Melatonin Is a Promising Silage Additive: Evidence From Microbiota and Metabolites

The safe and effective storage of forage are very important. As an important storage method, ensiling can keep fresh forage for a long time with less nutritional loss. Melatonin has antioxidant and bacteriostasis, usually used as a natural preservative. The influence of melatonin on silage microbial or fermentation quality has not been clarified. In the present study, we aimed to clarify whether melatonin affected stylo (Stylosanthes guianensis) silage quality via microbiota and metabolites. Melatonin addition significantly improved the silage fermentation quality, including the increased contents of lactic acid and total acid (244.18–255.81% and 63.95–78.97%, respectively), as well as the decreased in pH and butyric acid content compare with control group. Moreover, 16S rRNA sequencing indicated that melatonin addition enhanced the silage microbial diversity indices (such as increase in Shannon indices but decrease in Simpson indices), and significantly shaped the composition of silage microbiota (such as increased abundances of Pantoea, Stenotrophomonas, Sphingobacterium, and Pseudomonas, and decreased abundance of Weissella). Melatonin addition also dramatically affected the metabolites of sylo silage, such as raised malonic acid and some amino acid metabolism(glycine, threonine, methionine and ornithine), while reduced nucleic acid metabolism(2-deoxyuridine and thymine) and carbon metabolism(allose and 2-deoxy-D-glucose). Collectively, our results confirmed that the lowest melatonin addition (5 mg/kg) could improve the fermentation quality, and the potential mechanisms might be associated with the microbiota and metabolites in stylo.

Bacterial Succession Pattern during the Fermentation Process in Whole-Plant Corn Silage Processed in Different Geographical Areas of Northern China

Whole-plant corn silage is a predominant forage for livestock that is processed in Heilongjiang province (Daqing city and Longjiang county), Inner Mongolia Autonomous Region (Helin county and Tumet Left Banner) and Shanxi province (Taigu and Shanyin counties) of North China; it was sampled at 0, 5, 14, 45 and 90 days after ensiling. Bacterial community and fermentation quality were analysed. During fermentation, the pH was reduced to below 4.0, lactic acid increased to above 73 g/kg DM (p < 0.05) and Lactobacillus dominated the bacterial community and had a reducing abundance after 14 days. In the final silages, butyric acid was not detected, and the contents of acetic acid and ammonia nitrogen were below 35 g/kg DM and 100 g/kg total nitrogen, respectively. Compared with silages from Heilongjiang and Inner Mongolia, silages from Shanxi contained less Lactobacillus and more Leuconostoc (p < 0.05), and had a separating bacterial community from 14 to 90 days. Lactobacillus was negatively correlated with pH in all the silages (p < 0.05), and positively correlated with lactic and acetic acid in silages from Heilongjiang and Inner Mongolia (p < 0.05). The results show that the final silages had satisfactory fermentation quality. During the ensilage process, silages from Heilongjiang and Inner Mongolia had similar bacterial-succession patterns; the activity of Lactobacillus formed and maintained good fermentation quality in whole-plant corn silage.

Natural Fermentation Quality and Bacterial Community of 12 Pennisetum sinese Varieties in Southern China

This study investigated the fermentation quality of 12 varieties of Pennisetum sinese grown in different regions of Southern China. Following the production of silage from the natural fermentation of P. sinese, the interplay between the chemical composition, fermentation characteristics, environmental factors, and microbiome was examined to understand the influence of these factors on the fermentation quality of silage. The silage quality produced by most of the P. sinese was low; the pH value of the silage was high (4.26–4.86), whilst the lactic acid content was low (10.7–24.1 g/kg DM), with V-scores between 57.9 and 78.3. The bacterial alpha diversities of the 12 P. sinese silages were distinct. There was a predominance of undesirable bacteria (Pseudomonas, Massilia, and Raoultella), which likely caused the poor fermentation quality. The chemical composition and fermentation characteristics of the silage were closely correlated with the composition of the bacterial community. Furthermore, environmental factors (precipitation, temperature, humidity, location) were found to significantly influence the microbiome of the silage. The results confirmed that silage produced from the natural fermentation of 12 different P. sinese varieties had significant variation in their bacterial communities. The difference in environmental factors, due to the P. sinese being grown in various locations across south china, greatly affected the bacterial community found in the silage and thus the fermentation quality. The specific cultivar used for the silage and the environment in which the cultivar is grown must therefore be considered before the initiation of production of silage in order to ensure a higher quality product.

The use of PacBio SMRT technology to explore the microbial network and fermentation characteristics of woody silage prepared with exogenous carbohydrate additives

AIMS

To effectively use woody plant resources to prepare silage for ruminants, Pacific Biosciences (PacBio) single-molecule real-time (SMRT) sequencing was applied to study the microbial network and fermentation characteristics of paper mulberry (PM) silage prepared with corn meal (CM) and rice bran (RB) as exogenous additives.

METHODS AND RESULTS

PM is rich in nutrients and contains more than 26% crude protein in dry matter. After ensiling, the microbial diversity and abundance in PM, CM and RB decreased due to the anaerobic environment and acidic conditions. The CM-treated PM silage accelerated the conversion of the dominant microbial community from harmful bacteria to lactic acid bacteria and promoted lactic acid fermentation. When RB was used to treat PM silage, Enterobacter and Clostridium species became the main bacterial community during ensiling, leading to butyric acid fermentation and protein decomposition. Compared with RB, CM increased the amount of fermentation substrates, changed the microbial community structure and affected metabolic pathways (global metabolism, carbohydrate metabolism and amino acid metabolism), which improved the flavour and quality of the PM silage.

CONCLUSIONS

The CM addition of improved the fermentation quality of PM silage, with PM + CM being the ideal combination. The SMRT sequencing technology could accurately obtain specific details of the microbial networks and fermentation characteristics. Our results indicate that PM can be used as a potential high-protein silage in animal production.

SIGNIFICANCE AND IMPACT OF THE STUDY

In tropics, the effective use of abundant natural biomass resources such as woody plants to prepare silage for feed preservation can solve the problem of restricting livestock production due to the shortage of feed in the dry season. SMRT sequencing technology was used to accurately analyze the microbial network and fermentation characteristics of woody silage prepared with CM as an exogenous additive to improve the fermentation quality of silage.

Co-Occurrence of Regulated and Emerging Mycotoxins in Corn Silage: Relationships with Fermentation Quality and Bacterial Communities

Sixty-four corn silages were characterized for chemicals, bacterial community, and concentrations of several fungal metabolites. Silages were grouped in five clusters, based on detected mycotoxins, and they were characterized for being contaminated by (1) low levels of Aspergillus- and Penicillium-mycotoxins; (2) low levels of fumonisins and other Fusarium-mycotoxins; (3) high levels of Aspergillus-mycotoxins; (4) high levels of non-regulated Fusarium-mycotoxins; (5) high levels of fumonisins and their metabolites. Altersetin was detected in clusters 1, 3, and 5. Rugulusovin or brevianamide F were detected in several samples, with the highest concentration in cluster 3. Emodin was detected in more than 50.0% of samples of clusters 1, 3 and 5, respectively. Kojic acid occurred mainly in clusters 1 and 2 at very low concentrations. Regarding Fusarium mycotoxins, high occurrences were observed for FB3, FB4, FA1, whereas the average concentrations of FB6 and FA2 were lower than 12.4 µg/kg dry matter. Emerging Fusarium-produced mycotoxins, such as siccanol, moniliformin, equisetin, epiequisetin and bikaverin were detected in the majority of analyzed corn silages. Pestalotin, oxaline, phenopirrozin and questiomycin A were detected at high incidences. Concluding, this work highlighted that corn silages could be contaminated by a high number of regulated and emerging mycotoxins.

Contributions of epiphytic microbiota on the fermentation characteristics and microbial composition of ensiled six whole crop corn varieties

AIMS

The present study is aimed to reveal the variations in epiphytic microbial composition among six whole crop corn (WCC) varieties and their contributions on ensiling characteristics and microbial composition of WCC silage.

METHODS AND RESULTS

Six WCC varieties (JS06, YS23, BS20, JS39, JS40 and JS26) were ensiled for 90 days. All WCC varieties were well fermented with low pH value (<4·0) and high LA (73·6-124 g kg^-1 DM, dry matter) concentration. Of six varieties, JS40 had the highest LA (124 g kg^-1 DM) concentration, which was supported by highest relative abundance of Lactobacillus. Pantoea was the most dominant epiphytic bacteria in all fresh WCC varieties; however, the secondary dominant genera among six WCC were absolutely difference. Lactobacillus became predominant genus in 90-day silages except YS23. YS23 kept the more bacterial genus from fresh to 90-day silages than other silages, meanwhile Acinetobacter and Enterobacter were the dominant bacteria in YS23 silages.

CONCLUSIONS

Among six WCC varieties, JS40 silage had the highest LA. The variations in epiphytic microbiomes among fresh WCC affected terminal microbial community of 90-day silages. There were differences in fermentation characteristics among six WCC varieties, which might be partly attributed to variations in epiphytic microbiomes among fresh WCC.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study not only enriches the research on microbial communities of plant phyllosphere but also provides theoretical basis for selecting WCC varieties and inoculants for the forage production.

Effects of Citric Acid and Lactobacillus plantarum on Silage Quality and Bacterial Diversity of King Grass Silage

To better understand the mechanism underlying the citric acid (CA)-regulated silage fermentation, we investigated the bacterial community and fermentation quality of king grass (KG) ensiled without (CK) or with Lactobacillus plantarum (L), CA and the combination of L and CA (CAL). The bacterial community was characterized by using the 16Sr DNA sequencing technology. The L and CA treatments altered the silage bacterial community of KG, showing reduced bacterial diversity, while the abundance of desirable genus Lactobacillus was increased, and the abundances of undesirable genus Dysgonomonas and Pseudomonas were decreased. The additives also significantly raised the lactic acid content, dropped the pH, and reduced the contents of acetic acid, propionic acid, and ammonia-N in ensiled KG (P < 0.01). Besides, the combination treatment was more effective on silage fermentation with the highest pH and lactic acid content, while the contents of acetic acid, propionic acid, and ammonia-N were the lowest (P < 0.01). Moreover, CAL treatment exerted a notable influence on the bacterial community, with the lowest operational taxonomic unit (OTU) number and highest abundance of Lactobacillus. Furthermore, the bacterial community was significantly correlated with fermentation characteristics. These results proved that L and CA enhanced the KG silage quality, and the combination had a beneficial synergistic effect.

Assessment of Bacterial Community Composition and Dynamics in Alfalfa Silages With and Without Lactobacillus plantarum Inoculation Using Absolute Quantification 16S rRNA Sequencing

Relative quantification 16S-seq (RQS) has drawn deeper insights into bacterial community compositions in silage. However, it provides no information on dynamics of the total amount of bacterial DNA through the ensiling process and across different treatments. In this study, bacterial compositions in alfalfa silage with and without Lactobacillus plantarum inoculation after 10 and 60days of ensiling were investigated using absolute quantification 16S-seq (AQS), and bacterial composition and its interaction with fermentation properties of silage indicated by AQS and RQS were compared. Variation in total bacterial DNA amounts across different treatments and ensiling periods was illustrated by AQS. AQS indicated higher bacterial richness indices and closer correlations of these indices with fermentation properties than RQS via spearman's correlation analyses, as well as more taxa with significance on bacterial abundance via lefse analyses. In conclusion, AQS effectively illustrated the dynamics of bacterial communities during the ensiling process.

Beneficial Effects of Tannic Acid on the Quality of Bacterial Communities Present in High-Moisture Mulberry Leaf and Stylo Silage

Tannic acid (TA), a type of polyphenol, is widely distributed in plants, especially in legumes. Not only does it possess antimicrobial properties, but it also has the ability to bind with proteins. The fermentation parameters, nitrogen fractions, antioxidant capacity, and bacterial communities present in mulberry leaves and stylo (Stylosanthes guianensis) ensiled with or without 1 and 2% TA per kilogram of fresh matter (FM) were investigated after 75 days’ fermentation. The results showed that 1 and 2% TA both significantly decreased the butyric acid content (4.39 and 7.83 g/kg dry matter (DM), respectively) to an undetectable level in both mulberry leaf and stylo silage. In addition, 2% TA significantly increased the contents of lactate (24.0–39.0 and 8.50–32.3 g/kg DM), acetate (18.0–74.5 and 9.07–53.3 g/kg DM), and the antioxidant capacity of both mulberry leaf and stylo silage, respectively. With the addition of 1 and 2% TA, the pH values (5.55–5.04 and 4.87, respectively) and ammonia-N (NH₃-N) content (85.5–27.5 and 16.9 g/kg total nitrogen (TN), respectively) were all significantly decreased in stylo silage. In addition, TA increased the relative abundance of Weissella, Acinetobacter, and Kosakonia spp. and decreased that of undesirable Clostridium spp. TA can thus be used to improve the silage quality of both mulberry leaf and stylo silage, with 2% TA being the better concentration of additive to use.

Effects of antibacterial peptide-producing Bacillus subtilis and Lactobacillus buchneri on fermentation, aerobic stability, and microbial community of alfalfa silage

This study assessed the effects of antibacterial peptide-producing Bacillus subtilis (BS), Lactobacillus buchneri (LB), or their combination on fermentation, proteolysis, aerobic stability, and microbial communities during ensiling and aerobic exposure phases of alfalfa silage. The results showed that the BS-treated silage displayed a higher lactic acid concentration, less proteolysis, and higher aerobic stability than those in the control silage. Both LB and BS treatments increased Lactobacillus and Ascochyta abundance, and decreased Enterococcus and Sporormiacea abundance after 60 d of fermentation. LB and BS also inhibited the growth of Enterococcus after 3 d of aerobic exposure but similar to the control silage, the fungal community of BS silage was dominated by Candida and Pichia after 9 d of aerobic exposure. Therefore, inoculation of BS improved silage fermentation quality, aerobic stability and bacterial community during ensiling and after 3 d of aerobic exposure.

Microbial diversity and fermentation profile of red clover silage inoculated with reconstituted indigenous and exogenous epiphytic microbiota

The study investigated the effects of transplantation and reconstitution of indigenous and exogenous epiphytic microbiota on the fermentation quality and microbial community of red clover silage. Sterile red clover was inoculated with distilled water (RC0), extracted epiphytic microbiota of red clover (RC), maize (MZ), and sorghum (SG). RC inoculation rapidly decreased pH at the onset of ensiling. The LA concentration and ratio of LA/AA were higher in RC silage during entire ensiling while MZ silage during late phase of ensiling. Pediococcus was dominant in RC early silage, while Lactobacillus was abundant in MZ final silage. The SG terminal silage had higher pH (>4.50) and dominated by Sphingomonas, Enterobacter, and Novosphingobium. RC and MZ microbiota were beneficial in enhancing fermentation quality and microbial community in red clover silage. Transplantation and reconstitution of epiphytic microbiota can be a successful method to assess the effective and eco-friendly additive for the targeted crop.

Dynamic microbial diversity and fermentation quality of the mixed silage of corn and soybean grown in strip intercropping system

This study assessed the fermentation quality and microbial community of corn (Zea mays L.) and soybean (Glycine max Merr.) (CS) mixed silage in strip intercropping system. CS mixed silage increased lactic acid content and decreased ammonia-N content compared to 100% soybean (S) silage, while it decreased ammonia-N content compared to 100% corn (C) silage. The largest number of epiphytic lactic acid bacteria was detected in CS fresh materials. During ensiling, Weissella and Lactobacillus dominated silage, the relative abundance of Lactobacillus in mixed silage was higher than that in S silage with the same S variety. After aerobic exposure (AE), synergistic effect existed in low relative abundance bacteria correlating with ammonia-N content and pH at ensiling 60 days and AE 7 days. In conclusion, CS mixed silage modified microbial community and improved fermentation quality.

Silage Fermentation, Bacterial Community, and Aerobic Stability of Total Mixed Ration Containing Wet Corn Gluten Feed and Corn Stover Prepared with Different Additives

Simple Summary

Wet corn gluten feed (WCGF) is a feed containing high moisture and rapidly digestible, non-forage fiber and protein for dairy cows, that is difficult to preserve. The use of corn stover as roughage by ruminants is limited by its poor digestibility. Total mixed ration (TMR) silage is an ensiling mixed feed that can fully mix forage and concentrate in a specific ratio to satisfy the nutritional needs of dairy cows, which has become an effective method of preservation of high-moisture byproducts. The objective of this study was to investigate the effects of different additives on the fermentation quality, bacterial community, and aerobic stability of TMR silage containing WCGF and corn stover. Inoculation with lactic acid bacteria (LAB) + fibrolytic enzyme (EN) and LAB improved aerobic stability of TMR silages indicated by higher and more stable LA and AA contents, a smaller rise in pH, and yeast count than other silages. Total mixed ration silage inoculated the LAB + EN and LAB can become an effective method of preserving high-moisture WCGF and corn stover with poor digestibility.

Abstract

The objective of this study was to investigate the effects of different additives on the fermentation quality, bacterial community, and aerobic stability of total mixed ration (TMR) silage containing wet corn gluten feed (WCGF) and corn stover. The TMR was ensiled with four treatments: (1) no additive (control); (2) lactic acid bacteria (LAB); (3) fibrolytic enzyme (EN); (4) LAB + EN. The EN and LAB + EN decreased the neutral detergent fiber and acid detergent fiber contents. Additives led to a higher lactic acid (LA) content (p < 0.0001) compared to control at all ensiling times. Silages inoculated with LAB and LAB + EN had higher dry matter (p = 0.0007), LA (p < 0.0001) and acetic acid (AA) contents (p < 0.0001) compared to control. The LAB and LAB + EN had significantly lowest ammonia nitrogen among the treatments, while no significant difference occurred after days 7 of ensiling. Silages treated with LAB and LAB + EN had a higher LAB count (p < 0.0001) and a lower pH, yeast, and mold counts compared to other silages. The LAB and LAB + EN greatly increased the portions of Firmicutes and Lactobacillus (p < 0.0001, and p < 0.0001, respectively) and reduced undesirable bacteria. Inoculation with LAB + EN and LAB improved aerobic stability of TMR silages indicated by higher and more stable LA and AA contents, smaller rise in pH, and yeast count than other silages. The LAB + EN and LAB reduced microbial diversity and improved the fermentation quality and aerobic stability of TMR silage containing WCGF and corn stover.

Effects of Sodium Formate and Calcium Propionate Additives on the Fermentation Quality and Microbial Community of Wet Brewers Grains after Short-Term Storage

Simple Summary

The objective of this study was to examine the effect of sodium formate and calcium propionate on the fermentation quality and microbial community of wet brewers grains (WBG) after short-term storage. Both additives improved the silage quality of WBG ensiled for 20 days to different extents. However, ensiled WBG treated with sodium formate had higher contents of dry matter, water-soluble carbohydrates, and neutral detergent fibers and better fermentation quality, rumen degradation, and microbial composition. The addition of sodium formate enhances the abundance of desirable Lactobacillus and reduces the abundance of undesirable microorganisms, including Clostridium. In summary, during short-term storage of high-moisture feed, sodium formate has a more beneficial preservation effect than an equivalent dose of calcium propionate.

Abstract

The objective of this research was to examine the effect of sodium formate (SF) and calcium propionate (CAP) on the fermentation characteristics and microbial community of wet brewers grains (WBG) after short-term storage. In the laboratory environment, fresh WBG was ensiled with (1) no additive (CON), (2) sodium formate (SF, 3 g/kg fresh weight), and (3) calcium propionate (CAP, 3 g/kg fresh weight) for 20 days. After opening, fermentation characteristics, chemical composition, rumen effective degradability, and the microbial community of ensiled WBG were analyzed. The addition of CAP had no effect on pH and lactic acid concentration and increased the concentrations of propionic acid; the SF group had the lowest pH and acetic acid, butyric acid, and ammonia nitrogen contents and the highest lactic acid concentration. After fermentation, the SF group had the highest contents of dry matter (DM), water-soluble carbohydrates (WSCs), and neutral detergent fiber (NDF). The contents of the three nutrients in the CAP group were significantly higher than those in the CON group. The addition of the two additives had little influence on the crude protein (CP) and acid detergent fiber (ADF) contents of the ensiled WBG. Two additives elevated in situ effective degradability of DM and NDF compared with the parameters detected in the CON group; WBG ensiled with SF had higher effective in situ CP degradability than that in the CON and CAP groups. The results of the principal component analysis indicate that the SF group and two other groups had notable differences in bacterial composition. The analysis of the genus level of the bacterial flora showed that the content of Lactobacillus in the SF group was significantly higher than that in the two other treatment groups, while the content of Clostridium was significantly lower than that in the two other treatment groups. Therefore, the addition of sodium formate can suppress the undesirable microorganisms, improve the fermentation qualities, and ensure that WBG is well preserved after 20 days of ensiling.

Intrinsic tannins affect ensiling characteristics and proteolysis of Neolamarckia cadamba leaf silage by largely altering bacterial community

The mechanism that tannins alter microbial community to inhibit proteolysis and enhance silage quality is unclear. Neolamarckia cadamba leaf (NCL; rich in tannins) were ensiled alone or with addition of polyethylene glycol (PEG, tannins inactivator), and then fermentation quality, proteolysis activity and bacterial community were investigated during ensiling (Day 3, 7, 14 and 30). As a result, PEG addition increased lactic acid (1.09% vs 2.03%, on dry matter basis) and nonprotein-N (13.65% vs 17.59%, on crude protein basis) contents but decreased ammonia-N content (9.21% vs 2.29%, on crude protein basis) in NCL silage. Meanwhile, the dominant microbiome shifted from Cyanobacteria (60.92%-81.50%) to Firmicutes (48.96%-88.67%), where the unclassified genus (80.95%-85.71%) was substituted by Leuconstoc (42.03%-55.55%) and subsequently Lactobacillus (65.98%-82.43%). This study suggests that the intrinsic tannins inhibit lactic acid fermentation and protein degradation in NCL silage.

Lactobacillus plantarum Inoculants Delay Spoilage of High Moisture Alfalfa Silages by Regulating Bacterial Community Composition

The objective of this study was to investigate the mechanism of Lactobacillus plantarum (L. plantarum) involved in improving fermentation quality of naturally ensiled alfalfa under poor conditions. High-moisture wilted alfalfa was ensiled without inoculants (CK) or with inoculation of two L. plantarum additives (LPI and LPII). The pH and fermentation products of silage were determined after 30 and 90 days of ensiling. Additionally, the bacterial community compositions were analyzed. The L. plantarum inoculants significantly promoted lactic acid accumulation, and Lactobacillus abundance for both periods. At 90 days, silage in CK exhibited a high pH, a loss in dry matter, and a high concentration of ammoniacal nitrogen. The inoculations of L. plantarum significantly inhibited the growth of Clostridia, and reduced ammoniacal nitrogen concentration in silage (P < 0.05). Thus, inoculation with L. plantarum improved the fermentation quality of alfalfa silage and inhibited the growth of spoilage microorganisms, and further delayed spoilage of alfalfa silage under adverse ensiling conditions.

Dynamic profiles of fermentation characteristics and bacterial community composition of Broussonetia papyrifera ensiled with perennial ryegrass

Broussonetia papyrifera (B. papyrifera) has been proposed to improve silage fermentation due to its high content of protein and abundant active plant extracts. Thus, dynamic profiles of fermentation quality and bacterial community of B. papyrifera mixing with perennial ryegrass in different ratios: 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50 were examined during 60-d fermentation. Results showed that adding perennial ryegrass increased soluble carbohydrate content and lactic acid production in silage and decreased pH and population of epiphytic microorganisms. Adding ryegrass exerted a remarkable effect on the silage bacterial community with a dramatic decrease in the abundance of Enterobacter. Spearman's rank correlation showed that silage lactic acid concentration was positively correlated with Lactobacillus and Stenotrophomonas abundance, while ammonia nitrogen concentration was positively correlated with the abundance of Enterobacter. In conclusion, B. papyrifera ensiled with perennial ryegrass could improve B. papyrifera silage quality and provide high-quality forage resources for sustainable ruminant livestock production.

Effects of citric acid on fermentation characteristics and bacterial diversity of Amomum villosum silage

To study the effects of citric acid on fermentation process of Amomum villosum silage, A. villosum was ensiled without or with 1%, 2% citric acid and fermentation parameters and bacterial diversity were analyzed after 3, 7, 14, 30 days ensiling, respectively. Citric acid treated silages had lower dry matter loss (1.83% vs 2.23%), pH (3.84 vs 6.02), ammonia-N (0.33 vs 1.79 g/kg DM) and coliform bacteria number (<2.00 vs 7.27 log₁₀ CFU/g FM) than the control after 30 days ensiling. The relative abundance of lactic acid bacteria, Pediococcus and Lactobacillus increased, whereas undesirable microorganisms like Enterobacter, Escherichia-Shigella and Pantoea decreased in citric acid treated A. villosum silage. These results indicated that quality A. villosum silage could be obtained by citric acid addition.

Effects of Lactobacillus plantarum additive and temperature on the ensiling quality and microbial community dynamics of cauliflower leaf silages

In order to enable rapid disposal and proper preservation of discarded vegetable for waste valorization, ensiling was employed to preserve cauliflower leaves for 30 days at different temperatures (20 ~ 45 °C) with and without the addition of Lactobacillus plantarum L8. The L. plantarum inoculant reduced dry matter (DM) loss and enhanced the preservation of protein and soluble carbohydrate while decreasing pH and ammonia nitrogen content. The silages at 35 °C exhibited the best fermentation profile characterized by the highest lactic acid content (185 g·kg^-1 DM) and the lowest pH (4.08) and ammonia nitrogen content (37.6 g·kg^-1 total nitrogen) with L. plantarum inoculation. The presence of exogenous L. plantarum improved the silage fermentation, enriched Lactobacillus and Weissella, and reduced the microbial richness/diversity, resulting in efficient lactic acid fermentation, especially at 30 and 35 °C. Moreover, the microbial community dynamics was correlated with the chemical compositions and fermentation metabolites in silages.

Inoculation of exogenous lactic acid bacteria exerted a limited influence on the silage fermentation and bacterial community compositions of reed canary grass straw on the Qinghai-Tibetan Plateau

AIMS

This study evaluated the effects of exogenous lactic acid bacteria (LAB) on silage fermentation and bacterial community of reed canary grass (RCG) straw.

METHODS AND RESULTS

The leaf, stem and whole crop of RCG straw were separately ensiled in small bag silos, without (control) or with inoculation of two exogenous LAB (LP, Lactobacillus plantarum; LB, Lactobacillus buchneri), and stored at ambient temperature of <20°C. Inoculation of exogenous LAB decreased (P < 0·05) bacterial alpha diversity and shifted (P < 0·05) bacterial community compositions, but did not change (P> 0·05) the relative abundance of Lactobacillus. Particularly, inoculation of LB increased (P < 0·05) acetic acid and propionic acid contents, decreased (P < 0·05) butyric acid (BA) and ammonia-N contents, separated (P < 0·05) the bacterial community in silage. However, the exogenous LAB inoculated silages were characterized by main distribution of yeasts, presence of undesirable bacterial genera such as Clostridium and high levels of BA and ammonia-N.

CONCLUSION

Inoculation of exogenous LAB exerted a limited influence on the silage fermentation and bacterial community compositions of RCG straw on the Qinghai-Tibetan Plateau.

SIGNIFICANCE AND IMPACT OF THE STUDY

Commercial LAB inoculants are not always efficient on enhancing silage quality and stability. Thus, an alternative additive for inhibiting undesirable microbes during storage is important to improve RCG silage quality on the Qinghai-Tibetan Plateau.

Microbial Community Dynamics and Natural Fermentation Profiles of Ensiled Alpine Grass Elymus nutans Prepared From Different Regions of the Qinghai-Tibetan Plateau

Feed deficiency during the long cold period of a year is one of the major problems that the traditional year-round animal grazing system has faced on the Qinghai-Tibetan plateau (QTP) since ancient time. Therefore, ensiling the grasses from grassland could be a desirable feeding regime to preserve high quality forage and to alleviate the seasonal unbalanced feed supply problem on this plateau. The present study was designed to investigate dynamics of bacterial community and natural fermentation quality of ensiled Elymus nutans collected from grasslands in four different areas with different elevations [Tianzhu County (TZ), 2965 m; Golog Prefecture (GL), 3763 m; Damxung County (DX), 4228 m, and Nagqu Prefecture (NQ), 4752 m] on the QTP. The bacterial community was characterized by using the PacBio single molecule with real-time sequencing technology (SMRT). The harvested fresh E. nutans grasses were ensiled in vacuum-sealed polyethylene bags for 14, 30, 60, and 90 days. Obvious differences in the epiphytic bacterial community of the fresh E. nutans samples from the four areas were observed, which resulted in various bacterial community dynamics and fermentation qualities of ensiled E. nutans. Higher fermentation quality was observed in silage samples from Nagqu than in those from the other areas (P < 0.05). Lactic acid bacteria (LAB) involved in fermentation of E. nutans from low altitude areas consisted of Pediococcus pentosaceus, Lactobacillus sp., Leuconostoc mesenteroides, and Lactobacillus coryniformis, whereas major LAB species involved in the fermentation of E. nutans silage from high altitudes included L. mesenteroides, Lactobacillus brevis, and Lactobacillus sp. Correlation analysis between bacterial composition and fermentation quality of E. nutans silages made from the four different areas in the QTP indicated that the LAB species responsible for silage fermentation in different areas were totally different, which was mainly due to the different epiphytic bacterial compositions in fresh E. nutans before ensiling. The present results provide important information on revealing the bacterial communities and fermentation quality of ensiled E. nutans, and on future screening of LAB isolates for making high quality silage in order to alleviate feed shortage of the traditional year-round grazing system on the QTP.

Effects of different simulated seasonal temperatures on the fermentation characteristics and microbial community diversities of the maize straw and cabbage waste co-ensiling system

Ensiling is considered as a suitable method to preserve seasonal agricultural residues to enable long-term supply for wastes valorization. In this study, the effects of simulated seasonal temperatures (-3, 18 and 34 °C) on the organic compositions, ensiling fermentation characteristics, and microbial community evolution during 120 days co-ensiling of maize straw and cabbage wastes were investigated. Successful storage performance was obtained at all these three temperatures. Comparatively, silages at 18 and 34 °C showed lower ammonia nitrogen, lower pH and more intensive lactic acid bacteria fermentation than that at -3 °C. Both silages at -3 and18 °C were well-preserved for 120 days with higher biodegradation potential (BDP), accompanied by lower content of acid detergent lignin (ADL). However, the silages at 34 °C could only preserved for 90 days due to low carbohydrate, low BDP and higher ADL content than that at -3 or18 °C. The storage temperature is a critical parameter that significantly affected the silage quality by influencing the microbial community diversity in silages. Proteobacteria and Firmicutes were dominant bacteria at phylum level for all silages while the dominant lactic acid bacteria at genus level were Lactobacillus and Leuconostoc, which restrained the undesirable microbes such as Enterobacteriaceae, Pseudomonas, Flavobacterium, and Pantoea during co-ensiling. Co-ensiling of maize straw with vegetable wastes may provide a promising strategy for long-term preservation of air-dried crop straw while using vegetable wastes as regulatable supplement to achieve silages of desired quality. This study could provide valuable information for conservation and management of agricultural wastes.

The reconstitution mechanism of napier grass microiota during the ensiling of alfalfa and their contributions to fermentation quality of silage

To reveal the reconstitution mechanism of exogenous microbiota and their contributions to fermentation quality during the early stage of alfalfa ensiling. The chopped alfalfa was treated with the following: distilled water (A1); napier grass microbiota (A1N); γ-ray radiation + distilled water (A0); γ-ray radiation + napier grass microbiota (A0N). Inoculating napier grass microbiota to non-irradiated alfalfa decreased the LA concentration, while enhanced the LA production of irradiated alfalfa during the 7 d of ensiling. Inoculating napier grass microbiota increased AA and ammonia-N contents and enhanced the decline of WSC for both non-irradiated and irradiated alfalfa silages. Enterococcus and Pediococcus dominated A1 silage. Leuconostocs and Lactobacillus constituted the majority of bacterial community in A0N, Lactobacillus rapidly became the predominated genera, while Lactobacillus, Leuconostocs, Enterococcus, and Pediococcus constituted the majority of bacterial community in A1N. Thus forage microbiota transplantation may be a potential practice to improve fermentation quality of less readily fermentable forages.

Effects of microbial inoculants on the fermentation characteristics and microbial communities of sweet sorghum bagasse silage

Sweet sorghum bagasse (SSB) is a promising raw material for silage fermentation due to its high residual nutritive, but the efficient fermentation strategy of SSB has not been reported yet. This study evaluated the effects of microbial inoculant on the fermentation quality, chemical composition and microbial community of SSB silage. The silage inoculated with isolated lactic acid bacteria (LpE) achieved better fermentation than that of commercial inoculant A, B (CIA, CIB) and untreatment, including low pH value, high levels of lactic acid and water soluble carbohydrates (WSC) content, which demonstrated that the LpE inoculant could contribute to the preservation of nutrition and the manipulation of fermentation process of SSB. In addition, the results of microbial community analysis indicated that the LpE inoculant significantly changed the composition and diversity of bacteria in SSB silage. After ensiling, the LpE inoculated silage were dominated by Lactobacillus(95.71%), Weissella(0.19%). These results were of great guiding significance aiming for high-quality silage production using SSB materials on the basis of target-based regulation methods.

Effects of Lactic Acid Bacteria Isolated From Rumen Fluid and Feces of Dairy Cows on Fermentation Quality, Microbial Community, and in vitro Digestibility of Alfalfa Silage

The objective of this study was to select lactic acid bacteria (LAB) isolated from the rumen fluid and feces of dairy cows, and evaluate their effects on silage quality of alfalfa after 30 or 60 days of ensiling. One hundred and four LAB strains were isolated from rumen fluid and feces of six dairy cows, of which four strains (Lactobacillus plantarum F1, L. plantarum F50, Lactobacillus salivarius L100, and Lactobacillus fermentum L120) and one commercial inoculant (GFG) isolated from forage were employed for further study. The silages treated with F1 had the lowest (P < 0.05) pH value and the highest (P < 0.05) lactic acid (LA) content in all treatments. Besides, higher (P < 0.05) in vitro digestibility was also observed in F1-treated silage after 60 days of ensiling. The microbial analysis showed that the Lactobacillus abundance in the F1-treated silages increased to 60.32%, higher than other treatments (5.12–47.64%). Our research indicated that strain F1 could be an alternative silage inoculant, and dairy cows could be a source for obtaining excellent LAB for ensiling.

Gallic acid influencing fermentation quality, nitrogen distribution and bacterial community of high-moisture mulberry leaves and stylo silage

To investigate the feasibility of vegetal gallic acid (GA) improving silage quality, fermentation parameter, nitrogen distribution and bacterial community of mulberry leaves and stylo ensiled with 1% and 2% GA were analyzed after 60-d fermentation. The results showed that GA addition decreased dry matter loss (6.08% vs 5.35%, 17.79% vs 11.56% in mulberry leaves and style silage, respectively), pH (6.51 vs 5.98, 5.55 vs 4.57), butyric acid (0.41% and 0.83% DM, undetected in GA groups) and ammonia-N (0.71% vs 0.19%, 1.46% vs 0.29% TN) contents and increased lactic acid (2.27% vs 6.68%, 0.91% vs 1.91% DM) and acetic acid (1.68% vs 3.20%, 0.97% vs 2.02% DM) contents. Meanwhile, the relative abundance of Clostridium or Enterobacter was decreased, and that of lactate-producing bacteria was increased in mulberry leaves and stylo silage. In conclusion, GA could be used as a green additive to improve fermentation quality and protein preservation during ensiling.

Ensiling characteristics, proteolysis and bacterial community of high-moisture corn stalk and stylo silage prepared with Bauhinia variegate flower

Bauhinia variegate flower (BVF) was supposed to improve silage fermentation due to its abundant active components. Thus, corn stalk and stylo were ensiled with addition of 0, 5% or 10% BVF, and then ensiling characteristics, protein fraction and bacterial community were analyzed after 60-day fermentation. The contents of butyric acid (2.9 vs not detected, 13.2 vs 3.0 g/kg DM in corn stalk and stylo silage, respectively), ammonia-N (100.2 vs 83.2, 110.8 vs 61.9 g/kg total N) and free amino acid (35.6 vs 16.5, 35.0 vs 16.4 g/kg total N) were decreased in 10% BVF treated silages. The bacterial diversity was increased, where the relative abundance of Enterobacter or Clostridium decreased and that of lactic acid producing bacteria such as Lactobacillus, Weissella or Enterococcus increased. It is suggested that BVF could be used to improve fermentation quality and nutrient preservation of high-moisture corn stalk and stylo silage.

Evaluation of the Bacterial Diversity of Inner Mongolian Acidic Gruel Using Illumina MiSeq and PCR-DGGE

As a traditional fermented cereal, Inner Mongolian acidic gruel has a unique flavor and rich nutrition, but the microbial diversity of acidic gruel and the microbial differences among the products in different regions have not been reported. The bacterial diversity and the lactic acid bacteria species of 27 types of traditional handmade acidic gruel were evaluated using a combination of MiSeq high-throughput sequencing and PCR-DGGE. All 358,205 high-quality 16S rRNA reads were divided into 25,171 OTUs under the similarity of 97%. Firmicutes, Proteobacteria, and Bacteroidetes were the dominant bacterial phyla, and the core dominant genera were Lactobacillus and Acetobacter with average relative abundances of 64.06% and 24.13%, respectively. The primary genera that caused the differences in the bacterial community structure between the Bayan Nur and Ordos acidic gruel samples were Pseudomonas, Leuconostoc, and Acinetobacter as revealed by redundancy analysis (RDA). PCR-DGGE analyses revealed that the lactic acid bacteria in both the Bayan Nur and Ordos samples of acidic gruel were Lactobacillus (L.) amylolyticus, L. alimentarius, L. fermentum, L. hamsteri, L. helveticus, L. panis, L. plantarum, L. pontis, and Leuconostoc lactis. In addition, L. hamsteri was the core strain detected among all the samples. The results deepened the understanding of the microbial community composition and the diversity of acidic gruel to provide a theoretical basis for the preservation and protection of microbial resources in acidic gruel in the Inner Mongolia area.

Effect of Wild Lactobacillus buchneri Strains on the Fermentation Profile and Microbial Populations of Sugarcane Silage

BACKGROUND

Sugarcane silage has been increasing as a feed in the tropics by dairy farmers. However, sugarcane normally had high yeast population that leads to intense alcoholic fermentation and excessive Dry-Matter (DM) loss during ensilage and after air exposure, as well. There are several patents that have recently shown the benefits of applying Lactobacillus buchneri in forage preservation.

OBJECTIVE

This study aimed to investigate the changes in pH, DM, Water-Soluble Carbohydrates (WSC) and fermentation end product concentrations that occur in sugarcane silage with or without inoculation with L. buchneri after 45 days of ensiling.

METHODS

Sugarcane plants were harvested with approximately 16 months of growth and chopped at 2 cm. Four strains of wild L. buchneri (56.1, 56.4, 56.9 and 56.26) and the commercial inoculant "Lalsil Cana" were evaluated. For all treatments, the theoretical application rate was 1.0 × 106 colony- forming units (cfu) per g of fresh weight. Data from the silo openings were analysed as a completely randomized design, with four replicates per treatment (inoculants).

RESULTS

The treatment with L. buchneri affected the DM content, pH, Lactic Acid Bacteria (LAB) population, DM recovery, and concentrations of WSC, lactic acid, acetic acid and ethanol of sugarcane silage after 45 days of ensiling. Yeasts and molds populations and the concentrations of propionic and butyric acids were not affected by the treatments.

CONCLUSION

Lactobacillus buchneri 56.1 and 56.4 are considered the most suitable strains for improving the fermentation of sugarcane silage and thus are potential inoculants for silage production. At present, we are preparing the patent application.

The bacterial community and fermentation quality of mulberry (Morus alba) leaf silage with or without Lactobacillus casei and sucrose

To investigate the effects of adding Lactobacilluscasei (LC) and sucrose (S) on the fermentation quality and bacterial community of mulberry leaf silage, two kinds of mulberry leaves were harvested and ensiled with or without LC and S for 1, 7, 14, 30 and 60 days, respectively. Silages treated with LC and S contained more lactic acid (4.46-10.54%DM) and less ammonia-N (0.03-0.13%DM), acetic acid (0.73-3.40%DM) and coliform bacteria (<2.30 log cfu/g FM) and had a lower pH (<4.40) compared with controls. In addition, microbial analysis revealed less diverse bacterial communities and greater abundances of Lactobacillus (52.89-81.27%) and Pseudomonas (2.21-5.21%) in the LC and S silages. Furthermore, the addition of LC and S also inhibited the growth of undesirable Enterobacter. In conclusion, the addition of both LC and S has the capability of improving the silage quality of mulberry leaves.

Effects of mixing Neolamarckia cadamba leaves on fermentation quality, microbial community of high moisture alfalfa and stylo silage

Neolamarckia cadamba is not only a fodder of high nutritional value, but also a source of natural antimicrobial agent. The silage quality of high moisture alfalfa and stylo with or without N. cadamba leaves (NCL) was investigated, and microbial community after ensiling was analysed. Results showed that the silage samples with NCL have lower pH (4.32 versus 4.88, 4.26 versus 4.71 in alfalfa and stylo silage, respectively), ammonia-N content (67.5 versus 146, 42.2 versus 95.1 g kg-1 total N) and higher lactic acid (13.3 versus 10.4, 17.3 versus 13.6 g kg-1 dry matter), true protein N (592 versus 287, 815 versus 589 g kg-1 total N). The addition of NCL also influenced the bacterial community distribution. The relative abundance of Clostridium and Enterobacter decreased, whereas Lactobacillus abundance increased when NCL was added. In conclusion, NCL could inhibit undesirable microorganisms in high moisture alfalfa and stylo silage. Mixing with NCL could be a feasible way to improve the quality of silage.

Dynamics of Bacterial Community and Fermentation Quality during Ensiling of Wilted and Unwilted Moringa oleifera Leaf Silage with or without Lactic Acid Bacterial Inoculants

Moringa oleifera leaf is a high-quality feed source for livestock and is increasingly used all over the world. Ensiling might be an effective method for preservation of the leaves. In the practice of silage making, lactic acid bacterial inoculants and wilting are commonly used to improve nutrition preservation. Monitoring the changes in a bacterial community during fermentation gives an insight into understanding and improving the ensiling process. Our results suggest that wilting and lactic acid bacterial inoculants had an influence on the bacterial community and fermentation process of M. oleifera leaf silage. Wilting showed positive effects on silage fermentation by decreasing the abundance of Enterobacter spp., while LF and LL improved the fermentation quality by inhibiting Enterobacter spp. and enhancing Lactobacillus spp. Both LF and LL accelerated the ensiling process from cocci (like Lactococcus, Enterococcus, and Leuconostoc spp.) to lactobacilli.

To investigate the effects of wilting and lactic acid bacterial inoculants on the fermentation quality and bacterial community of Moringa oleifera leaf silage, fresh and wilted M. oleifera leaves were ensiled with or without Lactobacillus farciminis LF or Lactococcus lactis LL for 1, 7, 14, 30, and 60 days. The results showed that wilting, inoculants, and their interaction exerted significant (P < 0.05) effects on the fermentation characteristics covering dry matter loss, pH value, lactic acid bacterial number, the ratio of lactic acid to acetic acid, and the relative abundances of bacteria, like for species of Lactobacillus, Lactococcus, Pediococcus, Enterococcus, Leuconostoc, and Enterobacter. Both LF and LL improved the fermentation quality of wilted and unwilted M. oleifera leaf silage by accelerating lactic acid production and pH decline, decreasing dry matter loss, and inhibiting yeast and coliform bacterial growth through the whole fermentation process. During ensiling, the abundances of Lactococcus, Enterococcus, and Leuconostoc spp. increased from day 1 to day 7 and then declined sharply from day 7 to day 14. Members of these genera and Enterobacter were inhibited, whereas Lactobacillus spp. were enhanced by these two lactic acid bacterial inoculants. The relative abundances of Enterobacter, Enterococcus, and Pediococcus spp. in inoculated silages were relatively low during the whole ensiling process. A lower abundance of Enterobacter spp. was observed in wilted silages than in unwilted silages. In summary, wilting and lactic acid bacterial inoculants had an influence on bacterial community and the fermentation process; LF and LL improved the fermentation quality of wilted and unwilted M. oleifera leaf silage.

IMPORTANCEMoringa oleifera leaf is a high-quality feed source for livestock and is increasingly used all over the world. Ensiling might be an effective method for preservation of the leaves. In the practice of silage making, lactic acid bacterial inoculants and wilting are commonly used to improve nutrition preservation. Monitoring the changes in a bacterial community during fermentation gives an insight into understanding and improving the ensiling process. Our results suggest that wilting and lactic acid bacterial inoculants had an influence on the bacterial community and fermentation process of M. oleifera leaf silage. Wilting showed positive effects on silage fermentation by decreasing the abundance of Enterobacter spp., while LF and LL improved the fermentation quality by inhibiting Enterobacter spp. and enhancing Lactobacillus spp. Both LF and LL accelerated the ensiling process from cocci (like Lactococcus, Enterococcus, and Leuconostoc spp.) to lactobacilli.

Effects of Freeze-Thaw Event on Microbial Community Dynamics During Red Clover Ensiling

Freezing damages in forages represents a major economic loss to agriculture. This study was conducted to investigate the effects of freeze–thaw (FT) event on microbial community dynamics of red clover silage. Results showed that the FT-treated material displayed higher proportions of Weissella and aerobic bacteria, while lower Pantoea and Enterobacter compared with the control material. The FT event promoted the development of Lactobacillus in silage microflora, inducing more intense lactic fermentation after an initial short lag. The aerobic bacteria were suppressed immediately after the onset of ensiling. Microbiomes of the two silages tended to be almost similar after 2 days of ensiling. However, a small number of aerobic bacteria tended to revitalize in the FT silage with prolonged ensiling time, indicated by apparent abundances of Acinetobacter and Pseudomonas at the end of ensiling. The results obtained here suggest that the FT event could promote the development of Lactobacillus during ensiling and the control of aerobe revitalization need to be concerned with silages made from the freeze-damaged forages.

Bacterial Dynamics of Wheat Silage

Knowledge regarding bacterial dynamics during crop ensiling is important for understanding of the fermentation process and may facilitate the production of nutritious and stable silage. The objective of this study was to analyze the bacterial dynamics associated with whole crop wheat silage with and without inoculants. Whole crop wheat was ensiled in laboratory silos, with and without Lactobacillus inoculants (L. plantarum, L. buchneri), for 3 months. Untreated and L. plantarum-treated silages were sampled at several times during ensiling, while L. buchneri-treated silage was sampled only at 3 months. Bacterial composition was studied using next generation sequencing approach. Dominant bacteria, before ensiling, were Pantoea (34.7%), Weissella (28.4%) and Pseudomonas (10.4%), Exiguobacterium (7.8%), and Paenibacillus (3.4%). Exogenous inoculants significantly affected bacterial composition and dynamics during ensiling. At 3 months of ensiling, Lactobacillus dominated the silage bacterial population and reached an abundance of 59.5, 92.5, and 98.2% in untreated, L. plantarum- and L. buchneri-treated silages, respectively. The bacterial diversity of the mature silage was lower in both treated silages compared to untreated silage. Functional profiling of the bacterial communities associated with the wheat ensiling demonstrated that the abundant pathways of membrane transporters, carbohydrate and amino acids metabolisms followed different pattern of relative abundance in untreated and L. plantarum-treated silages. Only three pathways, namely base-excision repair, pyruvate metabolism and transcription machinery, were significantly different between untreated and L. buchneri-treated silages upon maturation. Lactic acid content was higher in L. plantarum-treated silage compared to untreated and L. buchneri-treated silage. Still, the pH of both treated silages was lower in the two Lactobacillus-treated silages compared to untreated silage. Aerobic stability test demonstrated that L. plantarum-, but not L. buchneri-supplement, facilitated silage deterioration. The lower aerobic stability of the L. plantarum-treated silage may be attributed to lower content of acetic acid and other volatile fatty acids which inhibit aerobic yeasts and molds. Indeed, high yeast count was recorded, following exposure to air, only in L. plantarum-treated silage, supporting this notion. Analysis of bacterial community of crop silage can be used for optimization of the ensiling process and the selection of appropriate inoculants for improving aerobic stability.

Bacterial diversity and fermentation quality of Moringa oleifera leaves silage prepared with lactic acid bacteria inoculants and stored at different temperatures

Four lactic acid bacteria strains (LP, LF, LL, W), isolated and selected from Moringa oleifera leaves (MOL) silage, were identified as Lactobacillus plantarum, L. farciminis, Lactococcus lactis, Weissella thailandensis, respectively. Fermentation quality and bacterial community of MOL ensiled without or with the four strains at 15 °C and 30 °C were investigated. Results showed that all the LAB strains decreased (P < 0.05) the pH and ammonia-N content of MOL silage. Silage stored at 30 °C showed higher (P < 0.05) DM loss, acetic acid and ammonia-N content, and lower LAB count than 15 °C. The environmental temperature also made a great influence on bacterial community of MOL silage. Bacterial diversity was lower and the abundance of Lactobacillus was higher in silages stored at 15 °C. In conclusion, LAB inoculants and a relatively low environmental temperature could be effective to improve the quality of MOL silage.

Trends in designing microbial silage quality by biotechnological methods using lactic acid bacteria inoculants: a minireview

Ensiling is one of the best known method to preserve fodder. The forage before ensiling intended for silages usually contains a low number of lactic acid bacteria (LAB), so it is necessary to apply starter cultures of selected strains. Traditionally, LAB starter cultures were applied to lower the pH by producing lactic acid and to inhibit the growth of undesirable epiphytic microorganisms by competing for nutrients. Nowadays, LAB inoculants have become an effective tool for creating microbial quality of silages by selecting species with extraordinary features. Epiphytic microflora characteristic of plant material used for the production of silages and the sources of undesirable microflora in the ensiling process are discussed. This review focuses on the most frequently studied issues related to the microbial silage quality and the recent trends in increasing the quality by LAB inoculants, with respect to recent directions for selecting types of modern LAB for inoculation. Among them, the main trends described were prevention of the growth of filamentous fungi and detoxification of mycotoxins by LAB inoculants, inhibition of yeast growth by LAB present in preparations and limiting the development of pathogenic bacterial microflora through controlled fermentation with the participation of LAB and the presence of their metabolites.

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

To reveal the mechanism of the survival and adaption of inoculated Lactobacillus plantarum during ensiling. Alfalfa was ensiled directly (A1), after γ-ray irradiation (A0), and after inoculation of the sterile (A0L) or fresh alfalfa (A1L) with Lactobacillus plantarum. The A0L had the higher lactic acid content and lower pH than that in A1L from 3 days of ensiling. Pediococcus was the dominant microbes in A1 silage, followed by Enterococcus and Lactobacillus, while Lactobacillus in A1L outnumbered all other genera at 3 d. In A0L silage, the relative abundance of Lactobacillus increased to 99.13% at day 3. It indicated that Lactobacillus could dominated the fermentation of inoculated silages regardless of the γ-ray irradiation, although there was a short lag period for irradiated alfalfa.

Dynamics of a microbial community during ensiling and upon aerobic exposure in lactic acid bacteria inoculation-treated and untreated barley silages

This study investigated the effects of lactic acid bacteria on bacterial and fungal community during the fermentation process and aerobic exposure phase of barley ensiled with preparation of lactic acid bacteria (LAB). The inoculated silages displayed higher contents of lactic acid, acetic acid, and propionic acid as well as a greater number of lactic acid bacteria during ensiling. LAB-treated silage decreased the bacterial diversity during both ensiling and aerobic exposure but increased the fungal diversity during ensiling of barley. LAB-treated silage during ensiling increased the abundance of Lactobacillus but decreased that of Weissella. After aerobic exposure, LAB-treated silage increased the abundance of Lactobacillus but decreased that of Acinetobacter. Acinetobacter, Enterococcus, Providencia, and Empedobacter were the dominant bacteria after aerobic exposure. In conclusion, LAB-treated silage enhanced the number of desirable Lactobacillus and inhibited the growth of undesirable microorganisms, such as Acinetobacter.

Assessing the fermentation quality and microbial community of the mixed silage of forage soybean with crop corn or sorghum

The silage quality of forage soybean (FS) rich in protein with crop corn (CN) or sorghum (SG) rich in water soluble carbohydrate was investigated, and microbial community after ensiling was analyzed. Results showed that pH in mixed silages dropped to 3.5-3.8 lower than 100%FS silage (4.5). Microbial analysis indicated that mixed ensiling could influence the microbial community. Although Lactobacillus and Weissella were the dominant genera in all silage samples, Lactobacillus abundance in mixed silages (33-76%) was higher compared with 100%FS silage (27%). In conclusion, FS ensiled with CN or SG could be an alternative approach to improve FS silage quality.