Agro-Ecological Estimation of Various Fertilization Systems under Conditions of the Republic of Tatarstan

Producers of agricultural plants are increasingly marking a decrease in the responsiveness of cultivated plants to the mineral fertilizers applied to the soil. The explanation of this phenomenon can be the shift of limiting factors that determine the yield from mineral components in the soil to substances of organic and biological origin. The paper presents comparative data of the influence of mineral and organic fertilizer system on main biological indicators of the soil – nitrogen transforming groups of microorganisms, total microbial number (TMN), and soil respiration. The change in total and mineral nitrogen in the soil is estimated. The novelty of the study is that organic fertilizers are used in amounts comparable to the doses of mineral fertilizers in physical weight – 200 kg/ha. The application is carried out locally simultaneously with the seeding. As a result of the analysis, it has been found that ammonifiers (by 20.0–45 %), nitrifiers (by 30.0–46.7 %) numerically dominate in soil with organic fertilizers under all crops (corn, sunflower, soybean, sugar beet), the total microbial number is higher by 24.6–48.3 %. The intensity of carbon dioxide emissions (soil respiration) is also higher by 19.0–45.6 %. The intensity of biogeochemical processes in the soil and the related transformations of mineral nutrients, respectively and the provision of plants with them closely correlates with the number of valuable groups of microorganisms. The correlation coefficient between the number of ammonifiers and nitrifiers with the total nitrogen content in the soil under all studied crops in an organic fertilizer system is r=0.93

Efficient method for identification of Escherichia coli strains isolated from various chicken (Gallus gallus domesticus) organs

Tracing of transmission routes and identification of pathogen sources are important issues in preventive measures aimed at controlling human and animal infectious diseases. A fast and accurate method for bacterial strain identification (genotyping) allows scientifically sound planning of preventive schemes. Despite the existence of numerous bacterium genotyping techniques, there is still room for developing a unified typing approach that would be applicable to a variety of bacterial species. The aim is to develop a genotyping method allowing identification of E. coli strains circulating at Russian chicken farms. The method is based on the earlier proposed idea of double digestion and selective labeling of DNA restriction fragments (DDSL). Bacterial genomic DNA is simultaneously digested with two restriction enzymes and labeled with biotinylated deoxynucleoside triphosphates with the presence of DNA polymerase. The enzymes are chosen in silico for each bacterial species so that a limited number of DNA fragments be generated for subsequent separation in conventional agarose gel. After implementation of the study with E. coli isolates, adequate reproducibility and high discriminatory power of the technique were demonstrated. This approach was previously applied to genotyping other pathogenic bacterial species. The advantages of the proposed technique are the short turn-around time of analysis and easy availability of reagents and equipment. Transmission of a pathogen among chicken within one farm and existence of slightly different E. coli genotypes in various organs of the same individual were observed. Bacterial isolates obtained from any organ except the intestine were suitable for genotyping. Chicken intestine contains endogenous E. coli strains, which hamper the interpretation of genotyping data obtained for a set of isolates. Thus, our work demonstrates the potential of the DDSL method for genotyping field E. coli isolates in the context of molecular epizootology