Protective role of cells and spores of Shouchella clausii SF174 against fructose-induced gut dysfunctions in small and large intestine.

The oral administration of probiotics is nowadays recognized as a strategy to treat or prevent the consequences of unhealthy dietary habits. Here we analyze and compare the effects of the oral administration of vegetative cells or spores of Shouchella clausii SF174 in counteracting gut dysfunctions induced by 6 weeks of high fructose intake in a rat model. Gut microbiota composition, tight junction proteins, markers of inflammation and redox homeostasis were evaluated in ileum and colon in rats fed fructose rich diet and supplemented with cells or spores of Shouchella clausii SF174. Our results show that both spores and cells of SF174 were effective in preventing the fructose-induced metabolic damage to the gut, namely establishment of "leaky gut", inflammation and oxidative damage, thus preserving gut function. Our results also suggest that vegetative cells and germination-derived cells metabolize part of the ingested fructose at the ileum level.

Chemopreventive effect of a milk whey by-product derived from Buffalo (Bubalus bubalis) in protecting from colorectal carcinogenesis.

BACKGROUND: Several studies show that natural foods are a source of compounds with anticancer properties that affect the gut microbiota and its metabolites. In the present study, we investigate the effect of a delactosed buffalo milk whey by-product (DMW) on colorectal carcinogenesis. METHODS: The effect of DMW on colorectal carcinoma (CRC) was investigated in the established mouse model of azoxymethane (AOM)-induced colon carcinoma, which closely resembles the human clinical condition of CRC. The effect of DMW on CRC immortalized cell lines was also evaluated to further identify the antineoplastic mechanism of action. RESULTS: Pretreatment of AOM-treated mice with DMW significantly (P < 0.05) reduced the percentage of mice bearing both aberrant crypt foci with more than four crypts (which are early precancerous lesions that progress to CRC) and tumors. In addition, DMW completely counteracted the effect of AOM on protein expression of caspase-9, cleaved caspase-3 and poly ADP-ribose polymerase in colonic tissue. Administration of DMW alone (i.e. without AOM) resulted in changes in the composition of the gut microbiota, leading to enrichment or depletion of genera associated with health and disease, respectively. DMW was also able to restore AOM-induced changes in specific genera of the gut microbiota. Specifically, DMW reduced the genera Atopobiaceae, Ruminococcus 1 and Lachnospiraceae XPB1014 and increased the genera Parabacteroides and Candidatus Saccharimonas, which were increased and reduced, respectively, by AOM. Blood levels of butyric acid and cancer diagnostic markers (5-methylcytidine and glycerophosphocholine), which were increased by AOM treatment, were reduced by DMW. Furthermore, DMW exerted cytotoxic effects on two human CRC cell lines (HCT116 and HT29) and these effects were associated with the induction of apoptotic signaling. CONCLUSIONS: Our results suggest that DMW exerts chemopreventive effects and restores the gut microbiota in AOM-induced CRC, and induces cytotoxic effect on CRC cells. DMW could be an important dietary supplement to support a healthy gut microbiota and reduce the prevalence of CRC in humans. Video Abstract.

Probiotics as an Alternative to Antibiotics: Genomic and Physiological Characterization of Aerobic Spore Formers from the Human Intestine.

A total of thirty-two aerobic spore former strains were isolated from intestinal samples of healthy children and analyzed for their hemolytic and antibiotic-resistant activities. Four strains selected as non-hemolytic and sensitive to all antibiotics recommended as relevant by regulatory agencies were short-listed and evaluated for their in silico and in vitro probiotic potentials. The four selected strains were assigned to the Bacillus velezensis (MV4 and MV11), B. subtilis (MV24), and Priestia megaterium (formerly Bacillus megaterium) (MV30) species. A genomic analysis indicated that MV4, MV11, and MV24 contained a homolog of the gene coding for the fibrinolytic enzyme nattokinase while only MV30 encoded a glutamic acid decarboxylase essential to synthesize the neurotransmitter GABA. All four strains contained gene clusters potentially coding for new antimicrobials, showed strong antioxidant activity, formed biofilm, and produced/secreted quorum-sensing peptides able to induce a cytoprotective stress response in a model of human intestinal (HT-29) cells. Altogether, genomic and physiological data indicate that the analyzed strains do not pose safety concerns and have in vitro probiotic potentials allowing us to propose their use as an alternative to antibiotics.

The Bacterial Spore as a Mucosal Vaccine Delivery System.

The development of efficient mucosal vaccines is strongly dependent on the use of appropriate vectors. Various biological systems or synthetic nanoparticles have been proposed to display and deliver antigens to mucosal surfaces. The Bacillus spore, a metabolically quiescent and extremely resistant cell, has also been proposed as a mucosal vaccine delivery system and shown able to conjugate the advantages of live and synthetic systems. Several antigens have been displayed on the spore by either recombinant or non-recombinant approaches, and antigen-specific immune responses have been observed in animals immunized by the oral or nasal route. Here we review the use of the bacterial spore as a mucosal vaccine vehicle focusing on the advantages and drawbacks of using the spore and of the recombinant vs. non-recombinant approach to display antigens on the spore surface. An overview of the immune responses induced by antigen-displaying spores so far tested in animals is presented and discussed.

Improvement of Bacillus subtilis Spore Enumeration and Label Analysis in Flow Cytometry.

The spores of Bacillus subtilis have already been proposed for different biotechnological and immunological applications; however, there is an increasing need for the development of methodologies that improve the detection of antigens immobilized on the surface of spores together with their quantification. Flow cytometry-based analyses have been previously proposed as fast, reliable, and specific approaches for detecting labeled cells of B. subtilis. Herein, we propose the use of flow cytometry to evaluate the display efficiency of a fluorescent antibody (FA) on the surface of the spore and quantify the number of spores using counting beads. For this, we used ethidium bromide as a DNA marker and an allophycocyanin (APC)-labeled antibody, which was coupled to the spores, as a surface marker. The quantification of spores was performed using counting beads since this technique demonstrates high accuracy in the detection of cells. The labeled spores were analyzed using a flow cytometer, which confirmed the coupling. As a result, it was demonstrated that DNA labeling improved the accuracy of quantification by flow cytometry, for the detection of germinated spores. It was observed that ethidium bromide was not able to label dormant spores; however, this technique provides a more precise determination of the number of spores with fluorescent protein coupled to their surface, thus helping in the development of studies that focus on the use of spores as a biotechnological platform in different applications.

Sporulation efficiency and spore quality in a human intestinal isolate of Bacillus cereus.

Bacteria classified as Bacillus cereus sensu stricto cause two different type of gastrointestinal diseases associated with food poisoning. Outbreaks of this opportunistic pathogen are generally due to the resistance of its spores to heat, pH and desiccation that makes hard their complete inactivation from food products. B. cereus is commonly isolated from a variety of environments, including intestinal samples of infected and healthy people. We report the genomic and physiological characterization of MV19, a human intestinal strain closely related (ANI value of 98.81%) to the reference strain B. cereus ATCC 14579. MV19 cells were able to grow in a range of temperatures between 20 and 44 °C. At the optimal temperature the sporulation process was rapidly induced and mature spores efficiently released, however these appeared structurally and morphologically defective. At the sub-optimal growth temperature of 25 °C sporulation was slow and less efficient but a high total number of fully functional spores was produced. These results indicate that the reduced rapidity and efficiency of sporulation at 25 °C are compensated by a high quality and quantity of released spores, suggesting the relevance of different performances at different growth conditions for the adaptation of this bacterium to diverse environmental niches.

Reprogramming of the gut microbiota following feralization in Sus scrofa.

BACKGROUND: Wild boar has experienced several evolutionary trajectories from which domestic (under artificial selection) and the feral pig (under natural selection) originated. Strong adaptation deeply affects feral population's morphology and physiology, including the microbiota community. The gut microbiota is generally recognized to play a crucial role in maintaining host health and metabolism. To date, it is unclear whether feral populations' phylogeny, development stages or lifestyle have the greatest impact in shaping the gut microbiota, as well as how this can confer adaptability to new environments. Here, in order to deepen this point, we characterized the gut microbiota of feral population discriminating between juvenile and adult samples, and we compared it to the microbiota structure of wild boar and domestic pig as the references. Gut microbiota composition was estimated through the sequencing of the partial 16S rRNA gene by DNA metabarcoding and High Throughput Sequencing on DNA extracted from fecal samples. RESULTS: The comparison of microbiota communities among the three forms showed significant differences. The feral form seems to carry some bacteria of both domestic pigs, derived from its ancestral condition, and wild boars, probably as a sign of a recent re-adaptation strategy to the natural environment. In addition, interestingly, feral pigs show some exclusive bacterial taxa, also suggesting an innovative nature of the evolutionary trajectories and an ecological segregation in feral populations, as already observed for other traits. CONCLUSIONS: The feral pig showed a significant change between juvenile and adult microbiota suggesting an influence of the wild environment in which these populations segregate. However, it is important to underline that we certainly cannot overlook that these variations in the structure of the microbiota also depended on the different development stages of the animal, which in fact influence the composition of the intestinal microbiota. Concluding, the feral pigs represent a new actor living in the same geographical space as the wild boars, in which its gut microbial structure suggests that it is mainly the result of environmental segregation, most different from its closest relative. This gives rise to interesting fields of exploration regarding the changed ecological complexity and the consequent evolutionary destiny of the animal communities involved in this phenomenon.

Use of halotolerant Bacillus amyloliquefaciens RHF6 as a bio-based strategy for alleviating salinity stress in Lotus japonicus cv Gifu.

Halotolerant (HT) bacteria are a group of microorganisms able to thrive in environments with relatively high salt concentrations. HT-microorganisms with plant growth-promoting (PGP) characteristics have been proposed to increase plant tolerance in salty soil. Here, we evaluated the PGP properties at increasing NaCl concentrations of HT-Bacillus strains, previously shown to have beneficial effects under physiological conditions. Most of the isolated showed indole acetic acid and ammonia production and were able to solubilize phosphate and suppress the proliferation of the phytopathogenic fungus Macrophomina phaseolina 2013-1 at high salt concentrations. One of the selected strains, Bacillus amyloliquefaciens RHF6, which retained its beneficial properties up to 400 mM NaCl in vitro, was tested on the legume model plant Lotus japonicus cv Gifu under salt stress. The inoculation with RHF6 significantly improved the survival of plants under high salinity conditions, as reflected in seedling root and shoot growth and total fresh weight (increased by 40%) when compared with non-inoculated plants. The ability of RHF6 to induce a plant antioxidant response, secrete the osmoprotectant proline and reduce ethylene level via the enzymatic ACC deaminase activity indicated this strain as a potentially helpful PGPB for the treatment of degraded soils.

Skeletal muscle insulin resistance and adipose tissue hypertrophy persist beyond the reshaping of gut microbiota in young rats fed a fructose-rich diet.

To investigate whether short term fructose-rich diet induces changes in the gut microbiota as well as in skeletal muscle and adipose tissue physiology and verify whether they persist even after fructose withdrawal, young rats of 30 d of age were fed for 3 weeks a fructose-rich or control diet. At the end of the 3-weeks period, half of the rats from each group were maintained for further 3 weeks on a control diet. Metagenomic analysis of gut microbiota and short chain fatty acids levels (faeces and plasma) were investigated. Insulin response was evaluated at the whole-body level and both in skeletal muscle and epididymal adipose tissue, together with skeletal muscle mitochondrial function, oxidative stress, and lipid composition. In parallel, morphology and physiological status of epididymal adipose tissue was also evaluated. Reshaping of gut microbiota and increased content of short chain fatty acids was elicited by the fructose diet and abolished by switching back to control diet. On the other hand, most metabolic changes elicited by fructose-rich diet in skeletal muscle and epididymal adipose tissue persisted after switching to control diet. Increased dietary fructose intake even on a short-time basis elicits persistent changes in the physiology of metabolically relevant tissues, such as adipose tissue and skeletal muscle, through mechanisms that go well beyond the reshaping of gut microbiota. This picture delineates a harmful situation, in particular for the young populations, posed at risk of metabolic modifications that may persist in their adulthood.

Comparative Genomics and Physiological Characterization of Two Aerobic Spore Formers Isolated from Human Ileal Samples.

Spore formers are ubiquitous microorganisms commonly isolated from most environments, including the gastro-intestinal tract (GIT) of insects and animals. Spores ingested as food and water contaminants safely transit the stomach and reach the intestine, where some of them germinate and temporarily colonize that niche. In the lower part of the GIT, they re-sporulate and leave the body as spores, therefore passing through their entire life cycle in the animal body. In the intestine, both un-germinated spores and germination-derived cells interact with intestinal and immune cells and have health-beneficial effects, which include the production of useful compounds, protection against pathogenic microorganisms, contribution to the development of an efficient immune system and modulation of the gut microbial composition. We report a genomic and physiological characterization of SF106 and SF174, two aerobic spore former strains previously isolated from ileal biopsies of healthy human volunteers. SF106 and SF174 belong respectively to the B. subtilis and Alkalihalobacillus clausii (formerly Bacillus clausii) species, are unable to produce toxins or other metabolites with cytotoxic activity against cultured human cells, efficiently bind mucin and human epithelial cells in vitro and produce molecules with antimicrobial and antibiofilm activities.

Modulation of intestinal epithelial cell proliferation and apoptosis by Lactobacillus gasseri SF1183.

The gut microbiota exerts a variety of positive effects on the intestinal homeostasis, including the production of beneficial molecules, control of the epithelial barrier integrity and the regulation of the balance between host's cell death and proliferation. The interactions between commensal bacteria and intestinal cells are still under-investigated and is then of paramount importance to address such interactions at the molecular and cellular levels. We report an in vitro analysis of the effects of molecules secreted by Lactobacillus gasseri SF1183 on HCT116 cells, selected as a model of intestinal epithelial cells. SF1183 is a L. gasseri strain isolated from an ileal biopsy of a human healthy volunteer, able to prevent colitis symptoms in vivo. Expanding previous findings, we show that bioactive molecules secreted by SF1183 reduce the proliferation of HCT116 cells in a reversible manner determining a variation in cell cycle markers (p21WAF, p53, cyclin D1) and resulting in the protection of HCT116 cells from TNF-alfa induced apoptosis, an effect potentially relevant for the protection of the epithelial barrier integrity and reconstitution of tissue homeostasis. Consistently, SF1183 secreted molecules increase the recruitment of occludin, a major component of TJ, at the cell-cell contacts, suggesting a reinforcement of the barrier function.

CotG Mediates Spore Surface Permeability in Bacillus subtilis.

Proteins and glycoproteins that form the surface layers of the Bacillus spore assemble into semipermeable arrays that surround and protect the spore cytoplasm. Such layers, acting like molecular sieves, exclude large molecules but allow small nutrients (germinants) to penetrate. We report that CotG, a modular and abundant component of the Bacillus subtilis spore coat, controls spore permeability through its central region, formed by positively charged tandem repeats. These repeats act as spacers between the N and C termini of the protein, which are responsible for the interaction of CotG with at least one other coat protein. The deletion but not the replacement of the central repeats with differently charged repeats affects the spore resistance to lysozyme and the efficiency of germination-probably by reducing the coat permeability to external molecules. The presence of central repeats is a common feature of the CotG-like proteins present in most Bacillus species, and such a wide distribution of this protein family is suggestive of a relevant role for the structure and function of the Bacillus spore. IMPORTANCE Bacterial spores are quiescent cells extremely resistant to a variety of unphysiological conditions, including the presence of lytic enzymes. Such resistance is also due to the limited permeability of the spore surface, which does not allow lytic enzymes to reach the spore interior. This article proposes that the spore permeability in B. subtilis is mediated by CotG, a modular protein formed by a central region of repeats of positively charged amino acid acting as a "spacer" between the N and C termini. These, in turn, interact with other coat proteins, generating a protein layer whose permeability to external molecules is controlled by the distance between the N and C termini of CotG. This working model is most likely expandable to most sporeformers of the Bacillus genus, since they all have CotG-like proteins, not homologous to CotG of B. subtilis but similarly characterized by central repeats.

Gut microbiota plasticity in insular lizards under reversed island syndrome.

Animals living on small islands are more drastically exposed to environmental changes, such as food or water starvation, and rapid temperature shifts. Facing such conditions, and probably thank to adaptive plasticity mechanisms, some animals display a Reversed Island Syndrome (RIS), a suite of traits, including skin pigmentation, voracity, sexual dimorphism, showed differently from mainland relatives. Here, we analyse a so far poorly explored aspect of RIS: the effect of this on the microbiota composition of host Italian wall lizard (Podarcis siculus), strongly influenced by the animal's lifestyle, and conditioning the same. We compare mainland and island populations, assessing the difference between their microbial communities and their response under unexpected food, experimentally provided. Our observations showed a significant difference in microbiota communities between island and mainland groups, depended mainly from changes in relative abundance of the shared genera (difference due to decrease/increase). Exposure to experimental diet regimes resulted into significative reshaping of bacterial composition of microbiota and a greater variation in body mass only in the island population. Our results could be an evidence that gut microbial community contributes to adaptive plasticity mechanisms of island lizards under RIS to efficiently respond to unexpected changes.

CotG controls spore surface formation in response to the temperature of growth in Bacillus subtilis.

Bacterial spores of the Bacillus genus are ubiquitous in nature and are commonly isolated from a variety of diverse environments. Such wide distribution mainly reflects the spore resistance properties but some Bacillus species can grow/sporulate in at least some of the environments where they have been originally isolated. Growing and sporulating at different conditions is known to affect the structure and the resistance properties of the produced spore. In B. subtilis the temperature of growth and sporulation has been shown to influence the structure of the spore surface throughout the action of a sporulation-specific and heat-labile kinase CotH. Here we report that CotG, an abundant component of the B. subtilis spore surface and a substrate of the CotH kinase, assembles around the forming spore but also accumulates in the mother cell cytoplasm where it forms aggregates with at least two other coat components. Our data suggest that the thermo-regulator CotH contributes to the switch between the coat of 25°C and that of 42°C spores by controlling the phosphorylation levels of CotG that, in turn, regulates the assembly of at least two other coat components.

Bacillus subtilis spores as delivery system for nasal Plasmodium falciparum circumsporozoite surface protein immunization in a murine model.

Malaria remains a widespread public health problem in tropical and subtropical regions around the world, and there is still no vaccine available for full protection. In recent years, it has been observed that spores of Bacillus subtillis can act as a vaccine carrier and adjuvant, promoting an elevated humoral response after co-administration with antigens either coupled or integrated to their surface. In our study, B. subtillis spores from the KO7 strain were used to couple the recombinant CSP protein of P. falciparum (rPfCSP), and the nasal humoral-induced immune response in Balb/C mice was evaluated. Our results demonstrate that the spores coupled to rPfCSP increase the immunogenicity of the antigen, which induces high levels of serum IgG, and with balanced Th1/Th2 immune response, being detected antibodies in serum samples for 250 days. Therefore, the use of B. subtilis spores appears to be promising for use as an adjuvant in a vaccine formulation.

An antimicrobial peptide specifically active against Listeria monocytogenes is secreted by Bacillus pumilus SF214.

BACKGROUND: Members of the Bacillus genus produce a large variety of antimicrobial peptides including linear or cyclic lipopeptides and thiopeptides, that often have a broad spectrum of action against Gram-positive and Gram-negative bacteria. We have recently reported that SF214, a marine isolated strain of Bacillus pumilus, produces two different antimicrobials specifically active against either Staphylococcus aureus or Listeria monocytogenes. The anti-Staphylococcus molecule has been previously characterized as a pumilacidin, a nonribosomally synthesized lipopetide composed of a mixture of cyclic heptapeptides linked to fatty acids of variable length. RESULTS: Our analysis on the anti-Listeria molecule of B. pumilus SF214 indicated that it is a peptide slightly smaller than 10 kDa, produced during the exponential phase of growth, stable at a wide range of pH conditions and resistant to various chemical treatments. The peptide showed a lytic activity against growing but not resting cells of Listeria monocytogenes and appeared extremely specific being inactive also against L. innocua, a close relative of L. monocytogenes. CONCLUSIONS: These findings indicate that the B. pumilus peptide is unusual with respect to other antimicrobials both for its time of synthesis and secretion and for its strict specificity against L. monocytogenes. Such specificity, together with its stability, propose this new antimicrobial as a tool for potential biotechnological applications in the fight against the dangerous food-borne pathogen L. monocytogenes.

Genomic study and lipidomic bioassay of Leeuwenhoekiella parthenopeia: A novel rare biosphere marine bacterium that inhibits tumor cell viability.

The fraction of low-abundance microbiota in the marine environment is a promising target for discovering new bioactive molecules with pharmaceutical applications. Phenomena in the ocean such as diel vertical migration (DVM) and seasonal dynamic events influence the pattern of diversity of marine bacteria, conditioning the probability of isolation of uncultured bacteria. In this study, we report a new marine bacterium belonging to the rare biosphere, Leeuwenhoekiella parthenopeia sp. nov. Mr9T, which was isolated employing seasonal and diel sampling approaches. Its complete characterization, ecology, biosynthetic gene profiling of the whole genus Leeuwenhoekiella, and bioactivity of its extract on human cells are reported. The phylogenomic and microbial diversity studies demonstrated that this bacterium is a new and rare species, barely representing 0.0029% of the bacterial community in Mediterranean Sea metagenomes. The biosynthetic profiling of species of the genus Leeuwenhoekiella showed nine functionally related gene cluster families (GCF), none were associated with pathways responsible to produce known compounds or registered patents, therefore revealing its potential to synthesize novel bioactive compounds. In vitro screenings of L. parthenopeia Mr9T showed that the total lipid content (lipidome) of the cell membrane reduces the prostatic and brain tumor cell viability with a lower effect on normal cells. The lipidome consisted of sulfobacin A, WB 3559A, WB 3559B, docosenamide, topostin B-567, and unknown compounds. Therefore, the bioactivity could be attributed to any of these individual compounds or due to their synergistic effect. Beyond the rarity and biosynthetic potential of this bacterium, the importance and novelty of this study is the employment of sampling strategies based on ecological factors to reach the hidden microbiota, as well as the use of bacterial membrane constituents as potential novel therapeutics. Our findings open new perspectives on cultivation and the relationship between bacterial biological membrane components and their bioactivity in eukaryotic cells, encouraging similar studies in other members of the rare biosphere.

Population genomic, olfactory, dietary, and gut microbiota analyses demonstrate the unique evolutionary trajectory of feral pigs.

Domestication is an intriguing evolutionary process. Many domestic populations are subjected to strong human-mediated selection, and when some individuals return to the wild, they are again subjected to selective forces associated with new environments. Generally, these feral populations evolve into something different from their wild predecessors and their members typically possess a combination of both wild and human selected traits. Feralisation can manifest in different forms on a spectrum from a wild to a domestic phenotype. This depends on how the rewilded domesticated populations can readapt to natural environments based on how much potential and flexibility the ancestral genome retains after its domestication signature. Whether feralisation leads to the evolution of new traits that do not exist in the wild or to convergence with wild forms, however, remains unclear. To address this question, we performed population genomic, olfactory, dietary, and gut microbiota analyses on different populations of Sus scrofa (wild boar, hybrid, feral and several domestic pig breeds). Porcine single nucleotide polymorphisms (SNPs) analysis shows that the feral population represents a cluster distinctly separate from all others. Its members display signatures of past artificial selection, as demonstrated by values of FST in specific regions of the genome and bottleneck signature, such as the number and length of runs of homozygosity. Generalised FST values, reacquired olfactory abilities, diet, and gut microbiota variation show current responses to natural selection. Our results suggest that feral pigs are an independent evolutionary unit which can persist so long as levels of human intervention remain unchanged.

Micellar Antibiotics of Bacillus.

Members of the Bacillus genus, particularly the "Bacillus subtilis group", are known to produce amphipathic lipopeptides with biosurfactant activity. This includes the surfactins, fengycins and iturins that have been associated with antibacterial, antifungal, and anti-viral properties. We have screened a large collection of Bacillus, isolated from human, animal, estuarine water and soil samples and found that the most potent lipopeptide producers are members of the species Bacillus velezensis. B. velezensis lipopeptides exhibited anti-bacterial activity which was localised on the surface of both vegetative cells and spores. Interestingly, lipopeptide micelles (6-10 nm diameter) were detectable in strains exhibiting the highest levels of activity. Micelles were stable (heat and gastric stable) and shown to entrap other antimicrobials produced by the host bacterium (exampled here was the dipeptide antibiotic chlorotetaine). Commercially acquired lipopeptides did not exhibit similar levels of inhibitory activity and we suspect that micelle formation may relate to the particular isomeric forms produced by individual bacteria. Using naturally produced micelle formulations we demonstrated that they could entrap antimicrobial compounds (e.g., clindamycin, vancomycin and resveratrol). Micellar incorporation of antibiotics increased activity. Bacillus is a prolific producer of antimicrobials, and this phenomenon could be exploited naturally to augment antimicrobial activity. From an applied perspective, the ability to readily produce Bacillus micelles and formulate with drugs enables a possible strategy for enhanced drug delivery.

Spore-adsorption: Mechanism and applications of a non-recombinant display system.

Surface display systems have been developed to express target molecules on almost all types of biological entities from viruses to mammalian cells and on a variety of synthetic particles. Various approaches have been developed to achieve the display of many different target molecules, aiming at several technological and biomedical applications. Screening of libraries, delivery of drugs or antigens, bio-catalysis, sensing of pollutants and bioremediation are commonly considered as fields of potential application for surface display systems. In this review, the non-recombinant approach to display antigens and enzymes on the surface of bacterial spores is discussed. Examples of molecules displayed on the spore surface and their potential applications are summarized and a mechanism of display is proposed.