Fungi and Their Metabolites Affecting Quality, Safety and Functionality of Silage

Topic Information

Dear Colleagues,

Ensiling is an effective and widespread technique for long-term feed preservation with the characteristics of low cost and easy operation. At the early stage of ensiling, water-soluble carbohydrates (WSC) are broken down into water, carbon dioxide, and energy under the respiration of aerobic bacteria. When oxygen is depleted, lactic acid bacteria (LAB) attached to forage multiply and convert WSC into organic acids, thereby creating an acidic and anaerobic environment, inhibiting the activities of undesirable microbes, such as molds and yeasts, and reducing the risk of forage spoilage. Generally, molds and yeasts are usually considered undesirable and pathogenic eukaryotes during ensiling. With the lactic acid production and the decrease in pH level during fermentation, growth of spoilage microorganisms containing aerobic bacteria, yeasts, and filamentous fungi can be limited. However, even if anaerobic and acidic conditions are ensured, a low fungal population can survive in silage and may activate their metabolism if necessary. Various yeasts, such as Candida, Hansenula, Saccharomyces, and Torulopsis spp., can produce lactic acid, acetic acid, and ethanol under anaerobic conditions, although their presence in silage is considered undesirable. To the best of our knowledge, the fungal microbiota and their metabolites and functionality involved in ensilage, and whether bacterial and fungal microbiota interact during ensiling, has not been well investigated. To date, an increasing number of studies have reported how silage microbiota, determined by high-throughput amplicon sequencing, could differ between crops and by the use of additives, but many studies have focused solely on bacterial microbiota. Few studies have examined the fungal microbiota involved in ensiling. Information on the correlation between fungal populations and fermentation characteristics of silage is currently not enough. Therefore, it is critical to perform a qualitative and quantitative assessment of the fungi communities during ensiling and to evaluate some methods to improve the quality, hygiene and safety of silage.

We are pleased to invite you to submit papers that showcase and discuss fungi community and their metabolites in silages. The submitted papers should use Next Generation Sequencing, Metagenomics, and Metabolomics methods to characterize fungi community compositions, diversity, interaction, and their functionality and metabolites during ensiling or aerobic exposure. This Topic aims to provide a fruitful collection of papers (both research articles and review articles) based on different silage managements including chemical additives and inoculants, harvest pretreatments, and other techniques, to ensure the silage quality, safety and hygiene.

We look forward to receiving your contributions.

Dr. Siran Wang
Dr. Qing Zhang
Dr. Lin Sun
Dr. Huili Pang
Dr. Musen Wang
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Agriculture agriculture	3.6	3.6	2011	17.7 Days	CHF 2600
Animals animals	3.0	4.2	2011	18.1 Days	CHF 2400
Fermentation fermentation	3.7	3.7	2015	14.3 Days	CHF 2600
Microorganisms microorganisms	4.5	6.4	2013	15.1 Days	CHF 2700
Toxins toxins	4.2	7.5	2009	18.4 Days	CHF 2700

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Published Papers (4 papers)

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All Agriculture Animals Fermentation Microorganisms Toxins

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17 pages, 3236 KiB  

Open AccessArticle

Effects of Cellulase and Xylanase Addition on Fermentation Quality, Aerobic Stability, and Bacteria Composition of Low Water-Soluble Carbohydrates Oat Silage

by Wei Liu, Qiang Si, Lin Sun, Zhijun Wang, Mingjian Liu, Shuai Du, Gentu Ge and Yushan Jia

Fermentation 2023, 9(7), 638; https://doi.org/10.3390/fermentation9070638 - 7 Jul 2023

Cited by 3 | Viewed by 1273

Abstract

Most oat forage has low water-soluble carbohydrates (WSC), which may be the main limited factor for silage fermentation safely, but oat is rich in cellulose and hemicellulose; therefore, we assume that xylanase and cellulase as additives can reduce the content of cellulose and [...] Read more.

Most oat forage has low water-soluble carbohydrates (WSC), which may be the main limited factor for silage fermentation safely, but oat is rich in cellulose and hemicellulose; therefore, we assume that xylanase and cellulase as additives can reduce the content of cellulose and xylan in oat silage, increase the microbial fermentable sugar content, and improve the fermentation quality of the silage. After wilting, oats were treated as follows: (i) distributed water (CK); (ii) silages inoculated with xylanase (X); (iii) silages inoculated with cellulase (C), ensiling for 3 days (early stage of silage) and 60 days (late stage of silage), respectively, after ensiling 60 days for a 5-day aerobic exposure study. The pH, neutral detergent fiber (NDF), and acid detergent fiber (ADF) were significantly reduced by xylanase and cellulase treatment during the late stage of silage, and the concentration of lactic acid, acetic acid, and ammonia nitrogen increased remarkably. The WSC content reached its peak with xylanase treatment during the late stage of silage. The content of crude protein (CP) was not affected by additives but by the silage period; CP and ether extract (EE) significantly increased during the late stage of silage compared to the early stage. After ensiling, the bacterial community showed that xylanase and cellulase treatment increased the relative abundance of lactic acid bacteria. Lactobacillus has a higher relative abundance with cellulase treatment after 60 days of ensiling; this can effectively reduce the pH of silage and ensure long-term, stable storage of silage. Cellulase and xylanase increased bacterial diversity during aerobic exposure and improved the aerobic stability of silage significantly. This study indicated that different additives and silage periods had significant effects on chemical compositions, fermentation quality, and bacterial community; meanwhile, both additives improved the aerobic stability of silage. In summary, when the WSC of oat is low, cellulase and xylanase have good effects as silage additives, and the comprehensive effect of cellulase is more prominent. Full article

(This article belongs to the Topic Fungi and Their Metabolites Affecting Quality, Safety and Functionality of Silage)

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18 pages, 3475 KiB  

Open AccessArticle

Effects of Alfalfa Hay to Oat Hay Ratios on Chemical Composition, Fermentation Characteristics, and Fungal Communities during Aerobic Exposure of Fermented Total Mixed Ration

by Mingjian Liu, Lin Sun, Zhijun Wang, Gentu Ge, Yushan Jia and Shuai Du

Fermentation 2023, 9(5), 480; https://doi.org/10.3390/fermentation9050480 - 16 May 2023

Cited by 2 | Viewed by 1416

Abstract

The application of fermented total mixed ration (FTMR) is an effective method to prolong the use time of feed, but the understanding of the interaction mechanism between fungal microorganisms and silage quality and aerobic stability in FTMR is still limited. This study aimed [...] Read more.

The application of fermented total mixed ration (FTMR) is an effective method to prolong the use time of feed, but the understanding of the interaction mechanism between fungal microorganisms and silage quality and aerobic stability in FTMR is still limited. This study aimed to evaluate the effects of alfalfa (Medicago sativa L.) hay to oat (Avena sativa L.) hay ratios on chemical composition, fermentation characteristics, and fungal communities during aerobic exposure of fermented total mixed ration (FTMR). The supplement levels of oat were as follows: 200 g/kg oat hay (LO), 300 g/kg oat hay (MO), and 400 g/kg oat hay (HO). The water content of the three treatments was adjusted to 50% using a sprayer. After 60 days of ensiling, the bags were opened, and the chemical composition, fermentation characteristics, and fungal communities were measured after 3, 6, 9, and 12 days of aerobic exposure. The results suggested that the LO treatment significantly (p < 0.05) increased the aerobic stability than that in other treatments. The crude protein and lactic acid content in the three treatments were significantly decreased with the extension of the aerobic exposure period. Additionally, there was a remarkable (p < 0.05) higher lactic acid content observed in the LO treatment than that in the HO treatment during the aerobic stage. The PCoA showed that the compositions of the fungal community in the HO treatment were distinctly separated from the other two treatments. Compared with HO and LO treatments, the MO treatment observed relatively higher OTU, Shannon, and Chao1 indexes. Compared with LO and MO treatments, the abundances of the genes Saccharomyces and Wallemia were greater increased and decreased in the HO treatment, respectively. Integrated correlation analysis also underscores a possible link between the fermentation characteristics, aerobic stability, and significantly altered fungal community. This study suggested that the use of FTMR in production might prolong aerobic storage time when alfalfa was fermented in a mixture with ≤30% oat. Full article

(This article belongs to the Topic Fungi and Their Metabolites Affecting Quality, Safety and Functionality of Silage)

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16 pages, 2331 KiB  

Open AccessArticle

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

by Yanzi Xiao, Lin Sun, Zhijun Wang, Wei Wang, Xiaoping Xin, Lijun Xu and Shuai Du

Fermentation 2022, 8(12), 707; https://doi.org/10.3390/fermentation8120707 - 4 Dec 2022

Cited by 5 | Viewed by 1570

Abstract

This study aimed to investigate the effects of lactic acid bacteria (LAB) inoculants on the fermentation quality, microbial compositions, and predicted functional profiles of forage oat. The forage oat was inoculated with distilled water, Lentilactobacillus buchneri (LB), and Lactiplantibacillus plantarum (LP) as the [...] Read more.

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

(This article belongs to the Topic Fungi and Their Metabolites Affecting Quality, Safety and Functionality of Silage)

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15 pages, 672 KiB  

Open AccessArticle

Effect of Homo-Fermentative Lactic Acid Bacteria Inoculants on Fermentation Characteristics and Bacterial and Fungal Communities in Alfalfa Silage

by Yanbing Li, E. B. da Silva, Jingchun Li and L. Kung, Jr.

Fermentation 2022, 8(11), 621; https://doi.org/10.3390/fermentation8110621 - 10 Nov 2022

Cited by 3 | Viewed by 1869

Abstract

We evaluated the effects of a homo-fermentative lactic acid bacteria (homo-LAB) inoculant on the fermentation and microbial communities of alfalfa ensiled at two dry matter (DM) contents of 38 and 46% DM. At both DMs, alfalfa was treated or not with an inoculant [...] Read more.

We evaluated the effects of a homo-fermentative lactic acid bacteria (homo-LAB) inoculant on the fermentation and microbial communities of alfalfa ensiled at two dry matter (DM) contents of 38 and 46% DM. At both DMs, alfalfa was treated or not with an inoculant containing Pediococcus acidilactici, Enterococcus faecium and Lactobacillus plantarum at a targeted application rate of 165,000 cfu/g of fresh weight and stored for 3, 30 and 60 days. Treatment with the inoculant resulted in a lower drop in pH and, in general, higher lactic acid and lower acetic acid when applied to medium DM silage. For the four most abundant microbial genera, increased abundances of Bacteroides and Lactobacillus (p < 0.05), as well as decreased abundances of Muribaculaceae were observed in high DM and inoculated silages. The abundance of Prevotellaceae-UCG-001 was lower in medium DM control silages than in high DM control silages. Inoculation and DM affected abundances of Vishniacozyma (p < 0.05). Increased abundances of Vishniacozyma, as well as decreased abundances of Leucosporidium were observed in medium DM-inoculated silages. Changes in the relative abundance (RA) of the main populations of bacteria and yeasts did explain the fermentation and nutrition differences among treatments. Full article

(This article belongs to the Topic Fungi and Their Metabolites Affecting Quality, Safety and Functionality of Silage)

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