Field of Study – Ecology and Environmental sciences (N 012)

A large share of valuable organic resources is currently composted, although it could be transformed into high value-added biotechnological feedstock. In the context of the circular economy, increasing attention is being given to the ability of insects, particularly the yellow mealworm (Tenebrio molitor), to efficiently convert various agricultural and industrial by-products into high-quality proteins and organic fertilizers. However, the efficiency of this process strongly depends on the composition of the substrates used, which remains insufficiently explored. This study aims to determine which types and mixtures of organic waste optimize larval growth, biomass production, and feed conversion efficiency. It also examines how different substrates influence the chemical composition of larval frass and its potential as a sustainable organic fertilizer. This approach can reduce waste volumes, lower gas emissions, and decrease reliance on mineral fertilizers, thereby contributing to more sustainable agricultural systems.

The Baltic Sea is one of the most polluted seas in Europe, with more than 20,000 civilian and military shipwrecks recorded on its seabed. Approximately 10% of these wrecks are sources of hazardous chemicals, including fuel, oil, and ammunition residues. More than 80 years after World War II, degrading shipwrecks continue to release hazardous substances into the environment. However, the effects of these contaminants on marine biota remain insufficiently studied. This dissertation aims to assess the in situ ecotoxicological risk posed by shipwrecks to Baltic Sea biota. The research will be conducted in coastal areas of Poland, Lithuania, and Germany.

Lantanoidais legiruotų nanodalelių (LNDs), pasižyminčių išskirtinėmis fiziko-cheminėmis savybėmis, taikymas pažangiose technologijose ir biomedicinoje sparčiai plečiasi, todėl didėja šių medžiagų patekimo į aplinką, ypač vandens ekosistemas, rizika. Patekusios į vandens aplinką, nanodalelės gali keisti savo aglomeracijos, sedimentacijos, tirpimo bei biologinio prieinamumo savybes, sąveikauti su biologinėmis sistemomis ir kauptis maisto grandinėje, todėl jų poveikis biotai gali būti sudėtingas ir ilgalaikis. Nors nanodalelių poveikis vandens organizmams yra plačiai tiriamas, dauguma tyrimų orientuoti į trumpalaikes ekspozicijas ir ūmaus poveikio vertinimą. Tuo tarpu ilgalaikis ir ypač transgeneracinis LNDs poveikis, pasireiškiantis palikuonių kartose, tebėra nepakankamai ištirtas ir apsunkina objektyvų šių medžiagų ilgalaikės rizikos vertinimą, kadangi transgeneraciniai efektai gali paveikti ne tik pavienių individų fiziologinę būklę, bet ir populiacijų stabilumą bei vandens ekosistemų tvarumą ilgalaikėje perspektyvoje. Atsižvelgiant į tai, disertacijoje bus siekiama sistemiškai įvertinti lantanoidais legiruotų nanodalelių ilgalaikį ir transgeneracinį poveikį skirtingų trofinių lygmenų vandens organizmams. Tyrimai bus atliekami kontroliuojamomis laboratorinėmis sąlygomis, taikant biologinių testų kompleksą ir vertinant organizmų atsaką fiziologiniu, biocheminiu ir molekuliniu lygmenimis, ypatingą dėmesį skiriant pokyčiams, pasireiškiantiems palikuonių kartose. Disertacijos tikslas – ištirti ilgalaikį ir transgeneracinį LNDs poveikį skirtingų trofinių lygmenų vandens organizmams, kompleksiškai vertinant jų biologinį atsaką. Tikimasi, kad gauti rezultatai prisidės prie gilesnio transgeneracinio nanodalelių poveikio supratimo, leis tiksliau prognozuoti galimą šių medžiagų riziką vandens ekosistemoms ir suteiks mokslinį pagrindą tobulinant aplinkos rizikos vertinimo bei nanomedžiagų reglamentavimo principus.
The expanding application of lanthanide-doped nanoparticles (LNDs) in advanced technologies and biomedicine increases the likelihood of their release into aquatic environments. Due to their distinctive physicochemical characteristics, LNDs can undergo transformations within natural waters, altering their bioavailability and interacting with biological systems. These substances can also accumulate within food webs, potentially resulting in complex and long-term ecological effects. Despite the extensive research conducted on the ecological effects of nanoparticles, the majority of studies have focused on short-term exposures and acute toxicity endpoints. Conversely, the long-term and especially transgenerational effects of LNDs remain inadequately understood. The effects manifested in subsequent generations may extend beyond the directly exposed individuals, influencing physiological performance, population stability, and ultimately the sustainability of aquatic ecosystems. This discrepancy hinders the comprehensive evaluation of the long-term environmental risks associated with nanomaterials. In response to this challenge, the dissertation aims to systematically investigate the long-term and transgenerational effects of lanthanide-doped nanoparticles on aquatic organisms representing different trophic levels. The research will be conducted under controlled laboratory conditions using integrative biological testing approaches to assess organismal responses at the physiological, biochemical, and molecular levels. Particular attention will be paid to effects emerging in offspring generations. The objective of the dissertation is to evaluate how long-term exposure to LNDs may induce biological alterations that persist across generations. The results of this study are expected to further advance the scientific understanding of transgenerational nanoparticle effects and contribute to the enhancement of environmental risk assessment frameworks for nanomaterials.

Chemical pollution and habitat alteration are among the principal anthropogenic drivers reshaping riverine and marine ecosystems, directly influencing fish migration dynamics, reproductive success, and population viability. In migratory salmonids, ecological processes such as spawning-site selection, homing behaviour, spawning success, and migration timing are tightly linked to both environmental conditions and contaminant exposure. However, current monitoring frameworks remain largely compartmentalized, emphasizing either chemical status or ecological indicators, while insufficiently addressing the mechanistic links between environmental contamination, fish health, and ecological performance. This doctoral research will adopt an integrated ecological–ecotoxicological approach, focusing on the spawning migrations of Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) in Lithuanian river systems.
The core of the study will examine ecological determinants of upstream spawning migration, including hydrological regime, temperature, habitat structure, connectivity, and spawning-ground suitability. Particular attention will be given to the assessment of spawning habitat quality and to evaluate how these variables interact with contaminant loads in water, sediments, and biota. Parallel investigations will quantify environmental pollutants and their accumulation in fish tissues, enabling analysis of relationships between contaminant burdens, physiological condition, and spawning success. By linking ecological performance metrics (migration timing, site fidelity, reproductive indicators) with ecotoxicological biomarkers, the study will seek to clarify how chemical stressors influence migration efficiency and reproductive outcomes.
To assess individual behaviour and river fidelity, adult fish will be marked with internal radio-frequency identification (RFID) tags, allowing long-term monitoring of return rates, homing accuracy, and interannual site consistency. Complementary laboratory experiments will compare the physiological and behavioural impacts of different tagging methods (internal versus external tags), evaluating stress responses, growth, condition indices, and selected biochemical and hematological parameters over time. Additional field experiments may include tagging juvenile salmonids prior to release into the Kaunas Reservoir to quantify migration speed, dispersal patterns, and survival in altered ecosystems, thereby integrating early life-stage ecology into the broader migration framework.
A substantial component of the research will address how ecotoxicological factors influence migratory behaviour, orientation, and overall fitness. The study will evaluate cytogenetic, biochemical, and physiological biomarkers in relation to contaminant exposure, with the objective of identifying early-warning indicators of sublethal pollution effects that may alter migration performance or spawning success. Comparative analyses among rivers with differing pollution profiles and habitat conditions will enable the establishment of ecological–toxicological baselines for Lithuanian salmonid populations.
By integrating habitat assessment, behavioural ecology, migration monitoring, and contaminant analysis, this research aims to elucidate cause-and-effect relationships between environmental quality, fish health, and reproductive performance. The findings will contribute to the development of ecologically meaningful monitoring tools that combine biological effect indicators with traditional chemical assessment, thereby supporting adaptive management of salmonid populations and advancing ecosystem-based evaluation of riverine and transitional waters.

The spruce bark beetle (Ips typographus) is one of the most important pests of coniferous forests in Europe, causing significant damage to spruce stands. Its increasing spread, driven by climate change, is encouraging the search for new, sustainable control measures that complement traditional methods. The aim of this study is to evaluate the pathogenicity of entomopathogenic nematodes against the spruce bark beetle and their suitability for its biological control. The results are expected to contribute to the development of new environmentally friendly forest protection measures.

Varroa mites and Ixodes ticks pose a significant threat to beekeeping and public health by transmitting dangerous diseases. Traditionally used synthetic acaricides and repellents lead to parasite resistance, leave chemical residues in products, and cause skin irritation, highlighting the urgent need for sustainable alternatives. Although organic products are becoming more common in the market, most are imported, and the potential of local flora remains insufficiently explored. The aim of this study is to evaluate the acaricidal and repellent effects of selected local plant extracts. During the study, plant extracts will be obtained using distillation and various solvents, and their chemical composition will be analyzed via gas chromatography-mass spectrometry. Laboratory tests will evaluate the effects of the extracts on mites and ticks, determining the lethal concentration and optimal repellent doses. These data will provide a scientific basis for developing natural, environmentally safe control measures and reduce reliance on synthetic chemicals.

Fungi play an important role in grasslands and sandy habitats; as participants in decomposition processes, they contribute to the breakdown of organic matter, maintain soil structure, and support plant nutrition through mycorrhizal interactions. Mycorrhizal relationships between plants and fungi are known to some extent, but knowledge of other plant-fungus interactions in grasslands and sandy habitats remains fragmented. There is still a lack of knowledge regarding how changes in plant diversity affect fungal diversity and how fungal diversity influences the structure, stability, and diversity of grassland plant communities. The rapid decline in natural grassland areas across Europe following the introduction of mechanized agricultural production was one of the main factors contributing to the loss of biodiversity in the second half of the 20th century.

The study’s target habitats are sandy areas and grassland habitats. The term “meadow fungi” can be applied to all fungi growing in meadows, but in this study, the term is used for macroscopic fungi associated with natural meadows that have been intensively grazed or regularly mowed and have not been fertilized or plowed for a long time. The fungi found in such habitats constitute a taxonomically diverse but ecologically related group of species from the Clavariaceae, Hygrophoraceae, Entoloma, Geoglossaceae, and Dermoloma taxa, otherwise known by the acronym CHEGD, formed from the first letter of each taxon.

Insects perform various functions in ecosystems and one of the most important in anthropogenic landscapes is biological control. The biological control potential of an individual, species population or the assemblage of species may vary depending on intrinsic and extrinsic environmental factors. Ground beetles (Carabidae) are among the main biological control agents in agroecosystems. These beetles often actively hunt pests and consume weed seeds in agricultural fields where they are exposed to various pesticides. However, it is not known whether and how such sublethal pesticide exposure may alter the feeding behavior of an individual or species, and consequently affect their biological control potential. The project consist of two subtopics investigating factors affecting functionality at individual and carabid community levels. The first subtopic will aim to determine whether and how carabid microbiota differs depending on pesticide exposure and whether microbiota composition may be associated with differences in feeding behavior. The second subtopic will examine the expected negative relationships between carabid functional diversity and anthropogenic factors within ecosystems (including pesticides). Together, the study will reveal the likely negative relationships between organism-to-community functionality and sublethal pesticide exposure.

Expertise in aculeate Hymenoptera, their ecology, behavior, trophic links, and ecosystem functions, as well as the ability to identify their species using contemporary methods, is relevant because:

• these insects provide ecosystem services such as plant pollination and pest control, which are important for both natural and agricultural ecosystems;
• the EU Green Deal program emphasizes the decline of pollinators, and member states are committed to monitoring their population status, which requires the expertise in their species’ identification;
• the venom composition of aculeate Hymenoptera is species-specific, thus ability of their credible identification is essential from an allergological perspective.

Species with known variability of the COI-5′ marker used for molecular identification (barcoding) will be selected for study. Variability of their cuticular hydrocarbon (CHC) composition, which is behaviorally used to recognize a conspecific mating partner, prey, host nest, and kleptoparasite visits in the latter, will be investigated. Using these species as a model, the following hypotheses will be tested:

1. COI-5′ variation is congruent with the variation of other DNA markers and the CHC composition, thus indicates cryptic speciation (will be tested using species delimitation algorithms and phylogenetic distances; the result is important for the identification of sibling species).
2. COI-5′ and CHC variation are related to the ecological interactions between hosts and kleptoparasites and chemical mimicry (the ability of different parasitoids to recognize the CHC of different host mitotypes will be assessed; the result is important for understanding of species ecology and mechanisms of sympatric speciation).
3. COI-5′ and CHC variation is caused by the adaptation of individual populations to anthropogenic environments (differences between populations from semi-natural and anthropogenic ecosystems will be tested; the result is important for pollinator conservation).

The White Stork (Ciconia ciconia) is an indicator of an ecological, healthy environment and sustainable agriculture. It is a protected bird species – listed in the first annex of the European Union‘s Birds Directive, which places special emphasis on the conservation of bird species in Europe. The breeding population of the White Stork in Lithuania is by far the densest and one of the most abundant in the species’ range. Intensive anthropogenic impact (changes in agriculture, changes in the proportions of landscape fragments, destruction of wetlands, development of wind farms and high-voltage overhead power lines) has a negative impact on White Storks in their breeding grounds and along their migratory route. The quality of foraging habitats determines the survival and breeding quality of the population as a whole and of individuals. The White Stork is a long-distance migrant. Global climate change is affecting birds, especially long-distance migrants: population abundance and range boundaries may change.

Studies of the foraging habitats of White Storks at breeding sites, stopover sites during migration and wintering grounds are of great importance for determining the causality between changes in population parameters and the specificity of habitat use and the impact of anthropogenic and natural factors.

The specifics of White Storks’ foraging habitat use in the annual cycle: at breeding sites, during migration and on wintering grounds will be determined by analysing telemetry data obtained by tagging White Storks with GPS transmitters (the data have been collected in the Laboratory of Avian Ecology since 2015). The abundance, spatial distribution and breeding success of White Storks in the study area will be determined, as well as the factors influencing them. Breeding habitat characteristics of White Storks will be determined. The relationship between the annual cycle of foraging habitat use and population parameters will be established.

In Lithuania, there are about 1,500 sites called hillforts, although not all of them are true ones (Zabiela, 2005). According to the data of the Department of Cultural Heritage under the Ministry of Culture, there are currently 931 hillforts registered in Lithuania, of which 209 have the status of state protected objects (Summary of the Register of Cultural Values, 2024). As most of the hillforts are maintained by state parks, they are not allowed to become overgrown with shrubs or forest, which results in relatively sustainable open habitats rich in economic plant species such as medicinal and aromatic plants, and crop wild relatives. This approach, which also conserves in situ biodiversity resources by protecting specific sites (in this case, archaeological heritage sites such as hillforts) outside the network of state protected areas, has recently been recognised internationally as an important concept – “Other effective area-based conservation measures” (OECM) (CBD, 2018). Although the research on economic plants on Lithuanian hillfort sites is still in its initial phase, it is already possible to predict its viability. Conservation planning of target species on hillfort sites largely avoids the conflicts of interest that are typical in other cases of land use. In addition, the coverage of some target species populations is significantly increased as hillforts’ distribution is quite wide across the country. One of the main research objectives within this theme is to assess at a national scale which economic plant species and at what population abundance can be effectively conserved on hillfort sites. This research would contribute to the implementation of the national biodiversity conservation strategy of Lithuania, as well as to a more comprehensive assessment of the country’s wild economic plant flora and to the improvement of the use of these resources.

Corn mint (Mentha arvensis, Lamiaceae), common in the middle-latitude climatic regions of Eurasia,is both a weed and a medicinal plant, the essential oil of which is included in the European Pharmacopoeia (European Pharmacopoeia, 2024). Plants of this species can intensively spread vegetatively as a weed with their creeping, abundant branched rhizomes and influence the growth and development of neighbouring plants through the allelopathically active biochemical compounds released from the underground parts into the soil. Due to gynodioecy characteristic of generative reproduction and intensive interspecific crossing, corn mint is characterized not only by a large interspecific diversity of morphological and anatomical features, but also by chemical polymorphism. Corn mint is the main source of natural origin menthol, widely used in food, pharmaceutical and other industries. This compound can make up to 80% of the essential oil of corn mint, but according to exploratory and unpublished research data, menthol has not been detected in plants of this species growing wild in Lithuania. Polymorphism is significantly influenced by the environment in which the plant grows. Therefore, the aim of the work should be to investigate the relationship between the corn mint polymorphism and environmental conditions, determining which chemotypes of corn mint are common in Lithuania and how this distribution depends on the environment. The allelopathic properties of different chemotypes of corn mint will also aim to determine.

From a scientific and environmental point of view, understanding how environmental factors and impacts, including anthropogenic ones, can affect the hydrology of rivers, their water quality and related to river basin ecosystems is essential. At the moment, there is an increased interest of possible emissions from the Belarusian nuclear power plant (NPP) and the response of the environment to them. Whereas the probability of sudden incidents of a large impact on the environment at nuclear power plants are minor, but when they occur lead to different level consequences due to sudden and strong destructive properties. One of the purpose of this work would be to create a predictive model of the Neris River assessing the impact of possible events leading to environment pollution. With the consequences of such events, we must learn to live, at least reasonably from a scientific point of view. Also, based on isotopic studies of the water system, to develop a dynamic model for tracking pollution sources, which could characterize the relationship between the water system and the source of risk, is of primary importance.
River systems are very complex, so modeling is one of the important tools that can show the impact of different events under different conditions. The developed risk assessment model would be an effective tool for systematically quantify random uncertainty due to processes in the river system, as well as providing information when making decisions on the control of sudden water pollution, identifying critical sources and quantities of pollution. For the implementation of the work, isotopic research methods and a modern modeling program would be used.
The importance of the transfer of tritium in aquatic ecosystems was highlighted in studies performed in Canada and France (CNSC 2010; ASN 2010). Calibration of the transport model according to tritium data in rivers and modeling of the groundwater age was carried out in the western basin of Lake Taupo, New Zealand (Gusyev et al. 2013). To better understanding the transport process simulation of HTO from surface water to the atmosphere was carried out (Marang et al. 2011). Modeling of groundwater discharges into the river based on radon mass balance using tritium data was performed on the Elbe River, Germany (Schubert et. al 2020). The characterization of water systems is therefore an important for both issues such as construction of new nuclear power plants and the decommissioning of old ones. Transport models realize a mathematical description of the movement of radionuclides in a particular component of the environment (air, surface water, groundwater, biota) the purpose of which is to predict the concentration of radionuclides. In Lithuania, investigations of water systems using modelling tools were carried out mostly in relation to groundwater. Number of studies have focused on the formation of groundwater in the Baltic Artesian Basin (Vaikmäe et al., 2001; Cheban, 1966; Mokrik and Vaikmäe, 1988, Mokrtik et al. 2014; Mokrik and Samalavičius, 2021). The research interests include various aspects of palaeohydrogeology, origin issues and formation scenarios. Isotopic studies of the hydrological cycle including precipitation, streams and lakes, groundwater and other water bodies were performed since the beginning of operation of the Ignalina Nuclear Power (Jakimavičiūtė-Maselienė et al. 2012; Vaitkevičienė et al. 2013; Mazeika et al. 2013; Jefanova et al. 2018).
Because of the tritium mobility in hydrological cycle and well-known atmospheric abundance it is of great importance in line with other mobile radionuclides to carry out tritium measurements in the water bodies surrounding nuclear facilities and use data fot the environmental quality and risk assessment.

Due to their functional and magnetic characteristics, graphene and iron-based nanocomposites have attracted remarkable scientific and economic interest in biotechnology and nanomedicine. In recent years, there has been a significant focus on the practical application of functionalized magnetic adsorbents in water purification processes, particularly when combined with magnetic separation technologies. Considering that the production and use of nanomaterials will only increase in the future and that legal regulation of these materials in the manufacturing and waste management sectors has yet to be implemented, research on the impact of these nanoparticles on aquatic organisms in the context of a changing environment becomes important.

Magnetic nanoparticles possess a magnetic moment, enabling them to generate a magnetic field or respond to one. The primary sources of (electro)magnetic fields are wind turbines and their accompanying infrastructure. The development of renewable energy resources is gaining momentum worldwide, including in Lithuania. A 700 MW wind turbine power station is expected to be operational in Lithuanian territorial waters in the Baltic Sea by 2028. However, there is currently a lack of scientific evidence regarding the effects of (electro)magnetic fields on species in marine ecosystems.

The examination of these materials’ shape and functional properties will include parts of the synthesis, modification, and characterization of specific graphene and iron nanoparticles, as well as their nanocomposites. The hazardous effects of these nanomaterials on fish and invertebrates will be examined at several levels of biological organization to find patterns of nanoparticle impacts on organismal functional systems, biochemical and behavioral response patterns, and probable toxicity pathways. Comparative studies will be conducted on the anthropogenic effect of (electro)magnetic fields on aquatic organisms, employing sophisticated indicators of biological response and biomarkers. The regularities of nanoparticle toxicity will be investigated in the relationship between (electro)magnetic fields and chemical stress to better represent the effect of the multifunctional environment on the biological accessibility and toxicity of nanoparticles. The findings may be used to forecast potentially harmful quantities of these nanomaterials in the environment, as well as their interactions with physical stressors, which might generate complicated biological impacts in the context of a changing environment.

Amphipod crustaceans play a key role in macroinvertebrate communities and the diets of bentophagous fish in lakes. As part of global change, in many places, native amphipods are being displaced by the invasive ones from the Ponto-Caspian region (the lower basins of the Black and Caspian seas). In Lithuanian lakes, intentionally introduced alien amphipods have spread the most, but soon they will also have to face competition from the aggressive self-dispersed compatriot species. Temperature and dissolved oxygen should be investigated as the primary factors that determine the species’ competitiveness and the likely changes in the amphipod assemblages as the climate warms and lake productivity increases. In turn, amphipod species differ in their preferences to feed on plant detritus, filamentous algae, fine organics, or small animals. Shifts in their assemblages can thus lead to significant changes in lake functioning. This work aims to investigate the competitiveness, dietary preferences, and potential effects on lake functions of native and invasive amphipods that occur or are spreading across the lakes of our region under warming climate conditions. The topic foresees laboratory and field studies on the influence of temperature on oxygen consumption (1) and coexistence (2) of amphipod species, their feeding preferences (3), and the influence of amphipod assemblages on the functional structure of macroinvertebrate communities and the overall function of detritus shredding (4). The results will significantly contribute to the ecological knowledge of invasive species spreading across Europe and will help to predict shifts in amphipod assemblages as well as the associated ecosystem changes.

The increased utilization of lanthanide-doped nanoparticles (LNPs) in various industries and biomedicine, due to their unique physicochemical properties, has led to an escalating concern regarding their entry into the environment, particularly into aquatic ecosystems. The processes of agglomeration, sedimentation, dissolution etc. of LNPs and other metal-based nanoparticles as observed in laboratory settings, are susceptible to alteration upon exposure to the environment, rendering them difficult to predict. Aquatic ecosystems are characterized by the presence of diverse species of organisms, each exhibiting varying degrees of sensitivity to nanoparticle exposure. However, it is the most sensitive species within these ecosystems that are most likely to respond to nanoparticle exposure. The presence of nanoparticles (NPs) in the environment has the potential to accumulate within the food chain, thereby posing a threat not only to extant aquatic animals and plants, but also to future generations and human health. The central aim of this dissertation is to study the response of organisms of different trophic levels to long-term exposure to newly created LNPs, and to assess the impact of this exposure on the sustainability and viability of aquatic ecosystems using a set of biological tests. The results obtained during the present study will be useful in assessing the long-term impact of LNPs on organisms in order to protect future generations, ensure the optimal state of the physiological, immune and reproductive systems of organisms, and clarify possible mechanisms of the impact of LNPs on future generations of aquatic organisms (algae, crustaceans, fish) and predict the possible risk of these NPs for the sustainability of aquatic ecosystems with constant exposure to nano[articles. The objective is to identify organisms and biomarkers that are most sensitive to the long-term effects of LNPs. In addition to traditional methods used in ecotoxicology, innovative systems for conducting, recording and analyzing experiments will be used. The transgenerational and multigenerational impact of LNPs on sensitive species of aquatic organisms of different trophic levels will be studied, depending on the physicochemical properties of nanoparticles, possible mechanisms of such impact and the nature of the impact. The predicted risk of long-term impact of LNPs on the aquatic environment will also be determined. The obtained results will be used to regulate the release of NPs into the environment.

Yeasts are a specific group of microscopic fungi that can function on a variety of substrates. The distribution, biological and ecological characteristics of medically important yeasts in the human environment have been little studied in Lithuania. There is also little data on the interaction of these yeasts with other microorganisms. The isolation and identification of yeasts from different substrates of the human environment as well as determination their morphological, physiological and biochemical characteristics are envisaged in this study. Assessment of their ability to assimilate different carbon sources and investigation of the enzymatic (urease, protease, lipase, cellulase) activity of these microorganisms will be conducted. Furthermore, their ability to develop in vitamin-free media and to produce organic acids and starch-like compounds will be assessed. The interactions of the isolated yeasts with other microorganisms on the substrate will be evaluated and the influence of different abiotic factors on their growth will be determined. Chemical and biological means to limit the activity of these microorganisms in the human environment will be identified. The results of the study will be used to regulate yeast activity and to improve the microclimate of the human living and working environment.