisture amaranth silage and will prove useful for preserving high-moisture silage.

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.

Current approaches on the roles of lactic acid bacteria in crop silage

Lactic acid bacteria (LAB) play pivotal roles in the preservation and fermentation of forage crops in spontaneous or inoculated silages. Highlights of silage LAB over the past decades include the discovery of the roles of LAB in silage bacterial communities and metabolism and the exploration of functional properties. The present article reviews published literature on the effects of LAB on the succession, structure, and functions of silage microbial communities involved in fermentation. Furthermore, the utility of functional LAB in silage preparation including feruloyl esterase-producing LAB, antimicrobial LAB, lactic acid bacteria with high antioxidant potential, pesticide-degrading LAB, lactic acid bacteria producing 1,2-propanediol, and low-temperature-tolerant LAB have been described. Compared with conventional LAB, functional LAB produce different effects; specifically, they positively affect animal performance, health, and product quality, among others. In addition, the metabolic profiles of ensiled forages show that plentiful probiotic metabolites with but not limited to antimicrobial, antioxidant, aromatic, and anti-inflammatory properties are observed in silage. Collectively, the current knowledge on the roles of LAB in crop silage indicates there are great opportunities to develop silage not only as a fermented feed but also as a vehicle of delivery of probiotic substances for animal health and welfare in the future.

Effect of lactobacilli inoculation on protein and carbohydrate fractions, ensiling characteristics and bacterial community of alfalfa silage

Introduction

Alfalfa (Medicago sativa L.) silage is one of the major forages with high protein for ruminants.

Methods

The objective of this study was to investigate the effects of lactobacilli inoculants on protein and carbohydrate fractions, ensiling characteristics and bacterial community of alfalfa silage. Wilted alfalfa (35% dry matter) was inoculated without (control) or with Lactobacillus coryniformis, Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus pentosus and ensiled for 7, 15, and 60 days.

Results and discussion

Silage inoculated with L. pentosus was superior to L. coryniformis, L. casei, L. plantarum in improving the fermentation quality of alfalfa silage, as indicated by the lowest ammonia nitrogen content and silage pH during ensiling. There was minor difference in water soluble carbohydrates content among all silages, but L. pentosus inoculants was more efficient at using xylose to produce lactic acid, with lower xylose content and higher lactic acid content than the other inoculants. Compared with the control, L. pentosus inoculants did not affect true protein content of silage, but increased the proportions of buffer soluble protein and acid detergent soluble protein. The L. pentosus inoculants reduced the bacterial diversity In alfalfa silage with lower Shannon, Chao1, and Ace indices, and promoted relative abundance of lactobacillus and decreased the relative abundance of Pediococcus compared with the control. As well as L. pentosus inoculants up-regulated amino acid, carbohydrate, energy, terpenoids, and polypeptides metabolism, and promoted lactic acid fermentation process. In summary, the fermentation quality and nutrient preservation of alfalfa silage were efficiently improved by inoculated with L. pentosus.

Fermentation Characteristics, Microbial Compositions, and Predicted Functional Profiles of Forage Oat Ensiled with Lactiplantibacillus plantarum or Lentilactobacillus buchneri

This study aimed to investigate the effects of lactic acid bacteria (LAB) inoculants on the fermentation quality, microbial compositions, and predicted functional profiles of forage oat. The forage oat was inoculated with distilled water, Lentilactobacillus buchneri (LB), and Lactiplantibacillus plantarum (LP) as the control (CON), LB and LP treatments, respectively, and the addition of Lentilactobacillus buchneri (LB) or Lactiplantibacillus plantarum (LP) resulted in 1 × 106 colony-forming units/g of fresh weight. After 30 days of fermentation, the lowest pH (4.23) and the lowest content of ammoniacal nitrogen (NH3-N) in dry matter (DM, 4.39%) were observed in the LP treatment. Interestingly, there was a significant (p < 0.05) difference in lactic acid (LA) concentration among the three treatments. The LP treatment had the highest lactate concentration (7.49% DM). At the same time, a markedly (p < 0.05) elevated acetic acid (AA) concentration (2.48% DM) was detected in the LB treatment. The Shannon and Chao1 indexes of bacterial and fungal communities in all the silage samples decreased compared to those in the fresh materials (FM). Proteobacteria was the dominant phylum in the FM group and shifted from Proteobacteria to Firmicutes after ensiling. Lactobacillus (64.87%) and Weissella (18.93%) were the predominant genera in the CON, whereas Lactobacillus dominated the fermentation process in the LB (94.65%) and LP (99.60%) treatments. For the fungal community structure, the major genus was Apiotrichum (21.65% and 60.66%) in the FM and CON groups after 30 days of fermentation. Apiotrichum was the most predominant in the LB and LP treatments, accounting for 52.54% and 34.47%, respectively. The genera Lactococcus, Pediococcus, and Weissella were negatively associated with the LA content. The genus Ustilago and Bulleromyces were positively associated with the LA content. These results suggest that the addition of LAB regulated the microbial community in oat silage, which influenced the ensiling products, and LP was more beneficial for decreasing the pH and NH3-N and increasing the LA concentration than LB in forage oat silage.

Influence of Lactobacillus plantarum inoculation on the silage quality of intercropped Lablab purpureus and sweet sorghum grown in saline-alkaline region

Ensiling legume with cereal is an effective method to ensure the energy rich-feed, but no information is available on the microbial fermentation mechanism of intercropped Lablab purpureus (Lablab) and sweet sorghum in the saline-alkaline region. Therefore, the present study investigated the silage quality and microbial community of intercropped Lablab and sweet sorghum silages grown in the saline-alkaline region with or without inoculation of Lactobacillus plantarum (LP). The experimental treatments were prepared according to the Lablab and sweet sorghum planting patterns: Lablab and sweet sorghum sowing seed ratios were 1:1 (L), 5:1 (M), and 9:1 (H). After harvesting, each mixture was treated with LP or sterilized water (CK), followed by 60 days of fermentation. Results showed that both LP inoculation and intercropping significantly raised the lactic acid (LA) content and decreased the pH value, acetic acid (AA), and ammonia-N in intercropped silages. The LP addition and intercropping also improved the relative feed value by reducing structural carbohydrates. Moreover, LP silages had a greater relative abundance of Lactobacillus than CK silages, and its relative abundance increased with an increased seed-sowing ratio of Lablab in intercropping. LP was the prevalent species in LP silages compared to CK silages, and its relative abundance also increased with an increased seed-sowing ratio of Lablab in intercropping. The genus Lactobacillus was negatively correlated with ammonia-N (R = -0.6, p = 0.02) and AA (R = -0.7, p < 0.01) and positively correlated with LA (R = 0.7, p < 0.01) and crude protein (R = 0.6, p = 0.04). Overall, the intercropped seeding ratios of Lablab and sweet sorghum of ≥ 5:1 with LP inoculation resulted in better fermentation quality and preservation of nutritional components providing theoretical support and guidance for future intercropped protein-rich silage production in the saline-alkaline region.

Effects of Different Additives on Fermentation Quality, Microbial Communities, and Rumen Degradation of Alfalfa Silage

This study examined the effects of different additives on the fermentation quality, nutrient composition, microbial communities, and rumen degradation of ensiled alfalfa. Six treatments were employed in which additives were applied to alfalfa on a fresh weight basis: CK (no additive), FA (0.6% formic acid), CaO (3% calcium oxide and 3% urea), LB (1 × 106 cfu/g Lentilactobacillus buchneri), GLB (2% glucose and 1 × 106 cfu/g L. buchneri), and FLB (2% fucoidan and 1 × 106 cfu/g L. buchneri). After 60 days of ensiling, all treatments altered the bacterial communities, improved the fermentation quality, reduced dry matter (DM) and crude protein (CP) losses, and enhanced the rumen degradation of nutrients. The addition of LB increased the relative abundance of Lactobacillus spp. (p < 0.05), whereas GLB reduced (p < 0.05) the NH3-N:TN ratio and elevated (p < 0.05) the concentrations of Lactobacillus and lactic acid content. The FA treatment reduced (p < 0.05) the pH, as well as the DM and CP degradations, while the CaO treatment increased the degradations of DM, acid detergent fiber, and neutral detergent fiber. We concluded that FA, LB, GLB, and FLB had beneficial effects on alfalfa fermentation, and that CaO increased alfalfa silage rumen degradation.

Effect of exogenous microorganisms on the fermentation quality, nitrate degradation and bacterial community of sorghum-sudangrass silage

This study aims to investigate the effects of adding Lactobacillus buchneri (LB), Lactobacillus brevis (LBR) and Bacillus subtilis (BS) on the fermentation quality, nitrate degradation and bacterial community of sorghum-sudangrass silage. The results showed that the addition of LB significantly increased the pH and acetic acid content (p < 0.05), but high-quality silage was obtained. The addition of LBR and BS improved the fermentation quality of sorghum-sudangrass silage. The use of additives reduced the nitrate content in sorghum-sudangrass silage. The LB group increased the release of N₂O at 3–7 days of ensiling (p < 0.05), and LBR and BS increased the release of N₂O at 1–40 days of ensiling (p < 0.05). On the first day of ensiling, all silages were dominated by Weisslla, over 3 days of ensiling all silages were dominated by Lactobacillus. Acinetobacter, Serratia, Aquabacterium, and unclassified_f_enterobacteriaceae showed significant negative correlations with nitrate degradation during sorghum-sudangrass ensiling (p < 0.05). The BS and LBR groups increased the metabolic abundance of denitrification, dissimilatory nitrate reduction, and assimilatory nitrate reduction (p < 0.05). Overall, the additive ensures the fermentation quality of sorghum-sudangrass silage and promotes the degradation of nitrate by altering the bacterial community.

Dynamic Changes in Fermentation Quality and Structure and Function of the Microbiome during Mixed Silage of Sesbania cannabina and Sweet Sorghum Grown on Saline-Alkaline Land

Protein-rich Sesbania cannabina and sugar-rich sweet sorghum [Sorghum dochna (Forssk.) Snowden] are characterized by their higher tolerance to saline-alkaline stresses and simultaneous harvests. They could be utilized for coensiling because of their nutritional advantages, which are crucial to compensate protein-rich forage in saline-alkaline regions. The current study investigated the fermentation quality, microbial community succession, and predicted microbial functions of Sesbania cannabina and sweet sorghum in mixed silage during the fermentation process. Before ensiling, the mixtures were treated with compound lactic acid bacteria (LAB) inoculants followed by 3, 7, 14, 30, and 60 days of fermentation. The results revealed that the inoculated homofermentative species Lactobacillus plantarum and Lactobacillus farciminis dominated the early phase of fermentation, and these shifted to the heterofermentative species Lactobacillus buchneri and Lactobacillus hilgardii in the later phase of fermentation. As a result, the pH of the mixed silages decreased significantly, accompanied by the growth of acid-producing microorganisms, especially L. buchneri and L. hilgardii, which actively influenced the bacterial community structure and metabolic pathways. Moreover, the contents of lactic acid, acetic acid, 1,2-propanediol, and water-soluble carbohydrates increased, while the contents of ammonia-N and fiber were decreased, with increasing ratios of sweet sorghum in the mixed silage. Overall, coensiling Sesbania cannabina with >30% sweet sorghum is feasible to attain high-quality silage, and the relay action between homofermentative and heterofermentative LAB species could enhance fermentation quality and conserve the nutrients of the mixed silage. IMPORTANCE The coensiling of Sesbania cannabina and sweet sorghum is of great practical importance in order to alleviate the protein-rich forage deficiency in saline-alkaline regions. Furthermore, understanding the microbial community's dynamic changes, interactions, and metabolic pathways during ensiling will provide the theoretical basis to effectively regulate silage fermentation. Here, we established that coensiling Sesbania cannabina with >30% sweet sorghum was effective at ensuring better fermentation quality and preservation of nutrients. Moreover, the different fermentation types of LAB strains played a relay role during the fermentation process. The homofermentative species L. plantarum and L. farciminis dominated in the early phase of fermentation, while the heterofermentative species L. buchneri and L. hilgardii dominated in the later phase of fermentation. Their relay action in Sesbania cannabina-sweet sorghum mixed silage may help to improve fermentation quality and nutrient preservation.

Effects of antibacterial peptide-producing Bacillus subtilis, gallic acid, and cellulase on fermentation quality and bacterial community of whole-plant corn silage

In the current study, we assessed the effects of antibacterial peptide-producing Bacillus subtilis (BS), gallic acid (GA) and cellulase (CL) on the fermentation quality and bacterial community of various varieties of whole-plant corn silage. Three different varieties of whole-plant corn (Yuqing386, Enxiai298, and Nonghe35) were treated with 0.02% BS (fresh material basis), 0.2% GA (fresh material basis) and 0.02% CL (fresh material basis), after which 45 days of anaerobic fermentation were conducted. With the exception of its low dry matter content, the results showed that Yuqing386's crude protein, water-soluble carbohydrate, and lactic acid contents were significantly higher than those of the other two corn varieties. However, its acid detergent fiber and cellulose contents were significantly lower than those of the other two corn varieties. Among the three corn variety silages, Yuqing386 had the highest relative abundance of Lactobacillus at the genus level and the biggest relative abundance of Firmicutes at the phylum level. In addition, the three additives markedly enhanced the quantity of dry matter and crude protein as compared to the control group. The application of GA considerably decreased the level of neutral detergent fiber while significantly increasing the content of lactic acid and water-soluble carbohydrates. Even though all additives enhanced the structure of the bacterial community following silage, the GA group experienced the greatest enhancement. On a phylum and genus level, the GA group contains the highest relative abundance of Firmicutes and Lactobacillus, respectively. Overall, of the three corn varieties, Yuqing386 provides the best silage qualities. GA has the biggest impact among the additions employed in this experiment to enhance the nutritional preservation and fermentation quality of whole-plant corn silage.

Multi-Omics-Based Functional Characterization of Hybrid Fermented Broussonetia papyrifera: A Preliminary Study on Gut Health of Laying Hens

More attention has been paid in recent times to the application of Broussonetia papyrifera (BP) silage in ruminants, owing to its nutritional value. This study aimed to characterize the functionality of fermented BP and preliminarily explore its dietary effects on the gut health of laying hens. In this study, we characterized the antioxidant and antibacterial activities, bioactive compound profile, and bacterial community in Lactobacillus plantarum-fermented BP (FBP), as well as its dietary effects on intestinal morphology, microbiota and gene expression of laying hens. Improved contents of protein, total polyphenol and flavonoids as well as antioxidant and antibacterial activities were found after fermentation of BP. Untargeted metabolomics displayed more abundant apigenin, luteolin, diosmetin, and quercetin within the FBP, which may contribute to its functionality. Microbiome demonstrated increased abundance of Firmicutes at the expense of Cyanobacteria phylum, accompanied with raised levels of Lactobacillus genus. The results of a feeding trial showed dietary FBP supplementation increased the serum superoxide dismutase, but down-regulated gene expression of aryl hydrocarbon receptor (AhR), mucin2, and ZO-2, without obviously affecting the intestinal morphology and colonic microbiota. These findings suggest that FBP warrants further investigation as it may serve as a functional dietary supplement in laying hen feed.

Effects of different cutting methods and additives on the fermentation quality and microbial community of Saccharum arundinaceum silage

To develop a new high-yielding and polysaccharide-containing forage resource for livestock, the effects of different cutting methods and additives on Saccharum arundinaceum silage were evaluated. The wilted S. arundinaceum were chopped and knead-wired. The silages from each cutting method were treated with Lactobacillus plantarum (LP), cellulase (CE) and the combination of LP and CE (LP + CE) for 3, 7, 15, 30, and 60 days. Compared with the CK treatment, CE treatment exhibited better effects in the degradation of neutral detergent fiber (NDF), LP exhibited a better performance in preserving the content of dry matter (DM), and adding LP + CE significantly enhanced (P &lt; 0.05) the contents of lactic acid (LA), crude protein (CP) and DM and significantly reduced (P &lt; 0.05) the pH and NDF content during ensiling. In addition, both additives exerted a remarkable effect on the silage bacterial community (P &lt; 0.05), with a dramatic increase in the Lactobacillus abundance and a decrease in the abundance of Enterobacter. Lactic acid bacteria (LAB) became the most dominant bacteria that affected the fermentation quality of LP and LP + CE silages. Meanwhile, chopped silages showed better fermentation quality and nutrient preservation and a higher abundance of LAB. Our research indicated that the chopped S. arundinaceum ensiling with LP + CE could exert a positive effect on LA fermentation and preservation of nutrient substances by shifting the bacterial community. In conclusion, S. arundinaceum can serve as a new silage resource for feed utilization by the ensiling method of LP + CE-chopped.

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.

Exploring the Epiphytic Microbial Community Structure of Forage Crops: Their Adaptation and Contribution to the Fermentation Quality of Forage Sorghum during Ensiling

In this study, the effects of epiphytic microbiota from different forages on the fermentation characteristics and microbial community structure of forage sorghum silage were investigated. The gamma irradiated sterilized forage sorghum was treated through sterile water, epiphytic microbiota of forage sorghum (FSm), Sudan grass (SDm), Napier grass (NPm), and maize (MZm). NPm and SDm inoculated silages showed similar pH value and lactic acid (LA) and acetic acid (AA) contents at day 3 and 60 of ensiling. The final silage of FSm and MZm showed lower (p < 0.05) pH and AA content and a higher LA content compared to the NPm and SDm silages. Bacterial species from the Weisella genus were predominantly present in FSm, NPm, and SDm, while Lactococcus dominated the MZm silage during early ensiling. Lactobacillus was predominant in all inoculated terminal silages. Overall, the four inoculated microbiota decreased the pH value of silage and were dominated by lactic acid bacteria (LAB); however, the NPm and SDm treatments resulted in comparatively higher AA contents which could have an inhibitory effect on the secondary fermentation developed by the yeast and enhanced the aerobic stability of forage sorghum silage.

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.

Dynamics of the fermentation quality and microbiota in Ephedra sinica treated native grass silage

AIMS

This study aimed to evaluate the effects of Ephedra sinica on physicochemical characteristics and bacterial community of ensiled native grass by multiple physicochemical analyses combined with high-throughput sequencing.

METHODS AND RESULTS

Treatments were a control treatment with no additive (CON), Ephedra sinica was added at 1% (CEa1), 3% (CEa2) and 5% of the fresh materials (CEa3). Compared to the CON group, the dry matter and water-soluble carbohydrate contents were significantly (p < 0.05) decreased in the CEa1 group. Compared to the CON group, the pH was significantly (p < 0.05) decreased in Ephedra sinica treated silages, and the higher lactic acid content was observed in Ephedra sinica treated silages. At the genus level, the abundance of Enterococcus, Lactobacillus, Pediococcus and Weissella were the predominant member in the CON, CEa1, CEa2 and CEa3 groups, respectively. The abundance of Lactobacillus was significantly (p < 0.05) increased in the CEa1 group and Pediococcus was significantly (p < 0.05) increased in the CEa2 group. According to the 16S rRNA gene-predicted functional profiles, the inoculation of Ephedra sinica accelerated the carbohydrate metabolism.

CONCLUSIONS

In summary, the addition of Ephedra sinica could improve the silage quality of native grass by regulating the bacterial community and the addition of a 1% percentage of fresh materials exhibited the potential possibility in responding to get high-quality native grass silages.

SIGNIFICANCE AND IMPACT OF THE STUDY

The utilization of herbal additives on fermentation quality combined with 16S rRNA gene-predicted functional analyses will contribute to the direction of future research in improving silage quality.

Lignocellulose conversion of ensiled Caragana korshinskii Kom. facilitated by Pediococcus acidilactici and cellulases

To explore the biofuel production potential of Caragana korshinskii Kom., Pediococcus acidilactici and an exogenous fibrolytic enzyme were employed to investigate the fermentation profile, structural carbohydrates degradation, enzymatic saccharification and the dynamics of bacterial community of C. korshinskii silage. After 60 d of ensiling, all additives increased the fermentation quality. The highest lactic and acetic acids and lowest non-protein nitrogen (NPN) and ammonia nitrogen (NH₃ -N) were observed in P. acidilactici and Acremonium cellulase (PA + AC) treated silage. Additionally, all additives significantly increased the ferulic acid content and fibre degradability with the highest values obtained from PA + AC silage. The bacterial community in all silages was dominated by P. acidilactici throughout the entire fermentation process. The bacterial community was also modified by the silage additives exhibiting a relatively simple network of bacterial interaction characterized by a lower bacterial diversity in P. acidilactici (PA) treated silage. The highest 6-phospho-beta-glucosidase abundance was observed in PA-treated silage at the mid-later stage of ensiling. PA treatment exhibited lower structural carbohydrates degradation but performed better in lignocellulose conversion during enzymatic saccharification. These results indicated that pretreating C. korshinskii improved its silage quality and potential use as a lignocellulosic feedstock for the production of bio-product and biofuel.

Succession changes of fermentation parameters, nutrient components and bacterial community of sorghum stalk silage

To better understand the ensiling characteristics of sorghum stalk, the dynamic changes of fermentation parameters, nutrient components and bacterial community of sorghum stalk silage were analyzed by intermittently sampling on day 0, 1, 3, 7, 14, 28, and 56 of ensiling duration. The results showed that high-moisture sorghum stalk was well preserved during ensiling fermentation, with the DM loss of 4.10% and the little difference between the nutrients of sorghum stalk before and after ensiling. The pH value of silage declined to its lowest value of 4.32 by Day 7 of ensiling, and other fermentation parameters kept steady since Day 28 of ensiling. The amplicon sequencing analysis revealed that the alpha diversity parameters of silage bacterial community including Shannon index, observed features, Pielou evenness and Faith PD gradually declined (P < 0.01) with ensiling duration. Principal coordinate analysis (PCoA) revealed that bacterial profiles of raw material would experience a succession becoming a quite different community during ensiling fermentation. Taxonomic classification revealed a total of 10 and 173 bacterial taxa at the phylum and genus level, respectively, as being detected with relative abundances higher than 0.01% and in at least half samples. LEfSe analysis revealed that 26 bacterial taxa were affected by sampling timepoint (P < 0.05 and LDA score > 4). When focusing on the dynamic trend of silage bacterial taxa, lactic acid bacteria successfully dominated in the bacterial community on Day 1 of ensiling, and the bacterial community almost came to a plateau by Day 28 of ensiling, with Lactobacillus and Leuconostoc as the dominant genera. In a word, the succession of fermentation parameters, nutrient components and bacterial community indicate a successful dominance establishment of LAB and a fast advent of fermentation plateau, suggesting that high-moisture sorghum stalk can be ensiled directly, but the pH of mature silage is a little high.

Changes in the fermentation products, taxonomic and functional profiles of microbiota during high-moisture sweet sorghum silage fermentation

The purpose of this study was to evaluate the fermentation quality, microbial community, and functional shifts of sweet sorghum during ensiling. The high-moisture sweet sorghum (SS) was naturally ensiled for 1, 3, 7, 15, 30, and 60 days. After 60 days of ensiling, sweet sorghum silage (SSS) showed homolactic fermentation with absent butyric acid, low pH value, acceptable concentrations of propionic acid, ethanol, and ammonia nitrogen and high lactic acid concentration. Acinetobacter, Sphingomonas, and Pseudomonas were the advantage genera in SS. While, Lactococcus, Weissella, and Pediococcus were dominant in 3-day SSS and subsequently replaced by Lactobacillus in 60-day SSS. Spearman’s correlation heatmap showed that Pediococcus and Leuconostoc were negatively related to the pH value of SSS. There were great differences in the Kyoto Encyclopedia of Genes and Genomes (KEGG) functional profiles of SS and SSS. Ensiling process downregulated the metabolism of amino acid, energy, cofactors, and vitamins, but upregulated the metabolism of nucleotides and carbohydrates. Overall, next-generation sequencing in conjunction with KEGG functional prediction revealed the distinct differences in the initial and late phases of ensiling in terms of both community succession and functional shifts. The knowledge regarding bacterial community dynamics and functional shifts of SS during ensiling is important for understanding the fermentation mechanism and may contribute to the production of high-quality sweet sorghum silage.

Epicuticular wax of sweet sorghum influenced the microbial community and fermentation quality of silage

Epicuticular wax, as secondary metabolites (hydrophobic compounds) covering plant surface, plays important roles in protecting plants from abiotic and biotic stresses. However, whether these compounds will influence fermentation process of silage is still not clear. In this study, two sweet sorghum cultivars with varying epicuticular wax on sheath (bloom), Yajin 2 (YJ, less bloom), and Jintian (JT, dense bloom), were harvested at flowering and maturing stages, and ensiled with or without bloom, aiming to evaluate the effects of bloom on fermentation quality, feed nutrition and microbial community. The bloom was collected manually with de-waxed cotton and extracted with chloroform. The results showed that the bloom reduced the concentrations of water-soluble carbohydrate and crude protein of the two cultivars at both stages, reduced lactic acid (LA) for YJ at both stages and for JT at flowering stage, and increased LA for JT at mature stage. The α-diversity of bacterial communities of the silage fermentation with bloom was significantly lower than that without bloom. Bloom increased the abundance of Lactobacillus, reduced that of Bacillus and Weissella, and significant correlations were observed between fermentative qualities and bacterial abundances. However, decreased diversity of bacterial community and the contents of LA implied that shifts in bacterial community might exert negative effects on silage fermentation. Our results suggest that bloom wax could alter the microbial community composition of ensiled sweet sorghums, which thus influence the fermentation qualities.

Effects of inoculation of Lactiplantibacillus plantarum and Lentilactobacillus buchneri on fermentation quality, aerobic stability, and microbial community dynamics of wilted Leymus chinensis silage

Leymus chinensis is an important crop that can be fed to ruminants. The purpose of this study was to investigate the roles of Lactiplantibacillus plantarum and Lentilactobacillus buchneri in fermentation quality, aerobic stability, and dynamics of wilted L. chinensis silage microorganisms. Wilted L. chinensis silages were ensiled with/without L. plantarum and L. buchneri. After 14 and 56 days of ensiling, the silos were opened and subjected to a 7-day aerobic deterioration test. This study looked at the composition of fermentation products as well as the microbial communities in silage. Silage inoculated with L. plantarum and L. buchneri had an increased lactic acid content as well as lactic acid bacterial (LAB) quantity, but a decrease in pH and levels of butyric acid, 2,3-butanediol, and ethanol was observed during ensiling. Non-treated and L. plantarum-treated silages deteriorated in the 7-day spoilage test after opening day-14 silos, whereas L. buchneri-inoculated silage showed no signs of deterioration. Lactobacillus abundance increased in the 7-day spoilage test after opening day-56 silos, while undesirable microorganisms such as Acetobacter, Bacillus, and molds, namely, Aspergillus and Penicillium were inhibited within L. plantarum- and L. buchneri-inoculated silages. The composition of fermentation products was related to the bacterial community, particularly Lactobacillus, Enterococcus, and Acetobacter. To summarize, L. plantarum- and L. buchneri-inoculated silage enhanced fermentation quality during ensiling and inhibited aerobic spoilage in a 7-day spoilage test of 56 days ensiling within wilted L. chinensis silage.

An innovative strategy to enhance the ensiling quality and methane production of excessively wilted wheat straw: Using acetic acid or hetero-fermentative lactic acid bacterial community as additives

Ensiling is an effective storage strategy for agricultural biomass, especially for energy crops (mainly energy grasses and maize). However, the ensiling of excessively wilted crop straw is limited due to material characteristics, such as a high lignocellulosic content and low water-soluble carbohydrate and moisture contents. In this study, acetic acid or hetero-fermentative lactic acid bacterial community (hetero-fermentative LAB) were employed as silage additives to improve the ensiling process of excessively wilted wheat straw (EWS). The results showed that the additives inhibited the growth of Enterobacteriaceae and Clostridium_sensu_stricto_12, whose abundances decreased from 55.8% to 0.03-0.2%, respectively. The growth of Lactobacillus was accelerated, and the abundances increased from 1.3% to 80.1-98.4% during the ensiling process. Lactic acid fermentation was the dominant metabolic pathway in the no additive treatment. The additives increased acetic acid fermentation and preserved the hemicellulose and cellulose contents, increasing the methane yield by 17.7-23.9%. This study shows that ensiling with acetic acid or hetero-fermentative LAB is an effective preservation and storage strategy for efficient methane production from EWS.

Metaprofiling of the bacterial community in sorghum silages inoculated with lactic acid bacteria

AIMS

to characterize the fermentation process and bacterial diversity of sorghum silage inoculated with Lactiplantibacillus plantarum LpAv, Pediococcus pentosaceus PpM and Lacticaseibacillus paracasei LcAv.

METHODS AND RESULTS

chopped sorghum was ensiled using the selected strains. Physicochemical parameters (Ammonia Nitrogen/Total Nitrogen, Dry Matter, Crude Protein, Acid Detergent Fiber, Neutral Detergent Fiber, Acid Detergent Lignin, Ether Extract and Ashes), bacterial counts, cell cytometry and 16sRNA sequencing were performed to characterize the ensiling process and an animal trial (BALB/c mice) was conducted in order to preliminary explore the potential of sorghum silage to promote animal gut health. After 30 days of ensiling, the genus Lactobacillus comprised 68.4 ± 2.3 % and 73.5 ± 1.8 % of relative abundance, in control and inoculated silages respectively. Richness (Chao1 index) in inoculated samples, but not in control silages, diminished along ensiling, suggesting the domination of fermentation by the inoculated LAB. A trend in conferring enhanced protection against Salmonella infection was observed in the mouse model used to explore the potential to promote gut health of sorghum silage.

CONCLUSIONS

the LAB strains used in this study were able to dominate sorghum fermentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

this is the first report using metaprofiling of 16sRNA to characterize sorghum silage, showing a microbiological insight where resident and inoculated LAB strains overwhelmed the epiphytic microbiota, inhibiting potential pathogens of the genus Klebsiella.

The Effect of Different Lactic Acid Bacteria Inoculants on Silage Quality, Phenolic Acid Profiles, Bacterial Community and In Vitro Rumen Fermentation Characteristic of Whole Corn Silage

Corn silage is an important source of forage, but whether or not bacterial inoculants should be applied is somewhat controversial in ruminant feeding practice. In the present study, chopped whole corn plants treated with a single inoculant of Lactobacillus buchneri (LB), Lactobacillus plantarum (LP), Pediococcus pentosaceus (PP) served as either homofermentation (e.g., lactate only) or heterofermentation (e.g., lactate and acetate) controls and compared with those treated with either a mixture of the lactic acid bacteria (QA: 60% LP, 10%PP, 30% LB) or a mixture of the lactic acid bacteria (QB: 60% LP, 15% PP, 25% LB), to investigate their effects on the fermentation quality, ester-linked phenolic acids, and in vitro digestibility. After 60 day ensiling, the addition of QA exhibited the lowest pH (3.51) with greater lactic acid (LA) production. The ester-linked ferulic acid (FAest) and p-coumaric acid (pCAest) concentrations were significantly decreased during 60 days ensiling. And among all these groups, the LB and QA treated group showed a lower concentration of FAest and pCAest than other groups. After 60 days ensiling, Lactobacillus was the dominant genus in all LAB treated groups. Meanwhile, negative correlations of Bacillus, Bacteroides, Bifidobacterium, Blautia, Prevotella, Ruminococcus, and Roseburia with FAest content after 60 days ensiling occurred in the present study. Komagataeibacter was mainly found in LB and PP addition silages, and presented a significant negative effect with the level of acid detergent fiber (ADF). To explore whether the addition of LABs can improve digestibility of whole corn silage, an in vitro rumen fermentation was conducted using the 60 day ensiled whole corn silages as substrates. The QA addition group exhibited a greater 48 h and 96 h in vitro dry matter and ADF disappearance, greater 48 h gas production and less methane emissions. Even though there were the same neutral NDF levels in corn silages treated with LB and QA after 60 days ensiling, the QA treated silages with lower FAest and pCAest presented higher IVDMD after 96 h and 48 h in vitro fermentation. In brief, the addition of mixed inoculants of 60% LB,10% PP, 30% LB compared with the addition of whichever single HoLAB or HeLAB inoculants, facilitated the release of ester-linked phenolic acids (e.g., ferulic and p-coumaric acids) and remarkably, improved silage quality in terms of sharp pH decline and greater lactate production. Taken together with the improvement in rumen microbial fermentation, the results obtained in the present study provided concrete evidence for the role of mixed LAB application in corn silage preparation for ruminant feeding practices.