An interest in cellulases free beta- 1,4-xylanase production has markedly increased in resent years due to its application in bleaching of kraft pulp and in the food industry. In the presented paper the influence of addition of hemicelluloses obtained from different sources on the formation of xylanases during cultivation of Trichoderma reesei strains in relation to cellulases was investigated. Replacement of lactose as a source of carbon of xylan from birchwood (Sigma) during batch cultivation of two Trichoderma reesei strains in the temperature 34°C caused 9 and 7-time increasing of xylanolytic activities and simultaneous decreasing of cellulolytic activities. Commercial preparation of xylan from birchwood (Sigma) appeared to be the best inducer for the production of xylanases during batch cultivation of Trichoderma reesei strains. Xylose was the main product of enzymatic hydrolysis of hemicelluloses obtained from different sources The highest concentration of xylose has been estimated after hydrolysis of hemicelluloses from oak sawdust (1 and 2 hours preparation).

The effect of enzyme preparation Ultraflo L on the features of congress worts and worts obtained from malts extract after dilution in water were determined. It was stated that the application of Ultraflo L preparation makes the filtration of congress worts more efficient, decreases of their viscosity and does not cause the worts carbohydrates profile during their concentrating in vacuum evaporator and during drying in spray drier.

The aim of work was to suggest a mashing programme for malts highly modified by proteolysis. Malts were obtained with addition of formaline and Geotrichum candidum starter cultures during steepping process of barley grain. Malts were mashed using congress (45°C 30 min., 70°C 60 min.) and modified (65°C, 90 min.) programme. Modification of mashing programme had no influence on wort filtration, viscosity and extract content. On the other hand it caused the amount of amino compounds to decrease and the colour of wort to brighten.

The aim of the work was to obtain fusants of Saccharomyces and Schwanniomyces yeast strains. Biological material was composed of: Schwanniomyces occidentalis ATCC 48086, S. cerevisiae V30, D43. Natural feature: the growth of Schwanniomyces strain in medium with cykloheximide and the growth of Saccharomyces at temp. 40°C afforded possibilities for selection of 33 intergeneric fusion products. As a result of DNA analysis two hybrids of Saccharomyces and Schwanniomyces containing DNA of both parental strains were identified.

The aim of this study was established the sensibility of different Listeria strains on divercin activity. Efficacy of divercin in combination with thermal treatment against Listeria monocytogenes was also examined. The results of this study showed the strongest divercin activity against Listeria monocytogenes at temperature of 4–10°C. The heating had also favourable effect on divercin activity. This process increased Listeria cells sensibility on divercin and broadened its spectrum of activity. It was proved that using divercin in combination with limited thermal treatment may be better method for food protection against Listeria and another foodborne pathogens contaminations.

The aim of the research was to obtain interspecific hybrids of distilling yeast Saccharomyces cerevisiae D₄₃ and xylose-fermenting yeast Yamadazyma stipitis ATCC 58376. Medium containing xylose as the sole carbon source and incubation temperature (42°C) was used for selecting hybrids. As a result of the fusion of protoplasts in polyethylene glycol, 9 stable mutants were obtained. Electrophoretic analysis of the products of PCR confirmed recombination of DNA of parental strains.

Viability and preservation of biotechnological characteristics by citric acid producer Y. lipolytica A-101-1-31 strain during long term storage were studied. There was proved that yeasts can be preserved on agar slants under parafine layer without subculturing for two years or in freeze-dried form with milk as a protecting agent with good viability level and saving initial acidifing activity and oct^- mutation that guarantee high purity of fermentation level. DMSO and its mixture with milk appeared to be not proper cryoprotectants for Yarrowia lipolytica A-101-1-31 strain liophilization.

Production of extracellular proteases and lipases by Yarrowia lipolytica A101 and W29 strains was substantially enhanced when the type of carbon and nitrogen source, the initial pH of culture medium were consecutively optimized. The best medium for biosynthesis of extracellular proteases and lipases was that containing natural oils and casein as sources of carbon and nitrogen, respectively. Higher concentration of glucose (5–10%) lowered the level of biosynthesis of lipases and proteases active on casein at pH 7.5, but resulted in higher activity of acid protease. The highest activity of proteases active on casein and lipases of the two strains was observed in cultures of initial pH 9.0, while pH 5.0 and 3.0 was optimal for biosynthesis of acid proteases of A-101 and W29 strain, respectively.

The aim of the work was to determine of killer phenotype of yeast strains C. famata, C. sphaerica, C. kefyr i C.lipolytica chosen as potential starter cultures for cheesmaking and the evaluation of interactions between them and other yeast isolates from cheeses. Starter cultures appeared neutral phenotype against K1 and K2 killer toxins produced by S. cerevisiae. No negative relationships between C. famata, C. sphaerica, C. kefyr isolates were observed. Strains of C. famata, C. sphaerica produced killer toxins active against C. lipolytica cultures.