Due to the challenges of antibiotic resistance to global health, bacteriocins as antimicrobial compounds have received more and more attention. Bacteriocins are biosynthesized by various microbes and are predominantly used as food preservatives to control foodborne pathogens. Now, increasing researches have focused on bacteriocins as potential clinical antimicrobials or immune‐modulating agents to fight against the global threat to human health. Given the broad‐ or narrow‐spectrum antimicrobial activity, bacteriocins have been reported to inhibit a wide range of clinically pathogenic and multidrug‐resistant bacteria, thus preventing the infections caused by these bacteria in the human body. Otherwise, some bacteriocins also show anticancer, anti‐inflammatory, and immune‐modulatory activities. Because of the safety and being not easy to cause drug resistance, some bacteriocins appear to have better efficacy and application prospects than existing therapeutic agents do. In this review, we highlight the potential therapeutic activities of bacteriocins and suggest opportunities for their application.

The strategic delay of aerobic deterioration in Sesbania cannabina and corn (SC) mixed silage, coupled with effective fermentation, could increase the protein-rich silage utilization by ruminants. Thus, we sought to investigate the role of a compound lactic acid bacteria (LAB) inoculant (Lactobacillus plantarum + Lactobacillus farciminis + Lactobacillus buchneri + Lactobacillus hilgardii; at a level of 106 CFU/g fresh weight) in enhancing the aerobic stability of SC mixed silage. Specifically, we focused on the potential for corn supplementation to improve fermentation quality while concurrently increasing the susceptibility of SC mixed silage to aerobic spoilage. Results revealed that compound LAB additive diversified the microbial community of SC mixed silage, making Lactobacillus hilgardii and Lactobacillus buchneri dominant bacterial species, while decreasing the abundance of Kazachstania humilis fungal specie. As a result, the LAB-treated mixed silages had higher acetic acid contents and lower yeast populations. Aerobic stability analysis revealed that the SC mixed silages with a high corn proportion deteriorated rapidly when the silages were exposed to air. The high aerobic stability of the LAB-treated mixed silages especially S7C3 contrasted with the low acetic acid concentrations in the CK mixed silages (processed with sterilized water), concomitant with increased Kazachstania humilis abundance. Our study revealed that inoculation with a compound LAB additive altered the consequences of aerobic exposure by increasing acetic acid production after ensiling, promoting diverse bacterial populations, and mitigating the negative effects of fungi on the aerobic stability of SC mixed silage.

Nisin Z is a possible alternative for treating bovine mastitis by inhibiting mastitis-causing pathogens and having anti-inflammatory activity. However, the anti-inflammatory mechanism of nisin Z on mastitis is unknown. Our study aimed to investigate the mechanisms of nisin Z on mastitis. Our results showed that nisin Z inhibited the activation of the ERK1/2 and p38 mitogen-activated protein kinase (MAPK) signaling pathway, decreased the release of pro-inflammatory cytokines (i.e., tumor necrosis factor-α, IL-1β, and IL-6), and increased the anti-inflammatory cytokine (IL-10) in lipopolysaccharide (LPS)-induced MCF10A cells. After intraperitoneal injection, nisin Z significantly decreased inflammatory cell infiltration in the mammary gland, as well as decreased myeloperoxidase and pro-inflammatory cytokines in serum and mammary gland. Western blot analysis revealed that nisin Z also dramatically suppressed the activation of the ERK1/2 and p38 MAPK signaling pathways in LPS-induced mastitis mice. We also found that nisin Z treatment could enhance the blood-milk barrier. In summary, our study demonstrated that nisin Z exerted an anti-inflammatory effect by inhibiting the ERK1/2 and p38 MAPK signaling pathway and promoting the blood-milk barrier on LPS-induced mastitis.

Background: Elucidating the mechanism of fiber transformation underlying microbial metabolism is critical for improving fiber-rich silage digestibility and preserving silage energy for ruminant nutrient absorption. However, few studies have combined quantitative microbial function and transformation products in silage to explain this mechanism. Here, we constructed a workflow to detect the substrates and products of fiber transformation in mixed silage of Sesbania cannabina and sweet sorghum (SS) and combined the absolute quantification 16S rRNA sequencing to reveal this mechanism. Results: The synergistic effect of Lactobacillus cocktail and cellulase (LC) simplified the microbial diversity and minimized the microbial quantity, making Lentilactobacillus buchneri the dominant species in SS silage. As a result, the LC-treated silage had greater lactic acid content, lower pH value, and less NH₃-N content. The indigestible fibers were significantly decreased due to the synergistic effect of the Lactobacillus cocktail and cellulase. Changes in microbial structure during ensiling also resulted in metabolic alterations. The increased levels of microbial enzymes, including β-glucosidase and sucrose phosphorylase, involved in starch and sucrose metabolism led to the enrichment of monosaccharides (including glucose, xylose, mannose, galactose, ribose, rhamnose, and arabinose) in the LC-treated silage. We found that L. buchneri was positively associated with β-glucosidase and sucrose phosphorylase, reflecting the crucial contribution of L. buchneri to fiber decomposition in SS silage. Conclusion: Using an absolute quantitative microbiome, we found that LC treatment decreased the microbial biomass in SS silage, which in turn promoted the energy preservation in the SS silage. The cooperative interaction of the Lactobacillus cocktail and cellulase improved the fiber decomposition and in vitro dry matter digestibility rate by changing the microbiome structure and function in the SS silage, providing guidance and support for future fiber-rich silage production in the saline-alkaline region. Graphical

Alfalfa is a vital feedstock for ruminants due to its high protein content. However, concerns regarding nitrogen (N) loss in alfalfa silage from protein transformation have arisen, but the underlying molecular mechanisms remain undefined. This study investigated the patterns of protein transformation in alfalfa during fermentation through multi-omics analysis. Lactiplantibacillus plantarum treatment effectively preserved the true protein PB1 and peptide-N, by mitigating N degradation. Proteomic profiling revealed a decrease in the abundance of higher molecular weight proteins (45-70 kDa), coupled with an increase in lower molecular weight proteins (15-45 kDa), mainly located in the membrane, cytoplasm and ribosome. Meanwhile, levels of protein hydrolysates, including peptides and essential amino acids, were elevated. Among these, Ile-Pro, Pro-Val, flavorful L-Glu and the proteogenic Arg were identified as the predominant constituents. Tripeptidyl-peptidase, carboxypeptidase, and serine protease were identified as the primary plant proteases mediating protein transformation. These findings highlight the synergistic effects of plant proteases and microbial activity, mainly from L. plantarum, in transforming large proteins into peptides and amino acids during fermentation. Our findings provide insights for the targeted regulation of alfalfa protein transformation during fermentation, potentially enhancing protein utilization in ruminants.

Cyperus esculentus L. leaves (CLL) are agricultural by-products produced from Cyperus esculentus L. harvesting, and can be used as livestock feed despite their low economic value for human consumption. This study aims to develop a favorable approach to processing Cyperus esculentus L. by-product as coarse fodder. The chopped CLL was pretreated by (1) mixing with canola straw at a 4:1 ratio, or (2) wilting it for 8 h, then it ensiling with or without compounded lactic acid bacteria (LAB) additives for 60 days. Our results demonstrated that compounded LAB additives: improved CLL silage fermentation quality by increasing acetic acid and lactic acid contents and decreasing ethanol and ammonia-N contents; preserved nutrients by raising the level of crude protein and water soluble carbohydrates; modified the bacterial community by increasing the relative abundance of Lactobacillus while decreasing the relative abundance of undesirable Enterococcus; and also might improve animal health by increasing the relative concentrations of antioxidant substances (such as 7-galloylcatechin) and antibacterial compounds (such as ferulic acid). This study provides strong evidence that Cyperus esculentus L. by-product can be a potential livestock feed after being ensiled with compounded LAB additives.