Evaluation and Selection of Bacillus Species Based on Enzyme Production, Antimicrobial Activity, and Biofilm Synthesis as Direct-Fed Microbial Candidates for Poultry

Bacteriocinogenic Potential of Bacillus amyloliquefaciens Isolated from Kimchi, a Traditional Korean Fermented Cabbage

Bacteriocin production is considered a favorable property for various beneficial cultures. In addition to their potential as biopreservatives, bacteriocins are also promising alternatives for the control of multidrug-resistant pathogens and the inhibition of some viruses and cancer cells. The objective of this study was to screen and characterize a bacteriocin-producing strain with the aim of its future application for control of Listeria monocytogenes, an important food-borne pathogen. A total of 22 potentially bacteriocinogenic strains active against L. monocytogenes ATCC15313 were isolated from locally produced kimchi through a three-level approach. Pure cultures were obtained according to good microbiological practices and differentiated through RAPD-PCR using the primers OPL01, OPL09, and OPL11. Altogether, 5 strains were selected for further study. Specific focus was given to strain ST05DL based on its specific inhibitory activity against L. monocytogenes ATCC15313, while not affecting different strains belonging to the genera Lactobacillus, Pediococcus, Leuconostoc, and Weissella, most of which are beneficial microorganisms. The strain ST05DL was identified as Bacillus amyloliquefaciens based on its sugar fermentation profile obtained through API50CHB analysis and 16S rRNA partial sequencing. The antimicrobial compound produced by B. amyloliquefaciens ST05DL was found to be sensitive to pepsin and α-chymotrypsin, evidence of its proteinaceous nature. The presence of skim milk, NaCl, Tween 80, glycerol, and SDS did not affect the antimicrobial activity. The addition of 20% cell-free supernatant (CFS) obtained from a 24-h culture of B. amyloliquefaciens ST05DL to an exponentially growing culture of L. monocytogenes ATCC15313 successfully inhibited the test microorganisms during the monitored 10-h incubation. Optimal bacteriocin production by B. amyloliquefaciens ST05DL was observed during the stationary phase at 12 h (800 AU/mL) and remained stable for the next 15 h. The ratio between live and dead cells during this period was 74.37% and 25.66%, respectively, as determined by flow cytometry. The presence of the virulence genes hblA, hblB, hblC, nheA, nheB, and nheC was not detected in the total DNA of B. amyloliquefaciens ST05DL, and the strain was resistant only to ampicillin out of 10 tested antibiotics. Future evaluation of expressed bacteriocin/s by B. amyloliquefaciens ST05DL (amino acid sequence, molecular mass, cytotoxicity, detailed mode of action, etc.), will be the next step in the characterization and its potential application as biopreservative and/or pharmaceutical product.

Bioprospecting for Novel Halophilic and Halotolerant Sources of Hydrolytic Enzymes in Brackish, Saline and Hypersaline Lakes of Romania

Halophilic and halotolerant microorganisms represent promising sources of salt-tolerant enzymes that could be used in various biotechnological processes where high salt concentrations would otherwise inhibit enzymatic transformations. Considering the current need for more efficient biocatalysts, the present study aimed to explore the microbial diversity of five under- or uninvestigated salty lakes in Romania for novel sources of hydrolytic enzymes. Bacteria, archaea and fungi were obtained by culture-based approaches and screened for the production of six hydrolases (protease, lipase, amylase, cellulase, xylanase and pectinase) using agar plate-based assays. Moreover, the phylogeny of bacterial and archaeal isolates was studied through molecular methods. From a total of 244 microbial isolates, 182 (74.6%) were represented by bacteria, 22 (9%) by archaea, and 40 (16.4%) by fungi. While most bacteria synthesized protease and lipase, the most frequent hydrolase produced by fungi was pectinase. The archaeal isolates had limited hydrolytic activity, being able to produce only amylase and cellulase. Among the taxonomically identified isolates, the best hydrolytic activities were observed in halotolerant bacteria belonging to the genus Bacillus and in extremely halophilic archaea of the genera Haloterrigena and Halostagnicola. Therefore, the present study highlights that the investigated lakes harbor various promising species of microorganisms able to produce industrially valuable enzymes.

Evaluation of in vitro and in vivo potential of Bacillus subtilis MBTDCMFRI Ba37 as a candidate probiont in fish health management

Bacillus subtilis MBTDCMFRI Ba37 (B. subtilis Ba37), an antibacterial strain isolated from the tropical estuarine habitats of Cochin, was evaluated for in vitro and in vivo potential, and its application as a candidate probiont in fish health management. B. subtilis Ba37 was characterized using their morphological and biochemical properties. It exhibited exoenzymatic activities, tolerance to various physiological conditions and a wide spectrum of antibacterial activity against aquaculture pathogens such as Vibrio and Aeromonas. In co-culture assay, B. subtilis Ba37 inhibited Vibrio anguillarum O1 (V. anguillarum O1) even with the initial cell count of 10⁴ CFUmL^-1. Cytotoxicity assay performed using the cell free supernatant (CFS) of B. subtilis Ba37 revealed its non toxic nature. A twenty one days of feeding trial was conducted in juveniles of Etroplus suratensis (E.suratensis) by administrating B. subtilis Ba37 to evaluate its efficacy on growth, immune parameters and antioxidant enzyme activities. Overall the supplementation of B. subtilis Ba37 enhanced significantly (P < 0.05) the survival rate, weight gain, specific growth (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and feed efficiency (FE) of the fed animals as compared with the control. The immune parameters and antioxidant activities such as total protein, alkaline phosphatase (ALP), superoxide dismutase (SOD) and catalase were also improved significantly (P < 0.05) while serum alanine aminotransferase (SGOT) and serum aspartate aminotransferase (SGPT) activities were decreased slightly than the control. After fifteen days of challenge test, the fish fed with B. subtilis Ba37 showed higher relative percentage survival (RPS) than the control. Thus the study indicated the advantages of B. subtilis Ba37 to be used as a candidate probiont, which could be effectively utilized in managing diseases in aquaculture systems and to improve the health of the host.

Live Bacterial Prophylactics in Modern Poultry

Commercial poultry farms frequently use live bacterial prophylactics like vaccines and probiotics to prevent bacterial infections. Due to the emergence of antibiotic-resistant bacteria in poultry animals, a closer examination into the health benefits and limitations of commercial, live prophylactics as an alternative to antibiotics is urgently needed. In this review, we summarize the peer-reviewed literature of several commercial live bacterial vaccines and probiotics. Per our estimation, there is a paucity of peer-reviewed published research regarding these products, making repeatability, product-comparison, and understanding biological mechanisms difficult. Furthermore, we briefly-outline significant issues such as probiotic-label accuracy, lack of commercially available live bacterial vaccines for major poultry-related bacteria such as Campylobacter and Clostridium perfringens, as well research gaps (i.e., probiotic-mediated vaccine adjuvancy, gut-brain-microbiota axis). Increased emphasis on these areas would open several avenues for research, ranging from improving protection against bacterial pathogens to using these prophylactics to modulate animal behavior.

Genome analysis reveals probiotic propensities of Paenibacillus polymyxa HK4

The legislations on the usage of antibiotics as growth promoters and prophylactic agents have compelled to develop alternative tools to upsurge the animal protection and contain antibiotic usage. Probiotics have emerged as an effective antibiotic substitute in animal farming. The present study explores the probiotic perspective of Paenibacillus polymyxa HK4 interlinking the genotypic and phenotypic characteristics. The draft genome of HK4 revealed the presence of ORFs encoding the functions associated with tolerance to gastrointestinal stress and adhesion. The biosynthetic gene clusters encoding non-ribosomally synthesized peptides, polyketides and lanthipeptides such as fusaricidin, tridecaptin, polymyxin, paenilan and paenibacillin were annotated in HK4 genome. The strain harbored the chromosomal gene conferring the resistance to lincosamides. No functional gene encoding virulence or toxins could be identified in the genome of HK4. The genome analysis data was complemented by the in vitro experiments confirming its survival during gastrointestinal transit, antimicrobial potential and antibiotic sensitivity. NUCLEOTIDE SEQUENCE ACCESSION NUMBER: The draft-genome sequence of Paenibacillus polymyxa HK4 has been deposited as whole-genome shotgun project at GenBank under the accession number PRJNA603023.

Bacilli-Mediated Degradation of Xenobiotic Compounds and Heavy Metals

Xenobiotic compounds are man-made compounds and widely used in dyes, drugs, pesticides, herbicides, insecticides, explosives, and other industrial chemicals. These compounds have been released into our soil and water due to anthropogenic activities and improper waste disposal practices and cause serious damage to aquatic and terrestrial ecosystems due to their toxic nature. The United States Environmental Protection Agency (USEPA) has listed several toxic substances as priority pollutants. Bacterial remediation is identified as an emerging technique to remove these substances from the environment. Many bacterial genera are actively involved in the degradation of toxic substances. Among the bacterial genera, the members of the genus Bacillus have a great potential to degrade or transform various toxic substances. Many Bacilli have been isolated and characterized by their ability to degrade or transform a wide range of compounds including both naturally occurring substances and xenobiotic compounds. This review describes the biodegradation potentials of Bacilli toward various toxic substances, including 4-chloro-2-nitrophenol, insecticides, pesticides, herbicides, explosives, drugs, polycyclic aromatic compounds, heavy metals, azo dyes, and aromatic acids. Besides, the advanced technologies used for bioremediation of environmental pollutants using Bacilli are also briefly described. This review will increase our understanding of Bacilli-mediated degradation of xenobiotic compounds and heavy metals.

The Practical Potential of Bacilli and Their Enzymes for Industrial Production

Bacillus spp. are an affordable source of enzymes due to their wide distribution, safety in work, ease of cultivation, and susceptibility to genetic transformations. Researchers are particularly interested in proteolytic enzymes, which constitute one of the most diverse groups of microbial proteins in terms of properties. Despite the long history of their research, this group of enzymes continue to show great potential for practical application in the biomedical industry, as well as in the agricultural industry. Thus, the unique properties of bacillary proteinases, such as stability in a wide range of temperatures and pH, high specificity, biodegradability of a wide range of substrates, and the high potential of sequenced Bacillus genomes are a powerful foundation for the development of new biotechnologies. The current review aims to discuss recent studies on various enzymes in particular, proteinases produced by bacteria of the genus Bacillus, along with their prospective practical applications. This article also presents an interpretive summary of the recent developments on the usage of probiotic Bacillus strains as potential feed additives.

Nanolipoidal α-terpineol modulates quorum sensing regulated virulence and biofilm formation in Pseudomonas aeruginosa

Aim: Pseudomonas aeruginosa has emerged as a major opportunistic pathogen meaning there is an immediate need to develop efficient antivirulence agents which offer a new class of superior therapeutics. Methods: Nanostructured lipid carriers (NLCs) containing α-terpineol (αT) were developed and characterized to determine expression profiles of quorum sensing regulated genes, antivirulence activity and antibiofilm effects against P. aeruginosa. Results: The αT-NLCs had a size of 145.4 nm, polydispersity index of 0.242 and ζ-potential of -31.4 mV. They exhibited pronounced effects on the inhibition of quorum sensing mediated virulence and biofilm formation which were confirmed by molecular docking analysis and gene expression profiles. Conclusion: αT-NLCs show promise as effective antivirulence agents against P. aeruginosa in the postantibiotic era.

Effect of Bacillus-direct-fed microbial on leaky gut, serum peptide YY concentration, bone mineralization, and ammonia excretion in neonatal female turkey poults fed with a rye-based diet

Rye is high in nonstarch polysaccharides (NSP), a complex carbohydrate which cannot be digested by poultry as they lack the endogenous enzymes to do so. Exogenous carbohydrases must therefore be supplemented to avoid the antinutritional effects associated with a high NSP diet. The objectives of the present study were to evaluate the effects of a rye-based diet with and without supplementation of a Bacillus direct-fed microbial (DFM) on body weight, bone mineralization, and leaky gut, as well as its role on influencing serum concentrations of peptide YY (PPY) and the ammonia concentration in turkey manure. Two independent trials were conducted. In each experiment, day-of-hatch female turkey poults were neck tagged and randomly assigned to either a control rye-based diet or a rye-based diet supplemented with the DFM (n = 25 birds/group). At 10 days-of-age, poults in both groups were administered with an appropriate dose of fluorescein isothiocyanate-dextran (FITC-d) by oral gavage. One hour later, all poults were euthanized. Blood was collected to evaluate serum FITC-d and PPY concentrations. Furthermore, in Trial 2 only, both tibias were removed for assessment of bone parameters, and turkey manure was collected to evaluate physicochemical analysis. In both trials, poults treated with the DFM showed a significant increase (P < 0.05) in body weight and body weight gain as compared with control nontreated poults. Poults that received the DFM also had a significant reduction in serum levels of PPY and FITC-d when compared with control nontreated poults. In Trial 2, turkeys treated with the DFM had a substantial increase in tibia strength, tibia diameter, total ash, calcium, and phosphorus when compared with control nontreated turkeys. Their manure was also shown to have a significant reduction in the concentration of ammonia. This is the first report of a commercial DFM reducing the concentration of this compound in turkey manure. In summary, the results of the present study confirm that turkeys fed with a rye-based diet have a significant increase in gut permeability, a reduced body weight, and decreased bone mineralization when compared with turkeys fed with the DFM. Turkeys that received the rye-based diet supplemented with the Bacillus-DFM also had a significant reduction in the serum concentration of PPY when compared with control turkeys. This finding suggests a possible prebiotic effect of rye, warranting future studies to test this effect. Further studies to evaluate the microbiota diversity, as well as the concentration of ceca short-chain fatty acids, are also necessary to confirm the reliability of PPY as a potential metabolomic biomarker in poultry.

Isolation, selection and evaluation of Bacillus spp. as potential multi-mode probiotics for poultry

Bacillus based probiotics are becoming relevant as alternatives to antibiotics used in poultry production and in other animal husbandry. This study describes the isolation of 48 Bacillus spp. candidates, from chickens and chicken environments, for use as potential probiotics in poultry production. These isolates, plus a further 18, were tested in a comprehensive in vitro screening regime that was specifically designed to select the best isolates that satisfied multiple modes of action desirable for commercial poultry probiotics. This screening programme involved the evaluation of the ability of the isolates to survive and grow in the limiting conditions of the chicken gastrointestinal tract. Only 11 of the isolates fulfilled these criteria; hence, they were further evaluated for the ability to adhere to epithelial cells, produce extracellular enzymes, and to demonstrate antagonistic activity against selected pathogens of significant importance in poultry production. Of these, a total of 6 isolates were selected, due to their all-round probiotic capability. Identification by 16S RNA sequencing confirmed these isolates as B. subtilis and B. velezensis, identities which are generally regarded as safe. The Bacillus isolates reported in our study exhibit strong all-inclusive probiotic effects and can potentially be formulated as a probiotic preparation for poultry production.

Evaluation of a Bacillus -Based Direct-Fed Microbial on Aflatoxin B1 Toxic Effects, Performance, Immunologic Status, and Serum Biochemical Parameters in Broiler Chickens

The aim of the present study was to evaluate the effect of a commercial Bacillus direct-fed microbial (DFM) on aflatoxin B1 toxic effects, performance, and biochemical and immunologic parameters in broiler chickens. Ninety 1-day-old Cobb 500 male broiler chicks were raised in floor pens for a period of 21 days. Chicks were neck-tagged, individually weighed, and randomly allocated to one of three groups: Negative control (basal feed), aflatoxin B1 (basal feed + 2 ppm AFB1), and DFM (basal feed + 2 ppm AFB1 + Bacillus direct-fed microbial). Each group had three replicates of 10 chickens (n = 30/group). Body weight and body weight gain were calculated weekly, while feed intake and feed conversion ratio were determined when broilers were 21 days old. On day 21, all chickens were bled, gastrointestinal samples were collected, and spleen and bursa of Fabricius were weighed. This study confirmed that 2 ppm of AFB1 causes severe detrimental effects on performance, biochemical parameters, and immunologic parameters, generating hepatic lesions in broiler chickens (P < 0.05). However, it was also observed that DFM supplementation provided beneficial effects that might help to improve gut barrier function, anti-inflammatory and antioxidant activities, as well as humoral and cellular immunomodulation. The results of the present study suggest that this Bacillus-DFM added at a concentration of 10⁶ spores/gram of feed can be used to counteract the negative effects that occur when birds consume diets contaminated with AFB1, showing beneficial effects on performance parameters, relative organ weights, hepatic lesions, immune response, and serum biochemical variables. The addition of this Bacillus-DFM might mitigate and decrease aflatoxicosis problems in the poultry industry, improving food security, alleviating public health problems, and providing economic benefits. Future studies are needed to fully elucidate the specific mechanisms by which this Bacillus-DFM counteracts the toxic effects of aflatoxin B1.

Post hatch recovery of a probiotic Enterococcus faecium strain in the yolk sac and intestinal tract of broiler chickens after in ovo injection

Concerns about antibiotic-resistant bacteria and their presence in animal products grow and thus alternatives to use of antibiotics in animal production are being investigated. Probiotics have gained increased focus due to improvements in performance, immune health and pathogen reduction when provided to poultry through feed. These traits may be further improved if probiotics can be provided to the embryo before hatch, before meeting environmental pathogens. The objective was to determine the faith of a probiotic Enterococcus faecium (M74) strain in the yolk sac and intestinal tract of broiler chickens after injection into hatching eggs. E. faecium M74 (1.4 × 107 CFU/egg) was applied in ovo at day 18 of incubation. From 1- and 7-day-old chickens, 20 samples from yolk sac, caecal tonsils and rest of the intestinal tract were subjected to CFU counting. Isolates from a sample subset were typed by pulsed-field gel electrophoresis (PFGE). Enterococci were found in varying numbers: 1.0 × 104-2.2 × 1010 CFU/g. The prevalence of M74 PFGE profiles was high in 1-day-old (88%) and 7-day-old chickens (67%). This demonstrates that the embryos ingested M74 before hatching, that M74 is viable for intestinal colonization through in ovo administration, and that the strain multiplies in the chickens gastrointestinal tract post hatching.

Evaluation of in ovo Bacillus spp. based probiotic administration on horizontal transmission of virulent Escherichia coli in neonatal broiler chickens

This study evaluated the effect of in ovo Bacillus spp. base probiotic (BBP) administration on hatchability, Gram-negative bacteria (GNB) recovery, performance, and microbiota composition in 2 independent trials using a virulent E. coli seeder challenge model. In each trial, one hundred and eighty 18-day-old embryos were allocated into 1 of 2 groups: Control and treated group (inoculated with 107 BBP). On day 19 of embryogenesis, seeder embryos (n = 18) were inoculated with 4.5 × 104E. coli/mL+272 μg/mL tetracycline and segregated into mesh hatching bags. Twelve chicks per group were euthanized at hatch and at day 7 to evaluate the gastrointestinal composition of total GNB or total aerobic pasteurized bacteria. Also, in trial 2, ceca content from five chickens at day 7 were collected to evaluate microbiota composition. Embryos inoculated with BBP showed a significant (P < 0.05) reduction in the total number of GNB at day-of-hatch (DOH) and day 7. Probiotic treatment increased BW at DOH and day 7, and BW gain (days 0 to 7) when compared with Control chickens. Proteobacteria phylum was significantly reduced, while the Firmicutes was significantly increased by the BBP as compared to the Control (P < 0.05). At family level, Enterobacteriaceae was significantly decreased, while the Lachnospiraceae was significantly elevated in the BBP as compared to the Control group (P < 0.05). The genus Oscillospira was significantly enriched in the BBP group, whereas the unidentified genus of family Enterobacteriaceae in the Control group (P < 0.05). The BBP group increased the bacterial species richness, although there was no significant difference between treatments (P > 0.05). Interestingly, beta diversity showed a significant difference in bacterial community structure between Control and BBP groups (P < 0.05). The results of the present study suggest that in ovo administration of a BBP can reduce the severity of virulent E. coli horizontal transmission and infection of broiler chickens during hatch. The reduction in the severity of the transmission and infection by the BPP might be achieved through alterations of microbiota composition and its community structure.

A novel Bacillus based multi-strain probiotic improves growth performance and intestinal properties of Clostridium perfringens challenged broilers

There is a necessity for the implementation of in-feed probiotics in the poultry production industry, following strict regulations around the use of antibiotic growth promoters (AGP). Bacillus spp. are becoming an attractive alternative because of their functionality and stability. This study aims to evaluate the effect of a novel multi-strain Bacillus based probiotic on growth performance and gut health in male Ross 308 broiler chickens challenged with Clostridium perfringens Type A. Broilers on a 4 phase feeding program were fed diets containing either a standard metabolizable energy (ME) (100%) or a reduced ME (98%) level. The test probiotic was compared to an un-supplemented negative control and a commercial benchmark product as positive control over a 35 D feeding trial, using a 2 × 3 factorial experimental design. Chicks were inoculated with a once-off dose of C. perfringens on day 14. Growth performance was measured weekly to calculate body weight (BW), feed intake (FI) and feed conversion ratio (FCR). Villi histomorphology, gut lesions, and liver weight were assessed at day 35. Broilers fed the reduced ME diet with the test probiotic achieved higher final BWs (P = 0.037) and FCR (P = 0.014) than the negative control. Broilers fed the standard ME diet with the test probiotic showed improved (P = 0.001) FCR than the negative control from day 21 onwards. Increased duodenal villi height (P = 0.012) and villi height to crypt depth ratio in the duodenum (P < 0.0001) and jejunum (P = 0.0004) were observed in broilers fed the reduced ME diet containing the test probiotic. Additionally, the test probiotic resulted in significantly reduced relative liver weights in both ME groups. Consequently, the results suggest that the novel multi-strain Bacillus based probiotic enhanced broiler performance and improved gut health and is thus attractive as an alternative to AGP's in broiler production.

Screening of differentially expressed immune-related genes from spleen of broilers fed with probiotic Bacillus cereus PAS38 based on suppression subtractive hybridization

The aim of this study was to construct the spleen differential genes library of broilers fed with probiotic Bacillus cereus PAS38 by suppression subtractive hybridization (SSH) and screen the immune-related genes. Sixty seven-day-old broilers were randomly divided into two groups. The control group was fed with basal diet, and the treated group was fed with basal diet containing Bacillus cereus PAS38 1×10⁶ CFU/g. Spleen tissues were taken and extracted its total RNA at 42 days old, then SSH was used to construct differential gene library and screen immune-related genes. A total of 119 differentially expressed sequence tags (ESTs) were isolated by SSH and 9 immune-related genes were screened out by Gene ontology analysis. Nine differentially expressed genes were identified by qRT-PCR. JCHAIN, FTH1, P2RX7, TLR7, IGF1R, SMAD7, and SLC7A6 were found to be significantly up-regulated in the treated group. Which was consistent with the results of SSH. These findings imply that probiotic Bacillus cereus PAS38-induced differentially expressed genes in spleen might play an important role in the improvement of immunity for broilers, which provided useful information for further understanding of the molecular mechanism of probiotics responsible to affect the poultry immunity.

Evaluation of the Antimicrobial and Anti-inflammatory Properties of Bacillus-DFM (Norum™) in Broiler Chickens Infected With Salmonella Enteritidis

Restrictions of in-feed antibiotics use in poultry has pushed research toward finding appropriate alternatives such as Direct-Fed Microbials (DFM). In this study, previously tested Bacillus isolates (B. subtilis and B. amyloliquefaciens) were used to evaluate their therapeutic and prophylactic effects against Salmonella enterica serovar Enteritidis (S. Enteritidis) in broiler chickens. For this purpose, initial antibacterial activity of Bacillus-DFM (10⁴ spores/g or 10⁶ spores/g) against S. Enteritidis colonization in crop, proventriculus and intestine was investigated using an in vitro digestive model. Furthermore, to evaluate therapeutic and prophylactic effects of Bacillus-DFM (10⁴ spores/g) against S. Enteritidis colonization, altogether 60 (n = 30/group) and 30 (n = 15/group) 1-day-old broiler chickens were randomly allocated to either DFM or control group (without Bacillus-DFM), respectively. Chickens were orally gavaged with 10⁴ cfu of S. Enteritidis per chicken at 1-day old, and cecal tonsils (CT) and crop were collected 3 and 10 days later during the therapeutic study, whereas they were orally gavaged with 10⁷ cfu of S. Enteritidis per chicken at 6-day-old, and CT and crop were collected 24 h later from two independent trials during the prophylactic study. Serum superoxide dismutase (SOD), FITC-d and intestinal IgA levels were reported for both chicken studies, in addition cecal microbiota analysis was performed during the therapeutic study. DFM significantly reduced S. Enteritidis concentration in the intestine compartment, and in both proventriculus and intestine compartments as compared to the control when used at 10⁴ spores/g and 10⁶ spores/g, respectively (p < 0.05). DFM significantly reduced FITC-d and IgA as well as SOD and IgA levels (p < 0.05) compared to the control in therapeutic and prophylactic studies, respectively. Interestingly, in the therapeutic study, there were significant differences in bacterial community structure and predicted metabolic pathways between DFM and control. Likewise, phylum Actinobacteria and the genera Bifidobacterium, Roseburia, Proteus, and cc_115 were decreased, while the genus Streptococcus was enriched significantly in the DFM group as compared to the control (MetagenomeSeq, p < 0.05). Thus, the overall results suggest that the Bacillus-DFM can reduce S. Enteritidis colonization and improve the intestinal health in chickens through mechanism(s) that might involve the modulation of gut microbiota and their metabolic pathways.

In vitro inhibition of avian pathogenic Enterococcus cecorum isolates by probiotic Bacillus strains

Enterococcus cecorum is a commensal bacteria and opportunistic pathogen that can cause outbreaks of Enterococcal spondylitis (“kinky back”) in poultry, with a growing concern worldwide. Numerous Bacillus-based probiotic strains are commercially available with proven effects in supporting gut health and growth performance, but efficacy against pathogenic E. cecorum is unknown. This study compared the in vitro inhibitory potential of cell-free supernatants (CFSs) of 18 Bacillus strains (14 commercial probiotic strains, 1 internal negative control and 3 type strains) on the growth of 9 clinical E. cecorum isolates. Standardized biomass cultures of live Bacillus were harvested and filtered to obtain CFSs. Inhibitory potential against E. cecorum isolates was assessed via a microdilution assay in which the final pathogen concentration was ∼ 10⁴ CFU/mL. Absorbance (OD) was measured every 15 min for 15 h and used to calculate percentage growth inhibition at an OD equivalent to 0.4 in the positive control (PC) (pathogen but no CFS), and growth delay vs. PC. Growth kinetic responses of pathogen isolate-Bacillus strain combinations ranged from total pathogen inhibition to partial inhibition, lag in growth, no effect, or increased growth vs. PC. Percentage inhibition of individual isolates varied markedly among Bacillus strains, from 100% to −100% (growth promotion as recorded for the type strain) (B. amyloliquefaciens DSM7^T). Five B. amyloliquefaciens CFSs produced higher average inhibition rates (>75%) than 2 out of 3 Bacillus licheniformis CFSs (−2.5, and −8.39% vs. PC, respectively) and 1 out of 2 Bacillus subtilis CFSs (7.3% vs. PC) (P < 0.05). Commercial strain 3AP4 exhibited the highest average percentage inhibition vs. PC (85.0% ± 7.9) and the most consistent inhibitory effect across pathogen isolates. The findings indicate that some commercially available poultry probiotic Bacillus strains are effective at inhibiting pathogenic E. cecorum in vitro, but effects are highly strain and pathogen isolate-dependent. Further work is required to confirm effects in vivo and isolate the inhibitory substances.

Evaluation of Intestinal Permeability and Liver Bacterial Translocation in Two Modern Broilers and Their Jungle Fowl Ancestor

The objective of this study was to evaluate the of intestinal permeability and liver bacterial translocation (BT) across a modern commercial broiler, a commercial broiler of 1995 genetics, and an unselected Jungle Fowl line. Modern 2015 (MB2015) broiler chicken, random bred line initiated from 1995 (RB1995), and the Giant Jungle fowl (JF). Chickens were randomly allocated to four different dietary treatments. Dietary treatments were (1) a control corn-based diet throughout the trial [corn-corn (C-C)]; (2) an early phase malnutrition diet where chicks received a rye-based diet for 10 days, and then switched to the control diet [rye-corn (R-C)]; (3) a malnutrition rye-diet that was fed throughout the trial [rye-rye (R-R)]; and (4) a late phase malnutrition diet where chicks received the control diet for 10 days, and then switched to the rye diet for the last phase [corn-rye (C-R)]. Paracellular permeability was evaluated using fluorescein isothiocyanate dextran (FITC-D). Liver BT was also evaluated. MB2015 and RB1995 consuming the rye-based diet showed increase serum levels of FITC-D when compared to the corn-fed chickens (P < 0.05). Overall, MB2015 appeared to have higher enteric permeability than the JF. To our knowledge, this would be the first paper to evaluate the effect of compensatory growth on intestinal permeability and liver BT. Further studies to evaluate microbiome and inflammatory markers in these chicken models are currently being evaluated.

Impact of a Bacillus Direct-Fed Microbial on Growth Performance, Intestinal Barrier Integrity, Necrotic Enteritis Lesions, and Ileal Microbiota in Broiler Chickens Using a Laboratory Challenge Model

Decreases in the use of antibiotics and anticoccidials in the poultry industry have risen the appearance of necrotic enteritis (NE). The purpose of this study was to evaluate the effect of a Bacillus direct-fed microbial (DFM) on growth performance, intestinal integrity, NE lesions and ileal microbiota using a previously established NE-challenged model. At day-of-hatch, chicks were randomly assigned to three different groups: Negative control (NC), Positive control (PC) challenged with Salmonella Typhimurium (day 1), Eimeria maxima (EM, day 13) and Clostridium perfringens (CP, day 18-19), and Bacillus-DFM group (DFM) challenged as the PC. Body weight (BW) and body weight gain (BWG) were measured weekly. Total feed intake (FI) and feed conversion ratio (FCR) were evaluated at day 21. Liver samples were collected to assess bacterial translocation and blood samples were used to measure superoxide dismutase (SOD) and fluorescein isothiocyanate-dextran (FITC-d). Intestinal contents were obtained for determination of total IgA and microbiota analysis. NE lesion scores (LS) were performed at day 21. Chickens consuming the DFM significantly improved BW and had a numerically more efficient FCR compared to PC at day 21. Additionally, there were no significant differences in FCR between the DFM group and NC. Furthermore, the DFM group showed significant reductions in LS, IgA and FITC-d levels compared to the PC. However, there were no significant differences in SOD between the groups. The microbiota analysis indicated that the phylum Proteobacteria was significantly reduced in the DFM group in comparison to PC. At the genus level, Clostridium, Turicibacter, Enterococcus, and Streptococcus were reduced, whereas, Lactobacillus and Bacillus were increased in the DFM group as compared to PC (p < 0.05). Likewise, the DFM significantly reduced CP as compared to PC. In contrary, no significant differences were observed in bacterial composition between NC vs. DFM. In addition, beta diversity showed significant differences in the microbial community structure between NC vs. PC, and PC vs. DFM. These results suggest that the dietary inclusion of a selected DFM could mitigate the complex negative impacts caused by NE possibly through mechanism(s) that might involve modulation of the gut microbiota.

Autochthonous Bacillus licheniformis: Probiotic potential and survival ability in low-fishmeal extruded pellet aquafeed

In recent years, Bacillus spp. have garnered attention as probiotic supplements in aquafeed owing to the production of heat stable and low pH resistant spores. Herein, we isolated and characterized an autochthonous Bacillus licheniformis KCCM 43270 from the intestine of olive flounder (Paralichthys olivaceus) for supplementation in low‐fishmeal extruded aquafeeds. The KCCM 43270 was screened based on amylase, protease, cellulase, and lipase as well as non‐hemolytic activities. The isolate was able to grow in carboxymethyl cellulose (CMC), xylan, and soybean meal (SBM) when used as a single carbon source in the minimal nutrient M9 medium. The KCCM 43270 spores displayed complete survival in acid (pH 2.5) and bile (0.3%, w/v) for 3 hr, strong biofilm formation, and nearly 50% adhesion with intestinal mucus. The spores of the isolate also showed significant survival ability at 80, 90, 100°C for 60, 30, and 1 min, respectively. In addition, the spores in a blend of SBM complex carrier showed significant heat stability at 120°C for 5 min and under different drying conditions. Furthermore, the spores also survived the extrusion process during low‐fishmeal aquafeed manufacturing, implying the potential application of B. licheniformis KCCM 43270 in aquafeed industry.

Evaluation of the Epithelial Barrier Function and Ileal Microbiome in an Established Necrotic Enteritis Challenge Model in Broiler Chickens

Necrotic enteritis (NE) is a recognized multifactorial disease that cost annually to the poultry industry around $2 billion. However, diverse aspects related to its presentation are not completely understood, requiring further studies using known induction experimental models. Therefore, the purpose of this study was to measure the changes occurring in performance, intestinal integrity and ileal microbiome using a previously established NE-challenge model. Chickens were assigned to a negative control group (NC) or a positive control group (PC). In the PC, broilers were orally gavaged with Salmonella Typhimurium (ST) (1 × 107 cfu/chick) at day 1, Eimeria maxima (EM) (2.5 × 104 oocyst/chick) at day 18 and Clostridium perfringens (CP) (1 × 108 cfu/chick/day) at 23-24 days of age. Weekly, body weight (BW), body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were evaluated. Morbidity and mortality were determined throughout the study, and NE lesion scores were recorded at day 25. Additionally, blood and liver samples were collected to measure gut permeability as determined by levels of serum fluorescein isothiocyanate-dextran (FITC-d) and bacterial translocation (BT). Ileal contents were processed for 16S rRNA gene-based microbiome analysis. Performance parameters and intestinal permeability measurements were negatively impacted in the PC resulting in elevated serum FITC-d and BT with a -6.4% difference in BWG. The NE lesion score in PC (1.97 vs. 0.00) was significantly higher in comparison to NC, although there was no difference in mortality. The microbiome analysis showed a dramatic shift of ileal microbiomes in PC groups as compared to NC (ANOSIM: R = 0.76, P = 0.001). The shift was characterized by reduced abundance of the phylum Actinobacteria (P < 0.01), and increased abundance of the genera Butyrivibrio, Lactobacillus, Prevotella and Ruminococcus in PC compared to NC (P < 0.05). Expectedly, Clostridium was found higher in PC (2.98 ± 0.71%) as compared to NC (1.84 ± 0.36%), yet the difference was not significant. In conclusion, results of the present study showed the different intestinal epithelial and microbiological alterations occurring in an established NE-challenge model that considers paratyphoid Salmonella infections in young chicks as an important predisposing factor for presentation of NE.

Bacillus probiotics: an alternative to antibiotics for livestock production

The use of probiotics as feed supplements in animal production has increased considerably over the last decade, particularly since the ban on antibiotic growth promoters in the livestock sector. Several Bacillus sp. are attractive for use as probiotic supplements in animal feed due to their ability to produce spores. Their heat stability and ability to survive the low pH of the gastric barrier represent an advantage over other probiotic micro-organisms. This review discusses important characteristics required for selection of Bacillus probiotic strains and summarizes the beneficial effect of Bacillus-based feed additives on animal production. Although the mechanism of action of Bacillus probiotics has not been fully elucidated, they are effective in improving the growth, survival and health status of terrestrial and aquatic livestock. Bacillus strains also have utility in bioremediation and can reduce nitrogenous waste, thereby improving environmental conditions and water quality. Finally, recent innovative approaches for using Bacillus spores in various applications are discussed.

Assessment of the potential of the multi-enzyme producer Bacillus amyloliquefaciens US573 as alternative feed additive

BACKGROUND

Recently, probiotics have increasingly been used as feed additives in poultry diets as an alternative to antibiotic growth promoters fostering resistance development.

RESULTS

This study was aimed at assessing the potential of Bacillus amyloliquefaciens US573 as a direct-fed microbial. The US573 strain was found to be free of harmful enzymatic activities and sensitive to antibiotics. In addition, it showed a good acid and bovine bile tolerance, high adhesion efficacy to chicken enterocytes, and an ability to form biofilms, which may favor its survival and persistence in the animal gastrointestinal tract. Moreover, besides the previously described extremely salt-tolerant and highly thermostable phytase, the US573 strain secretes xylanase, β-glucanase and amylase activities useful in neutralizing antinutritional factors and maximizing the absorption of nutrients. The secretion of such enzymes may be responsible for the good performance of the US573 isolate in the digestibility of wheat in vitro. Indeed, using the vegetative cells, a yield of wheat dry matter digestibility of approximately 48% was achieved, which is slightly lower than the commercial feed additive Rovabio used as a reference (56.73% digestibility).

CONCLUSION

The obtained results illustrate the potential of US573 strain as a promising direct-fed microbial candidate for application in the poultry industry. © 2017 Society of Chemical Industry.

Diversity and bioprospecting of extremely halophilic archaea isolated from Algerian arid and semi-arid wetland ecosystems for halophilic-active hydrolytic enzymes

The diversity of haloarchaea associated with different dry salt lakes in northeastern Algeria was investigated together with their potential of hydrolytic enzyme production. A total of 68 aerobic halophilic archaea were isolated from saline sediments. Based on the 16S rRNA gene sequencing, the isolates were assigned to seven phylotypes within the class Halobacteria, namely Haloarcula, Halococcus, Haloferax, Halogeometricum, Haloterrigena, Natrialba, and Natrinema. The results showed that Haloferax group was found to be dominant in all samples (30 isolates) (44%) with high diversity, followed by Halococcus spp. (13%) (9 isolates). All phylotypes are extreme halophiles and thermotolerant with the ability to grow at temperatures up to 48 °C. In addition, the screening for extracellular halophilic enzymes showed that 89.7% of the isolates were able to produce at least two types of the screened enzymes. The strains producing esterase, gelatinase, inulinase, cellulase and protease activities were the most diverse functional group. These data showed an abundant and diverse haloarchaeal community, detected in Algerian wetland ecosystems, presenting a promising source of molecules with important biotechnological applications.

Performance, gut morphology and microbiology effects of a Bacillus probiotic, avilamycin and their combination in mixed grain broiler diets

1. This study aimed to determine the effect of avilamycin (AGP) and a multi-strain Bacillus probiotic (DFM) on the performance, gut histology and microbiology of broilers fed on a mixed grain diet. 2. A total of 800 chicks were allocated to four treatments: a control diet, control+AGP, control+DFM, or control+AGP+DFM. Bodyweight, feed intake and FCR were measured at d 0, 21 and 42. Samples were taken at d42 to determine villus height (VH), crypt depth (CD) and ratio (VH:CD). Mucosal E. coli and Lactobacilli counts were measured at d42. 3. At d42, DFM and AGP+DFM significantly increased weight over the control, with AGP returning an intermediate value. FCR followed a similar pattern. DFM and AGP+DFM significantly increased VH and CD in all gut sections compared to the control. 4. DFM and AGP+DFM reduced E. coli counts compared to control, with AGP reducing caecal counts only, while Lactobacilli counts were increased. 5. Divergent histology and microbiology between treatments highlight the different modes of action of AGP and DFM for improving broiler growth and feed efficiency.

Different antibiotic growth promoters induce specific changes in the cecal microbiota membership of broiler chicken

Antimicrobials are sometimes given to food animals at low doses in order to promote faster growth. However, the mechanisms by which those drugs improve performance are not fully understood. This study aimed to investigate the impact of zinc bacitracin (55g/ton), enramycin (10g/ton); halquinol^® (30g/ton); virginiamycin (16,5g/ton) and avilamycin (10g/ton) on the cecal microbiota of broiler chicken, compared to a control group. Six hundred and twenty four chicks (Cobb 500) arriving to an experimental unit were randomly assigned into each treatment with four repetitions per treatment. The cecal content of 16 animals per treatment (n = 96) was used for DNA extraction and sequencing of the V4 region of the 16S rRNA gene using Illumina technology. The use of antimicrobials induced significant changes in membership but not in structure of the cecal microbiota compared to the control group, suggesting a greater impact on the less abundant species of bacteria present in that environment. Halquinol was the only drug that did not affect microbial membership. Firmicutes comprised the major bacterial phylum present in the cecum of all groups. There was no statistical difference in relative abundances of the main phyla between treated animals and the control group (all P>0.05). Treatment with enramycin was associated with decreased richness and with lower relative abundance of unclassified Firmicutes, Clostridium XI, unclassified Peptostreptococcaceae (all P<0.001) and greater abundance of Clostridium XIVb (P = 0.004) and Anaerosporobacter spp. (P = 0.015), and treatment with bacitracin with greater relative abundance of Bilophila spp. (P = 0.004). Several bacterial genera were identified as representative of usage of each drug. This study used high throughput sequencing to characterize the impact of several antimicrobials in broiler chicken under controlled conditions and add new insights to the current knowledge on how AGPs affect the cecal microbiota of chicken.