1,720,991 research outputs found
Spore Adsorption as a Nonrecombinant Display System for Enzymes and Antigens
Full text linkThe bacterial spore is a metabolically quiescent cell, formed by a series of protective layers surrounding a dehydrated cytoplasm. This peculiar structure makes the spore extremely stable and resistant and has suggested the use of the spore as a platform to display heterologous molecules. So far, a variety of antigens and enzymes have been displayed on spores of Bacillus subtilis and of a few other species, initially by a recombinant approach and, then, by a simple and efficient nonrecombinant method. The nonrecombinant display system is based on the direct adsorption of heterologous molecules on the spore surface, avoiding the construction of recombinant strains and the release of genetically modified bacteria in the environment. Adsorbed molecules are stabilized and protected by the interaction with spores, which limits the rapid degradation of antigens and the loss of enzyme activity at unfavorable conditions. Once utilized, spore-adsorbed enzymes can be collected easily with a minimal reduction of activity and reused for additional reaction rounds. In this paper is shown how to adsorb model molecules to purified spores of B. subtilis, how to evaluate the efficiency of adsorption, and how to collect used spores to recycle them for new reactions
Spore-adsorption: Mechanism and applications of a non-recombinant display system
No full textSurface 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
Oral priming of mice by recombinant spores of Bacillus subtilis
No full textRecombinant Bacillus subtilis spores were employed as a vaccine delivery system in a heterologous mucosal priming-parenteral boosting vaccination strategy in the mouse model. BALB/c and C57BL/6 mice were orally immunised with recombinant spores expressing tetanus toxin fragment C (TTFC) fused to the spore outer coat protein CotB, and then subcutaneously boosted with soluble TTFC (without adjuvant). Two weeks after boosting, a significantly higher serum TTFC-specific IgG response was stimulated in mice primed with recombinant spores (antibody concentration of 2600 +/- 915 in C57BL/6 and 1200 +/- 370 ng/ml in BALB/c) compared to mice inoculated with wild type spores (650 +/- 250 and 250 +/- 130 ng/ml, respectively). IgG subclass analysis showed a prevalence of IgG1 and IgG2b, indicative of a Th2 type of immune response. Oral administration of recombinant spores stimulated also a significant local TTFC-specific IgA response. These data show that recombinant spores of B. subtilis are able to prime the immune system by the oral route, and that a combined mucosal/parenteral strategy can stimulate both local and systemic antigen-specific immune responses
Characterization of surface properties of bacterial spores using optical tweezers
No full textThe electric charge and the hydrodynamic coefficient and of bacterial spores are key parameters in protein binding to spores and in the adhesion of spores onto surfaces. Using Optical Tweezers, it is possible to simultaneously measure the charge and the hydrodynamic coefficient of a trapped object. From an accurate analysis of the motion of a single spore confined by an optical trap when external electric or drag forces are applied, we measured the charge of Bacillus subtilis spores. These were purified from a wild type strain and from two isogenic mutants characterized by an altered spore surface. Our technique is able to discriminate the three spore types used and to give important information on the hydrophobic properties of their surface
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The temperature of growth and sporulation modulates the efficiency of spore-display in Bacillus subtilis
No full textBackground: Bacterial spores displaying heterologous antigens or enzymes have long been proposed as mucosal vaccines, functionalized probiotics or biocatalysts. Two main strategies have been developed to display heterologous molecules on the surface of Bacillus subtilis spores: (i) a recombinant approach, based on the construction of a gene fusion between a gene coding for a coat protein (carrier) and DNA coding for the protein to be displayed, and (ii) a non-recombinant approach, based on the spontaneous and stable adsorption of heterologous molecules on the spore surface. Both systems have advantages and drawbacks and the selection of one or the other depends on the protein to be displayed and on the final use of the activated spore. It has been recently shown that B. subtilis builds structurally and functionally different spores when grown at different temperatures; based on this finding B. subtilis spores prepared at 25, 37 or 42 °C were compared for their efficiency in displaying various model proteins by either the recombinant or the non-recombinant approach. Results: Immune- and fluorescence-based assays were used to analyze the display of several model proteins on spores prepared at 25, 37 or 42 °C. Recombinant spores displayed different amounts of the same fusion protein in response to the temperature of spore production. In spores simultaneously displaying two fusion proteins, each of them was differentially displayed at the various temperatures. The display by the non-recombinant approach was only modestly affected by the temperature of spore production, with spores prepared at 37 or 42 °C slightly more efficient than 25 °C spores in adsorbing at least some of the model proteins tested. Conclusion: Our results indicate that the temperature of spore production allows control of the display of heterologous proteins on spores and, therefore, that the spore-display strategy can be optimized for the specific final use of the activated spores by selecting the display approach, the carrier protein and the temperature of spore production
Genomic and Physiological Characterization of Bacilli Isolated From Salt-Pans With Plant Growth Promoting Features
No full textMassive application of chemical fertilizers and pesticides has been the main strategy used to cope with the rising crop demands in the last decades. The indiscriminate use of chemicals while providing a temporary solution to food demand has led to a decrease in crop productivity and an increase in the environmental impact of modern agriculture. A sustainable alternative to the use of agrochemicals is the use of microorganisms naturally capable of enhancing plant growth and protecting crops from pests known as Plant-Growth-Promoting Bacteria (PGPB). Aim of the present study was to isolate and characterize PGPB from salt-pans sand samples with activities associated to plant fitness increase. To survive high salinity, salt-tolerant microbes produce a broad range of compounds with heterogeneous biological activities that are potentially beneficial for plant growth. A total of 20 halophilic spore-forming bacteria have been screened in vitro for phyto-beneficial traits and compared with other two members of Bacillus genus recently isolated from the rhizosphere of the same collection site and characterized as potential biocontrol agents. Whole-genome analysis on seven selected strains confirmed the presence of numerous gene clusters with PGP and biocontrol functions and of novel secondary-metabolite biosynthetic genes, which could exert beneficial impacts on plant growth and protection. The predicted biocontrol potential was confirmed in dual culture assays against several phytopathogenic fungi and bacteria. Interestingly, the presence of predicted gene clusters with known biocontrol functions in some of the isolates was not predictive of the in vitro results, supporting the need of combining laboratory assays and genome mining in PGPB identification for future applications
Potentialities of Technosol-isolated PGPB consortium in promoting plant growth in lettuce seedlings
No full textBackground and aims: Reducing land degradation and safeguarding agricultural productions ensures the provision of ecosystem services and economic welfare, as highlighted by the 2030 Sustainable Development Goals. Among the promising solutions to tackle these issues, the study investigates the use of Technosol-isolated PGPB, as a novel approach for enhancing plant growth and the capability to cope with soil salinization. Methods: Several bacteria have been isolated from a Technosol in Naples (Italy), selected to produce a consortium, based on their PGP features and tested on lettuce. The promotion of lettuce growth was evaluated both in soil (sterilized and not-sterilized Technosols) and in water agar media differing in NaCl concentrations, focusing on total polyphenols, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, soluble proteins, and sugars, which were evaluated on seedlings. Results: Germination kinetics differed among treatments in both soil and artificial media setups. In the Technosol trial, the PGPB treated seeds were the quickest to emerge, showing a higher radical scavenging activity and lower soluble carbohydrate content. In the salinity trial, total soluble proteins were significantly higher in primed seeds at null saline cocentration. Conclusion: Our results indicate that the PGPB application has a beneficial outcome on the Technosol but under saline stress produces an inhibitory or a costly effect on the biochemistry and germination kinetics. However, Technosol PGPBs employement may open new research scenarios on their potential application considering Nature-Based Solutions and/or plant growth in degraded environments
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