Simple low-cost, nontoxic, environmentally friendly plant-extract-based polymer films play an important role in their application in medicine, the food industry, and agriculture. The addition of silver nanoparticles to the composition of these films enhances their antimicrobial capabilities and makes them suitable for the treatment and prevention of infections. In this study, polymer-based gels and films (AgRonPVA) containing silver nanoparticles (AgNPs) were produced at room temperature from fresh red onion peel extract (“Ron”), silver nitrate, and polyvinyl alcohol (PVA). Silver nanoparticles were synthesized directly in a polymer matrix, which was irradiated by UV light. The presence of nanoparticles was approved by analyzing characteristic local surface plasmon resonance peaks occurring in UV-Vis absorbance spectra of irradiated experimental samples. The proof of evidence was supported by the results of XRD and EDX measurements. The diffusion-based method was applied to investigate the antimicrobial activity of several types of microbes located in the environment of the produced samples. Bacteria Staphylococcus aureus ATCC 29213, Acinetobacter baumannii ATCC BAA 747, and Pseudomonas aeruginosa ATCC 15442; yeasts Candida parapsilosis CBS 8836 and Candida albicans ATCC 90028; and microscopic fungi assays Aspergillus flavus BTL G-33 and Aspergillus fumigatus BTL G-38 were used in this investigation. The greatest effect was observed on Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa bacteria, defining these films as potential candidates for antimicrobial applications. The antimicrobial features of the films were less effective against fungi and the weakest against yeasts.

UV-initiated green synthesis of metal nanoparticles by using plant extracts as photoreducing agents is of particular interest since it is an environmentally friendly, easy-to-maintain, and cost-effective method. Plant molecules that act as reducing agents are assembled in a highly controlled way which makes them suitable for metal nanoparticle synthesis. Depending on the plant species, their application for green synthesis of metal nanoparticles for diverse applications may contribute to the mediation/reduction in organic waste amounts, thus enabling the implementation of the circular economy concept. In this work, UV-initiated green synthesis of Ag nanoparticles in hydrogels and hydrogel’s thin films containing gelatin (matrix), red onion peel extract of different concentrations, water, and a small amount of 1 M AgNO₃ have been investigated and characterized using UV-Vis spectroscopy, SEM and EDS analysis, XRD technique, performing swelling experiments and antimicrobial tests using bacteria (Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa), yeasts (Candida parapsilosis, Candida albicans) and microscopic fungi (Aspergillus flavus, Aspergillus fumigatus). It was found that the antimicrobial effectiveness of the silver-enriched red onion peel extract–gelatin films was higher at lower AgNO₃ concentrations as compared to those usually used in the commercially available antimicrobial products. The enhancement of the antimicrobial effectiveness was analyzed and discussed, assuming the synergy between photoreducing agent (red onion peel extract) and silver nitrate (AgNO₃) in the initial gel solutions leading to the intensification of Ag nanoparticles production.

The intensive use of oil products is one of the most significant problems of environmental pollution. They pollute water, soil, and air. For these reasons, the search for effective methods of oil biodegradation is very important for solving environmental problems. The research aimed to isolate and select oildegrading microorganisms and to investigate their effectiveness in oil-contaminated soil “ex-situ”. Using microorganisms isolated from the contaminated soil, a biopreparation was developed consisting of bacteria, yeast and filamentous fungi. Microorganism isolates were identified using MALDI-TOF mass spectrometry (Bruker, USA). The biopreparation was tested in the soil treatment sites of GVT LT, Ltd (Kiškėnai village, Dovilai eldership, Klaipėda district) in two test variants. The count of microorganisms (CFU/g) in the soil was determined at the beginning of the research, after two weeks and every month thereafter until the end of the cleaning season by serial dilution method in media with 1% of diesel. The content of oil products (g/kg) was determined with the same periodicity according to LST EN ISO 16703. An effective biopreparation for the degradation of oil hydrocarbons has been developed. Within 5 months, it reduced the amount of oil products to 61,7% in variant No. 1 and 58,7% in variant No. 2.

The study aimed to investigate the prevalence and biodiversity of yeasts in the soil and water samples of the city and district of Alytus after a fire at a tire processing plant. 11 soil and 3 water samples were taken each year for the periods of 2019-2021. The yeast count in the soil samples ranged from 102 to 105 CFU/g. In water samples, the count of yeasts varied between 0.00-103 CFU/g. A total of 114 yeast isolates were isolated from the soil samples and 46 yeast species were identified. No statistically significant changes in the phyla distribution of yeast species isolated from the soil were observed during the different study periods. A total of 25 yeast isolates were isolated from the water samples and 14 yeast species were identified. Statistically significant differences in the phyla distribution of yeast species isolated from water samples were observed. The obtained research data showed that the results of all chemical soil tests do not exceed the limit values specified in Lithuanian legal acts. The obtained results of the study allow us to state that the fire at the tyre recycling plant did not affect the prevalence and biodiversity of soil yeasts, but the possibility that the effect will be noticed after a longer period of time cannot be ruled out. We believe that this study significantly contributes to the dissemination of information about the fire at the tire recycling plant and its impact on the environment, brings more clarity and reduces doubts about the possible impact of pollution on the environment.