Dietary Supplementation with Probiotic Bacillus licheniformis S6 Improves Intestinal Integrity via Modulating Intestinal Barrier Function and Microbial Diversity in Weaned Piglets

Antibiotics and Opportunities of Their Alternatives in Pig Production: Mechanisms Through Modulating Intestinal Microbiota on Intestinal Health and Growth

Antibiotics at subtherapeutic levels have been used in pig diets as antimicrobial growth promoters. However, concerns about antibiotic resistance have increased the demand for alternatives to these antimicrobial growth promoters. This review paper explores the mechanisms through which antimicrobial growth promoters and their alternatives exert their antimicrobial effects. Additionally, this systemic review also covers how modulation of intestinal microbiota by antimicrobial growth promoters or their alternatives affects intestinal health and, subsequently, growth of pigs. The mechanisms and effects of antimicrobial growth promoters and their alternatives on intestinal microbiota, intestinal health, and growth are diverse and inconsistent. Therefore, pig producers should carefully assess which alternative is the most effective for optimizing both profitability and the health status of pigs in their production system.

Nutraceuticals vs. antibiotic growth promoters: differential impacts on performance, meat quality, blood lipids, cecal microbiota, and organ histomorphology of broiler chicken

The main goal of this study was to evaluate the effect of nutraceuticals vs. in-feed antibiotics on performance, blood lipids, antioxidant capacity, cecal microbiota, and organ histomorphology of broiler chickens. A total of 320 one-day-old male broiler chickens were distributed into 5 treatment groups with 8 replicates each. The control group was fed on a basal diet without any additives (NC); the antibiotic group was fed on a basal diet supplemented with 100 mg kg-1 avilamycin (PC); the algal group was fed on a basal diet supplemented with a mixture of Spirulina platensis and Chlorella vulgaris (1.5 g + 1.5 g/kg feed) (SP+CV); the essential oil group was fed with a basal diet containing 300 mg/kg feed rosemary oil (REO); and the probiotics group (a mixture of 1 × 1011 CFU/g Bacillus licheniformis, 1 × 1011 CFU/g Enterococcus facieum, 1 × 1010 CFU/g Lactobacillus acidophilus, and 2 × 108 CFU /g Saccharomyces cerevisiae) was fed with a basal diet supplemented with 0.05% probiotics (PRO). The experiment lasted for 35 d. A beneficial effect of SP+CV and PRO (P < 0.01) was noticed on final body weight, body weight gain, feed conversion ratio, and breast yield. The dietary supplementation with SP+CV, REO, and PRO increased (P < 0.001) broilers' cecal lactic acid bacteria count compared to the control. Lower cecal Clostridium perfringens and Coliform counts (P < 0.001) were noticed in chickens fed the PC and supplemental diets. Malondialdehyde (MDA) concentration was decreased, while glutathione peroxidase (GPx), superoxide dismutase, and catalase enzymes were increased in the breast and thigh meat (P < 0.001) of broiler chickens fed SP+CV, REO, and PRO diets. Dietary SP+CV, REO, and PRO supplementation decreased (P < 0.001) serum total lipids, cholesterol, triglycerides, low-density lipoprotein, and MDA, but increased serum high-density lipoprotein and GPx compared to PC and NC. No pathological lesions were noticed in the liver, kidney, or breast muscle among broilers. The SP+CV, REO, and PRO groups had greater (P < 0.001) intestinal villi height and crypt depth while lower goblet cell densities (P < 0.01) than the control. The present findings suggest that PRO and SP+CV, followed by REO could be suitable alternatives to in-feed antibiotics for enhancing the performance, health, and meat quality of broiler chickens.

Dietary Triple-Strain Bacillus-Based Probiotic Supplementation Improves Performance, Immune Function, Intestinal Morphology, and Microbial Community in Weaned Pigs

Probiotics provide health benefits and are used as feed supplements as an alternative prophylactic strategy to antibiotics. However, the effects of Bacillus-based probiotics containing more than two strains when supplemented to pigs are rarely elucidated. SOLVENS (SLV) is a triple-strain Bacillus-based probiotic. In this study, we investigate the effects of SLV on performance, immunity, intestinal morphology, and microbial community in piglets. A total of 480 weaned pigs [initial body weight (BW) of 8.13 ± 0.08 kg and 28 days of age] were assigned to three treatments in a randomized complete block design: P0: basal diet (CON); P200: CON + 200 mg SLV per kg feed (6.5 × 108 CFU/kg feed); and P400: CON + 400 mg SLV per kg feed (1.3 × 109 CFU/kg feed). Each treatment had 20 replicated pens with eight pigs (four male/four female) per pen. During the 31 d feeding period (Phase 1 = wean to d 14, Phase 2 = d 15 to 31 after weaning), all pigs were housed in a temperature-controlled nursery room (23 to 25 °C). Feed and water were available ad libitum. The results showed that the pigs in the P400 group increased (p < 0.05) average daily gain (ADG) in phase 2 and tended (p = 0.10) to increase ADG overall. The pigs in the P200 and P400 groups tended (p = 0.10) to show improved feed conversion ratios overall in comparison with control pigs. The pigs in the P200 and P400 groups increased (p < 0.05) serum immunoglobulin A, immunoglobulin G, and haptoglobin on d 14, and serum C-reactive protein on d 31. The pigs in the P200 group showed an increased (p < 0.01) villus height at the jejunum, decreased (p < 0.05) crypt depth at the ileum compared with other treatments, and tended (p = 0.09) to have an increased villus-crypt ratio at the jejunum compared with control pigs. The pigs in the P200 and P400 groups showed increased (p < 0.05) goblet cells in the small intestine. Moreover, the pigs in the P400 group showed down-regulated (p < 0.05) interleukin-4 and tumor necrosis factor-α gene expressions, whereas the pigs in the P400 group showed up-regulated occludin gene expression in the ileum. These findings suggest that SLV alleviates immunological reactions, improves intestinal microbiota balance, and reduces weaning stress in piglets. Therefore, SOLVENS has the potential to improve health and performance for piglets.

Bacillus spp. as potential probiotics: promoting piglet growth by improving intestinal health

The application of Bacillus spp. as probiotics in the swine industry, particularly for piglet production, has garnered significant attention in recent years. This review aimed to summarized the role and mechanisms of Bacillus spp. in promoting growth and maintaining gut health in piglets. Bacillus spp. can enhance intestinal barrier function by promoting the proliferation and repair of intestinal epithelial cells and increasing mucosal barrier integrity, thereby reducing the risk of pathogenic microbial invasion. Additionally, Bacillus spp. can activate the intestinal immune system of piglets, thereby enhancing the body's resistance to diseases. Moreover, Bacillus spp. can optimize the gut microbial community structure, enhance the activity of beneficial bacteria such as Lactobacillus, and inhibit the growth of harmful bacteria such as Escherichia coli, ultimately promoting piglet growth performance and improving feed efficiency. Bacillus spp. has advantages as well as challenges as an animal probiotic, and safety evaluation should be conducted when using the newly isolated Bacillus spp. This review provides a scientific basis for the application of Bacillus spp. in modern piglet production, highlighting their potential in improving the efficiency of livestock production and animal welfare.

Modulation of Gut Microbial Community and Metabolism by Bacillus licheniformis HD173 Promotes the Growth of Nursery Piglets Model

Maintaining the balance and stability of the gut microbiota is crucial for the gut health and growth development of humans and animals. Bacillus licheniformis (B. licheniformis) has been reported to be beneficial to the gut health of humans and animals, whereas the probiotic effects of a new strain, B. licheniformis HD173, remain uncertain. In this study, nursery piglets were utilized as animal models to investigate the extensive impact of B. licheniformis HD173 on gut microbiota, metabolites, and host health. The major findings were that this probiotic enhanced the growth performance and improved the health status of the nursery piglets. Specifically, it reduced the level of pro-inflammatory cytokines IL-1β and TNF-α in the serum while increasing the level of IL-10 and SOD. In the gut, B. licheniformis HD173 reduced the abundance of pathogenic bacteria such as Mycoplasma, Vibrio, and Vibrio metschnikovii, while it increased the abundance of butyrate-producing bacteria, including Oscillospira, Coprococcus, and Roseburia faecis, leading to an enhanced production of butyric acid. Furthermore, B. licheniformis HD173 effectively improved the gut metabolic status, enabling the gut microbiota to provide the host with stronger metabolic abilities for nutrients. In summary, these findings provide scientific evidence for the utilization of B. licheniformis HD173 in the development and production of probiotic products for maintaining gut health in humans and animals.

Bacillus amyloliquefaciens attenuates the intestinal permeability, oxidative stress and endoplasmic reticulum stress: transcriptome and microbiome analyses in weaned piglets

Endoplasmic reticulum (ER) stress is related to oxidative stress (OS) and leads to intestinal injury. Bacillus amyloliquefaciens SC06 (SC06) can regulate OS, but its roles in intestinal ER stress remains unclear. Using a 2 × 2 factorial design, 32 weaned piglets were treated by two SC06 levels (0 or 1 × 108 CFU/g), either with or without diquat (DQ) injection. We found that SC06 increased growth performance, decreased ileal permeability, OS and ER stress in DQ-treated piglets. Transcriptome showed that differentially expressed genes (DEGs) induced by DQ were enriched in NF-κB signaling pathway. DEGs between DQ- and SC06 + DQ-treated piglets were enriched in glutathione metabolism pathway. Ileal microbiome revealed that the SC06 + DQ treatment decreased Clostridium and increased Actinobacillus. Correlations were found between microbiota and ER stress genes. In conclusion, dietary SC06 supplementation increased the performance, decreased the permeability, OS and ER stress in weaned piglets by regulating ileal genes and microbiota.

Enhanced sporulation of B. licheniformis BF-002 through automatic co-feeding of carbon and nitrogen sources

Bacillus licheniformis formulations are effective for environmental remediation, gut microbiota modulation, and soil improvement. An adequate spore quantity is crucial for the activity of B. licheniformis formulations. This study investigated the synergistic effects of carbon/nitrogen source consumption and concentration on B. licheniformis BF-002 cultivation, with the aim of developing an automatic co-feeding strategy to enhance spore production. Initial glucose (10 g/L) and amino nitrogen (1.5 g/L) concentrations promote cell growth, followed by reduced glucose (2.0 g/L) and amino nitrogen (0.5 g/L) concentrations for sustained spore generation. The spore quantity reached 2.59 × 1010 CFU/mL. An automatic co-feeding strategy was developed and implemented in 5 and 50 L cultivations, resulting in spore quantities of 2.35 × 1010 and 2.86 × 1010 CFU/mL, respectively, improving by 6.81% and 30.00% compared to that with a fixed glucose concentration (10.0 g/L). The culture broth obtained at both the 5 and 50 L scales was spray-dried, resulting in bacterial powder with cell viability rates of 85.94% and 82.68%, respectively. Even after exposure to harsh conditions involving high temperature and humidity, cell viability remained at 72.80% and 69.89%, respectively. Employing the automatic co-feeding strategy increased the transcription levels of the spore formation-related genes spo0A, spoIIGA, bofA, and spoIV by 7.42%, 8.46%, 8.87%, and 9.79%, respectively. The proposed strategy effectively promoted Bacillus growth and spore formation, thereby enhancing the quality of B. licheniformis formulations.

Bacillus paralicheniformis 809 and Bacillus subtilis 810 support in vitro intestinal integrity under hydrogen peroxide and deoxynivalenol challenges

We designed and conducted two in vitro experiments to evaluate the effects of two Bacillus spp. probiotics on gut barrier integrity using the transepithelial electrical resistance (TEER) assay under two different challenge models. In Exp. 1, intestinal epithelial cells received or not (CON) B. paralicheniformis 809 (BLI) or B. subtilis 810 (BSU) at a rate of 1 × 108 colony forming units (CFU)/transwell. Two hours after treatment application (CON, BLI, or BSU), 5 mM of the reactive oxygen species hydrogen peroxide, mimicking mucosal oxidative stress, was added alone (HYP) or with each of the Bacillus spp. (HYP + BLI or HYP + BSU). In Exp. 2, cells were assigned to the same treatments as in Exp. 1 (CON, BLI, and BSU), or mycotoxin deoxynivalenol (DON), which was added alone or in combination with BLI or BSU, resulting in another two treatments (DON + BLI and DON + BSU). Transepithelial electrical resistance was measured for 14 h postchallenge. In Exp. 1, a treatment × hour interaction was observed for TEER (P < 0.0001). Adding BLI and BSU resulted in greater TEER values vs. CON for most of the experimental period (P < 0.02), whereas HYP reduced mean TEER and area under the curve (AUC), while increasing the amount of sugar that translocated through the monolayer cells (P < 0.001). A treatment × hour interaction was also observed in Exp. 2 (P < 0.0001), as DON led to an immediate and acute drop in TEER that lasted until the end of the experimental period (P < 0.0001). Both BLI and BSU alleviated the DON-induced damaging effects on the integrity of intestinal epithelial cells, whereas both Bacillus spp. alleviated the damage caused by DON alone and the proportion of sugar that translocated through the monolayer cells was not different between CON and DON + BLI (P = 0.14) and DON + BLI and DON + BSU (P = 0.62). In summary, both Bacillus spp. strains (B. paralicheniformis 809 and B. subtilis 810) were able to counteract the damaging effects of the challenge agents, hydrogen peroxide and deoxynivalenol, on gut barrier integrity.

The Effect of Maternal Probiotic or Synbiotic Supplementation on Sow and Offspring Gastrointestinal Microbiota, Health, and Performance

The increasing prevalence of antimicrobial-resistant pathogens has prompted the reduction in antibiotic and antimicrobial use in commercial pig production. This has led to increased research efforts to identify alternative dietary interventions to support the health and development of the pig. The crucial role of the GIT microbiota in animal health and performance is becoming increasingly evident. Hence, promoting an improved GIT microbiota, particularly the pioneer microbiota in the young pig, is a fundamental focus. Recent research has indicated that the sow's GIT microbiota is a significant contributor to the development of the offspring's microbiota. Thus, dietary manipulation of the sow's microbiota with probiotics or synbiotics, before farrowing and during lactation, is a compelling area of exploration. This review aims to identify the potential health benefits of maternal probiotic or synbiotic supplementation to both the sow and her offspring and to explore their possible modes of action. Finally, the results of maternal sow probiotic and synbiotic supplementation studies are collated and summarized. Maternal probiotic or synbiotic supplementation offers an effective strategy to modulate the sow's microbiota and thereby enhance the formation of a health-promoting pioneer microbiota in the offspring. In addition, this strategy can potentially reduce oxidative stress and inflammation in the sow and her offspring, enhance the immune potential of the milk, the immune system development in the offspring, and the sow's feed intake during lactation. Although many studies have used probiotics in the maternal sow diet, the most effective probiotic or probiotic blends remain unclear. To this extent, further direct comparative investigations using different probiotics are warranted to advance the current understanding in this area. Moreover, the number of investigations supplementing synbiotics in the maternal sow diet is limited and is an area where further exploration is warranted.

Effects of Dietary Bacillus subtilis HC6 on Growth Performance, Antioxidant Capacity, Immunity, and Intestinal Health in Broilers

This study aimed to investigate the impact of Bacillus subtilis HC6 on the growth performance, immunity, antioxidant capacity, and intestinal health of broilers. A total of 180 one-day-old white feather broilers were randomly divided into two experimental groups, each comprising six replicates of fifteen chicks from 1 to 50 d of age. The groups were either fed a basal diet (CON) or the same diet supplemented with 5 × 108 cfu/kg of Bacillus subtilis HC6 (BS). Our results indicated that compared with the CON, dietary supplementation with BS increased feed efficiency during d 21-50 and d 1-50 (p < 0.05). Moreover, BS supplementation enhanced antioxidant capacity in the serum and liver, and also decreased the activity of diamine oxidase and the level of endotoxins (p < 0.05). Additionally, BS treatment increased the villi height in the jejunum and ileum, increased the ratio of villus height/crypt depth in the ileum, upregulated the expression of tight junction proteins in the jejunal mucosa, and downregulated the levels of IL-22 and IFN-γ on day 50 (p < 0.05). Principal coordinates analysis yielded clear clustering of two groups; dietary BS increased the relative abundance of Bacteroidales_unclassified (genus) and Olsenella (genus), and decreased the abundance of genera Alistipes on day 50, which identified a strong correlation with FCR, serum differential metabolites, or differential gene expression in the jejunal mucosa by spearman correlation analysis. The PICRUSt2 analysis revealed that supplementation with BS enriched the pathways related to xenobiotics biodegradation and metabolism, carbohydrate metabolism, energy metabolism, signaling molecules and interaction, the digestive system, and transport and catabolism. These results demonstrated that dietary BS increased feed efficiency, antioxidant capacity, and the mRNA expression of pro-inflammatory cytokines in the jejunal mucosa; and decreased the activity of diamine oxidase in serum, which might be attributed to the modulation of community composition and the functions of cecal microbiota in white-feathered broilers.

From probiotics to postbiotics: Concepts and applications

In recent years, the important role of gut microbiota in promoting animal health and regulating immune function in livestock and poultry has been widely reported. The issue of animal health problems causes significant economic losses each year. Probiotics and postbiotics have been widely developed as additives due to their beneficial effects in balancing host gut microbiota, enhancing intestinal epithelial barrier, regulating immunity, and whole‐body metabolism. Probiotics and postbiotics are composed of complex ingredients, with different components and compositions having different effects, requiring classification for discussing their mechanisms of action. Probiotics and postbiotics have considerable prospects in preventing various diseases in the livestock industry and animal feed and medical applications. This review highlights the application value of probiotics and postbiotics as potential probiotic products, emphasizing their concept, mechanism of action, and application, to improve the productivity of livestock and poultry.

Effects of Bacillus licheniformis on the Growth Performance, Antioxidant Capacity, Ileal Morphology, Intestinal Short Chain Fatty Acids, and Colonic Microflora in Piglets Challenged with Lipopolysaccharide

The aim of the present study was to investigate the effects of Bacillus licheniformis (BL) on the growth performance, antioxidant capacity, ileal morphology, intestinal fecal short-chain fatty acids, and microflora of weaned piglets challenged with lipopolysaccharide (LPS). Piglets were assigned into three groups: basal diet (Con), a basal diet with added 10⁹ CFU B. licheniformis/kg (BLl), and a basal diet with added 10¹⁰ CFU B. licheniformis/kg (BLh). On day 28, BLh piglets were intraperitoneally injected with LPS (CBL) and sterilized saline water (BL), Con piglets were injected with LPS (LPS) and sterilized saline water (Con), with the injections being administered for three consecutive days. The average daily gain significantly increased from day 1 to day 28 and the feed: gain ratio decreased with BL supplementation compared with the Con group. Supplementation with BLl and BLh reduced the diarrhea rate in piglets. Serum catalase activity increased and malondialdehyde concentration decreased in the CBL treatment group compared with the LPS treatment group. Both BL and CBL treatments increased the ileal villus length/crypt depth ratio compared with Con and LPS treatments. BL administration significantly increased colonic propionic and isobutyric acid concentrations compared with Con treatment. Both BL and CBL piglets had significantly increased fecal acetic, propionic, and butyric acid levels compared with LPS piglets. Analysis of the colonic microbial metagenome showed that Prevotella species were the predominant bacteria in piglets treated with BL and CBL. The CBL-treated piglets had higher scores for lysine biosynthesis, arginine biosynthesis, sulfur relay system, and histidine metabolism. BL-treated piglets had higher scores for glycosaminoglycan biosynthesis-keratan sulfate, oxidative phosphorylation, and pyruvate and carbon metabolism.

Lactobacillus rhamnosus GG ATCC53103 and Lactobacillus plantarum JL01 improved nitrogen metabolism in weaned piglets by regulating the intestinal flora structure and portal vein metabolites

At present, most studies have shown that probiotics have a positive regulatory effect on the nutritional metabolism of the body, but the mechanism is still unclear. Here, 48 piglets were divided into four groups. The control group was not fed probiotics, the Lac group was fed L. Rhamnosus GG ATCC53103, the Rha group was fed L. Plantarum JL01, and the mix group was fed two types of probiotics. Nitrogen metabolism and mRNA levels of mTOR and S6K in skeletal muscle were observed in each group. Then, metagenome and non-targeted metabonomics were used to observe the changes of intestinal microorganisms and plasma metabolites in portal channels after probiotics feeding. Finally, we combined the results of omics analysis to reveal the mechanism of probiotics on nitrogen metabolism in weaned piglets. The results showed that L. Rhmnosus GG ATCC53103 and L. Plantarum JL01 increased nitrogen apparent digestibility, nitrogen deposition rate, and nitrogen utilization rate of weaned piglets (P < 0.05); the relative expression of mTOR and SK6 mRNA in skeletal muscle increased significantly (P < 0.05). When L. rhamnosus GG ATCC53103 and L. plantarum JL01 were combined, we found that Clostridium and Prevotella significantly increased in the jejunum (P < 0.05). The relative abundance of Lactobacillus, Ruminococcus, Streptococcus, and Prevotella in the ileum increased significantly (P < 0.05). Compared with the control group, L-Tryptophan, 3-Phosphonyloxypyruvate, cis-Aconitate, and Carbamoyl phosphate were significantly increased in the mixed group portal vein. The result of the combinatorial analysis showed that the significantly increased microorganisms could encode the enzyme genes for the synthesis of L-Tryptophan, 3-Phosphonooxypyruvate, cis-Aconitate, and Carbamoyl phosphate. In summary, our results demonstrated that L. Rhamnosus GG ATCC53103 and L. Plantarum JL01 could stimulate the expression of skeletal muscle protein synthesis genes of weaned piglets by modulating the structure of the gut microbiota and its metabolites, thereby improving nitrogen metabolism in weaned piglets.

Exploring the Benefits of Probiotics in Gut Inflammation and Diarrhea-From an Antioxidant Perspective

Inflammatory bowel disease (IBD), characterized by an abnormal immune response, includes two distinct types: Crohn's disease (CD) and ulcerative colitis (UC). Extensive research has revealed that the pathogeny of IBD encompasses genetic factors, environmental factors, immune dysfunction, dysbiosis, and lifestyle choices. Furthermore, patients with IBD exhibit both local and systemic oxidative damage caused by the excessive presence of reactive oxygen species. This oxidative damage exacerbates immune response imbalances, intestinal mucosal damage, and dysbiosis in IBD patients. Meanwhile, the weaning period represents a crucial phase for pigs, during which they experience pronounced intestinal immune and inflammatory responses, leading to severe diarrhea and increased mortality rates. Pigs are highly similar to humans in terms of physiology and anatomy, making them a potential choice for simulating human IBD. Although the exact mechanism behind IBD and post-weaning diarrhea remains unclear, the oxidative damage, in its progression and pathogenesis, is well acknowledged. Besides conventional anti-inflammatory drugs, certain probiotics, particularly Lactobacillus and Bifidobacteria strains, have been found to possess antioxidant properties. These include the scavenging of reactive oxygen species, chelating metal ions to inhibit the Fenton reaction, and the regulation of host antioxidant enzymes. Consequently, numerous studies in the last two decades have committed to exploring the role of probiotics in alleviating IBD. Here, we sequentially discuss the oxidative damage in IBD and post-weaning diarrhea pathogenesis, the negative consequences of oxidative stress on IBD, the effectiveness of probiotics in IBD treatment, the application of probiotics in weaned piglets, and the potential antioxidant mechanisms of probiotics.