The problem of introduction genetically modified organisms – GMO into biotope and market in Poland, European community and in the other countries of the world was discussed. Then the advantages from the application of GMO in the production of foods and medicines were shown. The meaning of food’s marking for elimination consumer’s prejudices against this products was emphasized. The social consciousness state of the genetically modified organisms was evaluated and the official standpoint to the question of GMO of government in Poland was presented.

The aim of the study was to evaluate possibility of improving quality of low fat cheeses (content of fat was reduced to 30% in dry matter) by introduction of aroma preparation obtained with yeast Yarrowia lipolytica JII1c. The preparation was prepared by introduction of yeast culture to paracasein at concentration 10⁸ cfu·g^-1 and incubation at temp. 30°C for four days. Afterwards pasteurized and homogenous preparation was added to cheese milk at concentration of 3%. Following low fat cheeses of 1,5 and 3,3% NaCl were produced and ripened for 8 weeks. It was shown that application of degraded para-casein into cheeses caused increase of proteolytic and lipolytic changes. However they were more advanced in cheeses of lower salt content. But comparing to control cheeses produced without preparation the experimental cheeses contained higher amounts of low nitrogen compounds, free fatty acids and volatile aroma compounds. Their sensory parameters appeared also different in comparison to control.

The aim of the study was to evaluate the growth of potential heterologous proteins producers: Suc⁺ clones of Yarrowia lipolytica A-101. Growth of 26 transformants, parental strain (wild) and reference strain W29ura3-302 was studied. Transformants showed differences in the ability of growth on sucrose (biomass, lag time duration, beginning of stationary phase). Beside the type of transformation, no differences in yeasts growth were observed on glucose and fructose. Influence of pH (6,8) and peptone addition (0,01 and 1%) on XPR2 promoter induction was analyzed. Both inducers were effective, allowing yeasts growth on sucrose. Growth of two transformants: KLON1 and KLON10 on sucrose was abundant, even with minimal peptone dose (0,01%). Stabilization of pH at 6,8 in the first hours of yeasts growth had a positive effect on culture. Clones grew better with buffer in the medium with 30 % sucrose, a substrate concentration which has induced longer lag phase.