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

Improving fermentation quality, aerobic stability, and microbial community stabilization of triticale by Amomum villosum essential oil

This study aimed to examine the impacts of Lentilactobacillus buchneri (LB), Amomum villosum essential oil (AVEO), and vanillic acid (VA) on the fermentation traits, aerobic stability, and microbial community composition of ensiled triticale samples throughout the duration of air exposure. The chopped triticale was thoroughly blended, and the mixture was subjected to the following experimental treatments: CK, purified water at 1 mL kg-1 fresh weight (FW); AVEO, application at 1 mL kg-1 FW; LB, application at 1 × 106 CFU/g FW; and VA, application at 1 mL kg-1 FW. During the aerobic exposure phase, the dry matter and starch contents of the additive groups were greater, and the neutral detergent fiber content was lower than that of the control group (P < 0.05), particularly in the AVEO treatment group. The pH value, lactic acid concentration, and aerobic stability were also greater (P < 0.05) in the AVEO treatment group than in the other treatment groups. Compared with the control silage, the additive groups presented greater Bacillus and Lactiplantibacillus abundances, whereas the additive groups presented lower Sphingomonas and Stenotrophomonas abundances. The AVEO-treated silage had greater Lactiplantibacillus and Bacillus abundances and lower Sphingomonas and Stenotrophomonas abundances. Compared with the control silage, the additive groups presented greater Rhizopus abundances, while the additive groups presented lower Monascus and Cladosporium abundances. The AVEO-treated silage had more Rhizopus and fewer Monascus and Cladosporium abundances. The use of AVEO in triticale silages resulted in increased aerobic stability, while also reducing the presence of harmful microbial communities.IMPORTANCEThe utilization of ensiling for the preservation of forage has been demonstrated to be an effective and environmentally sustainable approach. Nevertheless, ensiled samples will inevitably come into contact with air during use or under unfavorable circumstances, leading to aerobic deterioration. AVEO helped maintain a high relative abundance of Lactiplantibacillus and Bacillus after aerobic exposure, suggesting that AVEO acts as an enrichment agent for Lactiplantibacillus and Bacillus in triticale silage. The AVEO treatment group also had a greater relative abundance of Rhizopus, resulting in the continuous generation of LA under aerobic conditions. This led to the maintenance of an acidic environment, inhibition of fungal proliferation, and delay in aerobic deterioration. These findings demonstrate that AVEO has the ability to positively impact the microbial community of triticale silage and thus improve fermentation quality and aerobic stability. This study provides a scientific foundation for producing triticale silages of superior quality.

Compound lactic acid bacteria enhance the aerobic stability of Sesbania cannabina and corn mixed silage

BACKGROUND

The strategic delay of aerobic deterioration in Sesbania cannabina and corn (SC) mixed silage, coupled with effective fermentation, could increase the protein-rich silage utilization by ruminants. Thus, we sought to investigate the role of a compound lactic acid bacteria (LAB) inoculant (Lactobacillus plantarum + Lactobacillus farciminis + Lactobacillus buchneri + Lactobacillus hilgardii; at a level of 106 CFU/g fresh weight) in enhancing the aerobic stability of SC mixed silage. Specifically, we focused on the potential for corn supplementation to improve fermentation quality while concurrently increasing the susceptibility of SC mixed silage to aerobic spoilage.

RESULTS

Results revealed that compound LAB additive diversified the microbial community of SC mixed silage, making Lactobacillus hilgardii and Lactobacillus buchneri dominant bacterial species, while decreasing the abundance of Kazachstania humilis fungal specie. As a result, the LAB-treated mixed silages had higher acetic acid contents and lower yeast populations. Aerobic stability analysis revealed that the SC mixed silages with a high corn proportion deteriorated rapidly when the silages were exposed to air. The high aerobic stability of the LAB-treated mixed silages especially S7C3 contrasted with the low acetic acid concentrations in the CK mixed silages (processed with sterilized water), concomitant with increased Kazachstania humilis abundance.

CONCLUSION

Our study revealed that inoculation with a compound LAB additive altered the consequences of aerobic exposure by increasing acetic acid production after ensiling, promoting diverse bacterial populations, and mitigating the negative effects of fungi on the aerobic stability of SC mixed silage.

Effects of Two Bacterial Exopolysaccharides on Microbial Community, Fermentation Characteristics and Aerobic Stability in Oat Silage

This study investigated whether two exopolysaccharides could serve as exogenous carbon sources to enhance fermentation quality in oat silage, providing a theoretical foundation for their future application in silage. The oats were harvested at the heading stage and, following a period of wilting, were chopped into 2-3 cm lengths for the ensiling experiment. The treatments applied were as follows: (1) a control group (CK), which received only sterile water; (2) a group with added dextran (D); and (3) a group with added levan (L). The fermentation process was monitored at various intervals: 3, 7, 14, 30 and 60 days (d), respectively. Following 60 days of ensiling, the silage was subjected to a 5-day period of aerobic exposure (AE). EPS changed the fermentation quality of silage, altered the composition of the bacterial community, and had an impact on the feature dissimilarity between sample groups. Meanwhile, EPS showed different regulatory effects on carbohydrate metabolism at different fermentation times. EPS treatment increased the lactic acid content and decreased the pH of silage. After 60 days of fermentation, the treatment also increased the relative abundance of Lactobacillus. Dextran and levan increased the relative abundance of Hafnia-Obesumbacterium and Sediminibacterium, respectively. Under the treatment of dextran, silage retained more WSC content and achieved higher aerobic stability. Upon comparing the bacterial correlation networks, it became evident that the fermentation time altered the composition of inter-bacterial correlations. In conclusion, EPS can effectively enhance the fermentation quality of oat silage, with dextran yielding the most pronounced positive effects.

Effects of Mixing Ratio and Lactic Acid Bacteria Preparation on the Quality of Whole-Plant Quinoa and Whole-Plant Corn or Stevia Powder Mixed Silage

Quinoa is the only single plant that can meet all the nutritional needs of human, and its potential for feed utilization has been continuously explored, becoming a prosperous industry for poverty alleviation. In order to further tap the feeding value of whole quinoa, develop quinoa as a feed substitute for conventional crops such as corn, and improve its comprehensive utilization rate, this experiment analyzed the silage quality and mycotoxin content of mixed silage of whole-plant quinoa (WPQ) with whole-plant corn (WPC) or stevia powder(SP) in different proportions, and further improved the silage quality of mixed silage by using two lactic acid bacteria preparations (Sila-Max and Sila-Mix). The quality, microbial population, and mycotoxin levels of quinoa and corn silage, as well as that of the mixed silage of quinoa and stevia, were evaluated using single-factor analysis of variance. The impact of various lactic acid bacteria preparations on the quality of whole-quinoa and whole-corn mixed silage was investigated through two-factor analysis of variance. WPQ and WPC were mixed at the ratio of 5:5 (QB5), 6:4 (QB6), 7:3 (QB7), 8:2 (QB8), 9:1 (QB9) and 10:0 (QB10). SP was mixed with WPQ at the supplemental levels of 0.2% (QB10S2), 0.4% (QB10S4), 0.6% (QB10S6), 0.8% (QB10S8) and 1.0% (QB10S10). After 60 days of silage, the silage indexes, the number of harmful microorganisms, and the mycotoxin levels were measured, to explore the appropriate ratio of mixed silage. The membership function analysis showed that the quality of mixed silage of WPQ with SP was better, and the optimal addition amount of SP was 0.6%. The results of Max and Mix on the quality improvement test of WPQ with WPC mixed silage showed that the two lactic acid bacteria formulations increased CP and AA content, and reduced NH3-N/TN; pH was significantly lower than the control group (p < 0.01), and LA was significantly higher than the control group (p < 0.01). The microbial count results showed that the addition of lactic acid bacteria preparation significantly reduced the number of molds and aerobic bacteria, and the effect of Mix was better than that of Max. When the mixing ratio was between QB7 and QB10, mold was not detected in the lactic-acid-bacteria preparation groups. Max and Mix significantly reduced the levels of mycotoxins, both of which were far below the range of feed safety testing, and 16S rRNA sequencing revealed that the silage microbiota varied with different mixing ratios and whether lactic acid bacteria preparations were used. Max and Mix increased the relative abundance of Firmicutes, with Mix having a more significant effect, especially in the QB6 (65.05%) and QB7 (63.61%) groups. The relative abundance of Lactobacillus was significantly higher than that of the control group (p < 0.05). The relative abundance of Enterobacteriaceae and Streptococcus were negatively and positively correlated with the addition level of quinoa, respectively. Comprehensive analysis showed that adding 0.6% SP to the WPQ and using Mix in mixed silage of WPQ and WPC with the proportion of WPQ no less than 70% had the best silage effect, and was more beneficial to animal health.

Effect of Regulation of Whole-Plant Corn Silage Inoculated with Lactobacillus buchneri or Bacillus licheniformis Regarding the Dynamics of Bacterial and Fungal Communities on Aerobic Stability

Enhancing the aerobic stability of whole-plant corn silage is essential for producing high-quality silage. Our research assessed the effect of inoculation with Lactobacillus buchneri or Bacillus licheniformis and its modulation of the bacterial and fungal microbial community structure in an aerobic stage of whole-plant corn silage. Following treatment with a distilled sterile water control, Lactobacillus buchneri, and Bacillus licheniformis (2 × 105 cfu/g), whole-plant corn was ensiled for 60 days. Samples were taken on days 0, 3, and 7 of aerobic exposure, and the results showed that inoculation with Lactobacillus buchneri or Bacillus licheniformis improved the aerobic stability of silage when compared to the effect of the control (p < 0.05). Inoculation with Bacillus licheniformis attenuated the increase in pH value and the decrease in lactic acid in the aerobic stage (p < 0.05), reducing the filamentous fungal counts. On the other hand, inoculation with Lactobacillus buchneri or Bacillus licheniformis increased the diversity of the fungal communities (p < 0.05), complicating the correlation between bacteria or fungi, reducing the relative abundance of Acetobacter and Paenibacillus in bacterial communities, and inhibiting the tendency of Monascus to replace Issatchenkia in fungal communities, thus delaying the aerobic spoilage process. Due to the prevention of the development of aerobic spoilage microorganisms, the silage injected with Lactobacillus buchneri or Bacillus licheniformis exhibited improved aerobic stability.

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.

Study on Dynamic Fermentation of Oat Silage Assisted by Exogenous Fibrolytic Enzymes

Based on the low content of water-soluble carbohydrate (WSC) and lactic acid bacteria (LAB) attachment in oat raw materials, we assumed that the neutral detergent fiber (NDF) content of oat can be reduced by adding cellulase or xylanase. The concentration of metabolizable sugars will be increased, which will assist the oat's bacterial community in fermentation and obtain a better quality of oat silage. After wilting the oat, it was treated as follows: (1) distributed water (CK); (2) silages inoculated with xylanase (X); and (3) silages inoculated with cellulase (C), ensiling for 3, 7, 14, 30, and 60 days. Cellulase and xylanase treatments both alter the fermentation and nutritional quality of ensiled oat, resulting in lower NDF, acid detergent fiber (ADF), cellulose, and hemicellulose contents, increased lactic acid and acetic acid contents, and a significant decrease in ensiling environment pH. The bacterial community undergoes significant changes with cellulase and xylanase treatments, with a significant increase in Lactobacillus abundance in the C_14, X_30, C_30, X_60, and C_60 treatment groups, while Weissella abundance gradually decreases with longer ensiling times. Two exogenous fibrolytic enzymes also alter the bacterial diversity of ensiled oat, with different bacterial species and abundances observed in different treatment groups. Ensiled oat treated with cellulase and xylanase experiences significant changes in its own bacterial community, particularly in the abundance of Lactobacillus. These changes result in improved fermentation and nutritional quality of oat, but the higher metabolism levels observed after 60 days of ensiling with cellulase treatment may lead to energy loss.