Corrigendum: Effect of storage time on the silage quality and microbial community of mixed maize and faba bean in the Qinghai-Tibet Plateau.

[This corrects the article DOI: 10.3389/fmicb.2022.1090401.].

Effects of Acremonium cellulase and heat-resistant lactic acid bacteria on lignocellulose degradation, fermentation quality, and microbial community structure of hybrid elephant grass silage in humid and hot areas.

To better evaluate the effects of Acremonium cellulase (AC) and previously screened heat-resistant Lactobacillus plantarum 149 (LP149) on lignocellulose degradation, fermentation quality, and microbial community during ensiling in humid and hot areas, this study used a small-scale fermentation system to prepare hybrid elephant grass silage at 30 and 45°C, respectively. Compared to control and commercial inoculant Lactobacillus plantarum (LP), the addition of AC or strain LP149 decreased the contents of neutral detergent fiber, acid detergent fiber, and cellulose and increased the contents of glucose, fructose, and sucrose during fermentation. Furthermore, AC and LP149 treatments altered the microbial communities' structure during ensiling. AC treatment provided more substrate for microbial fermentation, resulting in an increase in bacterial alpha diversity. LP149 treatment increased the Lactobacillus abundance and optimized the bacterial community compositions. In addition, AC and LP149 treatments had higher (P < 0.05) lactic acid and acetic acid contents and lower (P < 0.05) pH, butyric acid, and NH3-N levels compared to the control. These results indicated that AC and strain LP149 are promising silage additives that can promote lignocellulose degradation and improve the fermentation quality of hybrid elephant grass in humid and hot areas.

Assessment on the Fermentation Quality and Bacterial Community of Mixed Silage of Faba Bean With Forage Wheat or Oat.

Faba bean (Vicia faba L.), although a kind of high-quality and high-yield forage, could hardly achieve a great quality of silage because of its high buffering capacity. Mixed silage of faba bean with forage wheat (Triticum aestivum L.) or oat (Avena sativa L.) at different ratios could improve the fermentation quality and bacterial community. Compared with 100% faba bean silage (BS), mixed silage improved the fermentation quality, not only increased lactic acid production and reduced pH, but reduced the production of propionic acid and ammonia nitrogen. The chemical compositions of faba bean with forage wheat (BT) mixed silage were better than that of faba bean with oat (BO) mixed silage, and that of 3:7, 5:5 (fresh matter basis) mixing ratios were better than 1:9. However, the fermentation quality of BO mixed silage was better than that of BT, and that of 3:7 mixed silage (BO30) was the best overall. Analysis of the bacterial community showed that mixed silage increased the relative abundance of lactic acid bacteria after ensiling, and the relatively higher abundance of Lactobacillus showed the inhibitory effects on the proliferation of Serratia and Hafnia_Obesumbacterium, so that it alleviated their negative effects on silage and stabilized the fermentation quality. This present study exhibited that mixed silage of faba bean with forage wheat or oat not only had significant effects on chemical compositions and fermentation quality of materials but modified bacterial community so that improved the fermentation quality effectively. The mixed silage of 30% faba bean with 70% oat (BO30) is recommended in the faba bean mixed silage.

Effect of storage time on the silage quality and microbial community of mixed maize and faba bean in the Qinghai-Tibet Plateau.

Tibetan Plateau is facing serious shortage of forage in winter and spring season due to its special geographical location. Utilization of forages is useful to alleviate the forage shortage in winter and spring season. Consequently, the current study was aimed to evaluate the influence of storage time on the silage quality and microbial community of the maize (Zea mays L.) and faba bean (Vicia faba L.) mixed silage at Qinghai-Tibet Plateau. Maize and faba bean were ensiled with a fresh weight ratio of 7:3, followed by 30, 60, 90, and 120 days of ensiling. The results showed the pH value of mixed silage was below 4.2 at all fermentation days. The LA (lactic acid) content slightly fluctuated with the extension of fermentation time, with 33.76 g/kg DM at 90 days of ensiling. The AA (acetic acid) and NH3-N/TN (ammonium nitrogen/total nitrogen) contents increased with the extension of fermentation time and no significantly different between 90 and 120 days. The CP (crude protein) and WSC (water soluble carbohydrate) contents of mixed silage decreased significantly (P < 0.05) with ensiling time, but the WSC content remained stable at 90 days. The Proteobacteria was the predominant phyla in fresh maize and faba bean, and Pseudomonas and Sphingomonas were the predominant genera. After ensiling, Lactobacillus was the prevalent genus at all ensiling days. The relative abundance of Lactococcus increased rapidly at 90 days of ensiling until 120 days of fermentation. Overall, the storage time significant influenced the silage fermentation quality, nutrient content, and microbial environment, and it remained stable for 90 days of ensiling at Qinghai-Tibet Plateau. Therefore, the recommended storage time of forage is 90 days in Qinghai-Tibet Plateau and other cool areas.

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.