فصلنامه ایمنی زیستی
سال چهاردهم شماره 2 (تابستان 1400)

Nitrate with the chemical formula NO3- is one of the forms of nitrogen in the environment that plays an important role in the nitrogen cycle. Vegetables, water and meat are important sources of nitrate. Nitrate is made in the body through the arginine-NO pathway and enters the body through various sources. Oral nitrate is converted to nitrite (NO2-) by bacteria when it enters the mouth, and nitrite is converted to a carcinogen called nitrosamine after it enters the stomach. Many studies have confirmed the effect of nitrate on carcinogenesis in forty animal species. Nitrate can cause methemoglobinemia, cancers, thyroid diseases and tumors. On the other hand, the positive effect of nitrate on blood vessel health and the muscle-building process has been confirmed. The use of microbial agents and biofertilizers to reduce the residue of chemical fertilizers in agricultural products can be useful. In this article, nitrate sources, its role in the nitrogen cycle and its impact on human health are investigated. Also, the use of plant growth-promoting bacteria to reduce nitrate concentrations in greenhouse crops is described as a practical method.

Biochar is a coal that is prepared during the pyrolysis process by burning plant biomass and agricultural waste in the presence or absence of oxygen at a temperature around 450-550°C that is used as a fertilizer. In view of agriculture, one of the benefits of biochar is waste management in agriculture. This solid material is rich in carbon and has a large capacity to reduce greenhouse gases such as carbon dioxide and methane released from waste due to very slow decomposition rate compared to other organic materials, and can keep carbon for a thousands of years. Biochar is widely known as an efficient way for carbon sequestration and increasing soil fertility. It is used as a soil texture improver or to regenerate lands as well as protecting the environment against certain pollutants. By the addition of biochar, the stability of soil will increase the organic carbon against environmental factors and reduces mineralization which increases organic carbon and improves soil structure. Increasing water holding capacity and activity of microorganisms and better absorption of nutrients from soil is one of the main roles of biochar. In addition, biochar will improve crop yields, management of agricultural waste. Increasing plant's systemic resistance to a number of plant pathogens and uptake of pesticide and herbicide residues from the soil will cause the growth of healthier plants. Development of organic agriculture and problems that resulted in air pollution has made use of this type of fertilizer around the world, however, this organic material has remained somewhat unknown in Iran.

Green cucumber named Cucumis sativus is one of the most important vegetables. Currently, it has the highest level of cultivation in greenhouses in the country. To increase yields, greenhouse managers use chemical fertilizers at different stages of plant development, which upset the balance of the environment and the soil microbiome. Using growth-promoting bacteria, in addition to maintaining the balance of soil microorganisms, can improve crop quality. In this study, the effects of two bacterial strains of Amycolatopsis sp. strain 1119 and Pseudomonas sp. strain P3-57 on soil microbial population, production rate, and crop quality in commercial cucumber greenhouse were investigated. The use of P3-57 and 1119 strains increased the yield by 4% and 23%, respectively. Qualitative evaluation of the product revealed that both bacteria had a favorable effect on the overall acceptance of the product. Examination of the growth-promoting colonization bacteria showed that strain 1119 is an endophytic bacteria and strain P3-57 colonized on the root. The 1119 strain increased the number of cultivable fungi in the rhizosphere and decreased the number of bacteria. Treatment with strain P3-57 increased the population of both groups of microorganisms. Using these bacteria in the industry can significantly help protect the environment in the future.

Fungal and fungal-like diseases impose a great impact on crops annually, and fungicide-based plant protection is sometimes inevitable for efficient, economic and large-scale crop production. Regardless the long time and huge money investments to develop a new fungicide, the risk of resistance, especially to systemic fungicides, threatens the effectiency of these compounds. Today, due to the excludings of fungicides, not only from resistance, but increasingly from environmental and health concerns, the number of fungicides with different modes of action has become very restricted. Therefore, research and efforts to access fungicides with different modes of action, continuous population monitoring for fungicide resistance, finding the new resistance mechanisms and getting preventing strategies are of the most important parts for sustainable and economic fungal disease management.

Monogeneans are the most common external parasites of fishes, sharks, amphibians and crustaceans living in fresh and saltwater. The simple life cycle of these monoxenous parasites allow them to grow rapidly in aquatic habitats such as aqua farms and aquariums, causing extensive damage to the aquaculture industry by harming their host and contaminating other aquatic organisms in the environment. Several studies have been done on parasitic infections of aquatic animals, especially monogeneans, as well as their immune system, and also the interactions between the parasite and the host, all of which confirm the prevalence of these infections among aquatic animals. Though many efforts have been done to cure the aquatic infections, these diseases have been remained one of the main challenges in aquaculture. Chemical therapies are effective, but still have their own problems regarding the aquatic safety such as drug resistance and environmental considerations due to the releasing of chemical and antimicrobial drugs. In recent decades, efforts have been made to develop effective vaccines to protect aquatic species, but vaccination against parasitic infections has remained an unresolved issue due to the specific living conditions of parasites and resistance to the immune system. Studies on aquatic nutrition have also shown that fortifying of the aquatic feeds can be effective in strengthening the immune system and increasing aquatic resistance.

In the present century, the combination of conductive polymers, e materials that, in addition to improving the general properties of polymers, also have electrical and magnetic properties, with natural biopolymers for intelligent food packaging has received much attention. In this research, the effect of polypyrrole nanoparticles in the combination of different concentrations chitosan polypyrrole nanocomposite was prepared. The structural and functional properties of the films were investigated. The size, shape and morphology of the synthesized particles were investigated using electron scanning microscopy technique. The results showed that the synthesized polypropols are granular in shape and in the dimensions of 90-100 nm. The antioxidant properties and electrical conductivity of the films were investigated. The results showed that following the synthesis of polypyrrole nanoparticles in the chitosan polymer matrix, the electrical resistance decreased and the electrical conductivity increased. Also, the results of investigating the effect of polypyrrole on the physical properties of chitosan films showed that with increasing the concentration of polypyrrole and the time of synthesis of solubility and water vapor permeability of films decreased. The interaction between chitosan and polypyrrole was confirmed by infrared spectroscopy and X-ray diffraction pattern.

Gladiolus is one of the most widely used cut flowers in Iran and mainly they were produced by corm, but due to the long production time to reproduce commercial corm, they are imported from the Netherlands to Iran. The use of the micropropagation method in many plants is effective to further accelerate the propagation phase in the first stage and play a major role in shortening the propagation time and cost by increasing uniformity and preventing soil contamination due to corm imports. In this article, the stages of tissue culture, adaptation and maturation of gladiolus corms in order to get the resistance to Fusarium sp. by gene transformation were mentioned. The use of different parts of the culture, especially corms and tissue culture cormels with a combination of growth regulators containing less auxin and more cytokinin can, directly and indirectly, cause shoot production, rooting and ultimately corm production. Using larger glasses and more sucrose in culture media have effective roles in the retention of the cormels in the stages of adaptation to maturation. Reducing the dormancy by combining gibberellin and cold and using the soil with the precise combination has shortened the time of maturity corms and produce a suitable corm with a commercial size to complete the gene transformation cycle.

Parasites as eukaryotic pathogens can cause severe, acute or chronic diseases in humans and animals need complex therapeutic processes and through their adverse effects may cause damage to public health and economy. Since there are some reports of resistance of parasites to certain chemical medications and in lack of proper treatment programs, vaccination can be used either as a supplement approach to medical treatments or a preventative measure for diseases. Due to various social, economic and scientific problems, or for reasons such as the complexity of approving, currently no effective vaccine against human parasitic diseases has been commercialized, but a number of veterinary medicine vaccines with different efficacy have been marketed. In line with food safety and security policies and in response to the global demand, vaccines with appropriate effectiveness have been introduced to the market in the fields of animal husbandry and aquaculture. However, the use of high-throughput technologies, such as next-generation sequencing and omics, has opened new perspectives and made it possible to identify target antigens and predict immunological reactions precisely, lead to more useful vaccines. In this article, we have reviewed produced or under investigation vaccines against some protozoan parasites and worms discussing different aspects of them.