The aim of this study was to assess shelf life and nutritional value of apple juice, including the content of bioactive compounds, after pulsed electric field (PEF) treatment, taking into account different number of cycles: 4, 6, 8 (total 200, 300, and 400 pulses, respectively). Determination of vitamin C and polyphenols concentration, antioxidant activity as well as microbiological analysis were conducted immediately after PEF process and after 24, 48 and 72 h of storage. The results showed that PEF did not affect the content of bioactive compounds. PEF-treated juice did not show changes in the amount of vitamin C and total polyphenols during the storage for 72 h under refrigeration. PEF treatment was effective method for inactivation of a wide range of most common food spoilage microorganisms. PEF process can be used as an effective method of food preservation, allowing prolongation of shelf life and protection of nutritional value. This brings new opportunities for obtaining safe, healthy and nutritious food.

Due to the growing costs of agricultural production and the need to protect the environment, there has been a need to intensify activities leading to an increase in the effectiveness of natural biological processes. These measures should increase the biodiversity of the environment, enable the adaptation of microorganisms and the protection of plants and soils against the background of the concept of sustainable agricultural development. The soil is an important environment in which many elements are transformed, including nitrogen necessary for the proper yielding of plants. The aim of the article is to present the microbiological aspect of nitrogen transformation, starting with a review of historical findings and then to discuss the progress of the latest developments that have contributed to a detailed understanding of the biochemical reactions occurring during nitrogen transformation in soil. Moreover, the aim of the study is to present the current state of knowledge on the dynamics of nitrogen uptake and conversion by various species of microorganisms and the relationship between the activity of nitrogen microorganisms and nitrogen uptake by plants. The article also includes the latest information on the possibility of using microbiological biostimulants supporting plant growth (PGPR) and protection against the effects of phytopathogens.

The aim of the conducted research was to assess the effectiveness of the nitrification process, at different concentrations of ammonium nitrogen, in biologically treated wastewater in one of the largest municipal and industrial wastewater treatment plants in Poland. The studies also attempted to acclimate nitrifying bacteria to the limited concentration of ammonium nitrogen and determined the efficiency of nitrification under the influence of acclimated activated sludge in the biological wastewater treatment system. The obtained results indicate that the concentration of ammonium nitrogen above 60.00 mg·dm⁻³ inhibits nitrification, even after increasing the biomass of nitrifiers. The increase in the efficiency of the nitrification process in the tested system can be obtained by using the activated sludge inoculated with nitrifiers. For this purpose, nitrifiers should be preacclimated, at least for a period of time, allowing them to colonize the activated sludge. The acclimated activated sludge allows reducing the amount of ammonium nitrogen in treated sewage by approx. 35.0%. The process of stable nitrification in the biological treatment system was observed nine days after introducing the acclimated activated sludge into the aeration chamber.

Nanotechnology plays an important role in many fields of science and the economy. A special example of nanostructures is silver nanoparticles (AgNPs) created following the principles of green chemistry, i.e., without the use of toxic reducing compounds. The common tomato (Solanum lycopersicum) is a popular vegetable whose germination and growth process are studied by using, e.g., in vitro cultures. The aim of the experiment was to evaluate the inhibitory effect of the biodegradable gels containing silver nanoparticles on the development of microbial infection and to evaluate their influence on the germination degree of Tomato (Solanum lycopersicum) seeds in in vitro plant cultures. Based on macroscopic and microscopic observations, all experimental samples showed the presence of Gram-positive bacilli as well as mould fungi of the genus Rhizopus, Alternaria and Aspergillus. The study showed that the biocomponents containing silver nanoparticles obtained by using xylose as a reducing agent limit the development of microbial infection and stimulate the germination rate of tomato seeds. They could find their application as biodegradable raw materials in the production of modern disinfecting preparations for research in in vitro cultures. This study allowed to identify new research directions, especially to evaluate the metabolic regulation of seedlings treated with biodegradable silver nanoparticles.

Water reuse is now becoming a global necessity. However, one of the drawbacks in releasing wastewater into the environment is some persistent pollutants that are not completely removed in wastewater treatment plant. Residual bacteria and antibiotics in the inflowing wastewater can contribute to the antibiotic resistance spread in the aquatic environment. This study determined the effectiveness of activated sludge process for fecal coliform bacteria elimination, and also the Escherichia coli resistance to antimicrobial agents as erythromycin, azithromycin, clarithromycin, ofloxacin, ciprofloxacin, trimethoprim, and metronidazole in treated wastewater. The research was carried out using the membrane filtration technique, and the susceptibility of isolates to antimicrobial agents was tested by the disc diffusion method. The concentrations of fecal coliform bacteria and Escherichia coli differed significantly depending on the seasonal period in which it was carried out. Despite up to 99% reduction in the number of sanitary indicators in biologically treated wastewater, 89% of E. coli isolates resistant to the tested antibiotics was found, while 100% of the isolates were susceptible to metronidazole. Most of the isolates showed resistance to trimethoprim, and the fewest isolates were resistant to ofloxacin, indicating that some strains may react differently to antibiotics.

Due to the dynamic development of industry, related to the processing of plant materials and a subsequent significant increase in the number of employees working in this kind of industry, the indoor air quality is of great importance for the human health. The premises of plants processing plant materials are a specific environment, related to exposure to biological agents. The major sources of microbial contamination of premises are employees’ activities and the operation of devices used in the production process, quality of plant materials, technological processes, construction materials, ventilation (air-conditioning) systems, and outdoor air. Biological agents (primarily bacteria and fungi) transported in the air can cause numerous adverse health outcomes in exposed workers.