Aleksandra Burkowska

Chitinolytic Microorganisms and Their Possible Application in Environmental Protection

This paper provides a review of the latest research findings on the applications of microbial chitinases to biological control. Microorganisms producing these enzymes can inhibit the growth of many fungal diseases that pose a serious threat to global crop production. Currently, efforts are being made to discover producers of chitinolytic enzymes. The potential exists that natural biofungicides will replace chemical fungicides or will be used to supplement currently used fungicides, which would reduce the negative impact of chemicals on the environment and support the sustainable development of agriculture and forestry.

Municipal landfill sites as sources of microorganisms potentially pathogenic to humans

The present research was aimed at assessing the quality of air and soil on the premises and in the vicinity of the municipal landfill sites in Toruń with regard to the presence of pathogenic bacteria, potentially dangerous to humans. Air samples (the impaction method using a MAS-100 impactor) and soil samples were collected from seven sampling sites including the operating and closed landfill cells, sampling sites located near leachate ponds, and sampling sites located outside the above premises. The research also involved assessing microbial air contamination in three indoor spaces on the premises of the landfill sites. Microbial tests involved the determination of the number of culturable mesophilic, mannitol-positive, and α- and β-hemolytic bacteria in the air, determination of the number of coliform bacteria, spore-forming Clostridium perfringens in soil, and the presence of Salmonella in soil. The results indicate that bioaerosol emitted by this municipal facility is the source of hemolytic bacteria (≤ 300 CFU m(-3) of air), as well as of pathogenic bacteria (Pseudomonas aeruginosa and Bacillus subtilis). The highest risk of exposure to biological agents was determined in the sorting facility. Over sixty percent of air samples in this sampling site presented high pollution degree with mesophilic bacteria (500-2000 CFU m(-3) of air) and over one fourth of air samples presented very high pollution degree (>2000 CFU m(-3) of air). Indoor air in other rooms was considered highly/moderately contaminated (100-2000 CFU m(-3) of air). The highest risk related to the presence of Salmonella, Clostridium perfringens, and coliform bacteria in soil was determined at the operating landfill cell and near the leachate pond of the closed landfill cell. At the operating landfill cell the total coli ranged from 4-1226 MPN g(-1) of dry mass of soil and Clostridium perfringens ranged from <LOD-1604 CFU g(-1) of dry mass of soil. The results question the strategy of municipal landfill sites in densely populated areas, and emphasize the need for regular monitoring of microbiological tests in their vicinity as well as for control strategies in order to protect workers at landfill sites. The results of the study should be used for future decisions on the location of municipal landfill sites and suggest the need for better environmental control technologies in the sites that are already functioning.

Coexistence of Legionella pneumophila Bacteria and Free-Living Amoebae in Lakes Serving as a Cooling System of a Power Plant.

The study was aimed at determining whether potentially pathogenic free-living amoebae (FLA) and Legionella pneumophila can be found in lakes serving as a natural cooling system of a power plant. Water samples were collected from five lakes forming the cooling system of the power plants Pątnów and Konin (Poland). The numbers of investigated organisms were determined with the use of a very sensitive molecular method—fluorescence in situ hybridization (FISH). The result of the present study shows that thermally altered aquatic environments provide perfect conditions for the growth of L. pneumophila and amoebae. The bacteria were identified in the biofilm throughout the entire research period and in the subsurface water layer in July and August. Hartmanella sp. and/or Naegleria fowleri were identified in the biofilm throughout the entire research period.

Purification and characterization of Streptomyces albidoflavus antifungal components

Chitinolytic strain Streptomyces albidoflavus was isolated from soil of the central region of Poland. Its identification was based on analysis of 16S rRNA gene sequence. The colloidal chitin was revealed as the finest substrate for the production of chitinases by S. albidoflavus. The enzyme catalyzed the hydrolysis of the disaccharide 4-methylumbelliferyl-β-D-N,N′,N″-triacetylchitotriose most efficiently and was, therefore, classified as an endochitinase. The chitinase of S. albidoflavus was purified by applying the two-step procedure: fractionation with ammonium sulphate and chitin affinity chromatography. The molecular weight of the purified enzyme determined by SDS-PAGE was approximately 50 kDa. The enzyme was characterised as thermostable during 180 min of preincubation at the temperature of 35°C and 40°C. The activity of the enzyme was strongly inhibited in the presence of Hg2+ and Mn2+ ions, SDS but stabilized by Ca2+ and Mg2+ ions. Both purified and crude chitinases from S. albidoflavus inhibited the development of fungal phytopathogens. Purified chitinase inhibited the growth of Alternaria alternata, Fusarium culmorum, Fusarium oxysporum and Botrytis cinerea. Additionally, the crude chitinase inhibited the growth of Fusarium solani.

Synthesis and biocidal activity of novel N-halamine hydantoin-containing polystyrenes

Abstract Three homopolymers containing hydantoin substituents were obtained by chemical modification of reactive p-chloromethylated polystyrene. The prepared polymers were chlorinated to yield N-halamine materials with biocidal properties. The chemical structure of polymers was characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. All of the hydantoin polymers are insoluble in water and common organic solvents. Microbiological investigations prove the high biocidal activity of the obtained chlorinated polystyrene derivatives containing spirohydantoin moieties. The obtained polymers will be useful in designing and constructing medical and pharmaceutical equipment. The ability to crosslink allows to expect easy grafting of these biocidal macrochains, for example, on textiles.

Microbial activity in the landfill soil

The research objective was to determine the activity of microorganisms in the soil exposed to direct influence of a landfill, as well as in the soil beyond its influence. Fluorescein diacetate (FDA) hydrofytic activity and respiration in the soil were determined. The highest number of cultivated bacteria was recorded at the site located within the zone of direct influence exerted by the landfill, whereas the least amount was found at a distance of 1000 metres from the landfill. In contrast, the largest numbers of molds were observed in the soil at a distance of 1000 m from the headquarters of the landfill. The highest FDA hydrolytic activity and biological oxygen demand (BOD5) were recorded in the soil by the headquarters of the landfill, and the least parameters were revealed at a distance of 1000 m from the landfill. It was found a high correlation between the number of bacteria and FDA hydrolytic activity of soil and BOD5 in the north-eastern of the landfill. However, in the same place, there is a low correlation between the number of molds, and FDA hydrolytic activity of soil and BOD5.