Preparation of nanoscale Bacillus thuringiensis chitinases using silica nanoparticles for nematicide delivery

Development of a Safe and Effective Bacillus thuringiensis-Based Nanobiopesticide for Controlling Tea Pests

Mg(OH)2 was used as the nanocarrier of the Bacillus thuringiensis (Bt) Cry1Ac protein, and the synthesized Cry1Ac-Mg(OH)2 composites were regular and uniform nanosheets. Nano-Mg(OH)2 could effectively improve the insecticidal effect of the Cry1Ac protein toward Ectropis obliqua. It could enhance the damage degree of the Cry1Ac protein to intestinal epithelial cells and microvilli, induce and enrich the production of reactive oxygen species (ROS) in the midgut, and enhance the degradation of the Cry1Ac protein into active fragments. Furthermore, an anti-rinsing assay showed that the Cry1Ac-Mg(OH)2 composites were bound to the notch structure of the tea leaf surface. The retention of the Cry1Ac protein increased by 11.45%, and sprayed nano-Mg(OH)2 was rapidly absorbed by different tissues of tea plants. Moreover, nano-Mg(OH)2 and composites did not significantly affect non-target organisms. These results show that nano-Mg(OH)2 can serve as a safe and effective biopesticide carrier, which provides a new approach for stable and efficient Bt preparation.

Microbiology and Biochemistry of Pesticides Biodegradation

Pesticides are chemicals used in agriculture, forestry, and, to some extent, public health. As effective as they can be, due to the limited biodegradability and toxicity of some of them, they can also have negative environmental and health impacts. Pesticide biodegradation is important because it can help mitigate the negative effects of pesticides. Many types of microorganisms, including bacteria, fungi, and algae, can degrade pesticides; microorganisms are able to bioremediate pesticides using diverse metabolic pathways where enzymatic degradation plays a crucial role in achieving chemical transformation of the pesticides. The growing concern about the environmental and health impacts of pesticides is pushing the industry of these products to develop more sustainable alternatives, such as high biodegradable chemicals. The degradative properties of microorganisms could be fully exploited using the advances in genetic engineering and biotechnology, paving the way for more effective bioremediation strategies, new technologies, and novel applications. The purpose of the current review is to discuss the microorganisms that have demonstrated their capacity to degrade pesticides and those categorized by the World Health Organization as important for the impact they may have on human health. A comprehensive list of microorganisms is presented, and some metabolic pathways and enzymes for pesticide degradation and the genetics behind this process are discussed. Due to the high number of microorganisms known to be capable of degrading pesticides and the low number of metabolic pathways that are fully described for this purpose, more research must be conducted in this field, and more enzymes and genes are yet to be discovered with the possibility of finding more efficient metabolic pathways for pesticide biodegradation.

Nanobiopesticides: Are they the future of phytosanitary treatments in modern agriculture?

The world's population is continuously increasing; therefore, food availability will be one of the major concerns of our future. In addition to that, many practices and products used, such as pesticides and fertilizers have been shown harmful to the environment and human health and are assumed as being one of the main factors responsible for the loss of biodiversity. Also, climate change could agravate the problem since it causes unpredictable variation of local and regional climate conditions,which frequently favor the growth of diseases, pathogens and pest growth. The use of natural products, like essential oils, plant extracts, or substances of microbial-origin in combination with nanotechnology is one suitable way to outgrow this problem. The most often employed natural products in research studies to date include pyrethrum extract, neem oil, and various essential oils, which when enclosed shown increased resistance to environmental factors. They also demonstrated insecticidal, antibacterial, and fungicidal properties. However, in order to truly determine if these products, despite being natural, would be hazardous or not, testing in non-target organisms, which are rare, must start to become a common practice. Therefore, this review aims to present the existing literature concerning nanoformulations of biopesticides and a standard definition for nanobiopesticides, their synthesis methods and their possible ecotoxicological impacts, while discussing the regulatory aspects regarding their authorization and commercialization. As a result of this, you will find a critical analysis in this reading. The most obvious findings are that i) there are insufficient reliable ecotoxicological data for risk assessment purposes and to establish safety doses; and ii) the requirements for registration and authorization of these new products are not as straightforward as those for synthetic chemicals and take a lot of time, which is a major challenge/limitation in terms of the goals set by the Farm to Fork initiative.

Nanoparticles: A Potential and Effective Method to Control Insect-Borne Diseases

Insects act as vectors to carry a wide range of bacteria and viruses that can cause multiple vector-borne diseases in humans. Diseases such as dengue fever, epidemic encephalitis B, and epidemic typhus, which pose serious risks to humans, can be transmitted by insects. Due to the absence of effective vaccines for most arbovirus, insect control was the main strategy for vector-borne diseases control. However, the rise of drug resistance in the vectors brings a great challenge to the prevention and control of vector-borne diseases. Therefore, finding an eco-friendly method for vector control is essential to combat vector-borne diseases. Nanomaterials with the ability to resist insects and deliver drugs offer new opportunities to increase agent efficacy compared with traditional agents, and the application of nanoagents has expanded the field of vector-borne disease control. Up to now, the reviews of nanomaterials mainly focus on biomedicines, and the control of insect-borne diseases has always been a neglected field. In this study, we analyzed 425 works of the literature about different nanoparticles applied on vectors in PubMed around keywords, such as"nanoparticles against insect," "NPs against insect," and "metal nanoparticles against insect." Through these articles, we focus on the application and development of nanoparticles (NPs) for vector control, discussing the lethal mechanism of NPs to vectors, which can explore the prospect of applying nanotechnology in the prevention and control of vectors.

Nano-enabled agrochemicals/materials: Potential human health impact, risk assessment, management strategies and future prospects

Nanotechnology is a rapidly developing technology that will have a significant impact on product development in the next few years. The technology is already being employed in cutting-edge cosmetic and healthcare products. Nanotechnology and nanoparticles have a strong potential for product and process innovation in the food industrial sector. This is already being demonstrated by food product availability made using nanotechnology. Nanotechnologies will have an impact on food security, packaging materials, delivery systems, bioavailability, and new disease detection materials in the food production chain, contributing to the UN Millennium Development Goals targets. Food products using nanoparticles are already gaining traction into the market, with an emphasis on online sales. This means that pre- and post-marketing regulatory frameworks and risk assessments must meet certain standards. There are potential advantages of nanotechnologies for agriculture, consumers and the food industry at large as they are with other new and growing technologies. However, little is understood about the safety implications of applying nanotechnologies to agriculture and incorporating nanoparticles into food. As a result, policymakers and scientists must move quickly, as regulatory systems appear to require change, and scientists should contribute to these adaptations. Their combined efforts should make it easier to reduce health and environmental impacts while also promoting the economic growth of nanotechnologies in the food supply chain. This review highlighted the benefits of a number of nano enabled agrochemicals/materials, the potential health impacts as well as the risk assessment and risk management for nanoparticles in the agriculture and food production chain.

Encapsulation Strategies for Bacillus thuringiensis: From Now to the Future

Bacillus thuringiensis (Bt) has been recognized for its high potential in the control of various agricultural pests. Developments in micro/nanotechnology have opened new perspectives for the production of more efficient formulations that can overcome some obstacles associated with its use in the field, such as formulation instability and loss of activity as a result of the degradation of pesticidal protein by its exposure to ultraviolet radiation, among other problems. This review describes current studies and recent discoveries related to Bt and processes for the encapsulation of Bt derivatives, such as Cry pesticidal proteins. Different techniques are described, such as extrusion, emulsion, spray drying, spray cooling, fluidized bed, lyophilization, coacervation, and electrospraying to obtain micro- and nanoparticulate systems. It is noteworthy that products based on microorganisms present less risk to the environment and non-target organisms. However, systematic risk assessment studies of these new Bt biopesticides are necessary, considering issues, such as interactions with other organisms, the formation of toxic secondary metabolites, or the interspecific transfer of genetic material. Given the great potential of these new formulations, a critical assessment is provided for their future use, considering the technological challenges that must be overcome to achieve their large-scale production for efficient agricultural use.

Analysis of transcriptome difference between rapid-growing and slow-growing in Penaeus vannamei

Penaeus vannamei is the principle cultured shrimp species in China. However, with the increase of culture density, the growth difference between individuals is also expanding. Here, we make use of RNA-seq to study the growth mechanisms of P. vannamei. After 120 days, we examined the transcriptomes of rapid-growing individuals (RG) and slow-growing individuals (SG). A total of 2116 and 176 differentially expressed genes (DEGs) were found in SG and RG, respectively. Moreover, the main DEGs are opsin, heat shock protein (HSP), actin, myosin, superoxide dismutase (SOD), cuticle protein, and chitinase. GO analysis further revealed that the DEGs were enriched in biological processes significantly, such as "sensory perception," "sensory perception of light stimulus," "response to stimulus," and "response to stress." Additionally, KEGG enrichment analysis showed that the DEGs were mainly enriched in "pentose and glucuronate interconversions," "amino sugar and nucleotide sugar metabolism," "glycophospholipid biosynthesis," and "glutathione metabolism." Interestingly, the upstream genes in the ecdysone signaling pathway, including molting inhibition hormone (MIH) and crustacean hyperglycemic hormone (CHH), did not differ significantly between RG and SG, which suggests that the cause for the inconsistent growth performance is due to the stress levels rather than the ecdysone signal pathway. In summary, this work provides data that will be useful for future studies on shrimp growth and development.

Chitinases of Bacillus thuringiensis: Phylogeny, Modular Structure, and Applied Potentials

The most important bioinsecticide used worldwide is Bacillus thuringiensis and its hallmark is a rich variety of insecticidal Cry protein, many of which have been genetically engineered for expression in transgenic crops. Over the past 20 years, the discovery of other insecticidal proteins and metabolites synthesized by B. thuringiensis, including chitinases, antimicrobial peptides, vegetative insecticidal proteins (VIP), and siderophores, has expanded the applied value of this bacterium for use as an antibacterial, fungicidal, and nematicidal resource. These properties allow us to view B. thuringiensis not only as an entity for the production of a particular metabolite, but also as a multifaceted microbial factory. In particular, chitinases of B. thuringiensis are secreted enzymes that hydrolyze chitin, an abundant molecule in the biosphere, second only to cellulose. The observation that chitinases increase the insecticidal activity of Cry proteins has stimulated further study of these enzymes produced by B. thuringiensis. Here, we provide a review of a subset of our knowledge of B. thuringiensis chitinases as it relates to their phylogenetic relationships, regulation of expression, biotechnological potential for controlling entomopathogens, fungi, and nematodes, and their use in generating chitin-derived oligosaccharides (ChOGs) that possess antibacterial activities against a number of clinically significant bacterial pathogens. Recent advances in the structural organization of these enzymes are also discussed, as are our perspective for future studies.

Evaluation of baiting fipronil-loaded silica nanocapsules against termite colonies in fields

Various pesticide nanocarriers have been developed. However, their pest-control applications remain limited in laboratories. Herein, we developed silica nanocapsules encapsulating fipronil (SNC) and their engineered form, poly(ethyleneimine)-coated SNC (SNC-PEI), based on recombinant catalytic modular protein D4S2 and used them against termite colonies Coptotermes lacteus in fields. To achieve this, an integrated biomolecular bioprocess was developed to produce D4S2 for manufacturing SNC containing fipronil with high encapsulation efficiency of approximately 97% at benign reaction conditions and at scales sufficient for the field applications. PEI coating was achieved via electrostatic interactions to yield SNC-PEI with a slower release of fipronil than SNC without coating. As a proof-of-concept, bait toxicants containing varied fipronil concentrations were formulated and exposed to nine termite mounds, aiming to prolong fipronil release hence allowing sufficient time for termites to relocate the baits into and distribute throughout the colony, and to eliminate that colony. Some baits were relocated into the mounds, but colonies were not eliminated due to several reasons. We caution others interested in producing bait toxicants to be aware of the multilevel resistance mechanisms of the Coptotermes spp. "superorganism".

Nano-based smart pesticide formulations: Emerging opportunities for agriculture

The incorporation of nanotechnology as a means for nanopesticides is in the early stage of development. The main idea behind this incorporation is to lower the indiscriminate use of conventional pesticides to be in line with safe environmental applications. Nanoencapsulated pesticides can provide controlled release kinetics, while efficiently enhancing permeability, stability, and solubility. Nanoencapsulation can enhance the pest-control efficiency over extended durations by preventing the premature degradation of active ingredients (AIs) under harsh environmental conditions. This review is thus organized to critically assess the significant role of nanotechnology for encapsulation of AIs for pesticides. The smart delivery of pesticides is essential to reduce the dosage of AIs with enhanced efficacy and to overcome pesticide loss (e.g., due to leaching and evaporation). The future trends of pesticide nanoformulations including nanomaterials as AIs and nanoemulsions of biopesticides are also explored. This review should thus offer a valuable guide for establishing regulatory frameworks related to field applications of these nano-based pesticides in the near future.

Development of a thermo-stable and recyclable magnetic nanobiocatalyst for bioprocessing of fruit processing residues and D-allulose synthesis

The aim of the study was to covalently immobilize Smt3-D-psicose 3-epimerase onto functionalized iron oxide magnetic nanoparticles. After immobilization, K_m of the immobilized enzyme increased, however, V_max was nearly the same as that of its free form, indicating that immobilization has no detrimental effects on its catalytic output. The covalent immobilization caused a reduction in the deactivation rate constant (k_d) values leading to 4-5 fold enhancement in its half-life at 50-65°C, indicating significant thermal stability of the iron-enzyme nanobioconjugate. The immobilized enzyme showed excellent storage stability by losing only 20% activity even after 60days of storage at 4°C. The immobilized enzyme retained up to 90% of its initial activity even after 10 consecutive cycles of catalyzing D-fructose epimerization reactions. Thus, after immobilization the enzyme exhibited remarkable improvements in thermal tolerance, storage stability and recycling efficiency, useful for development of industrially exploitable process for D-allulose production.

The adsorption features between insecticidal crystal protein and nano-Mg(OH)2

Nano-Mg(OH)₂, with low biological toxicity, is an ideal nano-carrier for insecticidal protein to improve the bioactivity. In this work, the adsorption features of insecticidal protein by nano-Mg(OH)₂ have been studied. The adsorption capacity could reach as high as 136 mg g^-1, and the adsorption isotherm had been fitted with Langmuir and Freundlich models. Moreover, the adsorption kinetics followed a pseudo-first or -second order rate model, and the adsorption was spontaneous and an exothermic process. However, high temperatures are not suitable for adsorption, which implies that the temperature would be a critical factor during the adsorption process. In addition, FT-IR confirmed that the protein was adsorbed on the nano-Mg(OH)₂, zeta potential analysis suggested that insecticidal protein was loaded onto the nano-Mg(OH)₂ not by electrostatic adsorption but maybe by intermolecular forces, and circular dichroism spectroscopy of Cry11Aa protein before and after loading with nano-Mg(OH)₂ was changed. The study applied the adsorption information between Cry11Aa and nano-Mg(OH)₂, which would be useful in the practical application of nano-Mg(OH)₂ as a nano-carrier.

Adsorption of Insecticidal Crystal Protein Cry11Aa onto Nano-Mg(OH)2: Effects on Bioactivity and Anti-Ultraviolet Ability

The traditional Bacillus thuringiensis (Bt) formulations for field applications are not resistant to harsh environmental conditions. Hence, the active ingredients of the Bt bioinsecticides could degrade quickly and has low anti-ultraviolet ability in the field, which significantly limits its practical application. In the present study, we developed an efficient and stable delivery system for Bt Cry11Aa toxins. We coated Cry11Aa proteins with Mg(OH)₂ nanoparticles (MHNPs), and then assessed the effects of MHNPs on bioactivity and anti-ultraviolet ability of the Cry11Aa proteins. Our results indicated that MHNPs, like "coating clothes", could effectively protect the Cry protein and enhance the insecticidal bioactivity after UV radiation (the degradation rate was decreased from 64.29% to 16.67%). In addtion, MHNPs could improve the proteolysis of Cry11Aa in the midgut and aggravate the damage of the Cry protein to the gut epithelial cells, leading to increased insecticidal activity against Culex quinquefasciatus. Our results revealed that MHNPs, as an excellent nanocarrier, could substantially improve the insecticidal bioactivity and anti-ultraviolet ability of Cry11Aa.

Transcriptome analysis on the exoskeleton formation in early developmetal stages and reconstruction scenario in growth-moulting in Litopenaeus vannamei

Exoskeleton construction is an important issue in shrimp. To better understand the molecular mechanism of exoskeleton formation, development and reconstruction, the transcriptome of the entire developmental process in Litopenaeus vannamei, including nine early developmental stages and eight adult-moulting stages, was sequenced and analysed using Illumina RNA-seq technology. A total of 117,539 unigenes were obtained, with 41.2% unigenes predicting the full-length coding sequence. Gene Ontology, Clusters of Orthologous Group (COG), the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and functional annotation of all unigenes gave a better understanding of the exoskeleton developmental process in L. vannamei. As a result, more than six hundred unigenes related to exoskeleton development were identified both in the early developmental stages and adult-moulting. A cascade of sequential expression events of exoskeleton-related genes were summarized, including exoskeleton formation, regulation, synthesis, degradation, mineral absorption/reabsorption, calcification and hardening. This new insight on major transcriptional events provide a deep understanding for exoskeleton formation and reconstruction in L. vannamei. In conclusion, this is the first study that characterized the integrated transcriptomic profiles cover the entire exoskeleton development from zygote to adult-moulting in a crustacean, and these findings will serve as significant references for exoskeleton developmental biology and aquaculture research.