Bacterial community dynamics during ensiling of perennial ryegrass at two compaction levels monitored by terminal restriction fragment length polymorphism

Effects of Lactobacillus hilgardii 60TS-2, with or without homofermentative Lactobacillus plantarum B90, on the aerobic stability, fermentation quality and microbial community dynamics in sugarcane top silage

This study investigated the effects of Lactobacillus hilgardii (LH), alone or in combination with Lactobacillus plantarum (LP), on the aerobic stability, fermentation quality and dynamics of the bacterial and fungal communities of sugarcane top silage. Results demonstrated that LH and LHLP (LH combined with LP) improved the aerobic stability of sugarcane top silages. As the exposure time increased, the pH values and the contents of lactic acid, acetic acid, as well as propionic acid remained stable in silage treated with LH and LHLP. The abundance of L. hilgardii was enriched and the undesirable microorganisms, such as Acetobacter pasteurianus, Paenibacillus amylolyticus and yeasts like Kazachstania humilis, were suppressed in silages treated with LH and LHLP. In conclusion, LH-treated silage, whether with LP or not, positively impacted the fungal and bacterial microbes. This improved the quality of fermentation, the aerobic stability, and reduced aerobic spoilage in sugarcane top silage.

Sequencing and microbiota transplantation to determine the role of microbiota on the fermentation type of oat silage

This study was aimed to assess the effects of exogenous microbiota on fermentation quality and bacterial community dynamics in oat (OT) silage. The irradiated OT was treated with the following: (i) sterile water (STOT); (ii) epiphytic microbiota on oat (OTOT); (iii) epiphytic microbiota on maize (OTMZ); (iv) epiphytic microbiota on sorghum (OTSG). γ-Ray irradiation, microbiota transplantation and sequencing methods were firstly used. After 60 days of ensiling, OTMZ group had higher lactic acid (LA) and lower acetic acid (AA) contents than OTOT group. Inversely, lower LA content and higher ratio of LA to AA was observed in OTSG group than OTOT group. Lactobacillus was predominant in OTMZ-60 group, while Lactobacillus and Enterobacteriaceae were both dominant in OTSG-60 group. Overall, the higher amounts of Enterobacteriaceae and heterofermentative Lactobacillus are conductive to acetic acid-type fermentation, and forage microbiota transplantation may be a potential way to identify the role of microbe during ensiling.

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 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.

Impact of molasses and microbial inoculants on fermentation quality, aerobic stability, and bacterial and fungal microbiomes of barley silage

This study aimed to investigate the effects of microbial inoculants (L) and molasses (M) on the bacterial and fungal microbiomes of barley silage after the aerobic stage. The addition of molasses and microbial inoculants improved the aerobic stability of barley silage. The ML silage, which had a low pH value and high lactic and acetic acid contents, remained aerobically stable for more than 216 h. The ML silage exhibited low bacterial and high fungal diversities. Microbial inoculants and molasses enriched the abundance of Lactobacillus in silage after aerobic exposure. The enrichment of L. buchneri was significant in ML silage at days 5 and 7 during the aerobic stage. The abundance of harmful microorganisms, such as aerobic bacterial including Acinetobacter, Providencia, Bacillus, and yeasts including Issatchenkia, Candida, and Kazachstania, were suppressed in ML silage. M and L had an impact on bacterial and fungal microbes, resulting in the improvement of fermentation quality and reduction of aerobic spoilage in barley silage.

Corn microbial diversity and its relationship to yield

This study aimed to identify possible relationships between corn (Zea mays L.) productivity and its endosphere microbial community. Any insights would be used to develop testable hypotheses at the farm level. Sap was collected from 14 fields in 2014 and 10 fields in 2017, with a yield range of 10.1 to 21.7 tonnes per hectare (t/ha). The microbial sap communities were analyzed using terminal restriction fragment length polymorphism (TRFLP) and identified using an internal pure culture reference database and BLAST. This technique is rapid and inexpensive and is suitable for use at the grower level. Diversity, richness, and normalized abundances of each bacterial population in corn sap samples were evaluated to link the microbiome of a specific field to its yield. A negative trend was observed (r = -0.60), with higher-yielding fields having lower terminal restriction fragment (TRF) richness. A partial least square regression analysis of TRF intensity and binary data from 2014 identified 10 TRFs (bacterial genera) that positively, or negatively, correlated with corn yields, when either absent or present at certain levels or ratios. Using these observations, a model was developed that accommodated criteria for each of the 10 microbes and assigned a score for each field out of 10. Data collected in 2014 showed that sites with higher model scores were highly correlated with larger yields (r = 0.83). This correlation was also seen when the 2017 data set was used (r = 0.87). We were able to conclude that a positive significant effect was seen with the model score and yield (adjusted R² = 0.67, F_[1,22] = 46.7, p < 0.001) when combining 2014 and 2017 data. The results of this study are being expanded to identify the key microbes in the corn sap community that potentially impact corn yield, regardless of corn variety, geographic factors, or edaphic factors.

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.

Dynamic changes in fermentation profiles and bacterial community composition during sugarcane top silage fermentation: A preliminary study

Investigating the dynamic changes in bacterial community composition during sugarcane top silage production starting in late March and finishing in late June (storage temperature: 20 to 35 °C) will advance our understanding of ensilage in hot ambient temperatures. The results showed that, the fermentation process was dominated by Leuconostocaceae (until d 5), followed by Lactobacillaceae (from d 5 to d 30), and finally Lactobacillaceae and Clostridium (from d 60 to d 90). As the fermentation process progressed, there was a significant increase in Lactobacillaceae abundance, and on d 60 there was a sharp increase in Clostridiaceae abundance. Spearman's correlation showed that, Lactococcus and Leuconostoc abundance were negatively correlated with acetate, propionate, butyrate, and ammonia-N levels. Clostridiaceae and Lactobacillaceae abundance were positively correlated with acetate, propionate, butyrate, and ammonia-N levels. The high moisture content (DM 24.31%) of sugarcane tops stored in hot ambient temperatures may result in butyric acid fermentation.

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.

Microbial community and fermentation characteristic of Italian ryegrass silage prepared with corn stover and lactic acid bacteria

The bacterial community determined via PacBio single molecule, real-time sequencing technology (SMRT) and the fermentation characteristics of Italian ryegrass (IR, 82% moisture) silage prepared with corn stover (CS) were investigated. A selected strain of Lactobacillus plantarum (L694) and a commercial inoculant stain of Lactobacillus plantarum (LP) were used as additives. Lactic acid bacteria (LAB) effectively improved silage quality. After fermentation, Lactobacillus plantarum was the dominant species in IR + LP and IR + L694 treatments, which led to higher (P < 0.05) lactic acid and lower (P < 0.05) butyric acid production. Lactobacillus plantarum, Lactobacillus hammesii, Lactobacillus brevis, and Lactobacillus coryniformis were abundantly present in IR + CS + LP and IR + CS + L694 treatments, and acetic acid contents of these were higher (P < 0.05) than those of other silages. This study demonstrated that addition of CS and LAB can change the microbial community and influence the silage fermentation of IR, and PacBio SMRT reveals more specific microbial information.

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.