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The seasonal surplus and putrefactive property of moist forages inevitably increase the pressure on environmental protection and residual grass disposal. In the current work, the anaerobic fermentation approach was adopted to assist the sustainable recycling of leftover Pennisetum giganteum (LP), and its chemical composition, fermentation performance, bacterial community and functional profiles during anaerobic fermentation were studied. Fresh LP was spontaneously fermented for up to 60 d. At the end of anaerobic fermentation, fermented LP (FLP) displayed homolactic fermentation with low pH value, ethanol, and ammonia nitrogen concentrations but high lactic acid concentration. Weissella was dominant in 3-day FLP, yet Lactobacillus was the overwhelming genus (92.6%) in 60-day FLP. The anaerobic fermentation process promoted (P < 0.05) the metabolism of carbohydrate and nucleotide while suppressing (P < 0.05) that of lipid, cofactors, vitamins, energy, and amino acid. The results showed that the residual grass with LP as an example could be successfully fermented even if no additives were added, without signs of clostridial and fungal contamination., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pixian broad bean paste is a renowned fermented seasoning. The fermentation of broad bean is the most important process of Pixian broad bean paste. To enhance the flavor of tank-fermented broad bean paste, salt-tolerant Bacillus amyloliquefaciens strain was inoculated, resulting in an increase in total amount of volatile compounds, potentially leading to different flavor characteristics. To investigate the fermentation mechanism, monoculture simulated fermentation systems were designed. Metabolomics and transcriptomics were used to explore Bacillus amyloliquefaciens' transcriptional response to salt stress and potential aroma production mechanisms. The results highlighted different metabolite profiles under salt stress, and the crucial roles of energy metabolism, amino acid metabolism, reaction system, transportation system in Bacillus amyloliquefaciens' hypersaline stress response. This study provides a scientific basis for the industrial application of Bacillus amyloliquefaciens and new insights into addressing the challenges of poor flavor quality in tank fermentation products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

The objective of this study was to explore the microbiological factors that cause the difference in silage fermentation characteristics between grass and legume. Specifically, the effects of epiphytic microbiota from alfalfa, oat and Italian ryegrass on ensiling characteristics and microbial community of alfalfa were assessed. By γ-ray irradiation sterilization and microbiota transplantation technology, the sterile alfalfa was inoculated as follows: (i) aseptic water (STAL); (ii) epiphytic bacteria from alfalfa (ALAL); (iii) epiphytic bacteria from oat (ALOT); (iv) epiphytic bacteria from Italian ryegrass (ALIR). Alfalfa at the initial flowering stage was ensiled in laboratory-scale silos for 1, 3, 7, 14, 30 and 60 days. Compared with ALAL and ALIR, higher lactic acid contents and ratio of lactic acid to acetic acid, and lower acetic acid, propionic acid, ethanol and ammonia nitrogen contents were observed in ALOT after 60 days of fermentation. In each treated group, Lactobacillus was the most dominant genus after 60 days of ensiling. Relatively higher abundance of Weissella, Hafnia-Obesumbacterium, Enterobacteriaceae or hetero-fermentative Lactobacillus was found in ALAL and ALIR after 60 days. Co-occurrence network analysis proved Pediococcus and Lactococcus were pivotal in deciding the fermentation pattern of alfalfa silage. According to the 16S rRNA gene-predicted functional profiles, the metabolism of amino acids was inhibited by the epiphytic microbiota from oat. Overall, ALOT showed a homo-fermentative process, whereas ALAL and ALIR exhibited a hetero-fermentative pattern. Furthermore, the exogenous microorganisms inhibiting the metabolism of amino acids can be a good potential source to improve the silage quality of legume forage., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Ensiling density has significant importance for the quality and preservation of silage. Appropriate ensiling density could improve the nutritional value, extend the storage time of silage and reduce the risk of mold and spoilage. This work aimed to evaluate the effect of ensiling densities on the fermentation quality and aerobic stability of rice straw. The rice straw was obtained after threshing, then chopped and ensiled into a 10 L laboratory silo with three ensiling densities (high density at 700 g/L, medium density at 600 g/L and low density at 500 g/L). Five silos per density were opened after 3, 5, 7, 14, 30 and 60 days of ensiling, and then, the fermentation quality and aerobic stability were analyzed. During ensiling, high density had the highest lactic acid content, and the lowest pH and ammonia nitrogen. There was no difference (p > 0.05) in the propionic acid, butyric acid and ethanol contents among all silage, and the contents of propionic acid and butyric acid were trace amounts. On day 60 of ensiling, the Flieg's point of high density and medium density were higher than the low density. During aerobic exposure, the continuous lactic acid decrease and pH increase were observed in all silage. The aerobic bacteria and yeasts count in the high density and medium density were lower than that in the low density. The aerobic stability of the high density (26 h) and the medium density (24 h) were higher than that of the low density (13 h). It was suggested that if the ensiling density is higher than 600 g/L, it could effectively improve the fermentation quality and aerobic stability of rice straw. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the effectiveness of lactic acid bacteria (LAB) inoculants and chemical additives on the fermentation quality, aerobic stability and in vitro gas production kinetics and digestibility of total mixed ration (TMR) silage. Total mixed ration (568 g/kg dry matter (DM)) was ensiled with six experimental treatments: (1) no additives (control); (2) Lactobacillus buchneri (LB; applied at 1 × 106 cfu/g fresh weight (FW)); (3) Lactobacillus casei (LC; applied at 1 × 106 cfu/g FW); (4) calcium propionate (CAP; applied at 0.5% FW); (5) sodium diacetate (SD; applied at 0.5% FW); (6) potassium sorbate (PS; applied at 0.1% FW). All silos (18 L) were opened for fermentation quality, in vitro gas production kinetics and digestibility analysis after 90 days of ensiling, and then subjected to aerobic stability test for 14 days. All the TMR silage was well-preserved with low pH (4.36 ∼ 4.66) and acceptable levels of butyric acid (1.02 ∼ 2.51 g/kg DM) and ammonia nitrogen (86.3 ∼ 107 g/kg total nitrogen). All the groups were steady during 14 days of aerobic exposure, while SD group was more stable with lower (p < 0.05) yeast (4.60 vs. 5.17 ∼ 5.77 log10 cfu/g FW) and mould (3.33 vs. 4.12 ∼ 4.64 log10 cfu/g FW) populations than other treated groups on day 14. Moreover, SD group had the highest (p < 0.05) in vitro digestibility of dry matter (67.8 vs. 56.6 ∼ 63.5%) and neutral detergent fibre (61.7 vs. 50.5 ∼ 57.4%) among all groups. Overall, SD is recommended as additive to improve fermentation quality, in vitro ruminal digestibility, and aerobic stability of TMR silage. After 14 days of aerobic exposure, the yeast and mould populations in TMR silage can be efficiently inhibited by sodium diacetate treatment. Sodium diacetate treatment evidently enhanced in vitro digestibility of dry matter and neutral detergent fibre compared to other treatments. Sodium diacetate is recommended as additive to improve fermentation quality, in vitro ruminal digestibility, and aerobic stability of TMR silage. [ABSTRACT FROM AUTHOR]

BACKGROUND: The present study aimed to investigate the relationship between the phyllosphere microbiota of Italian ryegrass (Lolium multiflorum Lam.) harvested at heading (H) [> 50% earing rate or 216 g kg−1 fresh weight (FW)] and blooming (B) (> 50% bloom or 254 g kg−1 FW) stages and in‐silo fermentation products, and the composition, abundance, diversity and activity of bacterial community. In total, 72 (4 treatments × 6 ensiling durations × 3 replicates) laboratory scale (400 g) silages of Italian ryegrass were prepared: (i) irradiated heading stage silages (IRH) (n = 36) were inoculated with phyllosphere microbiota inoculum (2 mL) eluted from fresh Italian ryegrass at either heading (IH) (n = 18) or blooming (IB) (n = 18) stages; (ii) irradiated blooming stage silages (IRB) (n = 36) were inoculated with either IH (n = 18) or IB (n = 18). Triplicate silos of each treatment were analyzed after 1, 3, 7, 15, 30 and 60 days of ensiling. RESULTS: In fresh forage, Enterobacter, Exiguobacterium and Pantoea were the three major genera at heading stage, and Rhizobium, Weissella and Lactococcus were the most abundant genera at blooming stage. Higher metabolic activity was found in IB. After 3 days of ensiling, the large amounts of lactic acid in IRH‐IB and IRB‐IB can be attributed to the higher abundances of Pediococcus and Lactobacillus, 1‐phosphofructokinase, fructokinase, l‐lactate dehydrogenase and glycolysis I, II and III. CONCLUSION: The composition, abundance, diversity and functionality of the phyllosphere microbiota of Italian ryegrass at different growth stages could remarkably affect silage fermentation characteristics. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impacts of three organic acid salts and two bacterial additives on the fermentation profile, in vitro digestibility and gas production, and aerobic stability of total mixed ration (TMR) silage prepared with 10% fresh weight (FW) of wet hulless barley distillers' grains (WHDG), 35% FW of common vetch, 15% FW of whole-crop oat, 10% FW of hulless barley straw, and 30% FW of mixed concentrate. The total mixed ration (555 g kg−1 FW) was ensiled with six treatments: (1) no additives (control); (2) calcium propionate (CAP; 0.5% FW); (3) potassium sorbate (POS; 0.1% FW); (4) sodium diacetate (SDA; 0.5% FW); (5) Lactobacillus buchneri (LB; 1 × 106 cfu g−1 FW); and (6) Lactobacillus casei (LAC; 1 × 106 cfu g−1 FW). All silos (20 L) were opened for the fermentation profile and in vitro digestibility analysis after 95 days of fermentation, and then subjected to an aerobic stability experiment for 14 days. All the TMR silage was well preserved with a low pH (4.32~4.51), acceptable levels of butyric acid (1.34~1.56 g kg−1 dry matter), and ammonia nitrogen (69.1~87.1 g kg−1 total nitrogen). All the groups were steady during aerobic exposure, while the SDA treatment was more stable with lower populations of undesirable microorganisms on day 14. The CAP, POS, and SDA treatments evidently (p < 0.05) enhanced the in vitro digestibility of dry matter (54.8~57.5 vs. 48.4%) and neutral detergent fiber (48.4~51.6 vs. 41.1%) compared to the control. By comprehensive consideration, SDA is recommended as additive to enhance fermentation quality, aerobic stability, and in vitro digestibility of TMR silage containing 10% FW of WHDG. [ABSTRACT FROM AUTHOR]

Biomass microbiota and chemical constituent are closely associated with final anaerobic fermentation performance. But the limiting factors affecting anaerobic fermentation quality and bacterial community have been rarely explored. This study aimed to elucidate the relative contribution of initial microbiota and chemical constituent of sweet sorghum on its final anaerobic fermentation quality. Sweet sorghum at two developmental stages (heading-stage, G1; hard-dough-stage, G2) was treated as follows: G1 microbiota + sterilized G1 (M1C1), G2 microbiota + sterilized G1 (M2C1), G1 microbiota + sterilized G2 (M1C2), and G2 microbiota + sterilized G2 (M2C2). The results showed that chemical constituent rather than microbiota changes remarkably influenced the production of lactic acid, propionic acid and ammonia-N, the relative abundance of Lactobacillus, Weissella, Lactococcus, Pediococcus, and Pantoea of sweet sorghum after anaerobic fermentation. The chemical constituent was the key limiting factor affecting the anaerobic fermentation quality of sweet sorghum. This study could provide a reference for clarifying the key limiting factors affecting anaerobic fermentation and making recommendations for production. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the effects of delayed harvest and storage length on fermentation products, bacterial community, and metabolic shifts of elephant grass silage. The late-harvested elephant grass (LG) was naturally fermented (NLG) for 1, 3, 7, 15, 30, and 60 days, respectively. After 60-day ensiling, NLG displayed homolactic fermentation with low pH value, butyric acid, and ammonia nitrogen concentrations, and high lactic acid concentration, and ratio of lactic acid to acetic acid. Pseudomonas, Sphingomonas , and Pantoea dominated the bacterial community in LG, but Lactobacillus, Lactococcus , and Pediococcus were the advantageous genera in a 3-day and 60-day NLG. The correlation heatmap revealed that Acetobacter was positively related to acetic acid, ethanol, ammonia nitrogen, and butyric acid concentrations. There were distinct differences in the KEGG (Kyoto Encyclopedia of Genes and Genomes) metabolic profiles of fresh and ensiled LG. Ensiling suppressed the metabolism of amino acid, vitamins, and energy, while promoted the metabolism of carbohydrate. The LG can be well-fermented without additives, but its low crude protein content should not be ignored when applied in agricultural practice. The ensiling process remarkably affected the fermentation quality, bacterial community, and metabolic profiles of NLG. [ABSTRACT FROM AUTHOR]

This study investigated the effects of developmental stage and store time on the chemical composition, microbial community, co-occurrence networks and fermentation characteristics of sweet sorghum silage. Sweet sorghum harvested at two developmental stages (heading stage, S1; hard dough stage, S2) was treated as follows: (I) natural fermentation of S1 (NS1); (II) natural fermentation of S2 (NS2) and ensiled for 1, 3, 7, 15, 30 and 60 days. After 60 days of ensiling, NS2 silage had higher lactic acid concentration and the ratio of lactic to acetic acid, and lower pH value and acetic acid concentration than NS1 silage. Meanwhile, NS2 silage also had higher ammonia nitrogen (NH3-N) content than NS1 silage, but the NH3-N content of both treatments was lower than 100 g/kg TN. Leuconostoc and Lactococcus were respectively dominant in both 7-day NS1 and NS2 silages, while Lactobacillus was the most abundant genus in 30-day NS1 and NS2 silages. The developmental stage altered the bacterial co-occurrence networks of fresh and ensiled sweet sorghum. Spearman's correlation heatmap showed that the higher lactic acid content and ratio of lactic to acetic acid in NS2 silage could be associated with the higher water-soluble carbohydrate content in S2 material, the higher abundance of Lactococcus in the initial phase of ensiling and the higher abundance of Lactobacillus in the late phase of ensiling. These results concluded that the sweet sorghum harvested at the hard dough stage is preferred for silage production over the sweet sorghum harvested at the heading stage. Microbial succession pattern was studied on fresh and ensiled samples. Growth stage affected the chemical and microbial parameters of sweet sorghum. Epiphytic microbiota was correlated with the chemical composition of forage. Metagenomic sequencing showed Lactobacillus was dominated in all silages. Growth stage accelerated the fermentation of sweet sorghum silage. [ABSTRACT FROM AUTHOR]

In this study, the anaerobic fermentation technique was conducted to accomplish the clean recycling of surplus napiergrass. The surplus napiergrass harvested at two harvest dates (early vegetative stage, NI; late vegetative stage, NII) was treated as follows: (i) natural fermentation of NI (NNI); (ii) natural fermentation of NII (NNII) and stored for 1, 3, 7, 15, 30 and 60 days. After 60 days of anaerobic fermentation, NNI had higher lactic acid concentration and ratio of lactic to acetic acid, but lower pH value and ammonia–nitrogen concentration than NNII. Lactobacillus and Enterobacter were, respectively, dominant in both 7-day NNI and NNII, while Lactobacillus was the most abundant genus in 30-day NNI and NNII. Both harvest date and store time altered the bacterial co-occurrence networks of fresh and fermented napiergrass. The complexity of the bacterial networks decreased from NII, NI, NNII to NNI. The correlations were primarily positive in the bacterial networks of NI, NII, NNII-7 and NNII-30 with positive correlative proportion of 53.0%, 64.3%, 53.1% and 55.6%, but negative in those of NNI-7 (47.4%) and NNI-30 (46.2%) with positive correlative proportion of 47.4% and 46.2%, respectively. Overall, the fermentation quality and microbial community structure of napiergrass during anaerobic fermentation were highly influenced by harvest date and store time. Based on the principle of stable fermentation and high quality, anaerobic fermentation of NI for at least 15 days is recommended. The in-depth understanding of microbial community dynamics and co-occurrence networks during anaerobic fermentation of napiergrass is important for revealing the fermentation mechanism and can contribute to resource recycling without increasing cost. [ABSTRACT FROM AUTHOR]

Effect of temperature on synthesis of Clavulanic acid (CA) and impurity substance G during fermentation by Streptomyces clavuligerus were investigated. Results show that fermentation at 24 °C is the most favorable for CA synthesis though the fermentation duration was 20–30 hours longer than fermentation at 26 and 28 °C. Meanwhile, the impurity substance G was only 110 mg/L in the end broth of fermentation at 24 °C, which was significantly lower than 148 and 180 mg/L of fermentation at 26 and 28 °C, respectively. Correlation of specific growth rate and CA synthesis was statistically analyzed based on data of 10 batches of industrial fermentation. Two temperature-shift strategies were investigated in 50 L fermenter. Fermentation with 26–24 °C temperature strategy achieved 5097 mg/L CA titer, meanwhile the fermentation duration was shortened 24 hours comparing with fermentation at constant 24 °C. Fermentation with 26–24 °C control strategy was validated in a 60 m3 industrial fermenter, in which 4960 mg/L of CA was achieved while impurity G substance was decreased to titer 65 mg/L from 200 to 300 mg/L of normal production. [ABSTRACT FROM AUTHOR]

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: AMG, MG and PMG) × 3 (microbiota: AMM, MM and PMM) 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 PMG and MG silages compared to AMG silages. MM and PMM inoculum promoted lactic acid fermentation as indicated by higher lactic acid contents and lactic/acetic acid ratios in MM and PMM‐inculated silages compared to those in AMM‐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. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study aims to reveal the effects of hexanoic acid on the microbial communities, fermentation, and the hygienic quality of corn silages with or without fungal infection. Fungal‐infested (FI) and non‐infested (NFI) whole‐crop corn samples were separately ensiled without (control, CON) or with hexanoic acid (Hex, 90% purity) at 0.2 g·kg−1 fresh weight (FW). RESULT: The addition of Hex accelerated the pH decline during the first 5 days of ensiling regardless of fungal infestation. The lactic acid (LA) concentration in Hex silages was lower than that in CON during 45 days of ensiling; however the FI‐Hex silage had the highest LA concentration among treatments on day 90. The Hex silage showed lower aflatoxin B1 (AFB1), zearalenone (ZEA), and deoxynivalenol (DON) concentrations than CON for FI silages. On day 5, the addition of Hex decreased the relative abundance of Klebsiella, Pantoea, and Enterobacter compared with CON, regardless of fungal infestation. This inhibitory effect lasted until day 90 for NFI silages but disappeared for FI silages on day 90. The fungal infestation resulted in the accumulation of Candida (34.05%) and Wickerhamomyces (19.46%). Hex decreased the relative abundance of Asperigillus, Issatchenkia, and Penicillium for NFI silages on day 5; however, its inhibitory effects were not observed in FI silages on day 5. CONCLUSION: Fungal infestation was associated with poor fermentation and hygienic quality of corn silage. Adding Hex accelerated the pH decline and maintained the antifungal activity until 90 days of ensiling, attenuating adverse effects of fungal infestation on the fermentation and preventing the accumulation of mycotoxins in corn silages. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Aims: To enrich lignocellulolytic microbial consortia and evaluate whether a combination of these consortia and Lactobacillus plantarum can facilitate degradation of structural carbohydrates and improve fermentation quality of high‐moisture alfalfa silage. Methods and Results: Two novel microbial consortia (CL and YL) with high lignocellulolytic potential were enriched, and had higher enzyme activities at slightly acidic conditions (pH 3.5–6.5). Two consortia were inoculated with and without combined L. plantarum (LP) to alfalfa for up to 120 days of ensiling. The two consortia alone or combined with LP significantly (p < 0.05) increased lactic‐to‐acetic acid ratios and decreased contents of volatile organic acids and NH3‐N as compared to the control. Treatments that combining microbial consortia and LP further resulted in the higher contents of lactic acid (LA), water soluble carbohydrates (WSC) and crude protein, dry matter (DM) recovery, and lower neutral detergent fibre, acid detergent lignin and cellulose contents, with YLP silage showing the lowest pH (4.41) and highest LA content (76.72 g kg−1 DM) and the conversion of WSC into LA (184.03%). Conclusions: The addition of lignocellulolytic microbial consortia (CL or YL) to alfalfa silages as attractive silage inoculants could improve fermentation quality, and that their combination with L. plantarum appeared more effective on the degradation of structural carbohydrates and conversion of soluble carbohydrates into LA. Significance and Impact of the Study: High‐moisture alfalfa is difficult to ensile due to its high buffering capacity and low readily fermentable carbohydrate contents. Microbial consortia (CL and YL) can encode a broad selection of multi‐functional CAZymes, and their combination with LP could be promising for the degradation of structural carbohydrates simultaneously with improvement fermentation quality, with high performance in LA production. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to separate the effects of chemical and microbial factors on the fermentation quality and bacterial community of ensiled Pennisetum giganteum. Methods and Results: Fresh P. giganteum of two vegetative stages (stage I, GI; stage II, GII) was treated as follows: GI epiphytic microbiota + γ‐ray presterilized GI (MICI), GII epiphytic microbiota + γ‐ray presterilized GI (MIICI), GI epiphytic microbiota + γ‐ray presterilized GII (MICII), and GII epiphytic microbiota + γ‐ray presterilized GII (MIICII). Triplicates per treatment were sampled after 30 days of ensiling for chemical and microbial analyses and high‐throughput sequencing. Silages made from CII (MICII and MIICII) had higher lactic acid concentration and the ratio of lactic to acetic acid, and lower pH and ammonia nitrogen concentration than silages produced by CI (MICI and MIICI). Species differential analyses showed that the changes of chemical composition rather than epiphytic microbiota significantly affected the relative abundance of Lactobacillus, Pediococcus and Pantoea in P. giganteum silages. Conclusion: These above results manifested that chemical composition was the main factor influencing the fermentation quality and bacterial community of P. giganteum silage in this study. Significance and Impact of the Study: The obtained results may, therefore, be the first record to provide an in‐depth understanding of the relative contributions of chemical and microbial parameters on fermentation quality and bacterial community, which is of great importance for modulating silage fermentation and improving silage quality. [ABSTRACT FROM AUTHOR]

Aims: To isolate and enrich lignocellulolytic microbial consortia from yak (Bos grunniens) rumen and evaluate their effects on the fermentation characteristics and enzymatic hydrolysis in rice straw silage. Methods and Results: A novel microbial consortium M2 with high CMCase and xylanase activities was enriched and observed to be prone to use natural carbon sources. Its predominant genus was Enterococcus, and most carbohydrate‐active enzyme (CAZyme) genes belonged to the glycosyl hydrolases class. The consortium M2 was introduced with or without combined lactic acid bacteria (XA) to rice straw silage for 60 days. Inoculating the consortium M2 notably decreased the structural carbohydrate contents and pH of rice straw silages. Treatment that combines consortium M2 and XA resulted in the highest levels of lactic acid and lignocellulose degradation. The consortium M2 alone or combined with XA significantly (p < 0.01) increased water‐soluble carbohydrates (WSCs), mono‐ and disaccharides contents compared with the XA silage. Combined addition obviously improved the enzymatic conversion efficiency of rice straw silage with higher glucose and xylose yields (23.39 and 12.91 w/w% DM, respectively). Conclusions: Ensiling pretreatment with the microbial consortium M2 in sterile rice straw improved fermentation characteristics. The combined application of consortium M2 with XA had synergistic effects on promoting the degradation of structural carbohydrates and enzymatic hydrolysis. Significance and Impact of the Study: Rice straw is difficult to ensile because of its low WSC and high structural carbohydrate contents. The microbial consortium M2 identified herein exhibits great potential for degrading fibrous substrates, and their combination with XA provides a faster and more effective synergistic strategy for biorefinery of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

Postharvest management strategies like cutting height and anaerobic fermentation may affect the microbial risk of vegetables. This study evaluated the effects of cutting height and storage length on the fermentation characteristics, microbial diversity, co-occurrence networks, potential functionality and pathogenic risk of sweet sorghum stem (SSS). Fresh SSS harvested at two cutting heights (15 cm, F 15 ; 45 cm, F 45) was spontaneously fermented (S 15 and S 45) for 2, 4, 8, 16, 32 and 64 days. Decreasing the cutting height of SSS increased the dry matter, water-soluble carbohydrate content as well as Acinetobacter (23.0% vs. 44.9%) and Klebsiella (1.84% vs. 6.58%) proportion but decreased the crude protein content (P < 0.05). After fermentation, both cutting heights presented desirable fermentation. Anaerobic fermentation promoted the Glycolysis pathway (0.009 vs. 0.018) and related enzymes (l -lactate dehydrogenase, etc.) associated with lactate synthesis, but suppressed the degradation pathways of valine, leucine, isoleucine (0.011 vs. 0.003) and lysine (0.008 vs. 0.002). In microbial phenotype analysis, although F 15 had higher proportions of 'Potentially Pathogenic' than F 45 , this undesirable phenotype declined to negligible levels via fermentation. These results concluded that, for SSS, concerns about the risk of microbial contamination and pathogens from low cutting height can be dispelled by well fermentation. • Microbial succession was studied from fresh to fermented sweet stalk. • Low cutting height increased the risk of pathogenic contamination. • Sequencing showed potential probiotics were dominant in all fermented materials. • Spontaneous fermentation dispelled microbial risk from low mowing heights. [ABSTRACT FROM AUTHOR]

This study was conducted to assess the effect of different additives on the fermentation characteristics, in vitro digestibility and aerobic stability of fermented total mixed ration (FTMR) prepared with local feed resources in Tibet, China. Additives added to FTMR were Lactobacillus buchneri (1 × 106 cfu/g fresh weight (FW)), acetic acid (0.3% FW), propionic acid (0.4% FW), 1,2‐propanediol and 1‐propanol (0.5% FW). FTMR were opened after 90 days and subjected to a 14‐d aerobic stability test. The results showed that L. buchneri, 1,2‐propanediol and 1‐propanol increased (P < 0.05) pH values and acetic acid concentrations and decreased (P < 0.05) lactic acid concentrations in FTMR. Adding acetic acid decreased (P < 0.05) lactic/acetic acid ratio. FTMR treated with propionic acid had higher (P < 0.05) lactic acid, propionic acid and DM recovery compared with the other treatments. Treating FTMR with acetic acid, 1,2‐propanediol and 1‐propanol decreased (P < 0.05) yeast counts. The in vitro potential gas production tended to be lower in L. buchneri‐treated silage than other silages. During aerobic exposure, FTMR treated with propionic acid spoiled first, with marked pH increase and lactic acid decrease from days 9 to 14. Treatment with L. buchneri, acetic acid, 1,2‐propanediol and 1‐propanol markedly improved the aerobic stability, as indicated by nearly unchanged pH and lactic acid concentrations. The results suggest that L. buchneri, acetic acid, 1,2‐propanediol and 1‐propanol did not adversely affect the in vitro digestibility and could be effective additives for enhancing the aerobic stability of FTMR prepared on Tibetan plateau. [ABSTRACT FROM AUTHOR]

Napier grass (Pennisetum purpureum) is well-known due to its high biomass production. The epiphytic microbiota was prepared from Napier, alfalfa, and red clover grass and served as an inoculum. The chopped sterilized Napier grass was inoculated with reconstituted epiphytic microbiota, and treatments were designed as: distilled water (N0); Napier grass epiphytic microbiota (NP); alfalfa epiphytic microbiota (AL); and red clover epiphytic microbiota (RC). The results reveal that the reconstituted epiphytic microbiota bacteria efficiently adapted in Napier grass silage, improved fermentation, and produced lactic acid. The alfalfa-grass inoculum rapidly dropped pH and enhanced the lactic acid (LA) and the ratio of lactic acid-to-acetic acid (LA/AA) during the entire ensiling process. However, red clover attains high lactic acid, while Napier grass produces high acetic acid-type fermentation at terminal silage. After day 60 of ensiling, Lactobacillus proportion was higher in AL (85.45%), and RC (59.44%), inocula as compared with NP (36.41%), inoculum. The NP inoculum terminal silage was diverse than AL and RC inocula and dominated by Enterobacter (16.32%) and Enterobacteriaceae (10.16%) and also significantly (p < 0.05) higher in acetic acid. The present study concluded that AL and RC epiphytic microbiota successfully develop and more efficient than Napier grass microbiota. It is suggested that abundant microbiota isolate from alfala and red clover and develop more economical and efficient inocula for quality fermentation of Napier grass silage in practice. [ABSTRACT FROM AUTHOR]

The study evaluated the effects of growth stage and ensiling time on silage fermentation characteristics, bacterial communities and their predicted functional potential in Italian ryegrass (Lolium multiflorum Lam.) silage. Italian ryegrass (IR) was harvested at heading (Earing rate >50 %, IR1) and blooming stages (>50% bloom, IR2), respectively. The harvested IR was ensiled in 15-L plastic silos. The experiment had a completely randomized design. Triplicate silos were sampled after 1, 3, 7, 15, 30 and 60 days of fermentation, respectively. The fermentation products were analyzed on each sampling day. The bacterial communities and their functional potential and phenotype on day 3 and 60 were analyzed by high-throughput sequencing technique and PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) method. With the advancing maturity of IR, the neutral detergent fiber and dry matter (DM) contents, lactic acid bacteria, yeast, Enterobacteriaceae and aerobic bacteria populations increased, while water soluble carbohydrate contents and buffering capacity decreased. Larger lactic acid contents were accumulated in IR1 than IR2 at the early stage of fermentation. Higher contents of ethanol and ammonia nitrogen (NH 3 -N) were found in IR1 compared to IR2 at the late stage of ensiling. After 60 days, IR1 and IR2 both had good fermentation quality with low pH values (∼4.08), and acceptable levels of NH 3 -N (∼67.6 g/kg total nitrogen) and butyric acid (∼1.08 g/kg DM). The IR2 had lower abundance of Lactobacillus on day 3, and higher abundances of Kosakonia and Pantoea on day 60 compared to IR1. The bacterial community in IR2 had higher activity in metabolic pathway. Overall, high throughput sequencing technique combined with PICRUSt2 method can improve our understanding of the silage microbiology to further regulate the fermentation products. • Italian ryegrass harvested at heading and blooming stages are both preserved well. • High lactic acid contents are found in young Italian ryegrass silage initially. • Low ammonia nitrogen contents are found in matured Italian ryegrass silage. • Large ratios of Kosakonia and Pantoea are found in matured Italian ryegrass silage. • The metabolic activity of bacterial community in matured Italian ryegrass is high. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate the effects of natamycin, hexanoic acid, and Lactobacillus plantarum on fermentation characteristics, aerobic stability, mycotoxins concentrations, and bacterial community in high moisture whole-crop corn silage. Whole-crop corn was harvested at 1/2 milk lines stage and ensiled without additive (CON), with L. plantarum (LP, 1 ×106 cfu/g FW), natamycin (NAT, 0.2 mg/kg FW), or hexanoic acid (HEX, 0.4 mg/kg FW). The addition of NAT and LP enhanced (P < 0.05) lactic acid (LA) production as compared to CON and HEX silage. HEX depressed LA accumulation leading to higher (P < 0.05) pH and water-soluble carbohydrates (WSC). The HEX and NAT silages had lower (P < 0.05) yeast count and ethanol concentration than CON and LP silages. NAT and LP decreased the concentration of ammonia N as compared to CON silage with the lowest value in LP silage. After 60 d of ensiling, LP silage spoiled within 22 h, NAT silage was stable for 41 h, which was slightly (P > 0.05) longer than CON silage (34 h). The HEX silage showed the longest aerobic stability (>144 h) among all silages. Ensiling decreased zearalenone (ZEN) and deoxynivalenol (DON) concentrations (P < 0.05). The LP and NAT silages had significantly (P < 0.05) lower aflatoxin B 1 (AFB 1), ZEN, and DON concentrations than fresh corn, CON, and HEX silages. All additives depressed the growth of Lactococcus , but increased the relative abundance (RA) of Lactobacillus compared to CON. LP reduced the RA of Leuconostocs , while HEX showed stronger antibacterial abilities to Klebsiella than LP and NAT. In conclusion, HEX improved the aerobic stability, whereas NAT and LP improved fermentation quality by enhancing the proliferation of Lactobacillus during ensiling of high moisture whole-crop corn. • Ensiling decreased Zearalenone and Deoxynivalenol concentrations. • Adding hexanoic acid depressed lactic acid production in corn silage. • L. plantarum and natamycin enhanced the proliferation of Lactobacillus. • Hexanoic acid improved aerobic stability of high moisture whole crop corn silage. [ABSTRACT FROM AUTHOR]