فصلنامه ایمنی زیستی
سال شانزدهم شماره 4 (زمستان 1402)

Plant pathogens are a considerable risk to global food security due to the drastic reduction in yield and quality of crops. The deployment of RNA interference (RNAi) machinery for crop protection against plant pathogens agents is showing promising results. It is well set up that small RNA molecules, such as small interfering RNAs (siRNAs) and microRNAs (miRNAs), are included in regulating gene expression, and the process of RNA silencing at both transcriptional and post-transcriptional stages. Using host-induced gene silencing (HIGS), plants are genetically modified to produce small RNAs that infiltrate pathogen cells and deactivate specific genes. Alternatively, spray-induced gene silencing (SIGS) involves directly applying small RNAs onto plants, where they penetrate the pathogens and suppress target genes. This study delves into the roles of small RNAs and examines their potential application in combating a many plant pathogens through either HIGS or SIGS strategies providing an evaluation of their respective benefits and limitations.

Clustered regularly interspaced short palindromic repeats and its associated protein or CRISPR-Cas systems are valuable genetic targets for bacterial phylogeny analysis in epidemiological studies. In this study, the genomic data of 800 sequences of Clostridium botulinum strains from the National Center for Biotechnology Information (NCBI) database was collected and the occurrence and variety of the complete CRISPR-Cas systems and its spacer and repeat sequences evaluated in the genomes recorded for these bacteria with the in-silico method. Also, the secondary structures of repeat sequences were predicted based on the minimum free energy (MFE) algorithm. According to the results, from the 526 genomes with complete CRISPR-Cas array, 306 strains (58%) had Cas genes. Subtypes I-B, I-D, II-C, III-D, and III-B were identified in these arrays. The findings also revealed that Cas 6 is the main protein produced by expression module genes in the studied CRISPR-Cas systems, and diverse Cas proteins are produced by the adaptation and interference modules in these arrays. The average length of spacer and repeat sequences in CRISPR arrays was 30-35 and 30-36 bp, respectively. Moreover, the prediction of secondary structures of repeat sequences showed that subtype II-C, with longer stems than other subtypes, tends to form more stable RNA secondary structures.

Celiac disease in humans is caused by intolerance to the protein part of some grains called gluten. Therefore, food industry researchers have been carried out much researches in the field of gluten-free bread (GFB) production. Among the available solutions to improve gluten-free products's quality and sensory characteristics, sourdough biotechnology can play a prominent role. Sourdough is a mixture of flour and water, which is fermented by an ecosystem of lactic acid bacteria (LAB) and yeasts; and provides conditions for improving the quality and nutritional characteristics of bakery products. Metabolites produced by lactic acid bacteria can play the role of gluten in these products. It is also a cost-effective process with high potential in the field of producing GF products. The effects of sourdough in these products depend on factors such as the characteristics of gluten-free flour, the type of starter culture in fermentation, nutrients in the fermentation medium, fermentation temperature, fermentation time, etc. In this study, we will examine the effects of using sourdough technology in gluten-free breads and the influencing factors of this technology.

Blue-green algae or cyanobacteria are a group of algae that are able to grow rapidly in warm and nutrient-rich waters. The exponential growth of cyanobacteria in water bodies is affected by various factors, including an excess of nutrients, high temperatures, and excessive sunlight. Numerous studies have shown that with the increase in the growth of cyanobacteria in aquatic systems, there is also a possibility of an increase in toxins produced by them, which can have adverse effects on the health of aquatic animals and especially humans. Given the importance of the health of employees and local people in marine environments as well as workers in aquaculture centers, the present study aimed to introduce the most important and common toxins resulting from the growth of cyanobacteria and also to investigate the risks arising from them in order to determine the potential of these toxins in bioterrorism. For this purpose, 12 types of cyanobacterial toxins including including microcystin, nodularin, anatoxin-a, homoanatoxin, oscillatoxin A, cylindrospermopsin, nakienones A-C, aphantoxin, scytophycin/lyngbyatoxin, aplysiatoxin, and debromoaplysiatoxin were investigated. The results showed that among the aforementioned toxins, microcystin has received the most attention in scientific research compared to others, which can be attributed to the global prevalence of this toxin and its effects on human health. The effects of microcystin have often been manifested in the form of gastrointestinal diseases, liver and nerve damage, and cancer. Considering the adverse effects of these toxins, it is essential to employ various techniques to control and reduce the risks arising from the growth of cyanobacteria, as well as to adopt appropriate management decisions and strategies regarding the health of marine workers and people working in aquaculture centers who are exposed to the growth of cyanobacteria and their toxins.

The aim of this research is to present an eco-friendly plant-based insecticide formulated with nanotechnology using plant essential oils. In this regard, a nano-insecticide was initially prepared using the natural polymer chitosan and characterized through scanning and transmission electron microscopy techniques. Its insecticidal potential was evaluated for controlling Sciaridae mosquitoes, a pest affecting edible mushrooms. The average particle size of the prepared nano-insecticide was determined to be below 50 nanometers using Dynamic Light Scattering (DLS) and electron microscopy techniques.After that, various ratios of the nano-insecticide were analyzed, and the most stable nanoformulation was selected for preliminary laboratory tests with three replicates in a greenhouse to assess the treatment effects of the nano-insecticide on Sciaridae mosquitoes infesting edible mushrooms. The plant-based nano-insecticide (at a concentration of 1.5 g/L of plant essential oil) demonstrated an average efficacy of 99.7% in controlling Sciaridae mosquitoes. Compared to the chemical insecticide imidacloprid (at a concentration of 1.75 g/L of active ingredient), which achieved 100% efficacy, the plant-based nano-insecticide offers significant environmental advantages and eliminates concerns regarding chemical residues in food products, making it a highly promising and noteworthy result.

This article comprehensively reviews natural preservatives and antimicrobial agents proposed as suitable and safe alternatives to chemical preservatives in various industries, including food, pharmaceutical, and cosmetic sectors. The growing concerns about the negative effects of chemical preservatives on human health and the environment have shifted researchers' attention toward using natural substances such as plant extracts, organic acids, polyphenols, probiotics, propolis, and antimicrobial enzymes. These natural compounds not only possess preservative properties but also exhibit antioxidant and antimicrobial activities, contributing to the maintenance of product quality, safety, and extended shelf life. The study indicates that these natural preservatives can effectively combat microbial growth and prevent food spoilage while preserving the nutritional value of the products. However, challenges such as the stability of these substances under various conditions, interactions with other components in product formulations, and high production costs need to be addressed in future research. The article emphasizes the importance of further studies in this area to improve the performance of these compounds and facilitate their adoption in industrial applications. Natural preservatives, with their multifunctional properties, hold significant potential to replace chemical preservatives. However, their ultimate success depends on advancements in formulation development, industrial efficiency, and economic feasibility. Overall, this research demonstrates that natural preservatives could play a crucial role in enhancing public health and product sustainability, leading to their broader use across various industries.