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Biotic interactions through diffusible and volatile organic compounds (VOCs) are frequent in nature. Soil bacteria are well-known producers of a wide range of volatile compounds (both organic and inorganic) with various biologically relevant activities. Since the last decade, they have been identified as natural biocontrol agents. Volatiles are airborne chemicals, which when released by bacteria, can trigger plant responses such as defence and growth promotion. In this study, we tested whether diffusible and volatile organic compounds (VOCs) produced by soil bacterial isolates exert anti-oomycete and plant growth-promoting effects. We also investigated the effects of inoculation with VOC-producing bacteria on the growth and development of Capsicum annuum and Arabidopsis thaliana seedlings. Our results demonstrate that organic VOCs emitted by bacterial antagonists negatively influence mycelial growth of the soil-borne phytopathogenic oomycete Phytophthora capsici by 35% in vitro. The bacteria showed plant growth promoting effects by stimulating biomass production, primary root growth and root hair development. Additionally, we provide evidence to suggest that these activities were deployed by the emission of either diffusible organic compounds or VOCs. Bacterial VOC profiles were obtained through solid phase microextraction (SPME) and analysis by gas chromatography coupled with mass spectrometry (GC-MS). This elucidated the main volatiles emitted by the isolates, which covered a wide range of aldehydes, alcohols, esters, carboxylic acids, and ketones. Collectively, twenty-five VOCs were identified to be produced by three bacteria; some being species-specific. Our data show that bacterial volatiles inhibits P. capsici in vitro and modulate both plant growth promotion and root system development. These results confirm the significance of soil bacteria and highlights that ways of harnessing them to improve plant growth, and as a biocontrol agent for soil-borne oomycetes through their volatile emissions deserve further investigation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The development of carriers for the delivery of oligonucleotide therapeutics is essential for the successful translation of gene therapies to the clinic. In the present study, a delivery system, which combines the fusogenic lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) with a well-defined synthetic multifunctional peptide, was produced and optimized for gene delivery, with the aim to develop an efficient gene delivery platform for breast cancer cells. For this purpose, a breast cancer-specific cell targeting peptide (CTP) was incorporated into our leading peptide-based gene delivery system (to generate DEN-K(GALA)-TAT-K(STR)-CTP) to improve its cell-specific internalization, and investigated in combination with a formulation approach (DOPE/1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)). DEN-K(GALA)-TAT-K(STR)-CTP alone efficiently complexed with DNA or siRNA, and promoted efficient cellular uptake, but low levels of gene expression. By adding the formulation approach, synergistic improvements in gene expression and silencing were observed compared to the peptide or formulation approaches alone. Of significance, this current system demonstrated more efficient gene knockdown when compared to the leading commercial siRNA delivery agent Lipofectamine® RNAiMAX. The utility of this system was demonstrated through the delivery of BCL2 (B-cell lymphoma 2) siRNA to MCF-7 cells, which led to near complete knockdown of the Bcl-2 protein, and inhibition of MCF-7 cell migration in a wound healing assay. The present peptide/lipid hybrid system is an excellent candidate for the delivery of DNA or siRNA into breast cancer cells., Statement of Significance: The identification of safe and effective delivery systems for DNA and siRNA is of great importance. Herein, we developed a well-defined, multifunctional and cell-specific lipidic peptide DEN-K(GALA)-TAT-K(STR)-CTP as a breast cancer cell targeted gene delivery vector. When combined with a lipid component (DOTAP/DOPE), the peptide/lipid hybrid system demonstrated higher gene expression or knockdown levels compared to the peptide or lipid approach alone when used to deliver pDNA or siRNA respectively, indicating synergistic enhancement of gene delivery efficiency. Importantly, this delivery strategy achieved greater knockdown of the Bcl-2 protein when compared to the leading commercial siRNA delivery system Lipofectamine® RNAiMAX, suggesting its potential utility for the targeted treatment of Bcl-2 overexpressing breast cancers., (Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

A novel vaccine development platform that enables the site-specific conjugation of synthetic lipid adjuvants to recombinant proteins was produced. This technology facilitates the simple and efficient production of homogeneous, chemically-defined, semisynthetic lipoprotein vaccines. Using a polytope 'string-of-beads' approach, a synthetic gene incorporating seven Streptococcus pyogenes M protein strain-specific antigens, and a conserved M protein antigen (J14) was produced, expressed, and attached to a lipoamino acid based adjuvant (lipid core peptide; LCP). Nanoparticles (40 nm diameter) of an optimal size for stimulating antibody-mediated immunity were formed upon the addition of these lipoproteins to aqueous buffer (PBS). Systemic antigen-specific IgG antibodies were raised against all eight antigens in C57BL/6J mice, without the need to formulate with additional adjuvant. These antibodies bound cell surface M proteins of S. pyogenes strains represented within the polytope sequence, with higher antibody levels observed where a dendritic cell targeting peptide (DCpep) was incorporated within the LCP adjuvant., From the Clinical Editor: In this study, a novel vaccine development system is presented, combining adjuvants with recombinant protein antigens, and presenting the antigen in a nanoparticle system optimized for antibody production. They demonstrate efficient vaccination in a murine model system without the need for additional adjuvants., (Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.)