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MAIN CONCLUSION: Advances in nanotechnology make it an important tool for improving agricultural production. Strong evidence supports the role of nanomaterials as nutrients or nanocarriers for the controlled release of fertilizers to improve plant growth. Scientific research shows that nanotechnology applied in plant sciences is smart technology. Excessive application of mineral fertilizers has produced a harmful impact on the ecosystem. Furthermore, the projected increase in the human population by 2050 has led to the search for alternatives to ensure food security. Nanotechnology is a promising strategy to enhance crop productivity while minimizing fertilizer inputs. Nanofertilizers can contribute to the slow and sustainable release of nutrients to improve the efficiency of nutrient use in plants. Nanomaterial properties (i.e., size, morphology and charge) and plant physiology are crucial factors that influence the impact on plant growth. An important body of scientific research highlights the role of carbon nanomaterials, metal nanoparticles and metal oxide nanoparticles to improve plant development through the modulation of physiological and metabolic processes. Modulating nutrient concentrations, photosynthesis processes and antioxidant enzyme activities have led to increases in shoot length, root development, photosynthetic pigments and fruit yield. In parallel, nanocarriers (nanoclays, nanoparticles of hydroxyapatite, mesoporous silica and chitosan) have been shown to be an important tool for the controlled and sustainable release of conventional fertilizers to improve plant nutrition; however, the technical advances in nanofertilizers need to be accompanied by modernization of the regulations and legal frameworks to allow wider commercialization of these elements. Nanofertilizers are a promising strategy to improve plant development and nutrition, but their application in sustainable agriculture remains a great challenge. The present review summarizes the current advance of research into nanofertilizers, and their future prospects.
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Ecossistema , Desenvolvimento Vegetal , Agricultura , Fertilizantes/análise , NanotecnologiaRESUMO
Nanotechnology has been proposed as an important tool and strategy for applying new products in agriculture at the nanometer scale in order to improve the food crop at sustainability and productivity levels for contributing with the agriculture security. Nanoparticles (NPs) have been planted as an intelligent material with a large contact surface per unit mass respect to bulk-products, allowing its effect to be exerted with greater efficiency in a specific point on a plant target. Currently, NPs have been studied to be applied to various species of monocotyledonous and dicotyledonous plants. Some NPs properties such as concentration, shape, size, composition and surface functionality have the ability to regulate the NPs growth effects on the plant during germination and seedling stages under controlled and field conditions. Furthermore, several studies have tried to explain the mechanism of uptake, translocation and accumulation of NPs inside the plant at the organ and cell level, but further studies are needed to determine specific mechanisms and exact action. Nevertheless, evaluation of the toxicity effects of NPs on physiological indexes of the plant is needed to determine the effective dose without producing adverse effects on the plant and food chain. It is noteworthy that studies have indicated that nanoparticles, regardless of their nature, can be efficient inducers of plant growth. However, a series of laboratory tests are required to optimize their application conditions and their specific physiological impact on plants. In this review, we summarize the knowledge about NPs application to induce plant growth to direct future studies in order to propose NPs for technological innovation.
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Nanopartículas/administração & dosagem , Desenvolvimento Vegetal/efeitos dos fármacos , Nanopartículas/toxicidade , Nanotecnologia , Plantas/efeitos dos fármacos , Plantas/metabolismoRESUMO
In a scenario of accelerated global climate change, the continuous growth of the world population, and the excessive use of chemical fertiliser, the search for sustainable alternatives for agricultural production is crucial. The present study was conducted to evaluate the plant growth-promoting (PGP) characteristics of two yeast strains, Candida guilliermondii and Rhodotorula mucilaginosa, and the physicochemical characteristics of nanometric capsules and iron oxide nanoparticles (Fe2O3-NPs) for the formulation of nanobiofertilisers. The physiological and productive effects were evaluated in a greenhouse assay using lettuce plants. The results showed that C. guilliermondii exhibited higher tricalcium phosphate solubilisation capacity, and R. mucilaginosa had a greater indole-3-acetic acid (IAA) content. The encapsulation of C. guilliermondii in sodium alginate capsules significantly improved the growth, stomatal conductance, and photosynthetic rate of the lettuce plants. Physicochemical characterisation of the Fe2O3-NPs revealed a particle size of 304.1 nm and a negative Z-potential, which indicated their stability and suitability for agricultural applications. The incorporation of Fe2O3-NPs into the capsules was confirmed by SEM-EDX analysis, which showed the presence of Fe as the main element. In summary, this study highlights the potential of nanobiofertilisers containing yeast strains encapsulated in sodium alginate with Fe2O3-NPs to improve plant growth and photosynthetic efficiency as a path toward more sustainable agriculture.
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Copper oxide nanoparticles (NCuO) have emerged as an alternative to pesticides due to their antifungal effect against various phytopathogens. Combining them with fungicides represents an advantageous strategy for reducing the necessary amount of both agents to inhibit fungal growth, simultaneously reducing their environmental release. This study aimed to evaluate the antifungal activity of NCuO combined with three fungicide models separately: Iprodione (IPR), Tebuconazole (TEB), and Pyrimethanil (PYR) against two phytopathogenic fungi: Botrytis cinerea and Fusarium oxysporum. The fractional inhibitory concentration (FIC) was calculated as a synergism indicator (FIC ≤ 0.5). The NCuO interacted synergistically with TEB against both fungi and with IPR only against B. cinerea. The interaction with PYR was additive against both fungi (FIC > 0.5). The B. cinerea biomass was inhibited by 80.9% and 93% using 20 mg L-1 NCuO + 1.56 mg L-1 TEB, and 40 mg L-1 NCuO + 12 µg L-1 IPR, respectively, without significant differences compared to the inhibition provoked by 160 mg L-1 NCuO. Additionally, the protein leakage and nucleic acid release were also evaluated as mechanisms associated with the synergistic effect. The results obtained in this study revealed that combining nanoparticles with fungicides can be an adequate strategy to significantly reduce the release of metals and agrochemicals into the environment after being used as antifungals.
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Botrytis cinerea is the phytopathogenic fungus responsible for the gray mold disease that affects crops worldwide. Essential oils (EOs) have emerged as a sustainable tool to reduce the adverse impact of synthetic fungicides. Nevertheless, the scarce information about the physiological mechanism action and the limitations to applying EOs has restricted its use. This study focused on elucidating the physiological action mechanisms and prospection of lipid nanoparticles to apply EO of Mentha piperita. The results showed that the EO of M. piperita at 500, 700, and 900⯵Lâ¯L-1 inhibited the mycelial growth at 100â¯%. The inhibition of spore germination of B. cinerea reached 31.43â¯% at 900⯵Lâ¯L-1. The EO of M. piperita decreased the dry weight and increased pH, electrical conductivity, and cellular material absorbing OD260â¯nm of cultures of B. cinerea. The fluorescence technique revealed that EO reduced hyphae width, mitochondrial activity, and viability, and increased ROS production. The formulation of EO of M. piperita loaded- solid lipid nanoparticles (SLN) at 500, 700, and 900⯵Lâ¯L-1 had particle size â¼ 200â¯nm, polydispersity index < 0.2, and stability. Also, the thermogravimetric analysis indicated that the EO of M. piperita-loaded SLN has great thermal stability at 50 °C. EO of M. piperita-loaded SLN reduced the mycelial growth of B. cinerea by 70â¯%, while SLN formulation (without EO) reached 42â¯% inhibition. These results supported that EO of M. piperita-loaded SLN is a sustainable tool for reducing the disease produced by B. cinerea.
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Botrytis , Mentha piperita , Nanopartículas , Óleos Voláteis , Esporos Fúngicos , Botrytis/efeitos dos fármacos , Botrytis/crescimento & desenvolvimento , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Nanopartículas/química , Mentha piperita/química , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento , Fungicidas Industriais/farmacologia , Fungicidas Industriais/química , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Doenças das Plantas/prevenção & controle , Doenças das Plantas/microbiologia , Lipídeos/química , Lipídeos/farmacologia , Tamanho da Partícula , Espécies Reativas de Oxigênio/metabolismo , Óleos de Plantas/farmacologia , Hifas/efeitos dos fármacos , Hifas/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Antifúngicos/farmacologia , LipossomosRESUMO
Botrytis cinerea and Penicillium expansum are phytopathogenic fungi that produce the deterioration of fruits. Thus, essential oil (EO) has emerged as a sustainable strategy to minimize the use of synthetic fungicides, but their volatility and scarce solubility restrict their application. This study proposes the EO of Oreganum vulgare and Thymus vulgaris-loaded solid lipid nanoparticles (SLN) based chitosan/PVA hydrogels to reduce the infestation of fungi phytopathogen. EO of O. vulgare and T. vulgaris-loaded SLN had a good homogeneity (0.21-0.35) and stability (-28.8 to -33.0 mV) with a mean size of 180.4-188.4 nm. The optimization of EO-loaded SLN showed that the encapsulation of 800 and 1200 µL L-1 of EO of O vulgare and T. vulgaris had the best particle size. EO-loaded SLN significantly reduced the mycelial growth and spore germination of both fungi pathogen. EO-loaded SLN into hydrogels showed appropriate physicochemical characteristics to apply under environmental conditions. Furthermore, rheological analyses evidenced that hydrogels had solid-like characteristics and elastic behavior. EO-loaded SLN-based hydrogels inhibited the spore germination in B. cinerea (80.9 %) and P. expansum (55.7 %). These results show that SLN and hydrogels are eco-friendly strategies for applying EO with antifungal activity.
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Botrytis , Quitosana , Hidrogéis , Nanopartículas , Óleos Voláteis , Penicillium , Quitosana/química , Botrytis/efeitos dos fármacos , Botrytis/crescimento & desenvolvimento , Penicillium/efeitos dos fármacos , Penicillium/crescimento & desenvolvimento , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Hidrogéis/química , Nanopartículas/química , Lipídeos/química , Antifúngicos/farmacologia , Antifúngicos/química , Reologia , Tamanho da Partícula , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento , LipossomosRESUMO
Botrytis cinerea and Penicillium expansum produce deterioration in fruit quality, causing losses to the food industry. Thus, plant essential oils (EOs) have been proposed as a sustainable alternative for minimizing the application of synthetic fungicides due to their broad-spectrum antifungal properties. This study investigated the efficacy of five EOs in suppressing the growth of B. cinerea and P. expansum and their potential antifungal mechanisms. EOs of Mentha × piperita L., Origanum vulgare L., Thymus vulgaris L., Eucalyptus globules Labill., and Lavandula angustifolia Mill., were screened for both fungi. The results showed that the EO of T. vulgaris and O. vulgare were the most efficient in inhibiting the growth of B. cinerea and P. expansum. The concentration increase of all EO tested increased fungi growth inhibition. Exposure of fungi to EOs of T. vulgaris and O. vulgare increased the pH and the release of constituents absorbing 260 nm and soluble proteins, reflecting membrane permeability alterations. Fluorescence microscopic examination revealed that tested EOs produce structural alteration in cell wall component deposition, decreasing the hypha width. Moreover, propidium iodide and Calcein-AM stains evidenced the loss of membrane integrity and reduced cell viability of fungi treated with EOs. Fungi treated with EOs decreased the mitochondria activity and the respiratory process. Therefore, these EOs are effective antifungal agents against B. cinerea and P. expansum, which is attributed to changes in the cell wall structure, the breakdown of the cell membrane, and the alteration of the mitochondrial activity.
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Óleos Voláteis , Penicillium , Antifúngicos/farmacologia , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Óleos de Plantas/farmacologia , BotrytisRESUMO
Nanoparticles are recognized due to their particular physical and chemical properties, which are conferred due to their size, in the range of nanometers. Nanoparticles are recognized for their application in medicine, electronics, and the textile industry, among others, but also in agriculture. The application of nanoparticles as nanofertilizers and biostimulants can help improve growth and crop productivity, and it has therefore been mentioned as an essential tool to control the adverse effects of abiotic stress. However, nanoparticles have also been noted for their exceptional antimicrobial properties. Therefore, this work reviews the state of the art of different nanoparticles that have shown the capacity to control biotic stress in plants. In this regard, metal and metal oxide nanoparticles, polymeric nanoparticles, and others, such as silica nanoparticles, have been described. Moreover, uptake and translocation are covered. Finally, future remarks about the studies on nanoparticles and their beneficial role in biotic stress management are made.
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The rise in the global population demands an increasing food supply and methods to boost agricultural production. Pesticides are necessary for agricultural production models, avoiding losses of close to 40%. Nevertheless, the extensive use of pesticides can cause their accumulation in the environment, causing problems for human health, biota, and ecosystems. Thus, new technologies have emerged to remove these wastes efficiently. In recent years, metal and metal oxide nanoparticles (MNPs) have been reported as promising catalysts to degrade pesticides; however, a systematic understanding of their effect on pesticide degradation is still required. Therefore, this study focused on a meta-analysis of articles available in Elsevier's Scopus and Thomas Reuters Web of Science, found by searching for "nanoparticle pesticide" and "pesticide contamination." After passing different filters, the meta-analysis was performed with 408 observations from 94 reviews, which comprise insecticides, herbicides, and fungicides, including organophosphates, organochlorines, carbamates, triazines, and neonicotinoids. Herein, 14 different MNPs (Ag, Ni, Pd, Co3O4, BiOBr, Au, ZnO, Fe, TiO2, Cu, WO3, ZnS, SnO2, and Fe0), improved pesticide degradation, with the highest degradation rates achieved by Ag (85%) and Ni (82.5%). Additionally, the impact of the MNP functionalization, size, and concentration on pesticide degradation was quantified and compared. In general, the degradation rate increased when the MNPs were functionalized (~ 70%) compared to naked (~ 49%). Also, the particle size significantly affected the degradation of pesticides. To our knowledge, this study is the first meta-analysis performed about the impact of MNPs on pesticide degradation, providing an essential scientific basis for future studies.
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Herbicidas , Inseticidas , Nanopartículas Metálicas , Praguicidas , Humanos , Praguicidas/análise , Ecossistema , Inseticidas/análise , Herbicidas/análise , ÓxidosRESUMO
The excessive application of pesticides and fertilizers has generated losses in biological diversity, environmental pollution, and harmful effects on human health. Under this context, nanotechnology constitutes an innovative tool to alleviate these problems. Notably, applying nanocarriers as controlled release systems (CRSs) for agrochemicals can overcome the limitations of conventional products. A CRS for agrochemicals is an eco-friendly strategy for the ecosystem and human health. Nanopesticides based on synthetic and natural polymers, nanoemulsions, lipid nanoparticles, and nanofibers reduce phytopathogens and plant diseases. Nanoproducts designed with an environmentally responsive, controlled release offer great potential to create formulations that respond to specific environmental stimuli. The formulation of nanofertilizers is focused on enhancing the action of nutrients and growth stimulators, which show an improved nutrient release with site-specific action using nanohydroxyapatite, nanoclays, chitosan nanoparticles, mesoporous silica nanoparticles, and amorphous calcium phosphate. However, despite the noticeable results for nanopesticides and nanofertilizers, research still needs to be improved. Here, we review the relevant antecedents in this topic and discuss limitations and future challenges.
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2-Ketones are signal molecules reported as plant growth stimulators, but their applications in vegetables have yet to be achieved. Solid lipid nanoparticles (SLNs) emerge as a relevant nanocarrier to develop formulations for the controlled release of 2-ketones. In this sense, seedlings of Lactuca sativa exposed to 125, 375, and 500 µL L-1 of encapsulated 2-nonanone and 2-tridecanone into SLNs were evaluated under controlled conditions. SLNs evidenced a spherical shape with a size of 230 nm. A controlled release of encapsulated doses of 2-nonanone and 2-tridecanone was observed, where a greater release was observed as the encapsulated dose of the compound increased. Root development was strongly stimulated mainly by 2-tridecanone and leaf area (25-32%) by 2-nonanone. Chlorophyll content increased by 15.8% with exposure to 500 µL L-1 of 2-nonanone, and carotenoid concentration was maintained with 2-nonanone. Antioxidant capacity decreased (13-62.7%) in L. sativa treated with 2-ketones, but the total phenol concentration strongly increased in seedlings exposed to some doses of 2-ketones. 2-Tridecanone strongly modulates the enzymatic activities associated with the scavenging of H2O2 at intra- and extracellular levels. In conclusion, 2-ketones released from SLNs modulated the growth and the antioxidant system of L. sativa, depending on the dose released.
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Anaerobic digestion (AD) is the most widely used technology for organic matter treatment. However, multiple types of research have reported on improving the process because different operation inhibition factors and limitations affect the performance of AD process. Owing to the increasing use of iron-nanoparticles (Fe-NP) on AD, this review addresses the knowledge gaps and summarizes the finding from academic articles based on (i) the AD upgrading operations: limitations and upgrade techniques, (ii) Fe-NPs mechanisms on AD, (iii) Fe-NP effect on microbial communities associated to AD systems, and (iv) perspectives. The selected topics give the Fe-NP positive effects on the AD methane-production process in terms of gas production, effluent quality, and process optimization. The main results of this work indicate that (i) Fe-NP addition can be adapted among different feedstocks and complement other pretreatments, (ii) Fe-NP physicochemical characteristics enhance biogas production via direct interspecies electron transfer (DIET) mechanisms, and Fe-ion release due to their structure and their conductivity capability, and (iii) syntrophic bacteria and acetoclastic methanogens have been reported as the communities that better uptake Fe-NPs on their metabolisms. Finally, our research perspectives and gaps will be discussed to contribute to our knowledge of using Fe-NPs on AD systems.
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Ferro , Nanopartículas Metálicas , Anaerobiose , Biocombustíveis , Transporte de Elétrons , Metano/metabolismo , Reatores BiológicosRESUMO
Biosurfactant-producing bacteria can be found in contaminated environments such as biopurification systems (BPS) for pesticide treatments. A total of 18 isolates were screened to determine their ability to produce extracellular biosurfactants, using olive oil as the main carbon source. Out of the eighteen isolates, two strains (C11 and C27) were selected for biosurfactant production. The emulsification activities of the C11 and C27 strains using sunflower oil was 58.4 and 53.7%, respectively, and 46.6 and 48.0% using olive oil. Using molecular techniques and MALDI-TOF, the strains were identified as Bacillus amyloliquefaciens (C11) and Streptomyces lavendulae (C27). The submerged cultivation of the two selected strains was carried out in a 1 L stirred-tank bioreactor. The maximum biosurfactant production, indicated by the lowest surface tension measurement, was similar (46 and 45 mN/m) for both strains, independent of the fact that the biomass of the B. amyloliquefaciens C11 strain was 50% lower than the biomass of the S. lavendulae C27 strain. The partially purified biosurfactants produced by B. amyloliquefaciens C11 and S. lavendulae C27 were characterized as a lipopeptide and a glycolipid, respectively. These outcomes highlight the potential of the selected biosurfactant-producing microorganisms for improving pesticides' bioavailability and therefore the degradational efficacy of BPS.
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Volatile organic compounds (VOCs) emitted by microorganisms have demonstrated an important role to improve growth and tolerance against abiotic stress on plants. Most studies have used Arabidopsis thaliana as a model plant, extending to other plants of commercial interest in the last years. Interestingly, the microbial VOCs are characterized by its biodegradable structure, quick action, absence of toxic substances, and acts at lower concentration to regulate plant physiological changes. These compounds modulate plant physiological processes such as phytohormone pathways, photosynthesis, nutrient acquisition, and metabolisms. Besides, the regulation of gene expression associated with cell components, biological processes, and molecular function are triggered by microbial VOCs. Otherwise, few studies have reported the important role of VOCs for confer plant tolerance to abiotic stress, such as drought and salinity. Although VOCs have shown an efficient action to enhance the plant growth under controlled conditions, there are still great challenges for their greenhouse or field application. Therefore, in this review, we summarize the current knowledge about the technical procedures, study cases, and physiological mechanisms triggered by microbial VOCs to finally discuss the challenges of its application in agriculture.
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Interações entre Hospedeiro e Microrganismos/fisiologia , Desenvolvimento Vegetal , Compostos Orgânicos Voláteis/metabolismo , Agricultura , Arabidopsis/metabolismo , Bactérias , Fungos , Nutrientes , Fotossíntese , Reguladores de Crescimento de Plantas , Fenômenos Fisiológicos Vegetais , Plantas/microbiologia , Salinidade , Estresse Fisiológico/fisiologiaRESUMO
Background: Biostimulation and toxicity constitute the continuous response spectrum of a biological organism against physicochemical or biological factors. Among the environmental agents capable of inducing biostimulation or toxicity are nanomaterials. On the < 100 nm scale, nanomaterials impose both physical effects resulting from the core's and corona's surface properties, and chemical effects related to the core's composition and the corona's functional groups. Aim of Review: The purpose of this review is to describe the impact of nanomaterials on microorganisms and plants, considering two of the most studied physical and chemical properties: size and concentration. Key Scientific Concepts of Review: Using a graphical analysis, the presence of a continuous biostimulation-toxicity spectrum is shown considering different biological responses. In microorganisms, the results showed high susceptibility to nanomaterials. Simultaneously, in plants, a hormetic response was found related to nanomaterials concentration and, in a few cases, a positive response in the smaller nanomaterials when these were applied at a higher level. With the above, it is concluded that: (1) microorganisms are more susceptible to nanomaterials than plants, (2) practically all nanomaterials seem to induce responses from biostimulation to toxicity in plants, and (3) the kind of response observed will depend in a complex way on the nanomaterials physical and chemical characteristics, of the biological species with which they interact, and of the form and route of application and on the nature of the medium -soil, soil pore water, and biological surfaces- where the interaction occurs.
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Bactérias/metabolismo , Nanoestruturas/química , Nanoestruturas/toxicidade , Plantas/metabolismo , Bactérias/efeitos dos fármacos , Fenômenos Biológicos , Hormese , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Plantas/efeitos dos fármacos , Espécies Reativas de Oxigênio , Solo , Microbiologia do Solo , Propriedades de Superfície , ÁguaRESUMO
Much progress has been achieved in the preparation and application of engineered nanoparticles (NPs) in the field of medicine, mainly for antibacterial and antiviral applications. In the war against bacteria and viruses, besides traditional antibiotics and antiviral drugs, metal-based nanoparticles, such as silver (AgNPs), copper (CuNPs), copper oxides (CuO-NPs), iron oxide (FeO-NPs), zinc oxide (ZnO-NPs), and titanium oxide (TiO2-NPs) have been used as potent antimicrobial agents. These nanoparticles can be synthesized by traditional methods, such as chemical and physical routes, or more recently by biogenic processes. A great variety of macro and microorganisms can be successfully used as reducing agents of metal salt precursors in the biogenic synthesis of metal-based NPs for antimicrobial activity. Depending on the nature of the biological agent, NPs with different sizes, aggregation states, morphology, surface coatings and charges can be obtained, leading to different antimicrobial effects. Considering the drug resistance to traditional therapies, the development of versatile nanomaterials with potent antimicrobial effects is under intensive investigation. In this sense, this review presents and discusses the recent progress in the preparation and application of metal-based nanoparticles biogenically synthesized for antibacterial and antivirus applications. The strength and limitations are critically discussed.
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Nanoparticles (NPs) can be used in several ways in agriculture, including increasing production rates and improving nutritional values in plants. The present study aims to clarify how biogenic copper oxide nanoparticles (CuO NPs) applied by two routes of exposure (foliar spray and soil irrigation) affect the elemental uptake by lettuce. In vivo experiments using lettuce (n = 4) were performed with CuO NPs in comparison with copper salt (CuSO4), considering a final mass added of 20 mg of CuO per plant. The elemental composition of roots was mostly affected by the soil irrigation exposure for both Cu forms (NPs and salt). Neither Cu form added by soil irrigation was translocated to leaves. Copper concentration in leaves was mainly affected by foliar spray exposure for both Cu forms (NPs and salt). All Cu forms through foliar spray were sequestered in the leaves and no translocation to roots was observed. Foliar spray of CuO NPs caused no visual damage in leaves, resulted in less disturbance of elemental composition, and improved dry weight, number of leaves, CO2 assimilation, and the levels of K, Na, S, Ag, Cd, Cr, Cu, and Zn in leaves without causing significant changes in daily intake of most elements, except for Cu. Although Cu concentration increased in leaves by foliar spray of CuO NPs, it remained safe for consumption.
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Nanopartículas Metálicas , Nanopartículas , Cobre/análise , Lactuca , Raízes de Plantas/química , SoloRESUMO
Volatile organic compounds (VOCs) released from bacterial species have been reported as plant growth inducers. In this sense, Lactuca sativa was used as model vegetable to prospect the effects of 2-nonanone released by Bacillus sp. BCT9 at cellular and organ structure level, so we present preliminary results about the physiological effects. In this study, 2-day-old L. sativa were exposed to 2-nonanone for 10 days under two delivery systems: 1) 2-nonanone (abrupt delivery) and 2) 2-nonanone + lanolin (controlled delivery). The X-ray elemental microanalysis, scanning electron and confocal laser microscopies techniques were used to evaluate physiological changes "in vivo" conditions. The results indicated that 2-nonanone increased root and shoot length independently of 2-nonanone delivery system after 7 days of exposition. Additionally, 2-nonanone elicited the increase of anthocyanin and not affects chlorophyll content and electrolyte leakage percentage. The abrupt delivery elicited the increase of both length and density of root hair without causing changes in size of cell epidermis, while controlled delivery induced stomatal opening. Besides, 2-nonanone exposition did not modify the composition and distribution of carbon, nitrogen, phosphorus, potassium, and chlorine in the surface of plant tissue. The results suggested that 2-nonanone acts as a bacterial signal molecule to elicit changes related to root development without damaging the external morphology while epidermal cells at leaf level are not affected, suggesting that 2-nonanone can be an important tool to apply to vegetables.
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Bacillus/metabolismo , Cetonas/farmacologia , Lactuca/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Antocianinas/biossíntese , Clorofila/metabolismo , Células Epidérmicas/efeitos dos fármacos , Lanolina/farmacologia , Lactuca/microbiologia , Microscopia Confocal , Microscopia Eletrônica de Varredura , Folhas de Planta/metabolismo , Compostos Orgânicos Voláteis/metabolismoRESUMO
Staphylococcus aureus is a serious human pathogen that is highly adaptive to environmental conditions and rapidly develops antibiotic resistance. The use of efflux pumps to reduce antibiotic concentrations at the intracellular level is one of the main mechanisms by which bacteria develop antibiotic resistance. The management of efflux pumps, specifically NorA, which is expressed by S. aureus strains, is a valuable strategy for restoring susceptibility in strains resistant to antibacterial agents. In recent years, many studies have focused on searching for natural substances that can reverse efflux pump-mediated resistance in S. aureus. Extracts and compounds obtained from plants can be efficient efflux pump inhibitors (EPIs) and represent a potentially patient-friendly strategy for controlling S. aureus. In the present study, we evaluated the ability of essential oils, petroleum ether extracts, dichloromethane extract (DCME) and six compounds isolated from the heartwood of Pilgerodendron uviferum (Cupressaceae) and two synthetic derivatives to inhibit efflux in NorA pumps in the following three S. aureus strains: K2378, which overexpressed the norA gene (norA++), K1902 (norA-deleted, ΔnorA) and the parental strain, NCTC 8325-4. Efflux activity was evaluated using a fluorometric method that measured the accumulation of the universal efflux pump substrate ethidium bromide (EtBr). Only DCME and the compounds 15-copaenol and epi-cubenol inhibited EtBr efflux by K2378. Even the lowest concentration of 15-copaenol exhibited a stronger inhibitory effect than carbonyl cyanide m-chlorophenyl hydrazone on EtBr efflux by K2378. 15-copaenal only showed inhibition of EtBr efflux in K2378 cells at 125 µg/mL, but not superior to the control inhibitor and 15-copaenyl acetate exerted no intrinsic EPI activity against K2378. Fractional inhibitory concentration index (FICI) values obtained in the checkerboard assays, indicated that all combinations between DCME, epi-cubenol and 15-copaenol, and tested antibiotics showed a synergistic effect in wild type, norA ++ and ΔnorA strains. Moreover, those were not toxic for the HeLa cell line at concentrations in which the synergistic effect and inhibitory activity of efflux pumps was determined. Other extracts and compounds obtained from P. uviferum did not display EtBr efflux-inhibiting activity against the evaluated S. aureus strains.
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Agricultural practices require novel products that allow sustainable development and commercial production according to the needs of farmers and consumers. Therefore, in the last decade, eco-friendly alternatives have been studied, so volatile organic compounds (VOCs) emitted by microorganisms have emerged as a cheaper, effective, efficient, and an eco-friendly alternative. VOCs are lipophilic compounds derived from microbial metabolic pathways with low molecular weight (<300â¯gâ¯mol-1), low boiling point, and high vapor pressure that allow them to act as signal molecules over short and long distances. Main case studies provide evidence that VOCs released from diverse microorganisms (i.e. Bacillus, Pseudomonas, Arthrobacter, Fusarium, and Alternaria) can stimulate growth on a specific "target" seedling, such as Arabidopsis and tobacco. Some identified compounds, such as 3-hydroxy-2-butanone (acetoin), 2,3-butanediol, 2-pentylfuran, or dimethylhexadecylmine have shown their ability to elicit growth at root or leaf level. Few studies indicate that VOCs act in the regulation at phytohormone, metabolic pathways and nutrition levels according to genetic, proteomic, and metabolic analyses; but action mechanisms associated with growth-inducing activity are poorly understood. In this work, we reviewed case studies regarding identified compounds and action mechanisms for a better understanding of the information collected so far. Additionally, a brief description about the effects of VOCs for induction of resistance and tolerance in plants are presented, where compounds such as acetoin, dimethyl disulfide, 3-pentanol and 6-pentyl-α-pyrone have been reported. Furthermore, we summarized the knowledge to direct future studies that propose microbial VOCs as a technological innovation in agriculture and horticulture.